# Duncan's Dubious Device



## maxvtol (Nov 11, 2009)

Cool project.

As you've observed with roll centers, vehicle dynamics is more complex than simple kinematics (or static forces). I think with rear wheel torque and cg shift/torque, you should be able to plant more than 660 lbs of driving force to the rear wheels. Which would be good, because I think an equivalent WarP 11 motor with a Zilla will be able to put out more than 135 ft lbs of torque at the motor. 

Can't say the spreadsheet in my signature has much experience to draw on, but it's fun to play around with the numbers. Looks like you would have decent performance.


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## Woodsmith (Jun 5, 2008)

I think theoretical roll centres matter as it sets a 'ball park' for you to design and fine tune from. It also catches the plain silly designs early on.

Some aspects of the calcs causes problems like parallel wishbones having intersects at infinity and others having roll centres outside of the vehicle footprint during dynamic cornering.
So as a good starting point I would use them, from there on it has to be 'seat of the pants' for me.


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## TigerNut (Dec 18, 2009)

Roll centers theory can be used, among other things, to explain why swing axles are a Very Bad Idea. Also, the relative height of the roll centers between the front and rear axles can give you an idea of the expected understeer/oversteer characteristics that you might encounter. So don't throw those ideas in the waste bucket... since you're designing things from scratch you at least have the opportunity to ensure that the geometry you're designing moves things in the right way at the right time. As part of that, you should at least check that the theoretical roll centers and the roll couple are reasonably close in height, at the front and rear axles.

It's good you're working out all the numbers ahead of time... saves you from encountering a major roadblock in the middle of the build.


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## Duncan (Dec 8, 2008)

Hi Tiger
I totally disagree about roll centers - 
No use to man or beast

If you want to know what it will do you need
Position of center of mass
Roll stiffness of each end

What your suspension does to your tire on road angle

If you know these you can predict roughly what it will do

If you know your 'roll centers" and you don't know the other things then you can predict nothing!

Anyway mine is nice and simple as I am using struts all round!

Incidentally Subaru use their struts exactly as I would have predicted with a greater inwards incline (and hence angle recovery on roll) on the back.

I developed the suspension I used on my Lancia mini in the 80s - and I made a number of learning experiences (mistakes) in the process
The final car went very well indeed. 

Roll centers - Ba Humbug!


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## TigerNut (Dec 18, 2009)

Hi Duncan,
I don't think that anywhere in what I wrote, I suggested that roll center analysis gives you all you need to know about the suspension dynamics. What I intended to say is that, once you get your camber gains (front and rear) and caster angles (for the front) sorted, then running a quick check to see that the roll centers are in a reasonable place, throughout the suspension range of motion, is probably a good thing to do.

The nice thing about strut suspension is that if you take care of the camber gain, you almost automatically end up with the roll center in a reasonable range. It helps to make the lower control arms as long as possible, and if you can, make the inboard chassis pivots adjustable for height... that will also allow you to adjust anti-squat on the rear suspension, at least to the maximal extent allowed by the struts.

The books I found helpful for suspension analysis and design are Fred Puhn's "How to make your car handle", and anything written by Carroll Smith on the subject. His books "Engineer to Win" and "Tune to Win" are especially enlightening.


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## Duncan (Dec 8, 2008)

Hi Tiger
I like the books you mention, 
the Puhn book led to lots of rude remarks about door handles!

I also like the Alan Staniforth books although "High Speed Low Cost"has been out of print for decades.

I remember these books from when I used to play in the 80's

Is there anything more recent??

The car
I am cheating by using the Subaru sub-frames and control arms
This limits what I can change but makes things like rack location trivial

This will also help with certification


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## Duncan (Dec 8, 2008)

Hi
It is past time for me to update this thread.

I have completed the rear of the chassis,
I am using the right hand rear hub on the left hand side and vice versa,
On the Subaru the rear hubs are arranged with the strut in front of the wheel center line with a forward facing control arm and the handbrake cable going forwards
By reversing the hubs the strut moves back clear of the passenger area, the hand brake cable goes backwards where it can sweep round in a single curve to the transmission tunnel
The forwards arm on the Subaru would have to go under the seat area, 

A rearwards arm can be allowed for much easier

I did make a major mistake
I had intended to *lower* the motor into its location where the gearbox would normally go, 
This space is quite tight as the motor is eating space for the pedal box

I had brazed the top and bottom rails in place so that the motor would fit between the tunnel sides which are to be attached to the outside of my tubes.
This meant that the motor would not fit between the inside faces of the tubes!!
PANIC!!
Luckily I had plenty of height between the top and bottom tubes so I will have to install the motor by lowering it into the passengers foot-well and then moving it sideways into its home

A lot of the chassis is not yet triangulated this is because I intend brazing a floor-pan, front and rear bulkhead and battery boxes from steel sheet
(this removes the need for the diagonal bracing)
Several holes cannot have complete sheets but I intend to gusset them

I have made up the frame for the front battery box and the mountings for the rear of the front wishbones, the next stage is to make up the mounts for the front sub-frame and front strut tops

I must ration my time on this forum as it is slowing down my brazing!!


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## TigerNut (Dec 18, 2009)

Duncan said:


> I did make a major mistake
> I had intended to *lower* the motor into its location where the gearbox would normally go,
> This space is quite tight as the motor is eating space for the pedal box
> 
> ...


What about re-arranging or rebuilding the control arm so that it effectively becomes a Chapman strut, as used on Lotus rear suspensions and also the Datsun 240Z? 

When I built my tube frame race car, I ended up with a few ill-located tubes that required some irritating workarounds. In retrospect it would have been better to cut out the offending tubes and relocate them so that everything around them wasn't a compromise. What if you relocate the lower tubes for the motor tunnel so that you can jack the motor up into place from below? You could then attach the trans/motor tunnel sheetmetal to the inside of these tubes, and have very little impact on the footwell space.


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## Duncan (Dec 8, 2008)

Hi TigerNut

I decided that as I didn't have all of the drippy things in an IC engine I could have a complete flat floor pan
So I intend brazing a sheet of (22 gauge 0.7mm) steel under my chassis

This would make it difficult! to raise the motor up to fit it!!

I don't expect any problems in lowering it into the passengers foot-well and then moving it sideways into its home
It weights 102Kg but I will use a strap to take most of the weight when I am slipping it sideways

The rear suspension is what I would have called Chapman strut
It consists of a strut with a rubber mounting up high, two horizontal rods that stop the rear hub from steering and a forwards (or rearwards) arm to keep the hub in place

There is a lot of rubber involved at all of the joints - I suspect it would not move at all if each joint was perfectly constrained

The Subaru handled OK, I expect with less weight (and lower) I will be OK,
If it does feel squidgy there are lots of after-market plastic replacements for the rubber bushes


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## Duncan (Dec 8, 2008)

Update on my (small) progress 
Rear of chassis complete, 
I have swapped the RHS rear unit for the LHS so that the forward facing reaction rods face rearwards and do not go under my butt
The handbrake cables now come out facing rearwards which is good as they can sweep around to their mounts – facing forwards with me sitting so far back would have required an S curve

The front of the chassis was complete BUT I have sourced some different struts and springs so I am going to remove the front strut top mounts and associated tubing – two steps forward one back!

The motor now has its brushes advanced – four M10 x 1.5 holes drilled and tapped,
I stripped the rack to see how to convert to manual – know how to do it now but now I need another rack!

I’ve fought my way through the OpenRevolt thread and I’m getting a kit for Christmas
I am now thinking about 48 TS 60AH cells rather than 200AH cells
Much less money and much lighter – lose a lot of range but I’m not building a GT car!

I am using front wheel drive front hubs – but I don’t need the front driveshafts (and the CV joints get in the way) so I have cut the driveshafts down – hacksawed through four inches of steel! Twice! 
Good for the biceps! 

The front of the chassis is now complete – still need to braze in the steel panels for the floor bulkheads and battery boxes


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## Duncan (Dec 8, 2008)

Modified the steering column to tilt upwards to help for getting in and out 
(The Subaru column normally only tilts downwards a small amount)

Questions!
I have this reversing contactor pair – no numbers on it
I am not worried about using it in reverse – but what about the current through these terminals when I play at silly buggers in forwards (500Amps +) ??

I have this contactor – again no numbers on it – be OK for 150V and 500 Amps ??

Are these bits any use or should I try and find a museum


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## karlos (Jun 30, 2008)

Time for an update! 

Did you decide on a controller? The Solition Jr's are looking pretty good.


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## Woodsmith (Jun 5, 2008)

Duncan said:


> Hi
> I had brazed the top and bottom rails in place so that the motor would fit between the tunnel sides which are to be attached to the outside of my tubes.
> 
> I must ration my time on this forum as it is slowing down my brazing!!


Have you checked that brazing is an acceptable method of jointing an automotive frame in your country?

I know it wouldn't be acceptable in the UK for any structural part as the base metal isn't fused together and would only be relying on the strength of the brazing filler.
Even bicycle frames have a mecanical 'tube into a tight socket' connection before brazing. Yours looks like butt joints.

Just a thought.


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## Duncan (Dec 8, 2008)

Hi Woody

Just to be pedantic - true brazing involves a close fitting overlapped joint and the metal flows into the joint'
I am using bronze welding
End of pedantry back to calling it brazing

This is stronger that fusion welding as fusion welding always has a weak zone where the melt pool stops - often a small loss in section as well
Bronze welding was used on all of the famous racing cars when they were "space frames" Lotus, Maserati, Cooper.., - I believe it still is when maximum strength is required 
The reason it went out of general use is it's slow and expensive!!
Those rods are bloody expensive I should have spent the capital and bought a MIG!

The filler metal is stronger than mild steel and is used as a fillet so the joint is stronger than the structure

I used this years ago on replacement front wishbones for a Mallock - testing by Armco destroyed the wishbones but the brazed joints survived

Here in NZ I can use it for my structure - BUT I will have to get my roll bar welded as the sporting association specify the weaker process

Hi Karlos
I now have an OpenRevolt controller kit - it is a superb kit I hope that I can solder it up successfully 

I have a complete chassis and I am brazing in the floor pans and the bulkheads
I will do a proper update soon

My certifier has required me to do a full design and build "story" so this will be uploaded to this site when I get the famous round tuit.


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## Woodsmith (Jun 5, 2008)

Duncan said:


> Hi Woody
> The filler metal is stronger than mild steel and is used as a fillet so the joint is stronger than the structure
> 
> I used this years ago on replacement front wishbones for a Mallock - testing by Armco destroyed the wishbones but the brazed joints survived
> ...


OK, that sounds good.

Actually, I'm sure, now, that you may have said this before (I may have asked before). I recognise your explanation.

I hope it passes inspection.


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## alexcrouse (Mar 16, 2009)

Get a Soliton 1 or jr. Zilla's are hard to find, require LOTS of parts to do half of their features, require contactors, precharge....

Solitons have internal precharge, water cooling(optional!) and frankly, just seem to be a better controller from what i can see. Zilla's continuous current is 300 amps, Soliton is 1000amps. All day. Every day. None of that 10 second crap.

-my $0.02


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## Duncan (Dec 8, 2008)

Hi Alex

I have purchased an OpenRevolt controller kit - I would love a Soliton but I am a cheapskate - and building the controller should be fun in the winter


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## Duncan (Dec 8, 2008)

Hi Guys,

A quick update - making progress slowly two steps forwards - one back,

The floor and bulkheads have been brazed into the chassis, - starting a trial assembly!


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## Salty9 (Jul 13, 2009)

Duncan,

Thanks for the build thread. I had not seen the Locost before.

Chuck


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## JRP3 (Mar 7, 2008)

Duncan said:


> The floor and bulkheads have been brazed into the chassis


Shouldn't that read "bronzed"?  Any updates?


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## Duncan (Dec 8, 2008)

Hi Guys

Making slow progress - my certifier has told me to write it up as a story so I will publish a long update sometime

I have just bought the cells - currently stuck in customs at Auckland 

I have a "battery box" intended for a mess of TS cells - 580mm x 930mm
There is space for over 300 Headway 16Ah - and I'm fitting 88!

So what i intend is to space them well apart for cooling - I will also be able to fit a fan for extra cooling if I need it

What do you think - sensible idea?


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## karlos (Jun 30, 2008)

Duncan said:


> Hi Guys
> 
> Making slow progress - my certifier has told me to write it up as a story so I will publish a long update sometime
> 
> ...


Maybe you should space them so that later if you decide to double your cell number you can fit them between the others, so for now, a cell every second or third space?


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## JRP3 (Mar 7, 2008)

Has anyone reported temperature issues with the Headways? If not it seems like an unneeded hassle to spread them out, and you'll end up with longer interconnects.


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## Duncan (Dec 8, 2008)

I haven't updated for a long time,

I had expected to get to this point before Xmas but the roll cage caused problems,
The motorsport guys were busy updating their specs and I spent ages waiting for them
eventually I got somebody who new what was required and - a roll cage five months later!

Anyway - the rolling chassis is now on a trailer and I will be taking it to Dunedin on Saturday for its sign-off 
Then I will take it all to bits to paint it

Not all lost I made a fiberglass front - not sure about the aesthetics - I will just have to build it and see what it looks like


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## Caps18 (Jun 8, 2008)

That is looking good. But why did you put the steering wheel on the wrong side? 

How is the new left turns before right on a two lane road law going down there? I've driven in Australia and New Zealand, and it is amazing I didn't crash. I didn't get any instructions at the rental car place about that.


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## Duncan (Dec 8, 2008)

Caps18 said:


> That is looking good. But why did you put the steering wheel on the wrong side?
> 
> How is the new left turns before right on a two lane road law going down there? I've driven in Australia and New Zealand, and it is amazing I didn't crash. I didn't get any instructions at the rental car place about that.


Hi Caps

The new rule (same as the rest of the world) has gone down well,
haven't heard of any crashes 

I see a bit of hesitancy at intersections sometimes - not a bad thing!

The old New Zealand rule was logical but......


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## Duncan (Dec 8, 2008)

_Anyway - the rolling chassis is now on a trailer and I will be taking it to Dunedin on Saturday for its sign-off 
Then I will take it all to bits to paint it

_Back from the big city - largest city in the Southern Hemisphere!
(not a lot of people but you hit the city limit signs 40 minutes before the actual city)

*Passed certification *- next stage is the final check-up of a fully assembled car!

Now I have got to take it all apart and paint the bits!


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## Salty9 (Jul 13, 2009)

Duncan,

Looking good! In your original post you were concerned with component weight. How are you doing on weight management?

Chuck


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## Duncan (Dec 8, 2008)

Hi Salty

I am going to weigh all of the bits again when I strip down for painting,

I had decided that I could get down to 500Kg (from weighing the parts)

But I tried to weigh it one corner at a time (with bathroom scales) and I got 540Kg - with 100kg of bits still to fit

I will weigh all of the bits (bathroom scales) and go and use the local weighbridge and see what I get

650kg is half of the weight of the Subaru but 500Kg would be better


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## Duncan (Dec 8, 2008)

Hi Guys
I found this wonderful horn for my car

I will strip the paint and paint it another colour

It has adjustments on the contacts - when I got it it was silent, adjusting the contact up a bit produces a horrible noise (good) and a lot of sparking at the contacts

Does anybody know the correct way to adjust it?

I assume it is 12v as it has a resister in it

Any ideas, help?


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## MalcolmB (Jun 10, 2008)

I want one!
It looks as if it uses a simple electromagnet and points to make and break the circuit that drives the "speaker" coil. I made a similar device when I was at school to drive an induction coil and produce high-voltage sparks. If it's the same design you can change the vibration frequency by adjusting the pressure on the moving arm. It tends to be a bit hit and miss. They do spark a lot. You could try putting a capacitor from a distributor across the points to suppress the arcing – or just send it to me


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## DIYguy (Sep 18, 2008)

Duncan said:


> Hi Woody
> 
> Just to be pedantic - true brazing involves a close fitting overlapped joint and the metal flows into the joint'
> I am using bronze welding
> ...


Just to be clear.... brazing is not welding. Brazing is generally regarded as a higher temperature process than soldering, but not as high as welding as the filler is drawn in by capillary action and does not alloy (melt) with base metal. The term welding requires the melting of base metal. Bronze welding is a misnomer. There are many design and application specifics that can make brazing a good choice for many designs and often is favoured for thin materials. That said, the choice of filler alloy is obviously of prime importance when applying this process. The other very significant issue is joint design. Typically, an overlap of some kind is used to achieve joint strength due to area for bonding. Butt joints and "T" joints can be problematic depending on service requirements.

Don't get me wrong, as I am not saying your method/process won't work. . I just want to make a few points clear for readers. One cannot say that brazing is stronger than welding . . as a basic statement, this is incorrect. Of course there can be flaws/discontinuities in the application of any joining process.


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## Ziggythewiz (May 16, 2010)

Duncan said:


> Does anybody know the correct way to adjust it?
> 
> I assume it is 12v as it has a resister in it


Sounds similar to the function of a beetle horn. I don't have the manual on me but IIRC there's just an adjustment screw that set's the 'volume' and it should be set to the lowest reasonable value to keep the heat down.


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## TigerNut (Dec 18, 2009)

Duncan said:


> Hi Guys
> I found this wonderful horn for my car
> 
> I will strip the paint and paint it another colour
> ...


Not exactly the same, but the 'clear hooter' type horns used on Tigers and other Rootes products are adjusted by their current draw. They're of a similar basic electrical design with a resonator, coil, and contact points, although no resistor. On those horns the upper current limit is 5A and IIRC I adjusted mine for 3 or 4A - and that required ear protection.

Description:
http://www.tigersunited.com/resources/wsm/wsmN27.asp


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## Duncan (Dec 8, 2008)

DIYguy said:


> Just to be clear.... brazing is not welding. Brazing is generally regarded as a higher temperature process than soldering, but not as high as welding as the filler is drawn in by capillary action and does not alloy (melt) with base metal. The term welding requires the melting of base metal. Bronze welding is a misnomer. There are many design and application specifics that can make brazing a good choice for many designs and often is favoured for thin materials. That said, the choice of filler alloy is obviously of prime importance when applying this process. The other very significant issue is joint design. Typically, an overlap of some kind is used to achieve joint strength due to area for bonding. Butt joints and "T" joints can be problematic depending on service requirements.
> 
> Don't get me wrong, as I am not saying your method/process won't work. . I just want to make a few points clear for readers. One cannot say that brazing is stronger than welding . . as a basic statement, this is incorrect. Of course there can be flaws/discontinuities in the application of any joining process.



But I can - and I'll do it again!

*brazing (bronze welding) is stronger than welding (fusion welding) !

*And I can back it up

(1) For welding mild steel (as I am)
The filler rod is stronger than the mild steel 
You do not get a transition zone in the mild steel (at the edge of the melted area)
Therefore the bronze welded joint is stronger than a fusion welded joint if the fillet is the same size as the material

(2) For welding higher strength steels 
The filler rod is weaker than the steel so a bigger fillet is required,
the comments about the transition zone are even more important
Again a good bronze welded joint is stronger


If you fail a correctly designed and manufactured fusion weld it will fail at the edge of the melted zone - careful examination will almost always reveal a necking at this position

A bronze welded joint will normally fail at the parent metal - and I used to have a number of front wishbones demonstrating this
My friend went through so many that I made a good strong metal jig to make replacements - but he was a lot faster than me on the track

The reason bronze welding is no longer widely used is its slooooow and bloody expensive 
for my next project I will probably get a MIG/TIG - or possibly one of those newfangled plasma torches
Anybody have any experience with these?


Brazing - proper brazing is an entirely different process - look up bronze welding (that is the correct name) 

I believe the Americans have taken to calling it "Braze Welding" - but then they even drive on the wrong side of the road


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## Duncan (Dec 8, 2008)

MalcolmB said:


> I want one!
> It looks as if it uses a simple electromagnet and points to make and break the circuit that drives the "speaker" coil. I made a similar device when I was at school to drive an induction coil and produce high-voltage sparks. If it's the same design you can change the vibration frequency by adjusting the pressure on the moving arm. It tends to be a bit hit and miss. They do spark a lot. You could try putting a capacitor from a distributor across the points to suppress the arcing – or just send it to me



Hi MalcomB

I will have to search for an old distributor capacitor - 

The auto jumble I got this horn at had several similar units - I paid $5(NZ) about two pounds fifty

Do you want me to pick one up for you if I see one? -


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## TomA (Mar 26, 2009)

Duncan, I feel your pain. 

Bronze welding is a fine, lost art, and still the best technique available for building steel tube structures. Nobody wants to believe it anymore, and too many are willing to criticize without any investigation at all.

I was actually drummed off an ATV board by the local young TIG masters who had no idea what the process they call "some kind of brazing" really was or entailed. People just don't know, and are unwilling to learn, how the finest aircraft and racing cars of a certain era (many of which are still in service) were actually made. The only reason bronze welding isn't used today is its bloody tedious, and takes real skills and patience. But you know all that already... 

Keep the faith; stick to your guns, and continue to defend the master fabricators and techniques of a nearly forgotten age.


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## MalcolmB (Jun 10, 2008)

Duncan said:


> Do you want me to pick one up for you if I see one? -


Thanks for the kind offer! But I'm going to a couple of big auto jumbles myself this month, so I'll be keeping an eye out for something similar locally. I love the weird and wonderful stuff that shows up, especially at the steam rallies.


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## mizlplix (May 1, 2011)

In conventional welding where you use a like metal for the filler, you can be somewhat sloppy in your fit-up. 
It melts parent metal in with the filler to form a homogeneous mixture in the final weld.


In true brazing, your fit-up is critical to ultimate joint strength, they are usually perfect and almost air tight.
It does not melt the parent metal, but forms a molecular-level bond and the filler is 100% added material.

Brass/bronze will fail in a linear manner where as most other weld types fail in a more abrupt manner.
Like a cannon barrel of old. Bronze canons would split then they failed and cast iron cannons would fragment, killing more crews.


Brazing is rapidly becoming a lost art. 

It's chief advantage is it's ability to encapsulate the weldment where other types of welding just sticks things together.
(Yes, it is considered welding.)

Most bronze alloys are rated at 40,000-60,000psi, where as ferric fillers are 60,000-110,000 and more PSI tensile strength.



1950-1960's era British racing cars were fond of this method. Their usage was chiefly due to their easy field repair capability with brazing over anything else then available.

(sorry to run on like that, but my degree is in metallurgy and I dont get a chance to expound on it much.)

Miz


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## TomA (Mar 26, 2009)

This must be the old timers thread...

One more plug for bronze welding: its an excellent technique for the home builder. The tools are basic, consumables are reasonable, and the process is safer, with lower noxious gas output and much less hazardous UV light emission.

Better still, what makes the process so tedious is the requirement of perfect joint fit-ups, which is actually a really good set of skills to have, and costs only time. Combine that with the ability to just melt the joint and do it over if it doesn't come out perfectly, and you've got a very nice way to safely and economically fabricate in the garage.

Finally, since bronze welding doesn't change the base steel, you don't have to worry about post weld heat treatment, or embrittlement and cracking around your joints. If they look right, then they are right, and there aren't going to be any nasty metallurgical surprises down the road.


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## Duncan (Dec 8, 2008)

Chassis back from sandblasting and painting


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## Duncan (Dec 8, 2008)

Diff mounting bracket

Rear motor mounting bracket

Front motor mounting bracket - bar


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## Duncan (Dec 8, 2008)

Brake pedal box, pedal and top bit

Hand brake mounting parts

Brackets for the running boards

Rear suspension bits

Horn

Seat brackets

Interior panel parts


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## Duncan (Dec 8, 2008)

Hi Guys

Some small progress
Car is now back together, 
batteries top balanced and in place
Contactors, fuse, shunt - all wired in

Brakes all in and bled, throttle pedal in
Brake switches to operate brake lights and short out the TPS

Control switches in place (but not yet wired up)

Next report will be it is driving - or I have let the magic smoke out of something


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## piersdad (Aug 16, 2008)

lot easier to get a wof in 1976 my efforts then would get thrown out today but i had the help of one of the design team who worked on the famous mini morris. and we designed our conzept for humans not style or perceived shapes http://www.storydad.com/forum/index.php/topic,529.0.html the result was a car that deflected a incoming car/missile and slew the passengers away from the crash area looks like you are using the established lotus kit car design


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## Duncan (Dec 8, 2008)

It goes!!!

I just highly illegally drove it down the hill and along Ruia Street

Everything worked except the pre-charge (the bulb had blown)

Now I had better bolt some bodywork on - bolting the seats down might be a good idea as well


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## MalcolmB (Jun 10, 2008)

Congratulations Duncan. What battery pack are you using? I know you've mentioned a small headway pack in the past, just curious how you've set it up.

By the way, I spent a few days up in the Cairngorms and over in Mallaig last week. It was absolutely beautiful up there with clear blue skies and the first snow on the hills. Not trying to make you homesick, I'm sure New Zealand is just as spectacular.


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## mizlplix (May 1, 2011)

GRATS! Duncan..

This is the really fun part.

miz


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## piersdad (Aug 16, 2008)

know the feeling did a bert munro years ago in my electric sports car when i tried it out for the first time . just about to try it out at full speed when some motor bikes passed me and so gave it the gun and passed them easily the story here http://www.storydad.com/forum/index.php/topic,235.msg1147.html#msg1147 btw duncan you are member of my site now sent you an email.


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## Duncan (Dec 8, 2008)

Another update

When I first got it working there was a pop and smoke came out of the controller
I thought that's it buggered - but it seemed to work fine - I decided I had incinerated a spider


Anyway while making and fitting the body panels I did some more checking,

low resistance motor bus-bar - heat sink - not good

Stripped it down, I have blown up one of the MOSFETS 

ordered a new one - lets see what happens


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## Duncan (Dec 8, 2008)

Hi Guys

Replaced the MOSFET that had blown - and its neighbor that had a crack in it - possibly something to do with the pop

I think I found an issue in that the resister controlling the MOSFET that blew may not have been properly soldered in 

It was more difficult than I expected to work on the board - when I took the resisters off the solder filled the holes - much more difficult than assembling a new board

Ended up with Mega-ohms resistance from the High voltage bits to the heat sink - took the car for a brief drive (sat in the passengers seat while the wife drove)
Still no bodywork!
fairly leaps up our hill with 170 amps!
Great fun!


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## JRP3 (Mar 7, 2008)

If you don't have one a solder wick is helpful to remove excess solder from the board.


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## Joey (Oct 12, 2007)

JRP3 said:


> If you don't have one a solder wick is helpful to remove excess solder from the board.


Solder wick can help a lot. I also like to use a vacuum solder removal tool like this:
http://www.radioshack.com/product/index.jsp?productId=2062742
or this:
http://www.radioshack.com/product/index.jsp?productId=2062745


----------



## Duncan (Dec 8, 2008)

Thanks for the advice - I have a solder sucker but I had forgotten about the solder wick

I will try that next time (hopefully not soon)

Anyway as a mechanical guy I need some further advice

I am making a ''Bad Boy" charger 

It occurred to me that if I fitted diodes next to the battery pack the charging wires could only flow current into the battery and not out - this seems safer

Question - is this sensible?

Question - these diodes are rated at 15 amps - can I use two - would that allow 30 amps?

http://newzealand.rs-online.com/web...2267573743D35343420393536372677633D4E4F4E4526


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## piersdad (Aug 16, 2008)

i used 2 diodes but on the same heat sink so that if one gets greedy it reduces it flow and shares the current with the other at least that was what happened to my 2/30 amp rectifier set


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## Duncan (Dec 8, 2008)

Today's update

Controller repair seems OK 
Took car for Pre WOF (warrant of fitness) - passed OK
Have been given a VIN Number - plate now riveted to the chassis

Took the car up to Dunedin for its certification inspection - Left it there need to go back for it - probably Friday


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## Duncan (Dec 8, 2008)

Update
Just been up to Dunedin to collect my car - illness caused a weeks delay

Passed certification
Just need to;
Label the switches
Fit head restraints
Take it to a tire place and get a wheel alignment done


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## piersdad (Aug 16, 2008)

cool love to be there and see it working


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## karlos (Jun 30, 2008)

A big congratulations Duncan and a great story piersdad!


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## Duncan (Dec 8, 2008)

Hi Piersdad,

After I get it on the road I intend doing some motorsport - sprints/hillclimbs so I will be trailering it about
Might make it up to Christchurch some day - If I do we may be able to meet up

Or any time you are down here in the deep south???


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## piersdad (Aug 16, 2008)

that would be fantastic dont travel much as wife is disabled and needs me most of time so if you are up here could even offer you a bed


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## Duncan (Dec 8, 2008)

Car back from Dunedin

I needed 
- Headrests - Done
- Label the switches - Done
- Wheel alignment check - Done

Now I am just waiting for my Cert plate 

Now - What colour do I paint the front??


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## piersdad (Aug 16, 2008)

most electric vehicle owners have a permanent grinn so paint a EV grin on the front where the radiator would be with electrics you have any thing there very impressive job there


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## Duncan (Dec 8, 2008)

piersdad said:


> most electric vehicle owners have a permanent grinn so paint a EV grin on the front where the radiator would be with electrics you have any thing there very impressive job there


The wife says I should put a pair of big red lips there - like the Rocky Horror Show

I will wait and see what it looks like with a number plate

Charger
I have a basic bad boy charger,
110v transformer, capacitors, bridge rectifier, ammeter voltmeter

Now working on a switch to shut it off when it reaches target voltage,
I did have a switch but I seem to have let the magic smoke out of it


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## Duncan (Dec 8, 2008)

Hi Guys

Some pictures

Been on the road since Thursday - I drove it on Thursday with the plates in a bag on the passengers seat - not completely legally!

The black "Cert Plate" was what it was all about

I have been driving to work everyday since - and taking it around showing it off!

Range is a bit short - especially with a steep gravel road up to my place

Getting about 25Km on a charge ~ 1Ah/Km (144Wh) - unless I boot it -

I have nominally 32Ah - but the controller is set to limit me before I get too low

It can spin the back tires if I'm on my own and the tarmac is a bit iffy - need MORE current!


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## albo2 (Oct 4, 2011)

Congrads Duncan you're a true pioneer and piersdad I read through your story and couldn't believe what you accomplished, imagine how many electric cars would be on the road now if petrol prices remained high.


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## piersdad (Aug 16, 2008)

thanks albo2 at least i have 3 of my vehicles in museums and collections and my conzept with its deflection safety idea is still to come. the modern idea of crushing ability to reduce impact only makes the slightest hit write off a car -- ever watched a 200 km/h race car come out with the driver intact thats deflection safety---- love to see your car one day duncan


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## puddleglum (Oct 22, 2008)

Cool car Duncan. Wow, that was a huge undertaking. I have a couple of questions. When you advanced the brushes in your motor, did you move just the brush plate or the whole end cap? Did you end up using the 48 volt forklift contactors you talked about using early on? One more thing, would you say that the open revolt is something a novice could build or do you need a fair understanding of electronics?


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## Duncan (Dec 8, 2008)

Hi puddleglum

Advancing brushes
I moved the whole end cap, you will find it is located on a register - you just need to take it off and drill and tap some new holes in the main barrel

Contactors
I am using two contactors - one breaks pack positive, the other negative
in addition I am using the reversing contactor - all from a small forklift
I am also using the main plug and socket from the forklift on a cable as my "Oh Shit" Handle
(Pulling the old spade handle in the cab pulls apart the connector) 
These parts are all a bit weak for their function but they seem to be working OK - and they were the right price (free)

OpenRevolt
Talking as a complete novice - I did get it working but it did die on me
I am using a borrowed Soliton at the moment but I do intend rebuilding the OpenRevolt

It does not need any knowledge of electronics BUT it does require soldering - I learned a lot in building my one

The thing I did wrong (I think) is to leave a completed unboxed controller in a mucky workshop for a year - I had a failure on power up (blown MOSFET)- but the controller kept working,

I replaced the MOSFETS (one blown and it's neighbor) and it worked for a few weeks and then it blew comprehensively 

I think the initial failure was due to dirt or a spider, the second failure was due to the first failure

I really like the Soliton - But it is seven times the price! so I will definately rebuild the OpenRevolt - unless I win the lotto!


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## puddleglum (Oct 22, 2008)

Thanks Duncan, am I right in assuming the contactors are 48 volt too and came with the forklift motor? Free is always good if it works. I am planning on keeping the contactors as well, but I wasn't sure if I should use them for a high voltage system. Good to know they will work. Are you having any arcing in reverse with the motor advanced?
Have you tried cranking up the power on the Soliton, or are you too limited with your small battery pack?


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## Duncan (Dec 8, 2008)

Hi puddlegum

No the contactors came from a 24v forklift I bought and scrapped! 
I had hoped to use one of the motors but they were not suitable, while trying to sell some of the bits I found the place that had my motor 
I about broke even on the old forklift selling off the forks, batteries and scrap metal

Don't know about arcing in reverse but I don't gun it in reverse.

I have the Soliton set to 600 amps - with max battery at 500 amps and the voltage limits quite conservative,
I could set it higher but I would then feel very sorry for myself when I have to go back to the OpenRevolt


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## puddleglum (Oct 22, 2008)

Duncan said:


> Range is a bit short - especially with a steep gravel road up to my place
> 
> Getting about 25Km on a charge ~ 1Ah/Km (144Wh) - unless I boot it -
> 
> ...


Are these specs with the soliton and 600 amps or with the open revolt? Just trying to get a handle on what kind of performance /range I can expect as I was thinking of using the open revolt as well, Not sure I'm up to the challenge though.


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## Duncan (Dec 8, 2008)

Hi Guys
I have had to give the Soliton back - sob..

Thanks for the loan Owen!

Just got my OpenRevolt back working - 500amps is definitely NOT as good as 600amps
But it's still reasonably quick

I will have to watch the Amphour meter a bit closer now as I won't have the Soliton's power cut at lower voltages

Still it's nice to have MY controller back in place


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## Duncan (Dec 8, 2008)

Update,I have done just over 500Km

Got my controller working again 
I had a problem initially but that was due to the brake switch which I had arranged to short out the throttle pot
Unfortunately it was switching before I applied brakes, a quick adjustment and all was fine,

The Lee Hart Battery bridge worked perfectly and told me I had a problem!

I stripped out my battery pack and sure enough one of my 88 cells had effectively gone open circuit

The bridge worked really well - single green LED until I gave it some welly whereupon one of the red LEDs lit nicely 

I have decided this would be a good occasion for me to increase my pack size,
145v and 32Ah is a bit small
So I have ordered some more Headway 16Ah cells and I intend going from
2P 44S to 3P 44S

This will mean I will be hitting the cells a bit less, 
but as I am still hoping for the OpenSource guys to complete one of their 1000amp controllers.....


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## Duncan (Dec 8, 2008)

Back on the road again - 50% more batteries (and hopefully range)

Had to make a new battery box,
50% more cells and its actually a bit smaller than the old box

The funny labels identify the new cells


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## Duncan (Dec 8, 2008)

Hi guys
Long overdue time for a follow up

The Device is now painted – Kermit Green 
And has a tilt forwards front

The 44s 3p pack failed after my first autocross,
I blew three cells 

Headway have been very good and replaced a lot of cells and also gave me some more
However these cells (16Ah) are no longer being made and I have found some problems
(1) They are not 16Ah – some were as low as 12Ah
(2) They seem to just die sometimes

I believe that Headway is now making a new line of cells – I hope that they have learned and the new cells are better

Because my cell seem to be subject to sudden death and if paralleled up the death of one cell kills its brothers I have now split them into separate strings,
I now have four strings of 40 cells each with a Lee Hart Batt Bridge and an Alderson connector so that I can disconnect a string and keep driving

I have splashed out on new springs and I now have 100lb/in front and 125 lb/in rear

Now the big change
I have fitted a prototype Paul & Sabrina Controller 
This is an IGBT unit and is good for 1500amps – I have mine set for 1000amps at the moment (We need a mad scientist icon for things like this)


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## evmetro (Apr 9, 2012)

Looks great, and it looks like a whole lotta fun! nice work! I am always impressed with the origins of this EV.


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## Moltenmetal (Mar 20, 2014)

Excellent- enjoy it! I know I would...! Enjoyed your build snaps thoroughly.


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## Duncan (Dec 8, 2008)

The Device is on the trailer and we are booked into a hotel in Christchurch tomorrow night.

We haven't been back to Christchurch since the earthquake - not sure if I'm looking forwards to seeing it or not


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## Duncan (Dec 8, 2008)

I missed a bit out there!

I am going up to the Evolocity Event at Ruapuna Race Circuit,

There is a sprint and drag races - the circuit looks a bit fast for me but I will do my best

http://evolocity.co.nz/emotorsport/


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## piersdad (Aug 16, 2008)

you will find the central part of christchurch like a building site/sheep farm
and there is a warning sign in places(warning smooth road ahead) 
other wise the weather here on sunday is the odd shower and about 18c
so sorry cant do any thing better for the weather
my home ph is 039814888
i will have a name tag at the meet


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## evmetro (Apr 9, 2012)

Don't forget to take pics!


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## piersdad (Aug 16, 2008)

evolocity event in christchurch was a fantastic event


coming down the straight cant see the opposition












whew got it to right size


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## Duncan (Dec 8, 2008)

Just got back in
We did the event on Sunday and drove home today
I will have to look and see if Jane managed to take any usable pictures

Anyway the controller was great
But I have made a mistake!
I went down to 130v (40S) - BIG MISTAKE!
On the track it will only reach 100kph (59mph)
So I stonked out of the corners and then my tiger turned into a pussy cat and I poodled down the straights

Great fun but not fast

I did the sprints around the track and used up my charge so I missed the first drag races
When I turned up for the second series they put me next to a Ferrari! - lovely big red one
I complained but they laughed

This was the first time I had been on a proper side by side drag strip
The lights turned and I got away in front of it!
About 100 yards down the track it flew past me
But I was in front for the first bit!
He did a 14 seconds and 110mph
I did 18 seconds and 59mph - I think I had already stopped accelerating when he went past

When I came back for another go they put me next to the Tesla - Dam that thing was fast I just followed him all the way

Great fun - now I need to get my voltage back up,


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## tomofreno (Mar 3, 2009)

Duncan said:


> Just got back in
> We did the event on Sunday and drove home today
> I will have to look and see if Jane managed to take any usable pictures
> 
> ...


 Awww, you know how to calculate the rpm you will reach peak shaft power for a given peak torque, so why did you use 120V? Battery problems?


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## piersdad (Aug 16, 2008)

LOL duncan did a demo 1/4 mile in pukekohe 1974 changed my hybrid ( to get to the race) from vw motor to twin electric and found out the two motors were great for the first 20 meters but fought each other after 30 mph so just dribbled the rest of the 1/4 mile --- oh well 25 seconds still a record for me


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## Duncan (Dec 8, 2008)

tomofreno said:


> Awww, you know how to calculate the rpm you will reach peak shaft power for a given peak torque, so why did you use 120V? Battery problems?



Hi Tom
I don't know - that's the problem
It's simple to calculate torque/rpm and electrical power 

But calculating back EMF is more complex

My batteries should have been able to produce ~ 960amps (15C) at about 110v - 
105 Kw - 140hp!

But at 59mph I was only drawing 200 amps 
22Kw - 30Hp!

Because the back EMF was so high that even with the controller at 100% that was all the current that would flow

Now I know that at about 3500 motor rpm and 200 amps I must be producing a back EMF of about 100v!!!

It was not as obvious with the 500amp controller and 144v

I think I will do as you suggest and change to effectively 80S x 2P

I will need to sort out a charger and see what else I need to do first


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## Tesseract (Sep 27, 2008)

Duncan said:


> Hi Tom
> I don't know - that's the problem
> It's simple to calculate torque/rpm and electrical power
> 
> But calculating back EMF is more complex...


Back EMF is (roughly) proportional to current at any given RPM (or, conversely, roughly proportional to RPM at any given current).

I use the qualifier "roughly" because BEMF is actually proportional to the square of current well below saturation, transitioning over to a linear function above saturation. For example, the WarP-9 enters into saturation around 180-200A and requires about 50V for every 1000 RPM at 1000A. A similar 9" 36/48V forklift motor with stock (neutral) brush timing would likely require 75V per 1000 RPM at 1000A (but would also put out more torque per amp - them's the tradeoffs of advancing the brush timing).


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## tomofreno (Mar 3, 2009)

Tesseract said:


> Back EMF is (roughly) proportional to current at any given RPM (or, conversely, roughly proportional to RPM at any given current).
> 
> I use the qualifier "roughly" because BEMF is actually proportional to the square of current well below saturation, transitioning over to a linear function above saturation. For example, the WarP-9 enters into saturation around 180-200A and requires about 50V for every 1000 RPM at 1000A. A similar 9" 36/48V forklift motor with stock (neutral) brush timing would likely require 75V per 1000 RPM at 1000A (but would also put out more torque per amp - them's the tradeoffs of advancing the brush timing).


 Also increases roughly linearly with rpm I expect (dB/dt)? So can extrapolate to other rpm and currents fairly well? Looking at series DC motor torque-speed graphs it does seem first order dependence on current is a good approximation at other than low rpm - which isn't of concern here. But then that would predict a bit over 50V ~ 260/5 at 200A, 3500 rpm.


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## Duncan (Dec 8, 2008)

Hi Guys

50v/1000 rpm at 1000 amps
That would give 10v/1000rpm at 200 amps
and 35v at 3500rpm

What I observed was that foot down (requesting 1000amps) the car accelerated (really well) and then stopped accelerating

I did half of the 1/4 mile at a constant speed - about 3500rpm and 200 amps
200 amps is about right for my unaerodynamic device

So...
My "theory" is that I was getting enough back EMF to limit my current
About 100v of back EMF at 200 amps and 3500rpm

I have 8 degrees of advance and an 11 inch forklift motor (Hitachi) 

I should have more back EMF at a given rpm and current than a 9 inch motor - but is three times as much (35v to 100v) reasonable??

The controller has no speed input - just 12v power and throttle signal (0-5K pot)

I was not expecting this much back EMF - or am I doing something else wrong??


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## Tesseract (Sep 27, 2008)

tomofreno said:


> Also increases roughly linearly with rpm I expect (dB/dt)?
> ...
> So can extrapolate to other rpm and currents fairly well?


I addressed both of those questions in my initial reply... but because both you and Duncan missed it, I will summarize:

1. Back EMF is roughly proportional to current at a constant RPM, or to RPM at a constant current. 

2. The actual relationships between BEMF and current (or RPM) is square law below "saturation" of the field (roughly 200A for a WarP-9) and linear above saturation. There are also additive terms for the various resistive voltage drops in the motor as well.



Duncan said:


> 50v/1000 rpm at 1000 amps
> That would give 10v/1000rpm at 200 amps
> and 35v at 3500rpm...


Maybe, maybe not. First off, you are repeating the data for the WarP-9 which may not apply to your Hitachi motor. Furthermore, we don't know the value of current it takes to fully saturate your motor, and the linear relationship between BEMF and current and RPM only holds in saturation.


----------



## Duncan (Dec 8, 2008)

Hi Tess

The Hitachi is "rated" at 10Kw and 48v - about 200amps - I kind of assume that it will be saturated about there

What I really need to know is am I correct in my "theory" that I'm getting about 100v of back EMF at 200amps and 3500rpm
Is that reasonable??

Or is there something else going on?

I had initially assumed that the back EMF would be "similar" to the warp 9 - maybe 50% more

Which would have enabled me to spin to to 4000rpm - and then back off to avoid overspeed


----------



## Duncan (Dec 8, 2008)

Using the assumed 100v at 3500rpm and 200 amps
(and assuming linear)

I get
1000 amps to about 700rpm - 19Kph
800 amps to about 900rpm - 25Kph
600 amps to about 1100rpm - 30Kph
500 amps to about 1500rpm - 40Kph
400 amps to about 1900rpm - 50Kph
200 amps to about 3500rpm - 95Kph

And that is about how it felt - really fast off the line - then disappointing

So is that "reasonable" - or what am I missing


----------



## Tesseract (Sep 27, 2008)

Duncan said:


> The Hitachi is "rated" at 10Kw and 48v - about 200amps - I kind of assume that it will be saturated about there


Saturation is not sharply defined in a motor (or in any magnetic structure with an air gap) and so, e.g., the WarP-9 will begin to saturate at around 200A but won't be fully saturated until over 400A (NB - I did these tests 4+ years ago and the range is kind of squishy so the numbers maybe squishy as well).




Duncan said:


> What I really need to know is am I correct in my "theory" that I'm getting about 100v of back EMF at 200amps and 3500rpm
> Is that reasonable??


Where did you get this BEMF value? The proper way to determine BEMF is to calculate or measure the average voltage applied to the motor and then subtract out the fixed ohmic losses (which can be obtained by stalling the motor and measuring the voltage drop across it at a reasonably high current, say 20-50A; needless to say, don't take too long to make this measurement as it is hard on the brushes/commutator).

If you can't obtain the average voltage applied to the motor via the controller (ie - duty cycle * battery voltage) then note that an old fashioned analog meter will usually do an excellent job of directly reading the average value of PWM DC.


----------



## tomofreno (Mar 3, 2009)

I don't know if it is reasonable or not. I've always just used the published torque-speed curves for motors, which of course you don't have for yours. Perhaps you can find one for a 13" series DC motor and estimate based on that?



> I addressed both of those questions in my initial reply... but because both you and Duncan missed it, I will summarize:


Yeah, I missed your parenthetical comment about rpm Jeffrey, but not the one on current. My statement on that was just providing some verification of your comment.


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## Duncan (Dec 8, 2008)

Update on the Device

In the last year I have built a new house and moved into it - unfortunately my shed is still not finished

This lack of a shed has resulted in the Device spending the whole of last winter under a tarp 
I took the tarp off last week and discovered that it had leaked AND I had had a blocked drainage hole 
My battery boxes had two inches of water in them!
32 of my 160 cells are rusty and horrible!

I have stripped the battery boxes down but not yet tested any cells

On the other side I have purchased a Volt battery pack - should be here soon
So I intend doing a major rebuild on the Device

But first I need to get my damn shed built!


----------



## Duncan (Dec 8, 2008)

Update
Shed now built,
Volt battery has arrived and has been reconfigured to fit

I also took advantage of the fact that the Device is in bits to lower the rear a bit - not for performance just for aesthetics

Photographs soon


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## evmetro (Apr 9, 2012)

Duncan said:


> Update
> Shed now built,
> Volt battery has arrived and has been reconfigured to fit
> 
> ...


This is one of my favorite builds, so I am looking forward to the pics and updates.


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## MPaulHolmes (Feb 23, 2008)

I need to send you an updated .hex file. thingstodo on ecomodder is using a controller like yours, fighting against an AC controller for testing, and found that you can accidentally hit a little over 100% duty, which makes the controller shut down. It's just one line of code different, but still I should send it to you. I"ll email it now.


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## Duncan (Dec 8, 2008)

I haven't done much lately,
although I did get to drive a Tesla
Where did I get the notion that the S was "Mid Size" - it's big!
And really really lovely

Anyway here is a picture of the back of the device compared to what it used to look like
I didn't measure how much I cut off but the back is now more than 150mm lower and the rear panel now slopes a bit more

I've taken about 20mm off the bottom of the aluminium as well as over 130mm off the top 
I'm going to take 60mm off the seat frames to drop the seats a bit deeper into the car


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## miscrms (Sep 25, 2013)

Very cool! Would have loved to have done a LoCost if I had the time and/or fabrication skills. Someday


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## Duncan (Dec 8, 2008)

OK
Not a lot of progress but some,

I used the Chevy Volt battery clamps - removed from the base T thing

Welded together with a bit of fettling and a couple of pieces of square section tube under them
The bottom bracket clamping thing weighed 5Kg - not too bad

Then I made up the water feed system - the pipes are a bit long - 

I was worried about air in the system so I put it on end to ensure that the air came out

As you can see from the background I still have a building site rather than a garden


----------



## Moltenmetal (Mar 20, 2014)

I was a little concerned when I saw all that rigid pipe, but then I saw the flex hoses at the connection points and felt better about it. Looking good Duncan!


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## Yabert (Feb 7, 2010)

Haaa! The chevy Volt battery is so nice to play with. Good job.
Like my Smart, your Dubious Device will fly now with this battery. So much more power available compared to headway cells


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## galderdi (Nov 17, 2015)

Very nice mate. Its a work of art. What did your total weight end up being after the modifications? Let me know how you go with heat on the volt cells. So far I have never had any detectable heat at all on mine.

I was looking at some hill climb videos last night. Mostly at Mt Cotton. I was looking for the typical top speed of the faster cars. I was a little surprised to see its only around 100kmph. This is great news, because I am hoping with my recent progress my car should achieve that. So next year I will throw my hat in the hill climb ring. That will also mean I should be eligable for the interclub challenge.


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## Duncan (Dec 8, 2008)

OK making some progress

Made a new cooling block for my controller

Battery all plumbed together - bolted to it's bottom plate - on a sack barrow

Battery in it's new home
Took a fair bit of wiggling to get it in

Battery cover 

Controller mounted on a cradle just above the battery cover


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## Moltenmetal (Mar 20, 2014)

That battery looks like there's never been anything else installed there. It's a perfect fit, even if you did have some wiggling to do to get it in place.

What did you end up with as a charger?


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## Duncan (Dec 8, 2008)

Very very slow progress
I have bought one of those cheap second hand BRUSA chargers - now I have to re-program it
And work out how/where to fit it

The Volt module with the contactors - My one didn't seem to match any of the pin-outs I was given so I ended up removing the board with all of the electronics and just keeping the board with the three small contactors
After a bit of experimenting I was able to use the two big contactors (easy) and the three small ones to isolate the charging points and do the pre-charge

On the liquid cooling side I am flowing from the batteries to the controller and back with a thermocouple to monitor temperature
Once I know what it is doing I will know if I need to cool or heat

Now I just need to wire it all up and put the body back on


----------



## piotrsko (Dec 9, 2007)

Definitely want heat. The performance at 80 f is so much better. Cooling so far, not so much.


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## galderdi (Nov 17, 2015)

Nice work. It's an inspiration.


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## Duncan (Dec 8, 2008)

All back together! 
Highly illegal test drive and booked in for its "WOF" tomorrow morning

Haven't sorted out a charger - I'm currently on 316v (84 cells) - 3.76v per cell - about half charge
so I should have plenty to get it WOFed tomorrow 

I have a second hand BRUSA - this weekend I will be reprogramming it and sorting out how to use it

Pictures after the WOF


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## Moltenmetal (Mar 20, 2014)

Congrats Duncan-

I thought you had a clever charger solution worked out, other than the Brusa?


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## Duncan (Dec 8, 2008)

I seem to have misplaced high beam somewhere between home and the WOF station - so it failed and I'll have to go back

More problematic I may have welded together the two Chevy contactors
On the way home driving at 50kph I gave it full welly
Both back tires spun and I nearly crashed!
(controller is set to 1200amps)

But now the main contactors remain active even without the 12v supply
Didn't see the current - may have been a little high


----------



## galderdi (Nov 17, 2015)

Nice work Duncan. So glad you held it on the road. I am about to upgrade my contactor too. I will now be running dual 500 amp units.

Can you charge the pack in parts? For the past 6 months I have been charging mine 6 cells at a time using a hobby charger. It is slow but it works. But hopefully I am weeks aways from completing the controller / BMS upgrade which should allow me to use my big charger.

Keep up the great work.


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## Duncan (Dec 8, 2008)

Update

The two Chevy contactors did not like my full welly test,

I took them off and managed to rattle them a bit so now they are working but that's no good for actual driving

Shame the Chevy front bit made it all look very neat

The controller was a bit too big for my old NACA duct - so there is a big hole in the top bonnet
I'm thinking about making the top panel out of a bit of Lexane


----------



## piotrsko (Dec 9, 2007)

If you read this specs, they fail open at like 600 amps in a disengage mode, so, yes they are toast. Another Chevy bit of overengineering.

Definately not a fullblown welly item, more of a sanity check.


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## PStechPaul (May 1, 2012)

The hole in the bonnet (hood) looks like the perfect place for a "hood scoop", which could function to provide air cooling to the controller. There might need to be some provision for driving in rain and snow, or through swarms of insects, but from the pictures of the vehicle it appears that such conditions would also make it uncomfortable for the driver as well!


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## Duncan (Dec 8, 2008)

piotrsko said:


> If you read this specs, they fail open at like 600 amps in a disengage mode, so, yes they are toast. Another Chevy bit of overengineering.
> 
> Definately not a fullblown welly item, more of a sanity check.


Hi Piotrsko

I was driving at 50kph and the devil took hold and made me put my foot down, - the back tires spun and the car fishtailed - felt like it accelerated really well
I immediately backed right off to zero and waited until I reached a legal speed again
No sign of any problems then - drove it home

When I got home I switched off
First the negative contactor then the positive contactor

To my horror I still had 307 volts on my CA - which stayed there! 
I opened the bonnet and removed the Chevy service disconnect
I ended up using a wire to discharge the controller capacitor

Testing the contactors they were both closed - even with the wires off
A bit of shaking and they are both now working

They didn't "fail open" - unless they did as or after I took my foot off and they immediately closed again
Which would explain why they welded themselves closed

Where did you find the - "open at 600amps" spec? - and how would they do that?
I was just energizing them from my 12v battery - not using any of the Chevy electronics


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## piotrsko (Dec 9, 2007)

Google the panisonic number on the relay. 

The spec said they would guaranteed open 1 time at 400 amps then fail. THE data charts looked like it would still open at 600 amps, I thought they would fail open like a fuse.


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## electro wrks (Mar 5, 2012)

piotrsko said:


> Google the panisonic number on the relay.
> 
> The spec said they would guaranteed open 1 time at 400 amps then fail. THE data charts looked like it would still open at 600 amps, I thought they would fail open like a fuse.


As I recall, the typical failure mode is to weld themselves closed like Duncan's.


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## PStechPaul (May 1, 2012)

Contactors generally can withstand a high current surge without welding the contacts. But if they open while drawing current, especially with an inductive load, they will arc and cause pitting on the mating surfaces. Repeated operations cause a buildup of material on one pole and pitting on the other. The gradual degradation of the contact surfaces eventually creates a higher resistance, which can cause melting and welding at high currents.

The springs on the armature do not supply nearly as much force for opening as the solenoid does for closing. So the usual failure mode is stuck closed. It should be possible to design a contactor with solenoids for both opening and closing. Also it may help to reverse the line and load sides of the contactor periodically to counteract the migration of contact material from one surface to the other. But eventually the contacts will need to be serviced or replaced.


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## Duncan (Dec 8, 2008)

Hi Guys
Just got it back together - passed the WOF - paid the rego - now I'm road legal back on the road!

I had it weighed - with me (about 100Kg) in it - 430Kg front - 480Kg rear - 910Kg total


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## galderdi (Nov 17, 2015)

Nice work. I wish you were closer by so I could take a look in person.


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## galderdi (Nov 17, 2015)

By the way, I made all my panels (aside from the floor and firewall) from PolyCarbonate (Lexane). It is only 0.4mm thick and is really tough from an impact point of view. But not so tough in a tearing/ripping point of view. But it sounds perfect for the panel you were talking about. I get mine from bunnings in 5m rolls, quite cheap.


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## Duncan (Dec 8, 2008)

Some small progress,

I've stolen the wheels from my Subaru - it was really harsh with the 45 series tyres
It's now on higher profile tyres and these will do fine for the device

I've got a nice little rear cover - and I've put some Chevrolet Power stickers on

And the soil piles have been leveled - next up some grass

Also the local paper sent a reporter around and did a nice wee report on the car


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## akseminole (Jan 5, 2014)

Hello Duncan, I like your dubious device,visually it sort of reminds me of a chariot. 

I have a question about the Chevy power cables that bolt to the front plate with the contactors and water in/out ports. Do you know what gauge those cables are? (The inverter battery cables, I think?)

I have been considering using Volt batteries and accessories in my build, so am wondering what power they are capable of (the cables, I am well aware of what the DOE thinks the Volt batteries can do). I believe the Panasonic contactors are only rated to 150 or 250 amps continuos? 

I like the way that the connector holds the two cables together, plus it looks professional with the Orange cable etc. 

I had been thinking about doubling up the Panasonic contactors with a bus bar jumper similar to how I have seen EvWest do with a pair of smaller Smart Car contactors in order to increase their continuos rating. The only real reason to do so, would be so that I can use the (inverter battery cables). 

The picture for an example of what I am talking about, if I have been unclear.


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## Duncan (Dec 8, 2008)

Hi akseminole
I started off using the Volt contactors in the Chevy front unit thing along with the cables and those two connectors

Unfortunately something didn't like what I was doing - I think that the contactors froze shut - I certainly couldn't shut the voltage off

When I replaced the contactors with heavy duty ones (I kept one of the Chevy ones for the pre-charge) I ended up having to make a new contactor box and I didn't use the connectors and cable
They were not quite long enough for my new configuration

The cables are very neat - 35 mm sq conductor (or thereabouts) with a shielding layer


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## nucleus (May 18, 2012)

*Snap Jacks Keep Relays from Welding*

http://www.periheliondesign.com/suppressors/SnapJack.pdf


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## Duncan (Dec 8, 2008)

I have now been at two Autocross's - I ignored grass events before because I thought that they would be too "rough"
I was totally completely wrong!
The two I have tried were much more gentle than tarmac events - when the tires bite on tarmac it is much rougher than on grass

On the second one I did manage to get my camera to work so I have some video

The first two minutes are waiting for the go - I must find out how to edit that out

An earlier run - 50% throttle - this one starts at about 1 minute

https://www.youtube.com/watch?v=7lQFAjqQUD0&t=48s

https://www.youtube.com/watch?v=o7wpdyGSAk4

I have replaced the links - seems to work now


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## akseminole (Jan 5, 2014)

It may just be my phone, but I cannot access the videos that you posted.


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## Duncan (Dec 8, 2008)

akseminole said:


> It may just be my phone, but I cannot access the videos that you posted.


I think I have fixed it - dunno what went wrong


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## PStechPaul (May 1, 2012)

Looks like fun!  How fast were you going?


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## Duncan (Dec 8, 2008)

PStechPaul said:


> Looks like fun!  How fast were you going?


It was great fun!
Dunno how fast - the IC cars were all using second gear so 60kph??

I didn't have time to look at my CycleAnalyst - and I think that it wouldn't give sensible answers in that environment


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## galderdi (Nov 17, 2015)

That looks like my sort of event. Shame it was on the wrong side of the ditch....or did I see you cross the ditch? 

The launch wasn't as fast as I would expect, was it grip, power or a combination of the two that limited your launch....or was it just an illusion caused by the video (I know how that feels).

You should come over and drive mine in one of our local events.


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## Duncan (Dec 8, 2008)

Hi Galderdi

It was mostly lack of traction!

Just next to my steering wheel are my throttle limit switches, the first one drops me to about 45% - the other two each drop about 10%

https://www.youtube.com/watch?v=oLEt1sVCmMU&t=11s

This video doesn't start until about 2 minutes in - I decided to go on 80% - you can see the difference - after I took out the cone I switched back

I'm pretty sure that I didn't actually press the throttle all of the way down at any point at all on the course


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## galderdi (Nov 17, 2015)

You took out a cone!!!! Hasn't anyone told you smoking weed before or during a motorsport event isn't a good idea.

Although I see they removed all the sheep before you started, safety first right?


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## Duncan (Dec 8, 2008)

This apparently wasn't the paddock that they had prepared - it rained in the morning and they tested that paddock and found that the 2wd utes could not get up two of the hills so there was a very fast re-plan and we used a different paddock

Run (1) - 100 seconds - got completely out of shape - video (1) I think
Run (2) - 110 seconds (+5) - got out of shape and nearly stuck it in the weeds - thought I would have to wait for a tow at one point - then I took out a cone 
No video on that - still learning how to work it
Run (3) - 96 seconds - video (2) I think
Run (4) - 96 seconds (+5) - that was the run with full throttle and it stops part way

The quick guys were down at 83 seconds - didn't seem to matter what type of car!

Great fun - the car was capable of a much better time but the driver wasn't

And if you do come over and there is a event you are very welcome to have a drive


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## galderdi (Nov 17, 2015)

Ah damp grass. That explains why it was a handful if you strayed off the worn path.

It sounds/looks like you weren't far off the pace. A little more familiarity would make a massive difference.

There are a lot of factors in being competitive. I used to take great pleasure in beating expensive cars with my $400 Pulsar. It wasn't a super car (although it wasn't bad), I wasn't a super driver (although I hold my own) it was mostly competitive because I was willing to throw it around. I didn't have to hold back because of risk to the car.

It's my 25th wedding anniversary in Sept 2017. I should tell the wife: 

"Hey let's go to NZ to celebrate.......oh look, who's that over there, oh gosh it's Duncan with his EV, oh and wow there is an event happenning. What a cooincidence. Let's hang here for a while"


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## Duncan (Dec 8, 2008)

No probs! - probably even got a spare room


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## skeyes (Dec 3, 2016)

Looks like fun! I see those toggle switches you mentioned.


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## Duncan (Dec 8, 2008)

Some pictures from the Forbes Autocross back in December


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## Duncan (Dec 8, 2008)

Update
I made some "Brooklands Screens" for the device - they do seem to reduce the air flow 

What do you think of the looks?


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## Duncan (Dec 8, 2008)

I made myself a - Corner weight device

It lifts the wheel using about a 10:1 lever and a fishing scale - up to 40Kg

Seems to work quite well

Now to using it
The Device is almost perfectly symmetrical right to left and nearly so from to back

But when I get in there is 100Kg very close to the RHS rear - this means that the RHS rear tire has more weight than the LHS
So that tire spins when I throttle - 
I do have an LDS so the car still accelerates well 

What I have done is to move the spring pan on the RHS front wheel so that that wheel drops lower

Now when the car is empty it sits RHS high - and when I sit in it it is almost level

The rear wheels with "me" in the car have almost exactly the same load 
RHS is still about 15Kg heavy compared to the LHS

But now the front right is about 20Kg heavier than the LHS front

I will take it to the 1/8th mile drags like this - not sure about the Autocross

Comments?


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## BuildMore (Oct 28, 2016)

Duncan said:


> Update
> I made some "Brooklands Screens" for the device - they do seem to reduce the air flow
> 
> What do you think of the looks?


I think they look cool!...although, in the interest of full disclosure, I must admit one of my favorite cars of all time is Chitty Chitty Bang Bang...jus'saying, mate!


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## galderdi (Nov 17, 2015)

Duncan said:


> I made myself a - Corner weight device
> 
> It lifts the wheel using about a 10:1 lever and a fishing scale - up to 40Kg
> 
> ...


 Firstly congratulations on an excellent and simple solution to a common problem. The counter lever scales are brilliant. What are you charging for your IP?

I am not an expert in corner weights but what you have done certainly aligns with my understanding of the correct approach. I think you would be fine to run it like that at autocross.


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## Duncan (Dec 8, 2008)

Hi Guys
We had our annual 1/8th mile Drags on Sunday
A lovely HOT day - maybe nearly 30C - we were sweltering

The Device was fine
First run the guy at the light tower joked about me needing to warm the tires NOT
Then I lit up both rear tires and nearly took the sensor out!
Gave me one hell of a fright! - and apparently surprised a lot of people

Don't know my time as Southern Dragways was having some difficulty with their kit

Second Run - took it a bit easier
Reaction - 0.935
60ft - 2.658
1/8th mile - 9.242 at 83 mph
Something happened just before the end of the run - something went "Click" and I suddenly had no power - I coasted to the end - turned around on momentum and lined up in the row to return
When I shut everything down and restarted - it all worked fine

Third run
I gave it a bit more welly - it snaked out of line - backed off then more welly and it snaked again
Reaction - 1.213
60ft - 2.755
1/8th mile - 9.646 at 85 mph
No mysterious shutdowns this time

85mph is about 4700rpm - oops - I had intended to keep it under 4500rpm

Owen was there with his pick-up so they put both of the electric cars together - we have similar power but I have just over half the weight
But it was fun seeing Owen go faster than some of the IC cars

Great fun day!

Wonder how many revs I can use before it blows up?

One comment was about the way I spun the tires
Normally the tires spin when you drop the clutch
I'm direct drive - when I booted it it would take off THEN spin the rear tires
Couple of people commented that it was "spooky"


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## MPaulHolmes (Feb 23, 2008)

I can think of 2 possible reasons it shut down. 
1. Did you reprogram the controller awhile back with the bug fix? It had an issue where it could go over 100% duty, which resulted in the micro freezing up.
2. The PI loop might not be converging very well, so maybe it had a spurious current that tripped the hardware overcurrent. Right now I just have it permanently shut everything down if any of the 600amp IGBTs go over 600amp for > 3uS. I'm going to assemble one of the new boards, and will get the updated code working soon. work just keeps getting in the way. It's totally on my to-do list to get out of poverty, and stop working for the man. haha


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## Duncan (Dec 8, 2008)

Hi Paul
Your controller is superb - oodles of power!

One of the marshals near the end of the track was very impressed by the sound the car made
He said it sounded like a supercharger
Don't know if he was hearing the sound from the controller or the sound of my 1500rpm forklift motor doing 4700rpm

Would the controller shutting down have made a distinct "click" noise?

I was blaming one of my contactors for the shutdown - but the controller makes a lot more sense

The next time I do some work on the controller I will make sure that I have the latest software

It was going scarily good at the end of the 1/8th - it was almost as if the acceleration was increasing in the last few seconds


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## MPaulHolmes (Feb 23, 2008)

Hmm, if there was an overcurrent trip, it wouldn't open the contactor or cause a click, so I'd cross that one off the list. That leaves > 100% duty for an instant, which could happen if you still had the old code on it, and you were going really fast AND really torquey (I hereby declare that a word haha). That is my current theory..


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## Duncan (Dec 8, 2008)

Hi Paul
I'm using totally manual control of the contactors (switches) so the controller could not have switched one off
In fact I can't think of any reason why one would have switched! - I've been more worried about them welding shut

If I did exceed the 100% momentarily and the controller went from full power to OFF - would that make a noise?

When it happened I though I had blown the fuse -
I'm using the Chevy Volt fuse which is in the service disconnect - I decided that in the Volt it has to take 300 amps continuous and that therefore it would take 900 amps for a few seconds (probably)

I was surprised/amazed when everything started working again!

Next event is an Autocross with the longest straight only 100 meters - so I won't be able to get up to those sorts of speeds!

When I drive it on the road I have my 40% throttle switch - that's plenty fast enough!


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## MPaulHolmes (Feb 23, 2008)

Is your controller sounding like a white noise, like a hiss? Could it sound like a clicking noise if the hissing suddenly stopped? I'm grasping at straws right now. haha. I can't think of a reason the controller would make a clicking sound.


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## Duncan (Dec 8, 2008)

Hi Paul
The instrument that detected the "click" was me while wearing a full face helmet and frightening myself
Not what I would call a totally reliable instrument! 

The controller is quite noisy - in an electric car absolutely silent next to the dino burners - so when it stopped making a noise it could have been that I heard it as a click

I'm planning on leaving it alone and enjoying driving the car - I may do some investigation when winter comes


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## Duncan (Dec 8, 2008)

Video from the Drag Meeting 

https://www.youtube.com/watch?v=LUpyAY2sFWw

The first "twitch" is easily visible but the second "twitch" when I re-applied the power is also visible


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## MPaulHolmes (Feb 23, 2008)

Wow!! that was so cool! Thank you for posting. What is the max motor amps set to?


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## Duncan (Dec 8, 2008)

Hi Paul
I downloaded your software for 1200amps

no idea about actual currents -
I was too busy to look at my Cycle Analyst - and it seems to get all out of sorts when I use a lot of current and needs a couple of minutes to settle down and give sensible readings


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## Duncan (Dec 8, 2008)

Autocross at Teretonga Park today

Did a dual drive with Willy Williamson
I must have done a crap job telling him how to work the video because the only ones we caught were the ones I set going - of Willy driving!

https://www.youtube.com/watch?v=1osxw8Tq-a8&feature=youtu.be

https://www.youtube.com/watch?v=gD6mII53taw&feature=youtu.be

https://www.youtube.com/watch?v=FznBsw1yQPA&feature=youtu.be

First run spin - controller shut down - they towed it back to the paddock - when I shutdown and re-started all OK

Lots of spins - with the LSD when you break traction both tires go and you go sideways!

My first run was 75.57 seconds
Willy - spun DNC
My second run I got brain fade and missed part of the course
Willy - 80.72 - big spin on final straight
My third run was 72.28 
Willy - 73.35

I was 32nd overall (out of 42)

Great fun - enough power to spin off at any time - it was cold and overcast but dry


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## MPaulHolmes (Feb 23, 2008)

Avoiding the shutdown is an easy fix. Let me know if it becomes an extremely annoying issue.


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## Duncan (Dec 8, 2008)

Last Grass Autocross of the season

https://www.youtube.com/watch?v=FXhA9gVPW94

I got the camera wrong (again) only one run filmed - I think I will move the camera so that I can see it from my seat

Great event!

I actually did quite well on the grass

130 seconds (spin) - video
117 seconds
111 seconds
106 seconds - that put me in-between the two Miatas that were running

I was running with all three power switches in the "low" mode - so 43% power - 
On my final (fastest) run the "pedal hit the metal" for a couple of seconds on the fastest straight
(which is where I spun out on the first run)

Great fun!


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## Duncan (Dec 8, 2008)

Hi Guys
I have been driving with the Volt battery for about 5 months - including some driving on the track
I don't have a BMS - but I do have a Batt Bridge - everything looks OK

So time for my manual battery check
I drove until I got the battery down to my minimum voltage -295v 
Then started disassembling 
( I have to take a few bits out of the way to get to all my cells)
Friday Voltage - 295v (measured by CA)
Saturday - voltage had gone up to 296.9v (measured by CA)

Voltmeter on both sides of pack - both 149.7v (added together 299.4v)

Using my Celllog 8M I checked all of the cells 
max - 3.548v
min - 3.536v
range 12mv
Looking good!

So I charged it
341.6v on the CA
Voltmeter on both sides of pack - both 172.1v - 172.2v (added together 344.3v)

Using my Celllog 8M I checked all of the cells 
max - 4.078v
min - 4.064v
range 14mv

So all looking good!


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## piotrsko (Dec 9, 2007)

I have found that they don't go out of balance until you get crazy with battery current on discharge. In my case 600 amps. Then the most positive set go wonkers. Might have to do with cell count in modules, more cell connection, higher mismatch. The 120v module gets the worst, the 98 v modules stay balanced.


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## Dave Koller (Nov 15, 2008)

Kool! Thought I would lurk here - I see my stuff is still on here for my Saturn...


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## Duncan (Dec 8, 2008)

It's been cold and wet here - but we are past the shortest day so soon the weather will improve

I have fitted a tonneau cover - I can take the drivers side off and leave the passengers side on

It's a lot "bigger" than I expected but just the passengers side seems to help the aerodynamics 

Also I modified and improved my "Brooklands Screens" - I took about 20mm off the top and tidied up the threaded rod


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## poprock (Apr 29, 2010)

Hi Duncan. Long time no post because of frustration with my wandering IP address locking me out. Re your weight balance device ; IIRC London double- decker buses had a sliding counterbalance weight to prevent them falling over. ?? Anyone remember this?


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## poprock (Apr 29, 2010)

Perhaps it was an episode of Top Gear?


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## poprock (Apr 29, 2010)

Not wanting to be presumptuous but would removing the passengers Brooklands shield and head rest improve airflow?


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## Duncan (Dec 8, 2008)

Yes - but the screen is not that easy to remove (my bad) - but it is easy to lay flat!

Removing the headrest is easy - I had not thought of that - could well be worth doing at any high speed events - or if I need to drive far


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## Rdstrblk (Jul 13, 2017)

Duncan said:


> It goes!!!
> 
> I just highly illegally drove it down the hill and along Ruia Street
> 
> ...


Reading this build from start to finish and have gotten to this post. Belated congrats! I am a huge fan of the locost 7 and caterham design. 

Are you fabbing all of the structure or was some of it supplied? Maybe fabbing yourself based on a design. Excuse my ignorance, it seems as I have stumbled upon some magnificent information here.

Excited to keep reading! Thanks for such a detailed thread, but ya gotta get a better camera!


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## Duncan (Dec 8, 2008)

Hi
I made the structure up - it's quite simple!

_but ya gotta get a better camera!_

Camera was fine - it was a combination of the operator and the much smaller size of images that the site allowed back then - five years ago


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## Rdstrblk (Jul 13, 2017)

Wow that is very impressive. After reading thru this so far, I am very much considering changing base platforms. My little festiva would be fun, but a rwd or even awd platform would really be ideal.

How does one even begin to consider building their own frame? Good books to read? I'm starting school in a month for mechanical engineering and a project like this is exactly what I would like to be able to accomplish concurrently. I may just buy a kit car minus motor and electronics and convert to electric, I doubt I'll ever be able to design my own frame geometry. On a more optimistic outlook, i have already done this with bicycle frames so some of the design concepts I'm sure overlap.


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## Duncan (Dec 8, 2008)

Hi
The classic book is the "Locost" 
Build your own sports car for as little as £250 by Ron Champion (ISBN 1-85960-636-9).

https://en.wikipedia.org/wiki/Locost

I cheated 
- the rules here (NZ) mean that if you make your own wishbones then you need to do things like getting them crack tested
So I simply used the front and rear subframes off a production car - these locate most of the suspension stuff so all you need is a structure to go in between them (and sit in)

If I was doing it again I would look for the front suspension with double wishbones 
The Strut suspension from the Subaru works really well - but the body I made to go around the strut mountings is ugly 

As far as suspension geometry is concerned if you do go that far I recommend

https://www.amazon.com/Race-Rally-Car-Sourcebook-Competition/dp/1859608469


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## brian_ (Feb 7, 2017)

Duncan said:


> ...
> So I simply used the front and rear subframes off a production car - these locate most of the suspension stuff so all you need is a structure to go in between them (and sit in)
> 
> If I was doing it again I would look for the front suspension with double wishbones...


In the ancient history of British cars, this was the Triumph Spitfire. In this century, lightweight cars with double wishbone suspension are relatively uncommon, but the first two generations of Mazda Miata/MX-5 (the "NA" and "NB" platforms) are a popular choice. For instance, the Excocet is based on complete Miata subframes and suspensions (and complete drivetrain, but you don't need the engine). There is an interesting project in this forum which put Miata suspension under an NSU Prinz.


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## Rdstrblk (Jul 13, 2017)

Heh, coincidentally I also own a boosted '94 NA. Maybe one day it will be electric too!

If you could go back in time, would you have used the miata subframes Duncan?


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## Duncan (Dec 8, 2008)

Rdstrblk said:


> If you could go back in time, would you have used the miata subframes Duncan?


Maybe - 
I would have had a good look around at what I could find
So far just looking at images on the net the old triumph herald/spitfire front subframe looks best - but very very old now!

Dunno - I will have to have a good look
The Miata subframe would effectively raise my battery box - I wanted to have as low a C of G as was possible

Maybe I should have gone for a fabricated front subframe with my own wishbones and just paid to have them crack tested - 

Hell I'm in a Hot Rod Club - maybe I would have gone for a light weight front beam axle!


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## brian_ (Feb 7, 2017)

Duncan said:


> So far just looking at images on the net the old triumph herald/spitfire front subframe looks best - but very very old now!


I don't know about the Herald, but the Spitfire doesn't have any subframes - what you're seeing is a full frame (in a bizarre backbone design) with mounting points for the suspension (and engine mounts) as welded-in parts of it; a separate body rides on that frame

The antique Spitfire also features trunnion bearings instead of lower ball joints, because back when it was designed ball joints to carry the spring load were not affordable. Although called trunnion bearings, they are actually a coarse-threaded vertical nut and bolt plus a horizontal pin and bushing... and a bunch of seals. It's quite Rube Goldbergian. 

I had never heard of these things when we bought our Spitfire, so it was a interesting discovery. Following links to projects from this forum, I read about an interesting project in which the builder chose to use Spitfire parts... and by the time he replaced the parts which he found unsuitable for use, he had custom-machined spindles to use different bearings and hubs, custom-cast modified uprights to use lower ball joints different upper ball joints, aftermarket brakes... in other words, the Spitfire parts were of no value at all. To be fair, lots of people really do use actual Spitfire parts.


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## brian_ (Feb 7, 2017)

Duncan said:


> The Miata subframe would effectively raise my battery box - I wanted to have as low a C of G as was possible


Since front subframes are designed to fit the engine (and transmission if transverse), they can be a poor match to an entirely different powertrain; the crossmember which nicely nestles near an engine sump might really get in the way of a rectangular battery box.

Swapping larger engines into Miatas is somewhat popular, so more than one company offers a tubular steel bolt-in subframe, to use stock suspension bits with no fabrication, but allow more space for a different engine. One of them is available with no motor mounts, leaving a big clear space for a battery box. Yeah, it's a lot of parts to buy (Miata subframe with parts, aftermarket subframe) and you're still building your own frame (but a simple one without suspension mounting points).

One of the "interesting" features of vehicles using Miata subframes is that the shocks and springs - both front and rear - do not mount to the subframe, but to the body (in the stock vehicle). That means that the frame of a custom vehicle needs structural points for not just the subframes, but also for four spring/shock mounts. They're lower and further inboard than typical struts, but this is still no formula car setup.

I'm not trying to sell or discourage the idea of Miata bits - the commonly used but now old NA/NB or the more recent generations which are entirely different - but they are an option and provide some examples of the issues that car builders face.


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## brian_ (Feb 7, 2017)

Duncan said:


> So I simply used the front and rear subframes off a production car - these locate most of the suspension stuff so all you need is a structure to go in between them (and sit in)
> 
> If I was doing it again I would look for the front suspension with double wishbones
> The Strut suspension from the Subaru works really well - but the body I made to go around the strut mountings is ugly...


The Subaru BRZ / Toyota 86 / Scion FR-S came too late for Duncan's Dubious Device, but if repeating the project now, the BRZ could provide a set of running gear which are derived from the Impreza, but altered for a lower car and suited to a rear-drive (only) drivetrain. The front struts are lower and lean in more, there are no front axle shafts (no hacksawing required), and the final drive unit is the one from RWD Toyota products such as the Lexus IS, rather than the rear unit from an AWD Subaru.


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## knoef (Jul 11, 2017)

Hi Duncan,
I have just scored a hitachi 10kw 48v motor which I intend to mount in a Nissan Sunny, I am Chch based and am looking for a suitable controller. Do you have any advice for a newbie? what sort of voltage should I be working towards for runs around town and the occasional short stretch at 110 k/h?


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## Duncan (Dec 8, 2008)

Hi Knoef

Are you using the gearbox? - you may not need to with a light car like that

With 130v I topped out at 100kph - with 500 amps I was quite acceptably rapid in what is effectively top gear!

I like the Paul & Sabrina controller - it's 144v and 500 amps

What are you using for a battery?


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## knoef (Jul 11, 2017)

The Sunny has a transverse engine/gearbox going to two front wheels so it just seems easier to connect to the bell housing of the gearbox directly (with or without the clutch). I haven't sorted any batteries yet but want to go lithium iron phosphate with either 60 or 100Ah. I think these can be ordered through Ali express from China directly. Where did you source your Volt batteries?


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## Duncan (Dec 8, 2008)

Hi
I started off with batteries from China - nothing like as good as the Volt Pack and more expensive!

There is a local Hot Rod importer company that ships stuff over from the USA - my Volt pack cost $3,300 NZ all up - GST, transportation - the lot

They have also got a pack for a guy in Rolleston - dunno how he is doing 

I would strongly recommend getting a Volt (or Leaf) pack

With FWD then you are stuck with using the gearbox - that does give you more choice and you won't need a reversing contactor

How much space have you got? - you may need to apply some violence to the inner wing to make space for the motor


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## knoef (Jul 11, 2017)

Thanks Duncan, the motor should fit in the gap, it sort of depends on how far the shaft of the motor goes into the bell housing and whether I need to space out the adapter plate, I will be taking the old engine out in the next couple of weeks and will know more once I see the inside. Is the local hot rod guy Charlton in Gore by any chance? 
Did you assemble the controller yourself or buy it ready to plug in?


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## Duncan (Dec 8, 2008)

Charlton are the guys!
I bought my two post hoist off them as well

I assembled my first controller - learnt a great deal - and managed to blow it up!
Then I got another one (or at least new boards)(kept the rest of the hardware) - went really well until Paul (of Paul & Sabrina) offered me a beta version of his High Voltage High Current Controller
That's what I'm running now
340v and 1200 amps


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## knoef (Jul 11, 2017)

Is that controller still powering the 48v Hitachi? how much advance do you need for that?


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## Duncan (Dec 8, 2008)

Yep!
I gave it 8 degrees advance - which is about the most you want to give

As your DC motor spins you get back EMF - this is basically proportional to current and rpm
At 3500 rpm and 200 amps - I was getting about 110v Back EMF - and this current was what I needed to drive at that speed -100Kph

With 144v - I was able to reach 115Kph - 4000rpm

With 340 v - I can pull 1200 amps until my controller maxes out - then I am just on the battery

It feels as if it is still accelerating hard at about 135 Kph at the end of the 1/8th - 4700 rpm
It does not feel as if I have maxed the controller out - if anything it felt like it was really lifting it's skirts and flying then!

Am I being cruel to my motor?? I suppose I am - but it seems to be a tough old beast


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## Duncan (Dec 8, 2008)

Hi Knoef
I sent you a message - have you received it?


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## John Metric (Feb 26, 2009)

Remember to keep all four wheels on the ground.


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## John Metric (Feb 26, 2009)

Duncan what are you 1/8th mile times


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## brian_ (Feb 7, 2017)

John Metric said:


> Remember to keep all four wheels on the ground.




Many cars do lift one wheel in extreme cornering. It's not desirable, but may result from excessive roll stiffness bias toward the end which lifts, due to an attempt to manage other chassis problems. It may be the lesser of two evils.

On the other hand, it is the non-driven end which lifts a wheel in any reasonable vehicle: the rear in many front-wheel-drive cars (VW Rabbits/Golfs were known for this), and the front in some rear-wheel-drive cars (most commonly Porsche 911, but I've heard of it in BMWs and I'm sure it happens to a lot of cars). Lifting a wheel at the driven end (such as the rear of that Fiero) indicates a chassis setup problem... or at least that it's doing something for which it was not set up. 

Even if you have an aggressive limited-slip differential - so you don't spin a wheel out of control - lifting a driven wheel is generally still not good. On the other hand, with separate left and right drive motors or no differential, it can work - karts (with no differential) routinely depend on completely unweighting the inside rear wheel on corner entry to get them to turn.

And of course, sometimes one wheel comes up because of a bump (usually a curb), not indicating any problem.


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## Karter2 (Nov 17, 2011)

Karts depend on lifting th e inside rear wheel for critical handling.
As they have basicly no suspension they rely on chassis flex and front end geometry (king pin inclination) to jack weight off the inside rear when cornering. Kart chassis set up is much more complex than most folk think, with many more settings to adjust than most amature tracck race cars.
Many of the best chassis tuners learnt their craft setting up and racing karts.


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## Duncan (Dec 8, 2008)

Hi John
I am using the 8 year old tires that came with the wheels so I am a bit grip limited!

My last 1/8th I lost traction, lifted, then lost traction again - then it just went
I got 9.2 seconds and 87 mph

My cunning plan is to buy some nice sticky tires before next years drags 

I would like to sort out some form of traction control - when it goes it goes fast - but not sure when I will be able to do that


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## galderdi (Nov 17, 2015)

I think Arduino is your friend. They can be made to do almost anything and at a reasonable price. 

My initial thoughts are an input into the arduino from either:
a GPS module
a speedo (assuming the speedo isn't run off the driven wheels)
a G force meter

and another input from the tacho

Have the arduino do a mathmatical comparison of the two inputs. Set some limits (if x revs is between y and z kmph then thottle =100% otherwise throttle at 90%) 

I think it's doable


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## Duncan (Dec 8, 2008)

Hi Galderdi
That was my plan - I'm a complete novice at electronics but I have an arduino kit in the attic awaiting the traditional "round tuit" 

I was worried that some people have said that the arduino is no use in an EV because of the electromagnetic environment 

I was going to ask - arduino - or what??

But first I need to replace the ABS tone wheels That I used to have on each corner before an attack of stupidity made me remove them


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## galderdi (Nov 17, 2015)

I am a novice too but I have successfully programmed one to control my reversing contactor so my confidence is building.

My next task is to build a better timing system for our club. That is massive by comparison. But I plan to just take it one requirement at a time and then string them all together.

I would understand a recommendation not to place it within a couple of feet of the motor. But other than that I can't see why arduino electronics would be any different from all the other electronics we have in our EVs. Any any way, even if it were an issue, you could alway build a little faraday cage around it.

It is a good point though. I think I should program up some way to test the impacts. Any thoughts on a suitable test? 
Maybe have 2, one in the EV and one away from the EV both with the same timer program both triggered from the same switch so they are syncronised at the start. then drive around for a while. If they remain in sync then I would assume there hasn't been any significant disruption.


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## Duncan (Dec 8, 2008)

I have been "invited" to a burnout competition

I can put a switch in my brake/throttle isolater so that I can use the front brakes 

Do you have any idea what happens if I'm spinning my back tires? - what happens to the revs?

I'm worried that if I just keep the foot down I will over rev -

Any ideas?

My controller does not have a rev limiting feature


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## piotrsko (Dec 9, 2007)

My experiences from the dark ages of the '60s when everything was mechanical:

You get on it hard until they light, the onboard mark 2 visual monitoring system observes tach readout and causes the lower right throttle servo to back off a touch. Feedback loop increases throttle as tires warm up and get sticky and decreases throttle as rpms get near redline.

If the programmer did his job properly selecting proper gear, rpms dont go insane. Really shouldn't go above 3/4 throttle.


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## Duncan (Dec 8, 2008)

Hi Guys
I have been driving illegally for a while - my High Voltage sticker was on my NACA duct and when it went so did the sticker

New Stickers on the front and on the back!


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## Moltenmetal (Mar 20, 2014)

LOVE your stickers Duncan! So cool!

I have a sign hanging up on the inside of the hood for when I go to car shows (bonnet is always open at those, to draw the bewildered stares!) It contains this picture I stole from the internet, and says, "Warning- best to keep hands OFF the electric bits"









I didn't feel the need to add the other warning I read somewhere which I really liked: Warning: do not touch. Not only will this kill you, but it will hurt like hell the whole time you are dying"


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## JRP3 (Mar 7, 2008)

Not sure the best way to promote EV's to the general public it to make them appear more dangerous than they actually are. Assuming you build them with proper protection on high voltage parts.


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## Moltenmetal (Mar 20, 2014)

Given that some people at shows with cars that are polished like a mirror have signs that say "do not approach this car unless you are naked", mine is pretty tame...my voltage is pretty low at around 108V nominal, and everything in my car is "finger safe" or I wouldn't be opening the hood around strangers- but a warning inside the hood can't hurt. And Duncan's sign is entertaining!


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## Moltenmetal (Mar 20, 2014)

Besides- my sign is accurate- the worst that would likely happen to them is they'd get a cardboard lightning bolt stuck to their chest.


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## Duncan (Dec 8, 2008)

Hi Guys
I attended a neat EV event in Dunedin - they got 135 EV's all together for a photo event

I trailer the Device up there - 150 Km - bit beyond my range!


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## Duncan (Dec 8, 2008)

Autocross
Forbes Autocross
Two dry runs - without a camera and two wet runs with a camera

Great fun

https://www.youtube.com/watch?v=c3vOUHN3FeU&feature=youtu.be

https://www.youtube.com/watch?v=3khzV70XY2U&feature=youtu.be

I think these should work


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## galderdi (Nov 17, 2015)

Hey, Nice work there Duncan. I hope to have some vids from my new car shortly after Feb 11th.


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## Darxus (May 10, 2010)

I just finished reading through this thread, thank you very much for writing it up. I need to look into Volt battery packs.

I'd love to see you do something like a video tour of the details of the car.


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## Duncan (Dec 8, 2008)

Hi Everybody
Darxus - I will have another go at doing that soon - my last attempt was pathetic!

I have a problem - I have started to get an intermittent fault with my controller

I switch on and - nothing - I have the 12v low voltage feed and the high voltage is there but nothing
I switch it all of the way off - switch it back on and it's fine

Any ideas?


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## Duncan (Dec 8, 2008)

Hi Guys

Back on the road again

Paul Holmes told me what to do to update my controller hardware - a couple of resisters and a wire - no idea what they do!

So I took it all apart to do that - while it was all apart I did a battery check - all cells within 0.01v 

Car is back together and tested 

I have also been told my new tyres have arrived

A pair of 225/45/17 - NITTO 

I will pick them up next week for the back


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## Duncan (Dec 8, 2008)

Latest update

Did a "Bent Sprint" on saturday - Teretonga Park

This time the organisers had laid out a completely different type of track

It started out with the very short straights - chicanes and incredibly tight hairpin bends that I have been used to
Then it went out on a long straight with some sweeping high speed corners - some of the cars were going over 200 kph before the corners

I just don't have that sort of top end available!

The event
The new rear tyres are wonderful! - with the old ones the first thing I knew was they were both spinning and I was sideways off the track
The new super soft "Nitto's" not only had a huge amount more grip but they let go gradually so I was able to keep it on the track!

That was GREAT on the low speed part

On the high speed part I tried to keep below about 130 kph - but I started hitting the controller problem that I have seen a couple of times before 
The controller would simply shut down - and I would freewheel - while reaching down to switch it all of the way off - wait a bit - and switch it back on
Then I would have power again!
But on every run I had at least two shutdowns!
I took it progressively easier - but at the same time my battery was running down so it became worse!

Paul (Paul & Sabrina) is going to have look and see what is happening

I have downloaded them my Youtube thingy - 

https://www.youtube.com/channel/UC_5FQI_8-DZMjpslskj1oeA

Definitely the most fun track I have been on for years - despite the issues


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## LargoEV7 (Jan 8, 2018)

Duncan said:


> Definitely the most fun track I have been on for years - despite the issues


Great to see you out there getting into it.

I couldn't stand your steering ratio to be honest, way too much work, wanna cheap fix for that?


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## Duncan (Dec 8, 2008)

LargoEV7 said:


> Great to see you out there getting into it.
> 
> I couldn't stand your steering ratio to be honest, way too much work, wanna cheap fix for that?


I'm all ears!

I have a power steering rack - it's about 2.8 turns lock to lock and not too heavy without the power - Subaru

By the old manual rack standards that is actually a fast rack!

I'm basically Subaru all around - including wheelbase - but I do sit a long way further back - like driving my Subaru sitting in the back seat!

So - whats the fix?


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## brian_ (Feb 7, 2017)

Duncan said:


> I have a power steering rack - it's about 2.8 turns lock to lock and not too heavy without the power - Subaru


What is the current state of the hydraulics? Is it

bypassed (still filled)
just drained, or 
drained, seals removed, and greased for lubrication?

Depending on the state, it may be made easier to turn (less drag), or have hydraulic power restored, electrically assisted (in the column), or be completely replaced with either a slower manual rack or an electrically powered rack.


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## Duncan (Dec 8, 2008)

Hi Brian
I took a rack apart to see how it worked
It was grease lubricated with the hydraulics working two cylinders - to assist

I drained out the hydraulic fluid and cross connected the two cylinders - air and any residual oil can flow easily cylinder to cylinder

When the wheels are off the ground it feels about the same as any manual rack

When driving it is faster than the old manual racks we used to use - they were all 3 or 4 turns lock to lock - which means that it is heavier

But because I only have 405 Kg on both front wheels it's not too bad

I'm steering a LOT on that video because the corners of the low speed bit were incredibly sharp - two hairpins where we use the width of the track to do 180 degrees


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## brian_ (Feb 7, 2017)

Duncan said:


> ... It was grease lubricated with the hydraulics working two cylinders - to assist
> 
> I drained out the hydraulic fluid and cross connected the two cylinders - air and any residual oil can flow easily cylinder to cylinder
> 
> When the wheels are off the ground it feels about the same as any manual rack


Thanks Duncan. 

So it's both drained and bypassed, but the seals are still in it. Although it sounds like the seal drag isn't bad, you could help it a bit by removing the seals entirely; then the plumbing can be removed. This is commonly done on some racks, such as NA/NB Miata racks in various projects without a power steering pump.

Past that, to make a significant difference by restoring powered boost, the easiest fix is to put the fluid back in and hook it back up... but to an electric pump from a factory electro-hydraulic steering system. The other fix that doesn't mess with the rack itself is to swap the column for an electrically assisted column (rather than an electric rack) - lots of cars use that design now, but it's not a trivial installation. There are electrically-assisted column kits intended for motorsports which should work with any rack; I don't know if any Subaru (for maximum compatibility) powers the column instead of the rack. And of course you could swap it for an electric rack.

Any of the electric options could involve work with CAN communications, but the motorsport retrofit kits should avoid this, and there are specific pumps for which use off of a network has been worked out.


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## brian_ (Feb 7, 2017)

Duncan said:


> But because I only have 405 Kg on both front wheels it's not too bad


That's pretty similar to our stock Spitfire, which has a similar front axle load, rack-and-pinion steering, a fast ratio, and no power assist. I'm fine with it, but some drivers are surprised by the high effort, at least initially.


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## Duncan (Dec 8, 2008)

brian_ said:


> That's pretty similar to our stock Spitfire, which has a similar front axle load, rack-and-pinion steering, a fast ratio, and no power assist. I'm fine with it, but some drivers are surprised by the high effort, at least initially.


Hi Brian - whats the ratio on your Spitfire?

All modern cars are a LOT lighter on the controls! - Back in the late 80's I had a Lancia Spyder - lovely car but no power assist

I took a company Escort (mk3) away on business for a couple of days - when I got back in my Lancia none of the controls would move!

The steering was stuck - the clutch was frozen - even the throttle was heavy
It took me quite a while before I was sure that nothing had gone wrong - they were meant to be like that


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## brian_ (Feb 7, 2017)

Duncan said:


> Hi Brian - whats the ratio on your Spitfire?


I would have to dig the car out of storage to check, but it looks like there were two Spitfire racks, with 2.6 ("quick") and 3.5 (standard) turns lock-to-lock. Since the steering angle at the limit is impressively high (no CV joints to worry about), the steering is quicker than even those values would suggest, and with the short wheelbase the effect is dramatic. I will check, but I wouldn't be surprised if it is the quicker rack; on the other hand, we have 215/50R13 tires, which make the steering heavier than with the stock 155R13 tires.


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## LargoEV7 (Jan 8, 2018)

Duncan, in short you make up a simple reduction drive, overdriven in this case.You need a steering shaft end with the same spline as your current shaft so you don't have to change stuff there.

I use a piece of tube turned a little inside at each end to make an internal step to accept the appropriate bearings that take the cut down 2nd steering shaft with a flange welded or circlip'ed one end, and inner bearing spacer tube. 

The 2 sprockets are cheap industrial type welded on, as is the chain industrial. 

I then weld 2 5/8ths or 16mm (whatever) bolts to the tube. 

A simple plate with 2 holes to accept those 2 bolts with a nut either side of the plate to enable me to adjust the chain tension. Another shorter gusset plate to make triangulation, all welded on to the master column (be aware of nylon bushes).

I have done this 4 times to my own cars over the years and helped Mates and others to do it - never any trouble but it is your steering so over engineer it for your own sake.


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## brian_ (Feb 7, 2017)

LargoEV7 said:


> Duncan, in short you make up a simple reduction drive, overdriven in this case.


Yes, a mechanically slower mechanism is a way to reduce steering effort, but at the expense of having to spin the steering wheel even more.

The other route to slower steering is a different rack. Power steering has been standard equipment for a long time; the last unassisted rack I had was in a car built 25 years ago. The racks are still out there - it's just a matter of matching or adapting to length, rack travel, style/size of tie rod end, mounting points, and input shaft. For instance, that Spitfire rack is interchangeable with at least three ratios, up to 4.5 turns lock-to-lock; the slowest was used on six-cylinder models due to their high front axle load.


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## Duncan (Dec 8, 2008)

Hi Largo

Here that would NOT fly! - there is no way that I could get a chain drive steering system through certification!

I have seen chain drive systems use on off road machines but I have never seen one used on the road - yes I have - a steam traction engine!

When I'm driving I'm not conscious of having to steer excessively - even on the twisty bits - I've got a grass even this Saturday - I will think about when driving

If I do decide to do anything about it it will be by fitting another rack and pinion - Mine is off an old Subaru GT - I bet there are faster ones out there


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## Karter2 (Nov 17, 2011)

New Spitfire 2.5 turn rack..
https://www.ebay.com.au/i/161481355...%3D705-139619-5960-0%26rvr_id%3D1434624714234
But probably not much of a difference to your 2.8 turn.
You can also buy professional "steering quickeners". With 1.5:1 or even 2:1 ratios , to fit inline with your steering column.
https://www.ebay.com.au/i/323031856...%3D705-139619-5960-0%26rvr_id%3D1434495254285.
I dont know how you would go with legals though .


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## LargoEV7 (Jan 8, 2018)

brian_ said:


> Yes, a mechanically slower mechanism is a way to reduce steering effort, but at the expense of having to spin the steering wheel even more.


The point was to get closer to 2:1, not the other way.

Duncan, you could have 2 splines, one for legal road, and one for events. 

Anyway, was just a cheap fix.


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## Duncan (Dec 8, 2008)

Another Autocross

Great fun! 
https://www.youtube.com/channel/UC_5FQI_8-DZMjpslskj1oeA

Paul has sent me the updated software - but I haven't updated my controller yet - I intend doing that in the next few weeks before our annual 1/8th mile drag races


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## Duncan (Dec 8, 2008)

Hi Guys
I now have the new software in my controller - I don't know when the next event that hammers it enough for me to check that it's working but it seems to work fine so far

Annual Cobra 1/8th mile Drags on Sunday the 4th March - see if I can beat some more of the supercharged V8's

I have gone slightly backwards in one way - the laptop power supply that I have been using as a DC-DC to keep my 12v battery topped up has died 
So I have gone back to simply charging the 12v battery at the same time as the main pack
It's made of eight "16Ah" Headway cells - so that should be plenty of capacity


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## Duncan (Dec 8, 2008)

First update from the Drags

Not good!
The new tyres still spun on take off - so I should have done a warm-up spin

More of a problem at the end of my FIRST run there was a bang - and while I had power if I used more than a tiny bit of throttle there was a horrible noise
One of the guys said that sparks flew out from under my car

It did 8.69 seconds at 83 mph - not a bad time!

I limped home (not very far) and it died completely on my drive

I did win an award - the broken piston "Bad Luck" trophy

So it's take the motor out and see what I have done to the com and brushes!


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## Yabert (Feb 7, 2010)

Oh shit! sorry to know that.
Well this is probably not abnormal. How much Amps and Volt did you push during this race?
Can't wait to see the picture of the torn armature... and the solution you will find if you need to replace this motor.


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## galderdi (Nov 17, 2015)

Dang, Really sorry to hear that. I would also be interested to know the approximate revs when it went bang?


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## Duncan (Dec 8, 2008)

Hi Guys

Motor is out - brushes look chipped but not too bad

I have started adding some pictures - Armature first - it's only letting me do 10 pictures so the next post will be of the brushes

Sequence of events
Took off - spun rear tyres - backed off and they gripped - back to full throttle

Just before the end of the 1/8th there was a "Bang" and power went away
I lifted and then gently pressed the accelerator
I could get a small amount of throttle - then a rattling sort of noise - seemed to be from the front (brush end) of the motor

Rolled to the end of the parking area and turned around

I was second to last car of that group so when Owen in his electric pickup joined use we drove back to the start

I found that I could drive slowly so I drove past the start and waited to be let back onto the main road

There is a steep bank just there - managed to get up it but lots of rattling noise

Then it was about 500 meters to my house - two Stop signs which I treated as Give Way and it managed to roll almost to my drive

Then I got out and pushed it the last little bit


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## Duncan (Dec 8, 2008)

These are the four pairs of brushes - each is photo'd twice - good side and bad side


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## Duncan (Dec 8, 2008)

The Brush holders

One of the springs is obviously bad - and the other spring on that brush pair is also a little weak

None of this looks like enough damage to be causing the "Bang" and the rattle

I could see the bit that is broken off causing the bang - but not the rattle and lack of power 

Unless the brushes were simply sticking up and not contacting at all

I'm hoping that Major or one of the other experts comments

As far as revs when it happened are concerned my top speed was 2 mph slower than last year but my time was 0.6 seconds faster - more grip from the tyres which were fractionally larger 

225/45/17 rather than 215/45/70

I calculate 4580 rpm - I don't think that was relevant

I believe that my controller is on 100% before than so it would see 340v (full charge) minus the sag - maybe 300v ??


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## Duncan (Dec 8, 2008)

The spring that was "Bad" - it looks as if the post that it attaches to was bent

I measured the com runout - I get a total of 0.05 mm of runout

The more I look at the damage the less persuaded I become that this was the problem but while it's all apart I should make sure that it goes together BETTER than it was


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## Duncan (Dec 8, 2008)

Still looking for advice

Is that damage likely to have cause the symptoms? - possible?

Where can I get "better" brushes?
Where can I get new springs? - or new springs and brush holders


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## major (Apr 4, 2008)

Hi Dunc,

Been hoping to view your photos on larger screen. But this tablet will do. Guess you're lucky not to have big damage in the motor from the sounds of it. I don't see anything obvious which would cause symptoms of shutting down or losing power as you described. 

Comm looks a bit raw like high current/arcing has stripped the film. I'd definitely check out the comm for t.i.r. Needs to be 30 microns. 

When you lost traction it may have oversped the motor causing a bar to lift. A high bar, or segment could damage/chip those brushes. I think you need the bar-to-bar deviation at 5 microns. 

Replacement brushes/springs. Maybe forklift repair shops. Motor rebuilder.

If comm checks out or is serviced, I'd be tempted to install current brushes and do a lengthy break-in.

I found an excellent read on Mersen website. 
https://www.mersen.com/publications?s=Commutator&p=63

Regards,

major


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## Duncan (Dec 8, 2008)

Hi Major

Thanks for that - interesting read

I have checked runout and I get 0.05mm - 50 microns - so a bit more than you suggest

I have "fixed" the worst spring - the bar it mounts on was bent

My "plan"

Put it back together out of the car and run it on a 12v battery - just to see if it goes

Assuming that it spins OK - I will try and get it to a forklift motor shop - either that or I will try and "machine" the edges of the com blocks 
Just using a stone??
To get shot of the burnt looking area and the to get the chamfer looking like the chamfer in the Mersen doc you referenced

Then re-measure the runout and go around carefully segment by segment looking for steps

See what I find 

I have had a good look at the rest of the car - can't see anything else wrong but I can't test the controller until the motor is back in


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## galderdi (Nov 17, 2015)

Hey Duncan,

I am no expert but I wonder if one of the Comm bars may have raised at higher revs, chipped the brushes but then were pushed back down as the revs reduced. In other words I would be gently checking if any of the comm bars move at all.

But I am no expert

Also I wonder if you have overloaded a winding/conductor. Maybe check for resistance across your terminals.

But I am no expert

You can try "Find it parts" for brush springs

Did I mention I am no expert?


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## Duncan (Dec 8, 2008)

Something that I should have done FIRST

I just measured the resistance from the Com segments to the armature shaft - should be infinity or at least very high 
Instead I get 0.7 Ohms - NOT GOOD!

I think the armature is stuffed


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## Duncan (Dec 8, 2008)

This armature wire has blown completely through - and it has sprayed copper all across the inside

I should have taken it all apart on Monday - but I was sure that the problem was to do with the com and brushes

Time to look for another motor!
But I will ask about getting this armature re-built


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## Duncan (Dec 8, 2008)

Hi Guys

Motor failure 
It looks as if that wire simply cracked or otherwise nearly failed then arced 

I wonder if something got into the motor - damaged the insulation on one wire then did some more damage on the one that failed 

Looking for another motor!

As far as I can see a 9 inch motor will have about 25% less torque at a given current but will enable me to rev much higher 

I can still spin my lovely sticky "Nitto" tyres so giving away 25% of torque may not be too disasterous

I will just have to see what I can find in the way of second hand forklift motors


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## electro wrks (Mar 5, 2012)

Too late now, but I try to give these older, used at higher voltage motors, a good dose of spray-on, good quality insulating paint. Apply at different positions so it runs down the slots, lower windings, and, if possible, apply multiple coats while the arm. is slowly rotating on something like a BBQ rotisserie.

Motor shops can also do a commercial dip, rotate, bake, and re-balance. Sometimes they use a varnish, sometimes an epoxy for the severest duty. One trade-off is that the extra insulation may trap more heat in the windings - something to watch out for.


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## Moltenmetal (Mar 20, 2014)

Sorry for your loss, Duncan...that's going to be a lot of work for you that I'm sure you weren't expecting.


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## Duncan (Dec 8, 2008)

Hi Molten

I got five years of abuse out of a $100 motor - so I don't think I'm entitled to complain!
although I wish it had held on for another couple of runs - 8.6 seconds is good for an 1/8th miles but I think that when the track stickied up a bit I could have got into the 7's 

I have found a forklift breakers in Dunedin with a "pile of motors" - so I'm going there soon to see what I can find

I'm thinking about going down to a 9 inch motor - give away some torque for higher speeds - or maybe not


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## puddleglum (Oct 22, 2008)

Hey Duncan, any idea what motor volts/amps were at when it blew? Just wondering how much was too much for that motor. With your high voltage pack, what was your peak motor volts? I saw 1200 peak amps.


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## Duncan (Dec 8, 2008)

puddleglum said:


> Hey Duncan, any idea what motor volts/amps were at when it blew? Just wondering how much was too much for that motor. With your high voltage pack, what was your peak motor volts? I saw 1200 peak amps.


Hi
I can't read the instruments when I'm on the track
But I'm pretty sure I was well over peak motor current and into 100% controller territory

I would estimate about 700 amps 4500 rpm and about 300v when it blew

BUT it wasn't the com/brushes that went - I was sure that those would go first

I think that something went through the motor and damaged that specific wire which then failed and produced a big arc 

I have been abusing it for the last five years!


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## puddleglum (Oct 22, 2008)

I'm sure those windings get pretty hot at that level of power. That one armature winding may have came loose and threw out enough to tag something and arc. Doesn't really matter now anyway. Sorry you lost your motor. I've been keeping an eye on your car since I have the same motor that I still hope to use someday. I figured it could take some serious amps, but I never thought it would handle 300 volts.


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## galderdi (Nov 17, 2015)

Duncan, You have done us a great service. It's not everyday that we get the sort of data that you have given us. We now have a better idea of the limitations of a motor like yours. I am sorry it came at such a cost. I hope you can find a suitable / cost effective replacement soon.

Obviously we are pushing these motors past their designed purpose and sometimes past their physical limitations. It is very dificult to know where to draw the line. They don't give audible warnings like ICE motors do.....until it's too late. 

Please keep us posted on your progress.


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## Duncan (Dec 8, 2008)

Hi Guys

Just back from Dunedin
The guy had a LOT of motors so I have picked up one that is exactly the same model as my old one and a dinky little 9 inch motor to have a look at

He has another three or four more Hitachi's like mine but a bit later and about 20mm longer
$200 each for the big ones and $100 for the 9 inch

I will need to clean then up and take pictures!


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## electro wrks (Mar 5, 2012)

Coat those windings! Or get the arm. and stator dipped and baked at a motor shop.http://what-when-how.com/electric-motors/dip-and-bake-systems-electric-motors/

Megaohming the parts before and during the clean-up and re-coating process(es) would also be a good idea, since you're using it at such a high voltage.


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## galderdi (Nov 17, 2015)

electro wrks said:


> Coat those windings! Or get the arm. and stator dipped and baked at a motor shop.http://what-when-how.com/electric-motors/dip-and-bake-systems-electric-motors/
> 
> Megaohming the parts before and during the clean-up and re-coating process(es) would also be a good idea, since you're using it at such a high voltage.


 
This sounds like good advice. I will keep this in mind if I ever choose to increase my voltage. 

Duncan, Its great to hear you have some options up your sleeve. I can't wait to hear that you have it back up an running.


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## Duncan (Dec 8, 2008)

OK
I have completed the trolleys I promised to the high school and cleared the wood work out of my shed

Back to business!

Only allowed to up load 10 files at a time

Here we have the new armature - com area - looks good to me

The brush holder - looks like a bit of rust

Brushes - only 4 of the eight brushes present - and one of those was well stuck
Looks as if they were cocked over in the holders when running

The armature from the side - small amount of water damage


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## galderdi (Nov 17, 2015)

Duncan said:


> OK
> Only allowed to up load 10 files at a time


You should have a word with a site administrator about that 

Is this the past or future motor?


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## Duncan (Dec 8, 2008)

Part two

Another picture of the armature

Pictures of the inside of the stator - field coils

Now back to my old motor - copper plastered onto the field coils - and I think it has burnt into the insulation

I used to get nothing at all on my meters 20 MegOhm scale - now field coil to the metal gives me 0.5 MegOhm

So that's dead as well!

Plan is to select the best of the brush holders and springs 

QUESTION - I'm hoping that Major will help me here
Sand blast them?
If I do is there anything I should do to preserve them afterwards?

QUESTION
Dip or laqueur the armature? - I'm inclined to leave it the way that Hitachi left it

I'm being a lot more careful with the armature on this one ensuring that nothing bumps into the armature laminations - with the weight of the armature I may have banged the old one against the field coils - I'm using a hoist and doing it all in the vertical frame 


I also have a collection of brushes I was given - I intend to do some measuring and sorting - see exactly what I have

Taking a bit longer than I planned


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## Duncan (Dec 8, 2008)

Hi Galderdi 
The two pictures with molten copper sprayed onto the coils are my "old" motor

The rest are my "new" motor 

Bit of rust inside the "new" motor but I think that's ok - except for the rust on the brush holders - that will need to be fixed


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## electro wrks (Mar 5, 2012)

Duncan said:


> QUESTION
> Dip or laqueur the armature? - I'm inclined to leave it the way that Hitachi left it


Yes, but Hitachi probably dipped it many decades ago. The varnish may have dried out, cracked, or been worn away by now. As well as a insulator, the varnish glues the windings in place to keep them from shifting around and chafing the insulation. That's probably what doomed your old motor. 

Check what the motor shops suggest for a high voltage, current, and RPM severe duty usage. Also, check the condition of the fiberglass (usually) tension bands around the exposed windings. The glue holding them on may have dried out and weakened.


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## Duncan (Dec 8, 2008)

Hi Guys

Brush holders and brushes

The rusty brush holders are from the "new motor"
The black looking brush holders are from my old motor 
I'm thinking of using the "old" brush holders and giving them a very quick and gentle clean

Thoughts?? - or should I sand blast them down to clean metal?

Brushes
The brushes from the "new motor" looked horrible - were worn down and there only were three setts

The brushes with the blue insulation came from my old motor
I have been told that the blue means that they were soldered together here in NZ
Dimensions - Blue insulator
Width -24.9 mm Thickness 16.99 mm - Length - from 25 mm to 26 mm

I have been given the brushes with the grey insulation
These look in much better condition

Dimensions - Grey insulator
Width -24.9 mm Thickness 16.99 mm - Length - from 27 mm to 29 mm

There is a code on some of them E46X - it may be E48X
And one of each pair has a channel in it 

Current plan

Drill and tap the "Barrel" so that I can advance the brushes by 8 degrees - as before

Clean the outside and gently clean the inside

Fit my old brush holders and the brushes with the grey insulation

Run it in on 12v for an hour or so

Fit it into the Device!

I also have a new GPS Speedo and an idea for moving the instruments so that I will be able to see them in the sunshine - NOT a problem I had back in the UK


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## electro wrks (Mar 5, 2012)

Duncan! You're running the motor at 8-10 times the stock voltage. The motor is going to need all the help it can get to survive. At least apply the good part of a rattle can(spray paint can) of a good insulating varnish(paint) designed for motor windings from an industrial supplier. It's cheap insurance for the kind of thrashing you're going to put this motor through.

Since the paint is solvent based, the heavy coatings needed will take some time to dry-several days or more. Also, it can be baked. I've used it a lot. If the armature is rotated slowly mechanically or by hand incrementally every 10 to 20 minutes, initially, I've gotten good coverage and never had an imbalance problem. And, it makes the windings look good, easier to clean, shed dirt, and impress your fellow motor heads!!


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## electro wrks (Mar 5, 2012)

Here's a giant rotor out of a hydroelectric dam: http://emadrlc.blogspot.com/2012/07/rotor-out-of-nevada-side-generator.html

Obviously, it is too big to dip to renew the winding insulation! Witness the paper taped to the floor below the rotor to catch the over-spray from painting the windings. It looks like Schenectady Red winding paint-the traditional paint used.

This is probably the same paint used on a giant stator:https://teara.govt.nz/en/photograph/22477/benmore-rebuilt

In NZ, no less!


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## Duncan (Dec 8, 2008)

Hi Electro wrks

My limited experience with glues, paints and lacquers all says that the absolute KEY is the surface treatment before applying the "glue" 

As in the difference between a coat that can peel off and something that becomes part of the unit

My problem is that I really don't want to do anything aggressive to the armature assembly and I am definitely NOT going to strip it down to parts so that it could be re-done the way that Hitachi did it - decades ago - 

So I am loath to do anything aggressive to the existing coating - and at the same time I'm not at all sure than any extra "glue" will stick well enough to do any good without that aggressive cleaning

The examples you show are of large units - and I bet they will be very careful and know exactly how to approach the cleaning and re-gluing


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## electro wrks (Mar 5, 2012)

Good points about the cleaning before painting. I remember one hydro dam generator was cleaned with a walnut shell blast medium before painting. I have successfully used Stoddard (close to mineral spirits, paint thinner) solvent to clean the windings on dozens of motors from small universal motors in power tools to motors larger than yours. I've never seen these mild solvents harm the insulation coatings on motor windings. If you not sure, test the solvent on a sample area. Make sure the solvent is completely dried out before painting.

One large wound-rotor induction motor from a large printing press was so heavily caked with paper dust and grease, it needed to be scrubbed with soap and a water blast. After it was cleaned, it was rinsed with a lot of distilled water and baked dry. After it was dried, and before painting, it megaohmed out as good.

Did you have a chance to talk to a motor shop about their recommendations?


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## Duncan (Dec 8, 2008)

Hi electro works

I have been thinking about the failure I had and looking at the parts

I think that it may have been my own fault

When I look at the old armature the first few laminations have some gaps - looks a bit like the pages of a book 

The armature is quite heavy - 50kg? - and I took the barrel off the old armature a number of times in the horizontal mode

I worry that I managed to damage the armature - and its wires against the field coils - or more accurately their cores 

I'm going to take a great deal more care with the "new" one - doing everything in a vertical mode and using a hoist to take the weight of the barrel so I can ensure it does not bash on the rotor

With what I know about glues and preparation I'm not at all sure that I can actually improve on the original Hitachi work PLUS if I do do anything it will increase the amount of handling of a very heavy and possibly delicate armature 

I think I will rebuild this one using the bits that I have to get my car back on the road - I will also try and get my hands on another one (third) that could be possibly torn down and re-glued and baked over a longer time period


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## electro wrks (Mar 5, 2012)

As far as the paint adhering to the surfaces, the cloth sleeves(if used) around the wires, the insulating paper, and the wood wedges(if used) that lock the windings in the slots all soak up the paint somewhat to increase the insulation around the wires. And, as you say, "glue" the parts together to keep them from shifting around and chafing.

I've also damaged windings . Sometimes, not always, you can carefully pry back the wires(if they're not burned-up) in the damaged area, insert pieces of the insulating paper to re-insulate the wires, and repaint. Motor shops will give or sell you the small amounts of paper as well as the insulating sleeve material, if needed. They also would be a good source for the insulating paint.

You're right. It is a chore to do this. And, it sounds like you can't wait to get back on the road!


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## major (Apr 4, 2008)

Hi Dunc,

Sorry for the delay. Lucky you found the same motor for replacement since you were pleased with its performance. From what I see in the photos, it looks good to go except for the brushes. BTW, break in for longer than an hour. Like maybe a week.

For extra insulation and "gluing", use Glyptal 1202. Factory likely used a polyester resin. Retreating an entire armature nothing beats vacuum impregnation. 

You might be right about damage to the original armature but the arc flash event could have spread those laminations as well.

Good luck,


major


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## Duncan (Dec 8, 2008)

Hi Guys

Motor is now back together using the front housing and brush holders from the old one
The armature, barrel and rear housing from the "new one" 

I've drilled and tapped the barrel to get the same 8 degrees of brush advance

The brushes are the "new" ones that I was given

I'm giving it a gentle run in at 12v 
I have an old battery from somewhere - it runs for literally two minutes - then I stick it back on the charger!

There is an event on Saturday - but I'm going to give it a miss 
Instead I'm going to set it to my "grass track" setting - 20% throttle and drive it for a few weeks to bed the brushes in


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## Duncan (Dec 8, 2008)

The Device is back on the road
- 
Running the brushes in with the max current set to about 250 amps - and that would be full throttle

So far it seems to drive at traffic speeds with nowhere near that!

I will see how long I can do that before the power switches get moved up


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## MPaulHolmes (Feb 23, 2008)

That's very cool! Do you think I could use one of your videos as an advertisement for the control/driver board? I'm getting some new ones made (surface mount) and populated professionally, and they'll be here around the 5th of May. I will be jobless starting in May, and would like to see if I could make working from home for myself a reality.


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## Duncan (Dec 8, 2008)

Absolutely!

Help yourself

Are the ones on YouTube any good - can you download them or do I need to send some to you somehow?


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## MPaulHolmes (Feb 23, 2008)

OK I found you on youtube (I was subscribed to you! haha).


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## galderdi (Nov 17, 2015)

Great to hear it is back Duncan. Can't wait to hear how it goes when you compete next.


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## Dave Koller (Nov 15, 2008)

GREAT! On with the show ...


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## Duncan (Dec 8, 2008)

Hi Guys

Not much on here until spring - still running the brushes in at low power

Anyway I got to thinking 
When I blew up my old motor the brushes and com were not too bad 

I have done 1/8th mile drags and avoided 1/4 mile drags because I was worried about the com at high rpm's

Now that I seem to have a supply of "spares" I'm thinking of going to play with the big boys at the 1/4 mile events next spring

So I had a look at what could fail - and I decided to worry about the 
Volt "MANUAL SERVICE DISCONNECT - REMOVABLE PLUG"

Mine has the thumb bit broken off - but it works fine
Inside I believe is a 350 amp fuse

When I do a Drag - the battery current starts low - builds to somewhere about 1000 amps and drops off

So far I have not blown the 350 amp fuse - but holding the power on for another three or four seconds may just blow it

Are any of you guys near a Chevy dealer and would you be able to ask them about buying a spare?

My battery was out of a 2012 Chevy Volt

If I'm going to try a 1/4 mile having a spare "fuse" could save some embarrasment


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## MattsAwesomeStuff (Aug 10, 2017)

At that scale (I mean, technically at any scale) the "fuse" is just a chunk of wire.


You can (mechnically) measure it's dimensions and material, and just create a new one.


For racing, I would throw in something in the right ballpark and keep the factory one for normal driving.


The fuse is only there to protect your wiring from lighting on fire, so, "fusible links" are usually just 30-50% thinner than the main wiring, ensuring that it will melt at a level below where the main wiring melts.


I'd say start off with a chunk of thin wire, accelerate... and keep an eye on where you blow it up. Then use two wires, or heavier wire, then accelerate again. If you're watching the amps, you'll pretty easily mathematically determine the rough cross section you need. I.E. If a piece of 14g wire liquifies at 50 amps, and you want it to liquify at 350 amps, you'll need 7 of them, or one with the cross-section of 7 of them.


Keep it horizontal, DC will arc through a broken wire if vertical.


If you want to get fancy, take wire cutters and give it a pinch at either end. That gives a weak point for it to break. If it doesn't break at one end, and continues to arc, the opposite end will become the next weak point and it'll cut there and drop the whole wire out.


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## Emyr (Oct 27, 2016)

"Hey, this fuse blew, it must need a heftier one which I don't seem to have. I know, I'll use this paperclip/ringnail/baking foil..."

I'd rather an encased fuse was used so if a piece of fusewire detatches it can't short anything else.


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## MattsAwesomeStuff (Aug 10, 2017)

> I'd rather an encased fuse was used so if a piece of fusewire detatches it can't short anything else.



Oh la tee da Mr. Moneybags over here, too good to use household garbage as safety devices.



Duncan, this should get you started:


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## Duncan (Dec 8, 2008)

I like the 350 amp fuse!

But what I'm after is a spare BEFORE I blow the one I have to hell - or even break it by trying to disassemble it


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## Yabert (Feb 7, 2010)

Duncan said:


> So I had a look at what could fail - and I decided to worry about the
> Volt "MANUAL SERVICE DISCONNECT - REMOVABLE PLUG"...
> Are any of you guys near a Chevy dealer and would you be able to ask them about buying a spare?
> My battery was out of a 2012 Chevy Volt


Better than that, pay the shipping and my fuse is yours...
PM me for details.
I will be pleased to be part of your future motor destruction at the drag strip


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## Duncan (Dec 8, 2008)

Thanks Yabert

PM sent


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## Duncan (Dec 8, 2008)

Long past time for an update!

"New" motor - place, - need to run the brushes in - I gave it about two hours running on 12v - before starting to drive the car at 20% power (that would be full throttle - actually less)
It drove fine at that - didn't feel slow at all

So I drove for 120 km before going back to my usual 45% 

While the motor was out 
I fitted a new instrument panel with a neat GPS speedometer - looks a bit better and its easier to read when the sun is out

Also I got some padding for the seats! - just rectangular vinyl bags with foam inside held on with velcro

I have been invited to an EV event at Highlands MotorSport Park in Cromwell on the 9th of September

http://www.thenews.co.nz/community/open-day-will-pit-petrol-against-ev/

I had better do at least one test at full power before I go

I have just noticed the limits on picture file size are a lot larger now - I will have to re-set my camera again


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## Dave Koller (Nov 15, 2008)

Nice! and have a good time at the show!


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## Duncan (Dec 8, 2008)

Long time since I last posted here - sorry

I haven't been doing much - just family stuff

But Today was the annual Gore 1/8th mile drag race!

We had three electric cars there today
My Device, Owen's Ute and Johnathan's wee BMW - i3

They put the BMW in the "European Cars" class - the other car in that class was a Supercharged Mercedes Sports Car

The BMW did a very creditable 10 seconds - and was only beaten by 1/10th of a second 

I had a good day - no spray of molten copper this year!
And ended up the second fastest car there with 7.90 seconds and 93 mph!

There were six big bikes as well as about 30 cars - but I only beat two of the bikes

I started off doing a burnout to heat the tyres - seemed to work very well but on my last run I dropped the rear tyre pressure down from 19 psi to 15 psi
When I did my "burnout" they didn't spin!
And when I did my run I got no wheelspin and my fastest time

I may try dropping the pressure down even lower - or it may be that the track was well rubbered in by then


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## Duncan (Dec 8, 2008)

Hi Just done the calculations - 93.5 mph is 5288 rpm


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## DrGee (Aug 22, 2018)

Duncan said:


> Hi Just done the calculations - 93.5 mph is 5288 rpm


Fantastic Duncan! 
Would love to see a video...


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## Duncan (Dec 8, 2008)

No Video 
But here is a picture

And a worrying one - this is me braking to a stop after doing a burnout - My brakes are from a car twice the weight - should they be getting that hot?


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## electro wrks (Mar 5, 2012)

If it was just the left side glowing like a pool of molten lava, it's probably a jammed-up caliper or caliper piston(s).


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## Duncan (Dec 8, 2008)

electro wrks said:


> If it was just the left side glowing like a pool of molten lava, it's probably a jammed-up caliper or caliper piston(s).


I didn't notice it at the time - brakes pulled me down nice and square from 150 kph 

I didn't notice anything until I saw the photo - done a couple of brake downs from 70 kph - no sign of anything - both discs too hot to touch but not instant frazzle


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## dedlast (Aug 17, 2013)

What are the chances that you are seeing a reflection of the safety cone in the nice shiny brake disk? It seems a bit of a stretch, but maybe..?


Bill


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## galderdi (Nov 17, 2015)

dedlast said:


> What are the chances that you are seeing a reflection of the safety cone in the nice shiny brake disk? It seems a bit of a stretch, but maybe..?
> 
> 
> Bill




I think you are on the money.


I don't know about the cone part but I am convinced it is reflection. There are a couple of reasons.
1. The colour is consistant with the reflection on the other components like the wheel rim.
2. Take a closer look at the bottom right of the disc, just where it goes behind the spoke of the wheel. there is a portion there that is not orange. If it were glowing hot it would be consistant across the whole disc.


I think Duncan is safe......well safe from melting discs anyway.


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## MattsAwesomeStuff (Aug 10, 2017)

dedlast said:


> What are the chances that you are seeing a reflection of the safety cone in the nice shiny brake disk? It seems a bit of a stretch, but maybe..?


[Edited to add - Damnit, galderdi beat me to the same observations by 30 seconds while I was typing]

At first I laughed it off, as of course that's not happening... but...










1 - Why is the *outside* of the black rim orange/red? That's not reflected light from inside the wheel well.

2 - Why is the rightmost edge of the discbrake not orange, but grey?

3 - Why is the top of the disc brake only slightly warm, but the bottom glowing bright?

...

Was there bychance also an orange sandfence or safety fence nearby?

Alternatively, cameras pick up infrared much easier than our eyes do. Something that appears to emit zero heat light yet, will often show up as pink/purple/orange on a camera that has weak infrared filtering (nearly all cameras, if you point a TV remote at your camera in video mode, and hit some buttons, note that it lights up white hot on your camera screen).


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## galderdi (Nov 17, 2015)

Oh and I just noticed the top of the disc (through the gap in the wheel) is also not glowing. So again I can't see how it could be heat.


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## Duncan (Dec 8, 2008)

dedlast said:


> What are the chances that you are seeing a reflection of the safety cone in the nice shiny brake disk? It seems a bit of a stretch, but maybe..?
> 
> 
> Bill


I have never heard of that before - BUT there is orange on the rim of the wheel and on the polished black "spoke" 

And none of the smell and smoke I would associate with a disc that was actually orange hot

None of the other cars showed anything 

I think that you may be right!


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## galderdi (Nov 17, 2015)

But hey it still makes for an awesome photo!!!


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## Duncan (Dec 8, 2008)

Thanks guys for your comments - I do feel much better about that now

- I'm down to 7.90 seconds - how do I get down even further?


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## MattsAwesomeStuff (Aug 10, 2017)

galderdi said:


> Oh and I just noticed the top of the disc (through the gap in the wheel) is also not glowing.


Hah! I beat you to that one.

Regardless, we're 3/3 on the same observations.


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## galderdi (Nov 17, 2015)

MattsAwesomeStuff said:


> Hah! I beat you to that one.
> 
> Regardless, we're 3/3 on the same observations.



Yes same observations but the presentation in your interview would have landed you the job


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## galderdi (Nov 17, 2015)

Duncan said:


> Thanks guys for your comments - I do feel much better about that now
> 
> - I'm down to 7.90 seconds - how do I get down even further?



Aero? I am not talking about downforce. I mean streamlining. At those speeds don't underestimate how much power it takes to overcome every bit of wind resistance.


The balancing act is making some improvements that are either compatible with your normal use of the car or able to be applied on the morning of your events.


Your nose is good. 
The front wheels are a problem area but I'm not sure what you could do there short of a whole new front clip.
The passenger area is a fairly easy fix. Get some 0.4 mm polycarbonate and make some covers to extend the bonnet and sides to bridge the gap where the passenger seat is. 
Temporarily remove the passenger side headrest. It doesn't sound like much but try puting your palm against the wind at 130kmph and you'll see how much power it is sucking.
Remove the passenger side windscreen for these events.
I would make an alternate driver side windscreen which would extend up as high as you can cope with. Try and get it high enough to divert the air over your head.
The rear of the car possibly has some potential too but would take significant effort like making a streamlined tail to reduce the eddies behind the boot.


Please don't take this as criticism. I think the car is awesome just as it is. But we are always seeking those next few %


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## Duncan (Dec 8, 2008)

Excellent suggestions

I started to take the passengers side head rest off - but I stopped when it became clear that the nuts inside would come loose - Have to strip it down and re-make it

I do have tonneau covers for it - with a centre zip so that I can drive and help streamline the passengers side - I should have done that

Taking the passengers side aero screen off is a bit of a *** - I may try just putting it flat

Not sure if I need a taller drivers side screen - it already boosts the air up above my head (I think)

The back has a tonneau cover on it already

I'm stuck looking after my wife at the moment - so don't know when the next event will be


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## piotrsko (Dec 9, 2007)

Tuft it and get someone to take pictures. Bet you have lots of backwards facing ones.
5280 is close to your motor rpm limits? Also means lots of back emf which limits output power. Slightly taller tires, perhaps?

Chin spoiler / splitter. Underbody covering. Ask the experts over at ecomodder about aero.


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## galderdi (Nov 17, 2015)

Duncan said:


> Excellent suggestions
> 
> I started to take the passengers side head rest off - but I stopped when it became clear that the nuts inside would come loose - Have to strip it down and re-make it
> 
> ...



Good news then, sounds like you are on the right track. I also concur with the taller tyres comment. That would put your motor back into it's torque band. Maybe try adding some string or tape hanging off the top of your screen, drive the car and see where the string is hitting your helmet. If it is hitting your chest or chin then it's not high enough. If it's hitting the top of your visor then all is well. I would be surprised if it were up to your chin.


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## Duncan (Dec 8, 2008)

Major seems to think I would be OK at 6000 rpm - and I'm using 340v to keep the power at high revs
But I will look for taller tyres once these are worn out! - currently 225/45/17 and labeled "Recommended for competition use only" 
Not until then! - these were expensive $300 each

I like the tape idea on the screen - definitely try that


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## Duncan (Dec 8, 2008)

It looks as if I did do a little damage on my four full power runs 

Yesterday my reversing contactor stuck! - I had reverse but no forwards until I poked the contactor with a screwdriver to release one of the contactors

The contacts look a bit second hand - I've given them a quick clean and they seem to be OK now


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## piotrsko (Dec 9, 2007)

Imho you've gone down the slippery slope of fried contactor contacts. Good luck.


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## Duncan (Dec 8, 2008)

piotrsko said:


> Imho you've gone down the slippery slope of fried contactor contacts. Good luck.


Hi piotrsko - looks like you have put the evil eye on my contactor!

Still it came out of a small 24 volt forklift I scrapped 10 years ago so I suppose I need a new better one

Suggestions about where to get one?


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## MattsAwesomeStuff (Aug 10, 2017)

Duncan said:


> Suggestions about where to get one?


Bigger forklift?

Two in series handle double the voltage. Two in parallel handle double the current.

Start stacking them like Voltron.


----------



## Duncan (Dec 8, 2008)

Help Required!

I have got a lovely big beefy reversing contactor - an Allbright SW202

However it has 36 volt solenoid coils - it takes 18 volt to pull in but it maintains down at 4 volts

Any suggestions about how I use this on my 12 volt system?


----------



## Duncan (Dec 8, 2008)

What about using two of these? - one on each coil

They should each be good for 1.2 amps and I measure 0.4 amps from the solenoids 

https://www.banggood.com/3pcs-3V5V1...-p-1328577.html?rmmds=search&cur_warehouse=CN


----------



## MattsAwesomeStuff (Aug 10, 2017)

Duncan said:


> What about using two of these?


You can get 2587 boosters for a lot less than that. They should be around a bucks a piece, shipping included IIRC last time I ordered some. Ebay. Usually sold in 10-packs. Solder your own wires onto the board instead of using screw terminals if you want to save a few bucks. Cheap as chips but order extras because they take forever to get there and naturally you'll blow some up.

Handy little things.

I think they often claim they're good for 3 amps, but, in testing I seem to recall the solder melted and stuff started floating away north of 1.5-2amps.

For maintaining 0.4 amps, they'll be fine. Shouldn't even run warm.


----------



## Duncan (Dec 8, 2008)

Hi Everybody

Finally back able to do something with my car

First Autocross since February 2018

Great fun
My son Thomas drove as well - his first time driving on grass - and it was gently raining

https://www.youtube.com/watch?v=iUigfkOv6DA


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## Duncan (Dec 8, 2008)

Second Autocross
Forbes
And this time it stayed dry

We start off with a couple of pictures of us both in the car for the "indian file" to show us the route

Also took some Video

https://www.youtube.com/watch?v=jCGqaiAht88

Great fun


----------



## Baratong (Nov 29, 2012)

Glad to see your Dubious Device is still going strong!


----------



## dkubus (Oct 10, 2019)

Very very cool Device Duncan 👍👍


----------



## Duncan (Dec 8, 2008)

Getting ready for the Annual Cobra Drags tomorrow

Removed passengers side head rest
Removed passengers side mirror
Fitted Passengers side Tonneau cover
leaving the road tyres on on the front
Sticky track tyres on the rear

Tyre pressures....

I will increase the front - normally 20 psi to 30 psi

The rear.....
I got a lot of extra grip last year at 14 psi
Maybe try 12 psi


----------



## Evbeddy (Jan 5, 2020)

Hey Duncan 

How did you get on at the drags yesterday?


----------



## Duncan (Dec 8, 2008)

Successful day at the Drags

Improved from 7.90 seconds and 93 mph to 7.83 seconds and 96 mph

I beat all of the cars except for two of the T buckets - one just pipped me by 5 hundredths

But the other is a bit of a monster and di 6.50 seconds

It was hotter and I tried dropping the tyre pressure to 12 psi 
Made a lot of difference!
I could not make the tyres spin for my "burnout"

You know what that means

I need MORE TORQUE!

I will ask Paul if I can boost my 1200 amps to 1400 amps


----------



## drother (Sep 11, 2014)

Duncan said:


> The rear.....
> I got a lot of extra grip last year at 14 psi
> Maybe try 12 psi


What rear suspension and what tires? Are the rear shocks adjustable?


----------



## brian_ (Feb 7, 2017)

drother said:


> What rear suspension... ?


Duncan described the suspension (and his approach to suspension) in the first few posts of this thread. It is the McPherson strut setup from a Subaru Legacy, but I believe that he has the rear longitudinal links running rearward from the hub, instead of the stock forward, due to packaging constraints.


----------



## Duncan (Dec 8, 2008)

Hi Guys

Successful day at the drags - then a very fun tarmac autotest

Only when I got there I remembered the video camera still plugged into the charger - bugger

Great fun on the day - much longer and faster than before so even with giving it a top-up we only had enough power for the Indian file - then two runs for me and three runs for Thomas

Neither of us posted any really good times and a number of cones were murdered 

Great fun the car went like a demon!

At the end of the event it went on strike and refused to go into forwards
So we winched it onto the trailer

Back home it started working again - I think I wasn't getting enough juice from the auxiliary battery to pull in the solenoid 
This thought came AFTER I had started charging the auxiliary so I wasn't able to check the voltage

Anyway I took the contactor to bits to have a look at the contacts 

They are marked but feel quite smooth 

Should I trim them up?
With what?

Or should I leave them alone?


----------



## Duncan (Dec 8, 2008)

drother said:


> What rear suspension and what tires? Are the rear shocks adjustable?


Subaru - from a 1994 GT - 4.1:1 LSD 

Adjustable rear struts with 125 lb/inch springs - set to full soft on the dampers

The forward facing rods going backwards 

Tyres are NITTO 225/45/ZR 17 - recommended for competition use only on 17 inch x 7.5 inch rims

With me in it it has 55% of the weight (900 kg with me in it) on the back wheels
And I have corner jacked it to have the same weight on both rear tyres


----------



## drother (Sep 11, 2014)

Duncan said:


> Subaru - from a 1994 GT - 4.1:1 LSD
> 
> Adjustable rear struts with 125 lb/inch springs - set to full soft on the dampers
> 
> ...


Do you have any slow motion videos of trying to launch while drag racing? Preferably from a 45 degree angle so both front and rear sides can be seen. 

When you say full soft, is that compression, rebound, or does 1 knob control both?


----------



## Duncan (Dec 8, 2008)

drother said:


> Do you have any slow motion videos of trying to launch while drag racing? Preferably from a 45 degree angle so both front and rear sides can be seen.
> 
> When you say full soft, is that compression, rebound, or does 1 knob control both?


One adjuster adjusts both - and no useable video


----------



## major (Apr 4, 2008)

Hi Dunc,
I typically use emery cloth or even sandpaper, fine grit, for the contact buttons. Blow the dust out afterwards. Smooth to the touch and closing without any gaps should be good to go. 
Regards,
major


----------



## Duncan (Dec 8, 2008)

major said:


> Hi Dunc,
> I typically use emery cloth or even sandpaper, fine grit, for the contact buttons. Blow the dust out afterwards. Smooth to the touch and closing without any gaps should be good to go.
> Regards,
> major


Thanks Major

I was advised to avoid Silicon Carbide - so I used fine sandpaper 
The contact areas all cleaned up nicely and it now seems to be working fine

I also connected up the old microswitches so I can now see if the contactor has moved 

Just keep an eye on them


----------



## Duncan (Dec 8, 2008)

It's electric - but not a car

The Local Steampunk group is holding "Teapot Races"

So the Cookie Monster and I converted Thomas's old tank into a teapot racer

We got the prize for the "Most Amusing" when four of the starboard road wheels fell off as it crossed the finish line


----------



## zsnemeth (Jan 4, 2012)

Huge thumbs up! 





Duncan said:


> It's electric - but not a car
> 
> The Local Steampunk group is holding "Teapot Races"
> 
> ...


----------



## Hassleweed (Jan 20, 2020)

Hi Duncan,
Martin here from California (aka Hassleweed on the Locost USA forum). You were kind enough to introduce yourself on my Tesla powered Seven build. I wanted to thank you as I now am going to use the Chevy Volt battery pack. The batteries I was planning to use have been shutdown - LG Chem has been issuing cease and desist letters - and so I have ordered a 2nd Gen Volt pack. Thank you for the suggestion. I'll be digging around your blog for how to get it working!
Cheers
Martin


----------



## Duncan (Dec 8, 2008)

Hi Guys
Bit of a gap - went to a Tarmac Autocross at Teretonga yesterday

Car went well 
But I have identified a problem - its not been that quick at these events 
Yesterday it was blindingly obvious that my front grip was severely lacking!!














My back tyres are competition tyres - very grippy
My front tyres are the ones that were on the rims when I got them! - normal saloon tyres at least 12 years old

I have ordered another pair of sticky tyres - these are slightly taller and wider than the ones I have just now so they will go on the back and my lovely Nittos will go on the front

Its our annual Drag races on Sunday the 21st of February - will see how that goes


----------



## brian_ (Feb 7, 2017)

Duncan said:


> ...
> My back tyres are competition tyres - very grippy
> My front tyres are the ones that were on the rims when I got them! - normal saloon tyres at least 12 years old
> ...


Life is quite a bit more fun with tires the other way around: sticky on the front and slippery in the back.


----------



## galderdi (Nov 17, 2015)

Nice Work Duncan. Looks quick on a tight course. I've probably mentioned it before but bang for buck I love Nankang AR1 for a light car. Apparently they aren't so good on a heavier car.


----------



## Duncan (Dec 8, 2008)

galderdi said:


> Nice Work Duncan. Looks quick on a tight course. I've probably mentioned it before but bang for buck I love Nankang AR1 for a light car. Apparently they aren't so good on a heavier car.


Just picked up the tyres - haven't paid for them yet!
They are "NEXEN"
I could not get "NITTO" in the right size and the local expert said these were good
Now I have the 225/45/17 Nitto - to go on the front - and the 235/45/17 Nexen - for the rear
These are asymmetric - I need to put the correct wheel and tyre on the correct corner

Will see how grippy the new rear tyres are at our drags on the 21st February


----------



## Duncan (Dec 8, 2008)

Hi Guys
Last Sunday we had our annual 1/8th mile drag race

Did not do as well as before - possibly the tyres were too new!

A Hybrid 4WD Porsche was there to beat me - and he did!

My best time was 7.94 seconds and 96 mph (last year I got 7.83 seconds and 96 mph)
The Porsche got 7.88 seconds and 93 mph

I set up my cheapo GoPro knock off to look at my instruments - interesting

























"Series 3" was my fourth run - I spun the tyres and had to lift - that was half a second slower than the third run !!

My very first run I set the camera incorrectly - AND I spun the tyres half of the way down the strip and nearly went into the ditch

The "error bars" on those readings are quite large - just me taking the numbers from the videos

I seem to have increasing SAG until the controller maxes out at about 100 kph - only 20% - I was expecting more! - then steady away for 2 or 3 seconds before I lift


----------



## Duncan (Dec 8, 2008)

Grass event today
Our fourth attempt at running our Christmas autocross and barbeque - the weather gods vetoed the previous three goes

Great fun
The grass remained a bit slippery but I had a great time





















Running at 40% power - and I was nowhere near full throttle


----------



## Duncan (Dec 8, 2008)

Another day out at Teretonga - reminded me of Scotland it rained on and off and I got wet





















I have the new NEXEN's on the back and the NITTOS on the front - made a HUGE difference the car just felt so much more "planted"
And I moved from the back quarter of the results to the front quarter

Question
Spring Rates
I'm running 
100 lb/inch on the front which give me wheel frequency of 100 CPM
125 lb/inch on the rear which give me wheel frequency of 94 CPM

With the amount of roll I'm getting (damn all) I'm thinking of changing to

70 lb/inch on the front which give me wheel frequency of 78 CPM
100 lb/inch on the rear which give me wheel frequency of 84 CPM

Comments??


----------



## wjbitner (Apr 5, 2010)

Duncan said:


> Another day out at Teretonga - reminded me of Scotland it rained on and off and I got wet
> 
> 
> 
> ...


It's always a trade-off. More suspension travel can allow the alignment to change. More suspension travel can allow the tires to continue gripping with dynamic weight transfer. After watching a few of your runs, I'd say try softer and see if it matches your style of driving (and what happens to the times). Especially during the slaloms, I could see potential gains by allowing more
movement.


----------



## Duncan (Dec 8, 2008)

On Saturday I took my Device to a 1/4 mile drag strip
Could not stop the tyres spinning at the start - their rules would not let me do a burnout
Bit disappointing - managed 13.45 seconds and 104 mph
Acceleration is definitely dropping off!
It takes 7.9 seconds and 1/8th mile to get to 96 mph - the next 5 seconds and 1/8th mile only add another 8 mph

Note this is the European/Kiwi style - we do not allow the 1 ft run up that seems to be allowed in the USA


----------



## brian_ (Feb 7, 2017)

Duncan said:


> On Saturday I took my Device to a 1/4 mile drag strip
> Could not stop the tyres spinning at the start - their rules would not let me do a burnout
> Bit disappointing - managed 13.45 seconds and 104 mph
> Acceleration is definitely dropping off!
> It takes 7.9 seconds and 1/8th mile to get to 96 mph - the next 5 seconds and 1/8th mile only add another 8 mph


It's not just the slow acceleration in the second 1/8th that hurts: if you had hit the 1/8th at your usual 96 MPH and continued up to 104 MPH at constant acceleration, it would have taken only another 4.5 seconds for the second 1/8th (for a total of 12.4 seconds if the first 1/8th took 7.9 s), so presumably in this run the first 1/8th wasn't that fast due to the launch traction issue.


----------



## dkubus (Oct 10, 2019)

Duncan said:


> On Saturday I took my Device to a 1/4 mile drag strip
> Could not stop the tyres spinning at the start - their rules would not let me do a burnout
> Bit disappointing - managed 13.45 seconds and 104 mph
> Acceleration is definitely dropping off!
> ...


Hi Duncan, I've personally never drag raced so I don't have experience with the rules but I've never been to a drag racing event that didn't allow a tire "warm-up" (burn out),.. In fact I'd say it seems like it's encouraged here in Oz at least. 

Every hillclimb event I've ever raced in has always allowed a "single continuous forward moving tire warm-up" strictly within a set portion of the pre-start-line area. (Prior to getting to start line). 

Was this rule applied to your vehicle only? Or was nobody allowed to warm-up tires pre run? 

Thanks for sharing your Motorsport with us, helping us all stay motivated back in the garage. Cheers.


----------



## Duncan (Dec 8, 2008)

dkubus said:


> Hi Duncan, I've personally never drag raced so I don't have experience with the rules but I've never been to a drag racing event that didn't allow a tire "warm-up" (burn out),.. In fact I'd say it seems like it's encouraged here in Oz at least.
> 
> Every hillclimb event I've ever raced in has always allowed a "single continuous forward moving tire warm-up" strictly within a set portion of the pre-start-line area. (Prior to getting to start line).
> 
> ...


I do a burn out at our annual 1/8th mile drags
But this was with a different motor club and their rules are
(1) Only their club members get to do a burnout
(2) Only cars that do less than 12 seconds get to do a burnout

So no burn-out for me!


----------



## Duncan (Dec 8, 2008)

On Saturday I did a "Bent Sprint" at Teretonga

That is a higher speed event and I needed to get an actual speed license
Great Fun
I was not that quick ended up 13th out of 16!!

I moved my camera downwards to try and see the speeds - not a great success but you can see sometimes -
Straight up and down is 100 kph


















Still with the existing springs - I have a softer pair but not fitted them yet

The four full power runs ate my charge - not enough for a fifth run and the fourth run was slightly speed limited


----------



## Duncan (Dec 8, 2008)

Spring is here - So I got an Autocross at Teretonga!

I have reduced my spring rates
Replaced the 100 lb/inch on the front with 80 ib/inch and put the 100 lb/inch on the back in place of the 125 lb/inch
And it felt GOOD!

I failed to get the video running on my first three runs - 
shame as I got out of shape on one corner on the first run and then had a full spin on that corner on the next run - but no video!


----------



## galderdi (Nov 17, 2015)

Great work Duncan. The uneducated think stiff suspension is a good thing. It does have it's positives but for grip softer is often better. Role some of the weight onto the outside tyres and let em do most of the work.


----------



## brian_ (Feb 7, 2017)

galderdi said:


> Role some of the weight onto the outside tyres and let em do most of the work.


Body roll doesn't affect load distribution between inside and outside tires unless the centre of mass shifts (typically upward with jacking or outward due to a low roll centre). Whatever the amount of roll, in steady-state cornering the moment due to the track width and different in contact patch force must equal the moment due to the centre of mass height and the product of vehicle mass and lateral acceleration.

I agree that excessively stiff is bad for traction.


----------



## Duncan (Dec 8, 2008)

brian_ said:


> Body roll doesn't affect load distribution between inside and outside tires unless the centre of mass shifts (typically upward with jacking or outward due to a low roll centre). Whatever the amount of roll, in steady-state cornering the moment due to the track width and different in contact patch force must equal the moment due to the centre of mass height and the product of vehicle mass and lateral acceleration.
> 
> I agree that excessively stiff is bad for traction.


I would go further
"jacking" where the roll makes the center of mass higher will have an effect
The "roll center" will have zero effect - !


----------



## brian_ (Feb 7, 2017)

Duncan said:


> I would go further
> "jacking" where the roll makes the center of mass higher will have an effect


I covered that:


brian_ said:


> Body roll doesn't affect load distribution between inside and outside tires *unless the centre of mass shifts (typically upward with jacking* ...


The centre of mass can also rise (or fall) due to dive or squat resulting from deceleration or acceleration.




Duncan said:


> The "roll center" will have zero effect - !


I won't try to explain the roll centre in this thread, because the rest of the automotive world understands it.


----------



## Duncan (Dec 8, 2008)

brian_ said:


> I won't try to explain the roll centre in this thread, because the rest of the automotive world understands it.


You left out some letters

because the rest *most* of the automotive world *mis*understands it

Including our Brian


----------



## brian_ (Feb 7, 2017)

Duncan said:


> ...
> because the rest *most* of the automotive world *mis*understands it


----------



## MesquiteTim (Sep 30, 2021)

From your videos I saw room to improve braking performance. However, the video footage could be deceiving. Braking is the second accelerator (deceleration) in your toolbox of go fast parts.


----------



## Duncan (Dec 8, 2008)

MesquiteTim said:


> From your videos I saw room to improve braking performance. However, the video footage could be deceiving. Braking is the second accelerator (deceleration) in your toolbox of go fast parts.


Probably correct - but I suspect its the driver not the car!
I need to hang onto my speed for longer and then brake sharper


----------



## galderdi (Nov 17, 2015)

The one component that can be tweaked to provide a cost effective improvement is the nut behind the wheel. :-D


----------



## piotrsko (Dec 9, 2007)

Duncan said:


> Probably correct - but I suspect its the driver not the car!
> I need to hang onto my speed for longer and then brake sharper


I'm not sure braking sharper is the ultimate answer, otherwise race cars wouldn't need handling, just huge brakes and massive motors. Ever have a professional drivers schooling? Friends went to Bondurant and dramatically improved their lap times.


----------



## MesquiteTim (Sep 30, 2021)

Your friends that went to Bondurant learned how to drive at threshold braking among other great racing skills. There are three thresholds of grip. They occur at max acceleration, max braking, and max cornering. 

(I didn't want the thread to drift off topic but lets just say that I have 20+ years of road racing experience and have graduated Bondurant, Russell, Barber schools at Laguna Seca, Phoenix, Sears Point. I might have a clue about what I said)


----------



## Duncan (Dec 8, 2008)

Interesting idea

I'm an old dog - pensioner - not sure if I can learn new tricks!

But I am very aware that its my driving skills that are lacking!

Back in the 90's when I had a two litre twin cam mini I mechaniced for a guy with a Mallock - 
every now and the Keith would tell me to leave the mini at home and to co-drive the Mallock
I know my "rank" in that relationship - I was tyre warmer
I would do a lap in the middle of the field and then Keith would go and get FTD

I might have a word with the local track and see if there is a "racing course" I could go on


----------



## Darxus (May 10, 2010)

Darxus said:


> I just finished reading through this thread, thank you very much for writing it up. I need to look into Volt battery packs.
> 
> I'd love to see you do something like a video tour of the details of the car.


And four years later I've gotten through the thread again. I love this car, very relevant to my interests.

Please do that video walk through of the car


----------



## Darxus (May 10, 2010)

This read through I took notes, and kept track of reference links. A couple are from Duncan from other threads.

11" forklift motor, direct coupling
most of a Chevy Volt battery.
50km (31 miles) at 100kph (62mph).
"If you build a nice light car and use a 1000 amp controller and a Chevy Volt battery with the Warp 9 then you will easily beat" "0-60 time of under 5.5 seconds".
0-60 mph in ~4 seconds.
22 gauge 0.7mm sheet steel instead of tubes for triangulation
Open ReVolt controller - blew up a few times
Paul and Sabrina controller
the WarP-9 enters into saturation around 180-200A and requires about 50V for every 1000 RPM at 1000A
Started off with Headway cells, Chevy Volt battery pack
His youtube channel
What does he set his redline at? (At least "96 mph in 7.8 seconds") - 85mph is about 4700rpm - oops - I had intended to keep it under 4500rpm - so 81.4mph (with older tire size)
Battery check
Suspension geometry book recommendation: Race and Rally Car Sourcebook: The Guide to Building and Modifying a Competition Car
"I like the Paul & Sabrina controller - it's 144v and 500 amps"
Paul (of Paul & Sabrina) High Voltage High Current Controller
[url=https://www.diyelectriccar.com/threads/duncans-dubious-device.44370/post-969209]Blew an armature wire drag racing
"I would estimate about 700 amps 4500 rpm and about 300v when it blew"
225/45/17 competition tires
20% voltage sag drag racing


----------



## Darxus (May 10, 2010)

Duncan said:


> So I intend brazing a sheet of (22 gauge 0.7mm) steel under my chassis


How has brazing sheet steel instead of tubes for triangulation worked out for you? Anything you'd do different, other than switching to MIG for cost? Seems like a great idea for mine. 

Can you really... stand on that stuff? Is 0.7mm steel welded between several square tubes enough to hold my weight without denting? 

Did you use the same thickness all around, or was that one just the floor?


----------



## galderdi (Nov 17, 2015)

Darxus said:


> How has brazing sheet steel instead of tubes for triangulation worked out for you? Anything you'd do different, other than switching to MIG for cost? Seems like a great idea for mine.
> 
> Can you really... stand on that stuff? Is 0.7mm steel welded between several square tubes enough to hold my weight without denting?
> 
> Did you use the same thickness all around, or was that one just the floor?


Have you tried using a bead roller. If you are trying to use panels to add rigidity a bead or two can really make a massive difference. That's why floors are rarely flat. I love my bead roller!!!


----------



## Duncan (Dec 8, 2008)

Hi
I ended up using 1mm sheet - and you cannot make it move by jumping up and down in the center of a panel
Also you really never put any load there!
There is a cross member in front of the seat - you naturally put your feet on that 

Brazing the sheet was a bad idea - there are ripples brazed in in places - underneath where nobody can see them!

The steel thickness was overbuilding!!
I used the 1mm sheet everywhere except places like the strut tops where I used 2mm or 3mm

Video walk around - I am "planning" on doing a tear down repaint and tittivate next winter - I will try and do a video walk around then


----------



## Darxus (May 10, 2010)

galderdi said:


> Have you tried using a bead roller. If you are trying to use panels to add rigidity a bead or two can really make a massive difference. That's why floors are rarely flat. I love my bead roller!!!


I haven't tried anything, I am utterly unqualified for what I am planning. That does sound like a good tool to be aware of, thanks.



Duncan said:


> I ended up using 1mm sheet - and you cannot make it move by jumping up and down in the center of a panel
> Also you really never put any load there!
> There is a cross member in front of the seat - you naturally put your feet on that
> 
> ...


Very helpful, thank you. Yeah, I never really put my full weight on the floor of my truck either. I wasn't planning to have a cross member there in mine, but it sounds unnecessary. And if it buckles in an unsightly way I can replace the panel easily enough. 

You're entitled to do what you like, of course, but I think it would be really great to just spend five minutes or whatever walking around the car and telling us what and where everything is. We've gotten a lot of still pictures of the car, and a lot of video of you driving it, but I think video of walking around the car would be better for really getting an idea of how everything is set up.


----------



## MesquiteTim (Sep 30, 2021)

Sheets bonded to structure with hysol epoxy followed by rivets is a tried and true method for race cars and aircraft. It's easy and fast.


----------



## piotrsko (Dec 9, 2007)

Duncan said:


> Interesting idea
> 
> I might have a word with the local track and see if there is a "racing course" I could go on


Across the street 90 year old: "stop learning and you might as well just die."

We now return you to your regularly scheduled chat.


----------



## Darxus (May 10, 2010)

What has been your top speed in the 1/8 mile? That seems like it might be a good gearing goal. I feel like it was almost 100mph?


----------



## Duncan (Dec 8, 2008)

Darxus said:


> What has been your top speed in the 1/8 mile? That seems like it might be a good gearing goal. I feel like it was almost 100mph?


96 mph on the 1/8th - I did a 1/4 mile but I had difficulty stopping the wheelspin - 104 mph

These were with the 235/45/17 tyres


----------



## Darxus (May 10, 2010)

Duncan said:


> The Strut suspension from the Subaru works really well - but the body I made to go around the strut mountings is ugly


Post up some dimensions and ask people to help you with design?


----------



## Darxus (May 10, 2010)

Duncan said:


> Brazing the sheet was a bad idea - there are ripples brazed in in places - underneath where nobody can see them!


Do you think TIG welding would also be a bad idea, due to the potential of ripples? Or was that specific to brazing? I really like the idea.


----------



## mons2b (Nov 17, 2015)

Im wondering if anyone here has sucessfully welded to car sheet metal with a arc welder? (cheaper than other types of welders) It seems possible if you turn the welder right down and tac weld back and forth with stops to cool?


----------



## Duncan (Dec 8, 2008)

Darxus said:


> Do you think TIG welding would also be a bad idea, due to the potential of ripples? Or was that specific to brazing? I really like the idea.


The problem was the heat from the brazing - MIG or TIG should be better
There is also the rivet and glue approach - which I found tempting but chickened out as I was not sure about getting it through our certification process


----------



## Duncan (Dec 8, 2008)

mons2b said:


> Im wondering if anyone here has sucessfully welded to car sheet metal with a arc welder? (cheaper than other types of welders) It seems possible if you turn the welder right down and tac weld back and forth with stops to cool?


Yes I have done a fair amount of that in the past - it requires much more careful preparation than gas welding but it is doable


----------



## Darxus (May 10, 2010)

I know you've increased your tire diameter to decrease motor RPMs, is it worth changing diff gearing? Did the increase in tire diameter noticably decrease your low speed power at all? Seems like you have plenty of it?


----------



## Duncan (Dec 8, 2008)

Darxus said:


> I know you've increased your tire diameter to decrease motor RPMs, is it worth changing diff gearing? Did the increase in tire diameter noticably decrease your low speed power at all? Seems like you have plenty of it?


Not really
I went from my 195/60/15 to 225/45/17 Nittos to get more grip - THEN I went to 235/45/17 Nexxens to drop the revs a wee bit but mostly so that I could use the Nittos on the front when on the track

195/60/15 --- 518/km - initial -- RPM at 96 mph (153 kph) - 5436 rpm
225/45/17 ---- 502/km - 3% larger RPM at 96 mph (153 kph) - 5248 rpm
235/45/17 ----- 495/km - 4.6% larger RPM at 96 mph (153 kph) - 5175 rpm

I'm having difficulty getting the Nexxens to grip - the slightly smaller Nittos appear to have more grip - so that is the limit - not the available torque

A taller diff might help - If I see one I will grab it - currently a 4.1:1 Subaru limited slip diff


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## Duncan (Dec 8, 2008)

Duncan said:


> Not really
> I went from my 195/60/15 to 225/45/17 Nittos to get more grip - THEN I went to 235/45/17 Nexxens to drop the revs a wee bit but mostly so that I could use the Nittos on the front when on the track
> 
> 195/60/15 --- 518/km - initial -- RPM at 96 mph (153 kph) - 5436 rpm
> ...


On the 1/4 mile I got to 104 mph (no traction at the start)
195/60/15 --- 518/km - initial -- RPM at 104 mph (168 kph) - 5946 rpm
225/45/17 ---- 502/km - 3% larger RPM at 104 mph (168 kph) - 5762 rpm
235/45/17 ----- 495/km - 4.6% larger RPM at 104 mph (168 kph) - 5682 rpm

No chance of getting there with the 15 inch wheels! - no grip
I intend to try the Nittos at the next meeting

The chief forklift motor Guru (Major) has said that my motor "should" be OK at 6500 rpm !!!
At 6000 rpm with the Nittos I would be doing 175 kps - 109 mph

At 6500 rpm - 189.6 kph - 118.5 mph


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## Duncan (Dec 8, 2008)

Went Drag racing on Sunday
Great day out
I joined the local club so they put me in their shoot out - randomly selected lanes and opponents
First run against a turbocharged 5 liter Mustang - I won
Second run against an M3 BMW - I won
Third run against a supercharged and nitro Falcon - I won
Fourth Run - this guy had a bloody parachute bolted to the back of his EVO - I lost!

I only have the times for the last run
1/8th mile - 7.987 - 95.1 mph
1/4 mile - 12.218 - 109.5 mph

The EVO nearly broke into the 8's - 9.01 and 157 mph

109.5 mph is 6045 rpm - I think I need slightly taller tyres


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## remy_martian (Feb 4, 2019)

Did you note the EVO's time/speed in the eighth?


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## Duncan (Dec 8, 2008)

remy_martian said:


> Did you note the EVO's time/speed in the eighth?


It did 5.967 and 125.4 in the 1/8th

It was going a lot faster than me at the end but when he opened the parachute I was leaning hard on the brakes to stay behind him - then he stopped to remove it and I tootled past him and around the rest of the track
This drag race was set up as part of the Teretonga circuit so after the drag bit you are meant to drive sedately around the rest of the circuit - which of course is what I did!


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## Duncan (Dec 8, 2008)

On Saturday we had our first Autocross of the new year

Gardners Autocross - in a paddock owned by the Gardner family

It was superb - great fun


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## Duncan (Dec 8, 2008)

A couple of autocrosses - video on my Youtube page

Last Sunday we had a triple event - 1/4 mile drags - grass autokhana and tarmac autocross

Tried something new for the drags - 40 kg of sand in the boot 

Made a HUGE difference - ended up with an 11.75 !!! - the next fastest guy was 12.54 

The grass event was a wee bit bumpy but fun

Then in the Autocross the organizer asked if I would take a passenger - I said yes and took one of the lady firefighters 
(took the sand out)
Made a surprising difference - the car felt much better with a passenger - I ended up 4th - I'm normally more like 14th

With that behind me I went to the Good Friday Drags - used the sand again but could not quite get below the 12 seconds - the Autocross club uses a timer that starts when the car breaks the beam - which means that my 0.3 seconds reaction time doe not count

Still had a great time
First run was against a supercharged V8 T bucket - his reaction time was better than mine - we were almost level at the end but he was just in front
Then a nice newish white Falcon - beat him
Then another supercharged V8 T bucket - beat him

My last run was against the BMW M3 that I beat last time - he had got a "chip" and some drag tyres
A great race! - he beat me by about the length of his bonnet!

Last event for this season - My device has been on the road for 9 years so its time for some paint and a bit of a rework

I'm thinking about moving some of the batteries into the boot and trying to lose a bit of weight (the car as well) 

I'm 55/45 rear/front at the moment - should I aim for 60/40 ???

Any thoughts?


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## piotrsko (Dec 9, 2007)

[\quote]
Tried something new for the drags - 40 kg of sand in the boot

Made a HUGE difference - ended up with an 11.75

I'm thinking about moving some of the batteries into the boot and trying to lose a bit of weight (the car as well)

I'm 55/45 rear/front at the moment - should I aim for 60/40 ???

Any thoughts?
[/QUOTE]
Sandbag and passenger suggests you're traction limited. Ever go rock hard on the tires and did it get worse or go softer and it got better? In my V8 pinto we ended up with 15 psi in the rear M50-15 but should have used bead locks.

Sandbag also trends towards 50/50 but moving batteries means re doing the cables which would be a can of worms. Could add a couple of ohms and reduce motor power significantly. What happens with 2 sand bags or even 3?


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## remy_martian (Feb 4, 2019)

Duncan said:


> A couple of autocrosses - video on my Youtube page
> 
> Last Sunday we had a triple event - 1/4 mile drags - grass autokhana and tarmac autocross
> 
> ...


Ask the firefighter to be your girlfriend, throw her either in the trunk or the passenger seat as race conditions warrant.


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## Duncan (Dec 8, 2008)

piotrsko said:


> [\quote]
> Tried something new for the drags - 40 kg of sand in the boot
> 
> Made a HUGE difference - ended up with an 11.75
> ...


Sandbag and passenger suggests you're traction limited. Ever go rock hard on the tires and did it get worse or go softer and it got better? In my V8 pinto we ended up with 15 psi in the rear M50-15 but should have used bead locks.

Sandbag also trends towards 50/50 but moving batteries means re doing the cables which would be a can of worms. Could add a couple of ohms and reduce motor power significantly. What happens with 2 sand bags or even 3?
[/QUOTE]
I'm thinking of increasing the voltage at the same time !
Tyre pressures
For the track events I'm using 18 psi - which seems to work
For the drag races I drop down to 9 psi - and I have paint marks of the tyre/rim to check for any movement - OK so far


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## Duncan (Dec 8, 2008)

remy_martian said:


> Ask the firefighter to be your girlfriend, throw her either in the trunk or the passenger seat as race conditions warrant.


Don't think I would get away with that! - I would be in favor but she is (I think) about half my age


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## remy_martian (Feb 4, 2019)

That's why most old guys buy Corvettes over here....


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## piotrsko (Dec 9, 2007)

remy_martian said:


> That's why most old guys buy Corvettes over here....


Wife says it is embarrassed response to lack of male endowment. She also says she is sorry for them


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## Duncan (Dec 8, 2008)

Winter is here! - no more events for a few months - so its time for a titivate

I have stripped down to a bare chassis - when I have completed my modifications its going for a sandblast and new coat of paint

Improvements
Stainless steel cycle type mudguards - the front ones to go up and down and steer with the suspension
Stainless steel sides (replace the tatty MDF ones)
Diff - I have been telling everybody it was a 4.1:1 LSD - it wasn't ! it was a 4.44:1 LSD!! - so when I thought I was doing just over 6000 rpm I was doing over 6500rpm
So either a 4.1:1 or a 3.9:1 diff is going in there
Slight modifications to the front suspension geometry - reduced castor
Front and rear suspension optimised about a 5.5 inch ground clearance
Increase the battery from 84S to 96S - with three modules in the rear of the car - part of the drive to change from 45% front 55% rear to 40% front 60% rear
Move the controller - to enable better access to the battery
New Forwards/Reverse contactor 
Charger - going back to a Garage based charger - the motorsport guys were nervous about me charging at events so I agreed not to - in which case I don't need to carry the weight
Move the 12 volt battery back to the back of the car
The front is desperate for a respray - and I'm going to modify it a little first - got to keep the Kermit the frog look
New dashboard and instruments 
I have another later Hitachi motor - I think its got a longer "barrel" and would give me more torque - I will have to decide if I should change it
Replace the tired aluminium rear panel with stainless steel
Tyre sizes - I'm going to 225/45/17 all round - the 235/45/17 I did have on the back were a bit of a disappointment and that extra cm makes the rear wheel arches more difficult 

So this will keep me out of mischief for a while


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## remy_martian (Feb 4, 2019)

Stainless is heavy - real men use titanium...


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## Duncan (Dec 8, 2008)

remy_martian said:


> Stainless is heavy - real men use titanium...


Cheapskates use stainless - or possibly aluminium


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## MattsAwesomeStuff (Aug 10, 2017)

Duncan said:


> Cheapskates use stainless - or possibly aluminium


I have a mentor who, whatever he suggests, I start thinking about a halfassed step down from it as sufficient.

He suggests welding? Bah, JBWeld should hold.
He suggests JBWeld? Ehn, duct tape or superglue.
He suggests steel? Aluminum.
He suggests aluminum? Chunk of wood.
He suggests wood? Cardboard.

I'm usually wrong but only after a while. Always worth a chuckle, and most of what I build is just goofing off for a laugh around the shop anyway.


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## remy_martian (Feb 4, 2019)

Welding is cheaper than JB, lol...


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## piotrsko (Dec 9, 2007)

Welding is also stronger than JB.

Since his firefighter friend refused to be a trunk weight, stainless back there isn't a bad choice


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## Duncan (Dec 8, 2008)

My Device is completely in pieces - for its rebuild

Looked at the armature - oops - is that solder "leaking" out of the joints??

I have a spare motor - its a model after my old one - the armature and the barrel with the field coil is 16% longer than the present one

I'm going to change
(1) Diff from 4.44:1 to 3.9:1
(2) Voltage from 340 volts (84S) to 390 volts (96S)
(3) Move 50 kg from the front to just behind the rear wheels
(4) Fit the "new" 16% longer motor - ?????

Bodywork - stainless steel sides and back , cycle type front guards

I currently have a 36 volt Forward/Reverse contactor - which sticks sometimes

I have a brand new 48 volt Forward/Reverse contactor - I'm using a small electronic module to raise my 12 volts to enough to drive the 36 volt coils 

Is there a beefier DC voltage increase module that could boost 12v to enough for the 48v coils


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## remy_martian (Feb 4, 2019)

What the....








?

How many amps you need at the 48V? Why aren't you dropping it down from the HV battery?


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## Duncan (Dec 8, 2008)

remy_martian said:


> What the....
> View attachment 131146
> 
> ?
> ...


I'm keeping the two systems as separate as I can - for safety 
The contactor coil appears to draw 0.4 amps when it "clunks" 

Don't know what is happening there its where the Comm connects to the armature windings - it looks as if its starting to come apart - the solder is being thrown out of the joint

I suspect its the 1/4 mile events that are "pushing the limits"


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## remy_martian (Feb 4, 2019)

That looks like an arc gouge in the photo I annotated, which is why I asked...the photo doesn't do justice to a live inspection.

I thought the 48V was for the field coil. That's easily shut down no matter what battery it's sourced from.

I suggest silver soldering it all (for strength) with a high melt temperature solder....maybe even bronze brazing it.


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## Duncan (Dec 8, 2008)

remy_martian said:


> That looks like an arc gouge in the photo I annotated, which is why I asked...the photo doesn't do justice to a live inspection.
> 
> I thought the 48V was for the field coil. That's easily shut down no matter what battery it's sourced from.
> 
> I suggest silver soldering it all (for strength) with a high melt temperature solder....maybe even bronze brazing it.


It does look like an arc gauge - its actually less clear in real life 
I'm thinking about putting the other motor in just now - stripping that one down and resoldering it could well be a good idea
When I do take it apart I will be able to get some better pictures

Motor is series wound - so the field coil just gets the same 1200 amps 

There will now be a delay while I make my first trip back to the UK for 14 years - I'm going to skip the rest of winter and have it as summer in the UK it will be spring when I get back!


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## remy_martian (Feb 4, 2019)

It would seem to me to be a lot easier to put a relay on your contactor control (I assume that is what forces 48V?) and get a 12V coiled contactor, or 2 or 3 🤓


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## Duncan (Dec 8, 2008)

remy_martian said:


> It would seem to me to be a lot easier to put a relay on your contactor control (I assume that is what forces 48V?) and get a 12V coiled contactor, or 2 or 3 🤓


You know me - always doing things the odd way

I have a forklift reversing contactor - this is number 3
Number 1 came with a tatty old forklift 10 years ago - worked with 12v and died about 3 years ago
Number 2 was a second hand unit off a larger forklift - with 36 volt coils - works using "2587 boosters"
But has started hanging up - burning the contacts for some unknown reason.......

Number 3 I splashed out on the heaviest Allbright contactor I could find - new! - its 48 volts
I could swap the coils with number (2) - but the contacts appear to be in a sealed box so I don't want to break the seal - it may not be air in there 

The "controller" is just two switches 

The crude way would be to run a 48 volt battery (I have a number of left over Headway cells) just for the forward reverse contactors 
Or stick to my 12 volt battery (Headway) and add a 36 volt battery to give 12v for all of the ancillaries and 48 volt for the forward/reverse contactor


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## remy_martian (Feb 4, 2019)

There's a used one...



Amazon.com


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## Duncan (Dec 8, 2008)

remy_martian said:


> There's a used one...
> 
> 
> 
> Amazon.com


Thanks !!

I have ordered one - this is exactly what this site is all about - the external brains trust


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## Duncan (Dec 8, 2008)

Hi Guys - definitely going with the later Hitachi motor
And I'm going to fit forced air cooling

This is what the brushes from my old Hitachi motor look like


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## remy_martian (Feb 4, 2019)

The air cooling will only blow the plasma arc out - you need a liquid jacket, imo. 

Not enough mass in air to move your kind of heat.


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## Duncan (Dec 8, 2008)

remy_martian said:


> The air cooling will only blow the plasma arc out - you need a liquid jacket, imo.
> 
> Not enough mass in air to move your kind of heat.


All true - but probably better than just using the motor's fan which is what I have been using so far!!

The truth is that doing a 1/4mile at full bore is probably a step too far - but I do want at least one 11 second run at the actual drag races before I go back to just doing Autocross


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## remy_martian (Feb 4, 2019)

If you're going to do 11 second pulls, thermal mass, not air cooling, is the way to do it. Maybe do a phase change setup using paraffin wax.

Air cooling between runs, ok. During is peeing in the wind.


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## Duncan (Dec 8, 2008)

remy_martian said:


> If you're going to do 11 second pulls, thermal mass, not air cooling, is the way to do it. Maybe do a phase change setup using paraffin wax.
> 
> Air cooling between runs, ok. During is peeing in the wind.


Probably right
I intend using the blowers to drop the temperatures of the hot bits by a few degrees before the run - keep them running during the run and after the run to speed the cooling

Don't fancy paraffin wax in next to the hot bits - or ice/water

CO2 might be possible


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## evmetro (Apr 9, 2012)

Glad to see you are still at it. Haven't been around for awhile, but I think I might be getting into a new project myself. Hope all goes well with your Device!


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## piotrsko (Dec 9, 2007)

Hmmm cooked comm with bonus arc erosion on the brushes all done in 11 seconds? Looks like lifesytyle abuse to me.
Are you sure the new motor is going to absorb that new system voltage without zorching the comm? Looks like you are close right now. 
Contacts only arc on opening, they weld on closing. Quit being so cheap and get yourself a rated quenched contact high power contactor. Panasonic makes lovely ones for the money but there are other manufacturers.


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## remy_martian (Feb 4, 2019)

A homebrew air blast system on the brushes could work for Mr Cheap in extinguishing the arc, given it's 11 seconds.

Just need a SCUBA, or a few paint gun, tank(s) and some well-placed nozzles. The air/CO2 should not only blow out any arc, but its expansion should chill the F out of what it's aimed at.

The blowout sequence has to start up a few dozens of milliseconds before arc start or you may wind up fusing carbon into the copper from the CO2.

This should also work on an open contactor.


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## piotrsko (Dec 9, 2007)

So perhaps a 1lb computer style CO2 fire extinguisher blasting into the motor cooling inlet for each run starting on perhaps the green detection with motor idling? How about a replacement can of oil-less Freon or does that do weird breakdown stuff to high current devices? Asking for a friend....

Afaik, 1/4 mile and cheapo never mixed in my experiences


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## remy_martian (Feb 4, 2019)

I was saying it should be directed into the contact area. Merely blasting it into a coolant inlet I'm not sure will do much to deter/quench a plasma/arc as it initiates. The cooling is a secondary benefit.


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## piotrsko (Dec 9, 2007)

Misunderstood the arc quench aspect then. I thought flooding the entire area with semi-liquid C02 would accomplish that.


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## remy_martian (Feb 4, 2019)

Might...

But the main reason for adding CO2 to Argon for MiG is conductivity, isn't it?


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