# Aussie EV Autocross Special II



## galderdi (Nov 17, 2015)

I am creating this new thread for my second EV project.

I am still competing in my first EV (The Batt mobile). I will continue to update that thread until I decommission that car (probably at the end of 2017)
http://www.diyelectriccar.com/forums/showthread.php/autocross-ev-special-166009.html


This new thread is to share my progress on the new project. My direction has changed a few times during the planning phase.

Originally it was to be a totally new car, single seat, Front wheel drive, with a target weight of around 300kg.

I have now decided it will be single seat but a bit bigger than the previous idea and will be mid engined and rear wheel drive. I am confident the weight will be less than 430kg but I am not sure exactly what it will end up being.


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## galderdi (Nov 17, 2015)

Here are a couple of pics of the progress so far.

The idea is to take maximum advantage of the torque by making it rear wheel drive. I have decided to re-use my existing motor, gearbox, controller and batteries to ensure I still have the same power but with reduced weight.

Another key improvement will be the rear suspension geometry which I got totally wrong on the first car.


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## galderdi (Nov 17, 2015)

These mockups are using a spare gearbox that is identical to the one in my first car. The bucket represents the motor (I tell people it will be a 20L motor  )

As you can see I will still sit on the right side of the car with a gear shift in the centre. The batteries will sit down the left side and as close to the firewall as possible.

I will have passive steering on the rear wheels. I will have the ability to dial it up or down. I will increase it for motorkhana where you want the back end to slide sideways. I will decrease it for khanacross where you want maximum grip through corners.

I have purchased a reversing contactor and I have programmed an Arduino to control it and the throttle. This will allow me to switch it fast but in a controlled sequence to protect the key components.

The car is 160mm narrower than the old car and 50 mm lower. The length will be about the same. 

As I mentioned I am aiming for sub 430kg. Some people are thinking it will be more like 330kg but I think that is too optimistic.


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## galderdi (Nov 17, 2015)

Its a little dificult to form a mental image of the finished product from these pictures. But if you think of a rather squarish / agricultural, single seat version of a Ford Indigo without the front wing and add a full roll cage.


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## Duncan (Dec 8, 2008)

Hi
Looks like fun - I do like RWD - but then my old mini FWD was also great fun

What was your gearbox again?

Did you think about going to the layout I used with the Subaru diff and direct drive?

I can spin my rear tires - and I got an LSD with the Subaru bits

Looks like you will be sitting about a foot further forwards (compared to the rear wheels) than I do
What front suspension are you going to use?


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## galderdi (Nov 17, 2015)

Duncan said:


> Hi
> Looks like fun - I do like RWD - but then my old mini FWD was also great fun
> 
> What was your gearbox again?
> ...


 Going purely by stats FWD is quicker in my sports. But I don't think it is true for EVs. One reason is there is less weight over the front wheels and the other is that I am losing the advantage of the torque through wheel spin. 

So I have decided to take full advantage of the launch by makign it rear wheel drive.

The gearbox is a 5 speen Nissan N13 box (LSD variant).

Yes I have a couple of the Subi diffs. But goign down that path would have meant a lot more expense and tiem to achieve the correct outcome. Mostly because of the custom drive shafts required and some way of bringing the gearing down to what I need. But it is still on the cards for my next project using my 8 inch motor.

The lower control arms will be pulsar n13 on all 4 corners. The upper control arms will be home grown same as last time. All 4 corners will be similar to the front of the last car with the shocks sitting up over the top. The new front will sit a lot lower as they won't have to sit over the motor and gearbox.

I will be concentrating a lot more on Aero too. with no motor and gearbox out front I can make the airflow much better from front to rear. The floor plan will be entirely flat (not even a bolt protruding through). I will also have a cover over the left side of the car from the dash all the way back over the motor. Eventually I will also add my big GTR wing over the back.

The current car is fairly quick so I can't wait to experience a lighter version with the same power and even better launch.


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## brian_ (Feb 7, 2017)

galderdi said:


> Going purely by stats FWD is quicker in my sports.


I'm not sure how you are analyzing the data, but I think autoslalom is dominated by front wheel drive simply because the vast majority of small and light cars are front wheel drive.



galderdi said:


> The gearbox is a 5 speen Nissan N13 box (LSD variant).


I think the transmission could be valuable, compared to a single-speed configuration, even if it is never shifted during a competition run. The gear can be chosen to suit the course... like changing gearsets in a quick-change, but much cheaper.


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## galderdi (Nov 17, 2015)

The data I am refering to is the outright record times for all the Australian Motorkhana championships. 90% of the records are held by front wheel drive cars. 

But 100% are held by specially build motorkhana vehicles (front or rear wheel drive). In other words when we choose to build a motorkhana car we get to choose between front or rear wheel drive. So its not really driven by car manufacturers at all.

I think you hit the nail on the head regarding the gearbox. If money were no issue of course it would make sense to remove the weight of the gearbox and have quick change gears. But I am on a super tight budget so the whole car (The current car) is cobbled together based on whatever I can find from wrecked cars and whatever I can make myself. The new car won't be too different from this. But there are a few things that will be a little less aggrecultural like the suspension mounts where I will be using a fair amount of Rose joints.


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## brian_ (Feb 7, 2017)

galderdi said:


> The data I am refering to is the outright record times for all the Australian Motorkhana championships. 90% of the records are held by front wheel drive cars.
> 
> But 100% are held by specially build motorkhana vehicles (front or rear wheel drive). In other words when we choose to build a motorkhana car we get to choose between front or rear wheel drive. So its not really driven by car manufacturers at all.


Interesting!  Thanks for the insight.

In every form of motorsport I've seen - including autoslalom - front wheel drive is distant third choice of drive configuration for purpose-built competition vehicles, behind rear wheel drive and all wheel drive. Motorkhana does appear to be unusual - I had not heard of this sort of event as competition (with reversing, etc) in recent decades, although there was gymkhana before my time.

I see that in a random set of motorkhana rules that I found online (for Western Australia), FWD and RWD specials are in separate classes. Often people choose a class for the competition, rather than choosing a design and falling into a class as a result. If the fast cars are in any class, those wanting to race against them choose the same class.

Our autoslalom events (in Canada) have no reversing and are on paved surfaces; rallycross runs on mixed surfaces.


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## galderdi (Nov 17, 2015)

brian_ said:


> Interesting!  Thanks for the insight.
> 
> In every form of motorsport I've seen - including autoslalom - front wheel drive is distant third choice of drive configuration for purpose-built competition vehicles, behind rear wheel drive and all wheel drive. Motorkhana does appear to be unusual - I had not heard of this sort of event as competition (with reversing, etc) in recent decades, although there was gymkhana before my time.
> 
> ...


Yes it is a bit unusual and I believe it also may be a dying sport unfortunately. As it relies on a decent piece of sealed suface in an area where engine and tyre noise is not an issue. Once upon a time a shopping centre car park was perfect. But these days they are open on weekends and usually have the carpark all divided up with gardens, shade sails etc. 

Motorkhana can be held on dirt or grass but usually those are more for fun rather than championship status as the surface changes so quickly.

So I am trying to cover off hillclimbs, autocross and khanacross in the same vehicle. But it would be nice to get in the record books as the only electric to win the championship if the sport does die. Don't get me wrong I hope it doesn't die as it is a great entry level sport and is awesome for kids learning to handle a car.

All wheel drive in not allowed in motorkhana unless it was manufactured that way as a production car. WA run under the same rules as us. Yes we have front and rear wheel categories. Rear wheel drive actually get a handicap advantage to level the playing field a little. The stats I am refering to are outright (not allowing for handicap)

You can see the stats here: http://motorkhana1.webs.com/AMC_Times.pdf

The official rules are managed through the Confederation of Australian Motor Sport (CAMS)

I do think that any advantage that I might stand to gain by being front wheel drive is then more than lost through front wheel spin on launch thus losing all the advantage of the torque. By makign the new car rear wheel drive I can take better advantage of the torque during the launch.

Google "Full Charge Motorsport" to see some of my videos. 
But make note there is a mix of motorkhana and khanacross in there.


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## galderdi (Nov 17, 2015)

Here are the latest pics of my latest project. It is basically the same concept as last time except it is totally different  

This time it will be around 440KG, rear wheel drive, mid engined, narrower, better aero, better suspension design. I can't wait to drive it. 

I still have a fair amount of work to have it ready for the first event on Feb 11. I will provide another update soon.


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## Duncan (Dec 8, 2008)

Looking absolutely magic!


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## galderdi (Nov 17, 2015)

Thanks Duncan. I am fairly happy so far. Lets hope it performs as good as it looks.


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## galderdi (Nov 17, 2015)

Here are the latest pics of my new car. I am close to having it running. But I had some delays with steering components.


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## brian_ (Feb 7, 2017)

Looks good! 


galderdi said:


> ...
> As I mentioned I am aiming for sub 430kg. Some people are thinking it will be more like 330kg but I think that is too optimistic.


Now that it is complete, have you had a chance to weigh it?


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## Duncan (Dec 8, 2008)

Excellent
Half the weight of the Device - and it looks like a bit more rear biased

I look forward to seeing the front and rear weight and what it goes like

I sit a good bit further back and my front wheels are a good bit further forwards - I suspect that your layout will be gentler on the driver


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## galderdi (Nov 17, 2015)

Thanks guys.

I think the weight distribution is misleading. The motor and gearbox sit just infront of the rear axle. The batteries are roughly the same weight and sit between the half way point and the front axles (somewhat compensating for the motor and gearbox). Then my weight will be just to the rear of the centre point. The really good news is that there is almost no weight hanging out past either axle. So as long as I can get enough weight on the front wheels to hold them down I think it will work well. It has been concerning when it severely understeers as I push it around my yard. But that was without the batteries, without me and also without a wheel alignment. So I hope to see a fair improvement as I load up the front half of the car.

It's not fully complete just yet. If I am lucky it will be finished in the next two weeks. I am not sure I will get a chance to weigh it before Feb 11 but I am sure I will get to weigh it soon after then.


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## brian_ (Feb 7, 2017)

galderdi said:


> The motor and gearbox sit just infront of the rear axle. The batteries are roughly the same weight and sit between the half way point and the front axles (somewhat compensating for the motor and gearbox). Then my weight will be just to the rear of the centre point. The really good news is that there is almost no weight hanging out past either axle.


Centralized mass, for a low polar moment of inertia, is great for transient response. That and short wheelbase seem well-suited to this type of competition. It should be good. 

The layout is similar to the road racing Cobra described in this forum... but improved by placing the motor ahead of the axle rather than behind it. All of the components are different; it is only the layout which is similar.

A rear-biased weight distribution is good for drive traction, and not necessarily a problem for handling, depending on tire selection and suspension design. Too extreme is bad, of course.



galderdi said:


> It's not fully complete just yet. If I am lucky it will be finished in the next two weeks. I am not sure I will get a chance to weigh it before Feb 11 but I am sure I will get to weigh it soon after then.


There's no rush on the weighing, of course; it's just curiosity. I am looking forward to hearing about both the weight, and the weight distribution (both front:rear and left:right).

I am also curious about wheelbase, track, and tire sizes. Sorry if those details were already given somewhere - I may have missed them.


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## itchyback (May 28, 2014)

Looking good! I cant wait to see how it goes!


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## galderdi (Nov 17, 2015)

Thanks Itchy.

Brian, The front track is slightly wider than the rear track. This is to minimise the chance of the rear wheels taking out a flag as I turn around it (more so for tighter corners). Also I will usually be running larger tyres on the back than the front, so the difference between the two won't be much.

The wheels and tyres on it in those latest photos are just to move it around during construction. 

I have 3 pairs of semi slicks (think super soft road tyres). These are all 205 wide and on 15 inch wheels. I will use these in the wet or for events that don't matter.

For the serious events I have 1 set of slicks (uncut wets). The fronts are Hoosier 205 wide and the rear are Dunlops and are 250 wide. All are 15 inch wheels.

Weight bias L to R will be firmly to the right as I am 120KG and the batteries are about 60KG. I am putting the Auxilliary battery up in the nose on the left side to help compensate. But the chassis is quite narrow so all the weight is close to the centre line. I don't expect this to be much of a factor.


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## galderdi (Nov 17, 2015)

Oh I forgot to mention you can see the slicks on the car in the previous set of photos posted on Jan 10th

Wheelbase is an interesting question.

We have a minimum wheelbase in our sport. It helps prevent someone turning up in a go kart. 
But my wheelbase is quite a bit longer than the minimum for a number of reasons:

I am 6 foot 4 so I need a fair amount of leg room
I have opted for a full cage. Due to the minimum angles for the cage joints it dictates where the cage feet end up (any smaller would result in joint angles too accute)
In the previous car I had some clearance issues on the front wheels at full lock. I also had some clearance issues on the lower control arms. So this time around I pushed the front wheels forward about 8 inches to avoid these issues.
Component packaging has been a real challenge. I have done fairly well on a lot of areas. In particular fitting the motor and gearbox in the space under the cage. But the required space in the chassis is dictated by the batteries, gear lever, 2 handbrakes, and all the electronics. As it is I have found a major weakness in my original design. The space behind the batteries was reserved for all the electronics and switches. But now that I can sit in it and check the layout I find I can't twist far enough to operate the switches. I am having to re-think the placement of these items. I am currently thinking the switches etc will be in the panel (yet to be added) between the driver and the batteries. But the depth of the components may become an issue. I will find out in the next few days.


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## Duncan (Dec 8, 2008)

Right/left weight bias

Are you going to corner jack the front right to try and compensate for your weight?


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## brian_ (Feb 7, 2017)

galderdi said:


> The front track is slightly wider than the rear track. This is to minimise the chance of the rear wheels taking out a flag as I turn around it (more so for tighter corners). Also I will usually be running larger tyres on the back than the front, so the difference between the two won't be much.


The wider front track will also allow for more load transfer by the lightly-loaded front end before lifting the inside tire. You can claim that you carefully planned for this. 



galderdi said:


> The wheels and tyres on it in those latest photos are just to move it around during construction.
> 
> I have 3 pairs of semi slicks (think super soft road tyres). These are all 205 wide and on 15 inch wheels. I will use these in the wet or for events that don't matter.
> 
> For the serious events I have 1 set of slicks (uncut wets). The fronts are Hoosier 205 wide and the rear are Dunlops and are 250 wide. All are 15 inch wheels.


Thanks for the details. I did see the likely competition tires in the earlier image.



galderdi said:


> Weight bias L to R will be firmly to the right as I am 120KG and the batteries are about 60KG. I am putting the Auxilliary battery up in the nose on the left side to help compensate. But the chassis is quite narrow so all the weight is close to the centre line. I don't expect this to be much of a factor.


The left sidewall could be further outboard, shifting the rear battery module outward and perhaps allowing the driver to shift a bit left... but of course it's a little late for that. 
The placement of the motor on the right side, which is determined by the transaxle layout, is likely aggravating the right-side bias. The only obvious fixes for that are:

unequal-length half-shafts (longer on the right), shifting the entire powertrain left
transaxle configured for left-side engine, placing the motor on the left; Honda is the most common source
swap the driver and battery side-to-side, so the driver bias and the motor bias partially cancel out... a little late for that, too
I'm sure that the current setup will work fine.


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## brian_ (Feb 7, 2017)

galderdi said:


> We have a minimum wheelbase in our sport. It helps prevent someone turning up in a go kart.


The legal minimum here for autoslalom used to be 185 cm, for the same reason. In practice, even custom-built competition vehicles (which have always been rare here) are not that short... generally due to packaging. The smallest car that I remember was an old Formula 500 (500 cc motorcycle-engined single-seater), updated with a modern one-litre bike engine; that still would have had more than 185 cm wheelbase.


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## galderdi (Nov 17, 2015)

Duncan, Thanks for the suggestion but I don't know Jack and I doubt anyone would be willing to sit out on the suspension to help with weight distribution.

Seriously though. I will take the corner weights once it is finished and decide from there.

Brian, You provide Such detailed responses. I appreciate the input.
The control arm length idea is a good one. 
I had considered driving from the left side but the position of the gear shift dictated that arrangement. Which in turn was dictated by the length of the available drive shafts.
I could also loose a few pounds if I was more serious. All these things are on the cards. But first I will just see how it performs. I expect it will be fairly competitive straight out of the box. My biggest fear isn't L to R bias it is more about understeer.


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## galderdi (Nov 17, 2015)

Hey guys I am looking for some input.

I compete in two main forms of motorsport. 

One is Khanacross, which is much like Autocross. Conducted only in a forward direction and with moderate speeds reaching around 100Kmph / 60mph. For this I will be advancing the timing and for manouvering the car between runs I can use the mechanical reverse.

The other sport is Motorkhana. Motorkhana is lower speed (max of about 60Kmph or 35mph) but does involve reversing at speed. Reversing probably only represents about 5-10% of the total run time. And the time taken to switch between forward, reverse and back again is a factor in the overall performance. Until now I have been using the mechanical reverse. I had some issues engaging reverse in the old car which often cost me multiple places in the results. 

I believe I have resolved the reverse engagement issue by constructing my own gear selector and linkage system. At least for the initial events this is how I will operate.

I had considered installing an electric reverse. I have all the gear ready to go. I have a circuit to control the timing of the switch to ensure there is enough delay as I can't leave it to the driver as the driver will be trying to switch super quick. But I decided to hold off for the moment. One reason is the time required to install it all. But also I am concerned about the amount of arcing with the motor advanced in the wrong direction when in reverse.
Back when I was running the motor with neutral timing I did experience significant arcing as the revs increased. 

For khanacross I would definately just advance the motor and use the mechanical reverse....no issues.

But for motorkhana I think I have some decisions:
1) Forget about the electric reverse, advance the motor and use the mechanical reverse.
2) Advance the motor so it runs well in the forward direction. Then, when in reverse, introduce an arteficial throttle limit in a hope that it won't go fast enough to arc.
3) Leave the motor neutrally timed for motorkhanas and maybe leave it in a higher gear so it won't arc in forward or reverse. Then use the electric reverse rather than mechanical reverse. 

Any thoughts?


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## Duncan (Dec 8, 2008)

Hi
My tuppence worth - I hope a real expert like Major comes in and corrects me

Even the low speed events will be using more revs and volts than the forklift does so I think that you do need to advance even for those

Which means that you do not want to be overspeeding in reverse with the motor advanced!

So overall - advance the motor and use your mechanical reverse gear

Do note that the advance does rob you of torque at low rpm - I believe my 8 degrees advance cuts down my initial torque by about 20%

On a different subject the "Nitto" rear tyres I bought worked beautifully - more grip and progressive breakaway


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## galderdi (Nov 17, 2015)

I totally agree with the advice.

I did run the motor with 0 advance for a short period early in it's development. It did arc but only once the revs increased. Generally this was in 1st gear. 

So I still think it is worth a test with the motor on 0 advance but starting from 2nd or even 3rd to ensure the revs never get to that arcing point. It wouldn't have worked in the old car because of the extra weight. But I am hoping the extra torque from 0 advance plus the reduced weight (around 100kg lighter) might be enough to compensate for starting in the higher gear. 

If there is any sign of arcing I will scrap the idea and revert to mechanical reverse with the motor advanced.


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## galderdi (Nov 17, 2015)

I got the car running last night. This is a huge releif as it means I am fairly certain of competing in the event this Sunday. I do still have a few things to do but they are fairly minor.

I also weighed the car (As best I can). The car came in at 480Kg with weight distribution of about 44/56 toward the back which isn't too bad.

The first drive felt very good. I think it has promise. I just need to do a wheel alignment, brake bleed and some minor additions to be ready for Sunday. I should have some good videos early next week.


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## Duncan (Dec 8, 2008)

Excellent!
And we have our annual Cobra 1/8th mile drags this sunday (4th March) as well so I will see how the Nitto's do!


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## brian_ (Feb 7, 2017)

galderdi said:


> I also weighed the car (As best I can). The car came in at 480Kg with weight distribution of about 44/56 toward the back which isn't too bad.


Great, thanks 
The weight bias sounds very workable to me.


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## galderdi (Nov 17, 2015)

Agreed. Those measurements were without me in the car. I have checked the centre of mass for the average person and it is around 56% up their total height. I also checked the weight of a person's legs as a percentage. I think my body will add an extra 24 kg toward the front of the car and an additional 96kg towards the back. This would alter the bias to something like 39/61. Not ideal.

I think I will turn my seat around so I can shift the majority of that weight forward.


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## galderdi (Nov 17, 2015)

Well the event was good. But it did reinforce why a practice event would have been an advantage. The car understeers severely and the front brakes lock on anything more than a slight touch. I also blew a fuse part way through my first run. 
I went for an extra run after the timing was finished for the day. It was oversteering as normal but then it suddenly gripped and snapped the back around unexpectedly. I over corrected and speared off into a culvert. It made for some gread video though.
I have some work ahead of me to somewhat neutralise the handling.

https://www.youtube.com/watch?v=kT7YvMQiqQY

https://www.youtube.com/watch?v=8lZK1kgPxh8


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## galderdi (Nov 17, 2015)

I managed 24th place outight. On the surface that isn't too impressive. However that included my first run where my fuse had blown. If I just take that run out of the equation I would have placed 10th outright. So for it's first outing I am fairly happy with those results. 

Now I just need to work on the brake bias and understeer to move my way up the standings toward the podium.


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## galderdi (Nov 17, 2015)

Just a quick update. During the first outing the new car demonstrated noticable understeer, front brake lockups, slow steering and slightly reduced launch speeds. All of these were expected at this stage in the development. 
•The understeer and front brake lockups are due to the lack of weight over the front wheels. 
•The reduced launch speed was because I have not yet installed a clutch pedal and master cylinder resulting in the need to launch in a higher gear.
•The slow steering is because I have not yet modified the steering to speed it up.


I can't do too much about the weight distribution, although I have added a second auxillary battery in the nose. This adds another 7kg to the front of the car.
This past wekend I altered the front suspension pivots to substantially soften the front. I added some more caster and some more negative camber to the front both of which should increase front grip during cornering.


I still need to:
•Reinforce the panels around the brake pedal to give a stiffer feel
•Add a brake bias adjustment to send more pressure to the back brakes and eliminate the front brake lockups
•Add a steering quickener to speed the steering rate
•Make and install a hydraulic clutch conversion 
•Finish and install the replacement handbrake handle
•Make an adjustment to the ackerman angle
The first 5 of these modifications must be complete before my next event on April 15th. I will provide another update before then.


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## galderdi (Nov 17, 2015)

I still have some fairly significant adjustments to complete. I have made some progress but have stumbed on a few items like having a bolt stuck in an awkward spot and needing to "easy out" it. Plus this little issue has meant I needed to order in some replacement bolts. I have also had some clearance and width issues etc with the latest steering rack. I have finished the new handbrake handle. I have also finished the brake bias except I have not filled the fluid, adjusted or tested the system (due to the missing bolt).

I only have one more weekend to sort it all out before my next event. The next event is a motorkhana on Apr 15. Followed by a khanacross hosted by the Lotus club on Apr 29. The lotus day in 2017 was my favourite event so I am really looking forward to this day. But I really need to have the car dialled in to have a good showing. There will be some top end Lotus and Porsche cars competing so I will be very happy with any place in the top 25% of the field.


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## galderdi (Nov 17, 2015)

We had an interesting event yesterday. It was the Motorkhana round of the Interclub challenge. We ended up with 60 entries which was our biggest in a very long time. We had a good turn out from the Porsche, Lotus, MG and MX5 clubs. But we were off to a rocky start as the Venue management had double booked us. So we had to alter our plans. It meant that the complex tests I had been memorising for the past 3 weeks were off the agenda.

My car was a real handful. I had run out of front steering adjustment during the wheel alignment last week. This left the car with significant Toe in on the front. This made it very twitchy and added to the understeer issues. It also became quite clear the handbrake will not be able to break traction as there is too much weight over the rear wheels. This isn’t an issue for the sweeping style tests but for the tighter ones it makes it very difficult and uncompetitive. You can see this in the 5th video. On the positive side the car’s acceleration was awesome as you will see in the 3rd and 4th videos. Plus I can now see that solving the steering properly may make all the difference to the car.

So the short term plans are:
· Complete the Ackerman angle modification and shorten the steering arms prior to the Lotus Lakeside day on April 29.
· Connect the Clutch pedal so I can change gears for the Lotus Lakeside day on April 29.

Long term:
· Make new upper control arms for the front to provide more caster adjustment and improved range of movement.
· Install fiddle brakes to enable separate left and right braking to swing the car around the really tight corners.

The results from yesterday will probably be released tomorrow morning.


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## galderdi (Nov 17, 2015)

https://www.youtube.com/watch?v=DHDBpP9fx3Y
https://www.youtube.com/watch?v=uJMca1QEMbk
https://www.youtube.com/watch?v=LqZEdE8aJNc
https://www.youtube.com/watch?v=-zyv8UilDqs
https://www.youtube.com/watch?v=7PaeTOUMCXo


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## Duncan (Dec 8, 2008)

Looks like great fun - and a LOT more "nimble" than my device


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## galderdi (Nov 17, 2015)

Thanks mate. I am fairly happy with it so far. I think once I get the front alignment right it will be a vast improvement. It will be so nice to actually go around a corner for once.


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## itchyback (May 28, 2014)

well done!


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## galderdi (Nov 17, 2015)

Thanks,

I placed 21st of 55 competitors (excluding those who did not complete the day). All in all it is obviously not what I had hoped for. But I did manage to beat 6 of the 11 Porsche entries. The result was to be expected considering how bad the understeer is. On the tightest of the courses (88), I was 30% slower than the faster cars. On the more open courses I was only 10% slower. These results confirm that handling is my issue.

But this is only the second outing for the car so I think it is doing ok considering the stage of it's development. I have a heap of modifications planned for the next 10 days before the next event on April 29. Hopefully I can get the car turning by then.


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## galderdi (Nov 17, 2015)

I had a ball at the Lotus day at Lakeside yesterday. The car was very unstable and not quick. But the main purpose was another opportunity to test the car. The great news is I have gone from massive/uncontrollable understeer to massive/uncontrollable oversteer. This is great because it proves that I can overcome the handling issues and eventually make the car competitive in the autocross/khanacross events at least.

I did have to retire early with a split CV boot. Not a big deal as I already had plenty of information to work with.

Even with the handling issues I managed to place 36th from 55 cars. So I am confident with a few tweaks I can be dicing with the leaders in no time.

https://www.youtube.com/watch?v=AA7EVYUd6F8
https://www.youtube.com/watch?v=V2hsGr94Gb4
https://www.youtube.com/watch?v=rZOJEE3YC-U
https://www.youtube.com/watch?v=lTcVFKXH0Lo
https://www.youtube.com/watch?v=OTfyEgYMCpU


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## Duncan (Dec 8, 2008)

Looks great fun
And catchable when it lets go - 
When I had the standard road tyres the Device would just spin

With the Nittos on the back I can feel it start to go and then catch it

The "Season" is finished here - no events until the Spring


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## galderdi (Nov 17, 2015)

Your season is finished???? We are just getting into the best part of ours. We should live in NZ for summer and Aus for Winter and have racing all year round  Now if I could just find a job to support that lifestyle.

It was sort of fun, but a nervous sort of fun. Once I get it settled it will truely be fun. It was only catchable because I slowed enough to catch it. I should have been going much quicker. But its beside the point. This event is not part of my season so I entered just to test/diagnose the car. I certainly achieved that. Now I need to make some new rear upper control arms so I can wind in some negative camber on the rear. Then any oversteer should be truely catchable.


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## galderdi (Nov 17, 2015)

I will be attending and displaying my car at the EV Expo being held at Noosa tomorrow. You can see the details at
https://www.noosaevexpo.com/


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## galderdi (Nov 17, 2015)

I will be competing in the car at the Noosa Winter Hill climb this weekend. June 9 & 10. It is my first time to this event so I do not expect to be particullarly quick.
I will be #62. I will post some videos shortly after the event.


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## galderdi (Nov 17, 2015)

I had an good weekend at Noosa. The car was ok. The batteries are on the way out but still manage to give me enough to keep going. The car is awesome off the start line. But it struggled to get any top end speed. The handling was terrible at the beginning of the weekend but I made some changes over the two days and at the end it was coming good. The first few runs were so bad I was 100% focused on not crashing so I couldn’t learn the track. The last few runs I was able to actually drive the car and start focusing on making the most of the track. My results are not great but also not embarrassing and it was a great experience.

https://www.youtube.com/watch?v=u3Mlsh2cK6Y
https://www.youtube.com/watch?v=HhoOsafWW10


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## Karter2 (Nov 17, 2011)

galderdi said:


> ....... The batteries are on the way out but still manage to give me enough to keep going. ....


 Do you mean low on charge,...or is there some other issue with them ?


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## galderdi (Nov 17, 2015)

The batteries are not lasting like they used to. Part of it is that I am pushing harder (using more amps). But even so the difference in capacity is noticable. They will keep me going for now. I will need to start charging them during my events / through the day. But I am investigating options for their replacement in the medium term. This time around I will go with more capacity and more cells in parrallel for better current capability.


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## galderdi (Nov 17, 2015)

I had a great day at the khanacross Sunday.Here are a few of my runs. The first one is in 360 degree format which isnot compatible with Internet Explorer. I am still waiting for the results. Iwon’t have won outright. But I am confident I will have won my class.


360 degree
https://www.youtube.com/watch?v=CaHJflcOGaI

Standard view
https://www.youtube.com/watch?v=9DD6UrHv5Uc
https://www.youtube.com/watch?v=NtLd-YdL9VA
https://www.youtube.com/watch?v=GjY7zD6L3nw
https://www.youtube.com/watch?v=IPqwlFQ-Ys4


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## Duncan (Dec 8, 2008)

Looks like great fun!
We only get a couple of tarmac events a year here

Those looked magic!

How are your battery voltages holding out?


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## galderdi (Nov 17, 2015)

Thnks Duncan, Yes I am quite happy overall. Still room for improvement though. Once I see the final results I will have some great data to refine my driving techniques to take advantage of the things that work best.


The batteries are not great but they will keep me going long enough to purchase replacements.


I am starting my next poject. I am building a chassis to have a crack at the Australian Salt Lake racing record for an Electric vehicle under 500 kg. I am aiming for Feb 2020


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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)




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## Duncan (Dec 8, 2008)

Hi
I have found this

https://cleantechnica.com/files/2018/08/Tesla-Model-3-SOC-Dyno-Results.jpg

It's a Tesla run on the dyno at different levels of charge - the results make sense when we think of our earlier battery conversation
With the provision that the Chevy volt chemistry has a steeper voltage/charge slope - which makes it easy to see how much charge I have left - but will make this effect even worse


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## itchyback (May 28, 2014)

great photos. Lovely looking car! so jealous of the time you have to pump out this project and then commit to another car by 2020!

How is the handling?


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## galderdi (Nov 17, 2015)

The handling at first was absolutely terrible. This was demonstrated at the first event by a bit of a moment ending up with me almost hitting a wall but instead heading through a significan culvert. The good news was the experience proved the strength of the car.


But I have been chipping away at it over the months since then. It is starting to come good.


Some of the problems I have faced have been some binding at the pivot points, insufficient travel, excessive stiffness, camber issues, caster issues, damage caused by an excursion, damage caused by another excursion.
Where it stands at the moment:
It is fairly good but only competitive enough for me to place in about the top third of my events. I think this is mostly down to handling. I am loosing a lot of momentum through the corners. This shouldn't be the case in a small, light, low car. The front is now quite soft so front grip is great. The back is softer than early 2018 but still not soft enough in my view. Under extreme load the front roll is significant but not excessive. The rear of the side being leaned on doesn't compress much (because of the stiffness). Instead the front roll is pulling up the oposite side of the rear. Eventually this results in a reduction of rear traction. 
I have a custom front sway bar. I have started to work out how/where to mount it. I hope to have it mounted this weekend. I am fairly sure it will help the back but I am a little concerned it will stiffen the front too much.
I have also started work on a front wing.


My next event is only a motorkhana so it won't prove anything much. But I am hoping to compete at the Mt Cotton Hill climb late September. That will be a better test.


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## brian_ (Feb 7, 2017)

galderdi said:


> The front is now quite soft so front grip is great. The back is softer than early 2018 but still not soft enough in my view. Under extreme load the front roll is significant but not excessive. The rear of the side being leaned on doesn't compress much (because of the stiffness). Instead the front roll is pulling up the oposite side of the rear. Eventually this results in a reduction of rear traction.


While it seems obvious that cornering on three wheels is not as fast as using all four, there are certainly circumstances where it makes sense that at maximum cornering force the inside wheel on the non-driven and light end of the car (famously the front of a Porsche 911 and commonly the rear of front-wheel-drive cars such as the VW Golf). Lifting the rear of a rear-drive car, especially one which is not front-heavy, is definitely a problem to be fixed.

With a rear weight bias, the rear should be seeing more load transfer than the front, but maybe it's seeing more than its share.

What I'm reading between the lines here is that the rear might be jacking up: if the outside rear is not compressing much but the inside rear is running out of extension travel, is the rear average (or height at the centreline) coming up? This could be a rear geometry issue.



galderdi said:


> This was demonstrated at the first event by a bit of a moment ending up with me almost hitting a wall but instead heading through a significan culvert.


After this event (as you reported in March), I wondered about the front-rear balance of both roll stiffness and load transfer due to suspension geometry (as indicated by the roll centre height). You were on top of the issues, so I didn't comment at the time.

In transient conditions, as lateral force is produced by the tires the geometry works instantly, but you don't see the effect of roll stiffness (spring and, if you use them, swaybars) until the car leans. The result can be one end gripping better initially (because it isn't doing much load transfer due to geometry), then the other end gripping better (if it gets much less load transfer due to roll stiffness) at the limit, and a difficult-to-manage change in balance as the turn-in progresses. This is especially bad in transitions between turns in each direction - in the middle of an S-bend you can have the acceleration (and load transfer due to suspension geometry) in one direction, while the car is still leaning (and thus experiencing load transfer due to roll stiffness) the other way! That first event moment looked like a transition issue.

There's also camber change - if the front and rear change by different amounts with travel, one end can lose more traction than the other, ruining balance... but you have already looked at camber change in detail.

This is all easiest to manage when front and rear have similar suspension geometry. One reason for the brilliance of the original Miata is the exceptional (for the class of car) use of double-A-arm suspension at the front and upper-and-lower arm suspension of similar camber and roll centre characteristics at the other end; it leaned a lot (because it was soft), but was always balanced. Your car has compatible upper-and-lower-arm suspensions at both ends, so this should work... if you can get all the factors coordinated.


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## galderdi (Nov 17, 2015)

Great reply thanks Brian.


Yes the centre of rear is rising mid corner. I can see it in that last photo.


I don't think there is too much of a geometry issue in the rear. I think it is more about the contrast between the softness of the front and stiffness of the back. The front is wanting to lean significantly and the only way the back can accomodate is by lifting the inside wheel.


I do think the rear is seeing a lot of load bias but it is so stiff it isn't resulting in a lean. I have already softened the back once (from 900lbs to 800lbs). But ideally I would like to soften it again (probably to 700 lbs). The problem is finding reasonably priced shocks with a clear spring rating prior to purchase. I will keep searching.


The suspension has undergone multiple significant changes since the event in March so until now I have been dealing with wildly varying results. But now it is consistant and predictable but still requires improvement to be where it needs to be. So I am confident I am nearing the end of the step changes and moving on to minor adjustments.


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## Duncan (Dec 8, 2008)

Galderdi

800 lb/inch - 700 lb/inch !!!

I'm running 100 lb/inch front and 125 lb/inch rear - with no roll bars at all

The basic logic is you measure your corner weight and then you aim for a specific natural frequency

Big old saloons have a natural frequency of 60 - 80 cycles per minute, sports cars 80 - 100 and 100 - 125 for racers

The equation in Imperial (as that is what your springs are) - 187.8 x Square root of Wheel Rate in lbs/inch divided by sprung weight in lbs

So my car has 544 lbs rear corner and 445 lbs front corner (ignoring my corner jacking)

So that gives 187.8 x sqrt (100/445) = 89 at the front 
187.8 x sqrt (125/554) = 89.2 at the rear

Apparently I should have the two natural frequencies a wee bit further apart

I have the attachments for anti-roll bars - but I don't think I need them 
On the video's I don't see any roll at all

You have some sort of mechanism rear suspension - I can't see what ratio it is but you are lighter than I am - IMHO you should be aiming at a much much lower spring rate


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## brian_ (Feb 7, 2017)

As Duncan suggested, it is the effective spring rate at the wheel (just called wheel rate for short) which is important. With his Device's struts the wheel rate equals the spring rate, but when there is a linkage (as you have) the wheel rate is the spring rate divided by the square of the motion ratio. For example, if the motion ratio is 2:1 (wheel moves twice as far as spring strokes), and you have 800 lb/inch springs, you have a wheel rate of only 200 lb/inch. Do you know the motion ratio for each end (which will vary through the suspension travel), or have you directly measured the wheel rates?


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## galderdi (Nov 17, 2015)

I don't have those measurements. I basically guestimated based on my experience from the previous car and have been adjusting from there.


I am pretty sure we are talking two different languages here. The front of my car is quite light yet 400Lbs springs were too light to hold it up. The 800Lbs I have in the back are too hard but are not that far from the mark. The rates I am quoting are based on the labels from the supplier. I suspect they are not the Lbs per inch as you have both quoted but are probably the weight they are recommended to support. I can get the rear to depress about an inch by jumping up and down on the rear structure. It is hard but not totally solid. I think 700Lbs will make a difference. Although for motorkhana I think I will stick with the 800Lbs to all the rear to break free when required. But the 700Lbs will be better for the faster events.


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## brian_ (Feb 7, 2017)

galderdi said:


> I don't have those measurements. I basically guestimated based on my experience from the previous car and have been adjusting from there.


For the motion ratio, do you know how much the spring/shock compresses for a given distance of wheel travel? With adjustable spring perches, you can just adjust them any measured amount, and see how much that changes the height of the frame from the ground. If they're not adjustable (I can't tell in the most recent photo) you can swap between two different sets of spring/shock units (as long as they have significantly different lengths when loaded. With any spring/shock units (or none installed at all), you unbolt them from one end so they're not supporting the car, support the frame with a jack, then raise and lower the jack to get a vertical suspension travel and a change in distance between upper and lower shock mounting points.

This is assuming that the shocks are working through some sort of linkage, and not mounted directly to the hub carriers or to the upper arms right out at the outboard joints.

It looks like the rear shocks might be mounted directly to the upper arms - if so, what is the distance from the inner pivot to the shock pivot, and the distance from the inner pivot to the ball joint? Sorry if you already covered this, but I don't remember... it looks like the rear suspension may have started as a McPherson strut, but with a ball joint mounted in the top of the strut tube and located by an upper arm, rather than an actual strut.



galderdi said:


> I am pretty sure we are talking two different languages here. The front of my car is quite light yet 400Lbs springs were too light to hold it up. The 800Lbs I have in the back are too hard but are not that far from the mark. The rates I am quoting are based on the labels from the supplier. I suspect they are not the Lbs per inch as you have both quoted but are probably the weight they are recommended to support.


Do you have a photo of the label, or a link to the supplier?


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## brian_ (Feb 7, 2017)

brian_ said:


> ... it looks like the rear suspension may have started as a McPherson strut, but with a ball joint mounted in the top of the strut tube and located by an upper arm, rather than an actual strut.


Okay, I went right back to post #11, where the suspension is much more clearly visible. 

It appears that yes, both front and rear suspensions are based on production McPherson strut designs. In each case, the strut is replaced by a rigid (not telescoping) tube topped by a ball joint, which is located by a fabricated tubular upper arm; that makes the tube part of the hub carrier, and the suspension and upper-and-lower control arm (or double A-arm, or double wishbone) type. In each case the springs and shocks act on the upper arms, relatively far outboard on the arm, but not all the way out to the ball joint.

The *rear* vertical tubes are long, producing an extended hub carrier design. The spring/shock units act directly on the upper arms. The shocks attach perhaps 80% of the way out on the arms, so the result might be a close to 1:0.8 ratio of wheel to spring travel (so the wheel rate would be about 2/3rds of the spring rate).

The *front* vertical tubes are shorter, producing a more conventional double-A-arm design. The spring/shock units act through bell crank rockers on pull rods, which in turn act on the upper arms. The shocks are approximately perpendicular to the bell cranks, the cranks appear have a nearly 1:1 ratio, and the pull rods attach perhaps 80% of the way out on the arms, but the pull rods don't act directly on the cranks. The overall result might be a close to 1:0.8 ratio of wheel to spring travel (so the wheel rate would be about 2/3rds of the spring rate), but with the pull rod angles to the cranks it looks like it has a falling rate (with more compression, the wheel rate drops) - this is the opposite of conventional and desirable practice.


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## galderdi (Nov 17, 2015)

Thanks again Brian, You obviously know your stuff. I am a novice but I am learning more all the time.


The photos you refered to are out of date in terms of the front design. I have replaced those shocks with longer units which has rotated the pivots about 30 degrees. The result is a longer pull rod and better movement through the compression arc. It still isn't ideal as you mentioned but it is an improvement.


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## Duncan (Dec 8, 2008)

Hi Galderdi

First thing that I would do is to get a better idea of what you have
Plug your numbers - coil size, number of coils, thickness of wire into the calculator

https://www.thespringstore.com/spring-rate-calculator.html

The critical number is the thickness of the coils - the spring rate is dependent on the forth power of the wire diameter
Don't worry too much about the material - as far as springs are concerned steel = steel 

You can make something up to actually measure the spring rate - I stopped doing that as it kept trying to kill me

As far as the geometry of the suspension is concerned the best way is to make up a "string computer" 

https://www.youtube.com/watch?v=FE8g1RDGHx4

This shows a string computer - it's not in English but just have a look at the first few frames

Basically you model your suspension with some cardboard and paper and pins

I am a "Heretic" as far as I can see "roll centers" are a load of bollocks so I ignore all that crap

But you can use the string computer to see how everything moves - to give you the difference between spring rate and wheel rate

This can be very important - many years ago a good friend bought a fancy single seater - with push rod suspension and bell cranks - it was awful to drive
So I did the string computer bit and found that the front suspension had FALLING RATE - as you rolled into a bend the spring rate DROPPED - designed new bell cranks and it was fine

I use this to look at spring rate as the car rolls and also to look at what the tyre does against the ground as the car rolls and also in dive and squat

Which the most important thing that your suspension can do - keep the tyre square to the road at all times

This book is good bible - if you can get a copy

https://www.amazon.com/s/ref=nb_sb_...ce+and+rally,stripbooks,354&crid=9S8AXI9WZH4E

Race and Rally Car Source book - allan Staniforth

Staniforth's first book - High Speed Low Cost - is also worthwhile and I would love to have a copy


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## galderdi (Nov 17, 2015)

Thanks Duncan.


I used a string computer when I designed the supension arms.
I did take roll centres into account in the design.
It has taken a while but I am now fairly happy with the angles of the wheels under load in relation to the ground. I just want a little less roll and a bit more give in the rear.


The pivots for the frnt suspension were as a result of a design change mid flight. In hidnsight I should have stuck to my original design but made my own lower control arms to utilise MX5 lower ball joints. But at the time I was not aware of that option. There's always next time right ;-)


Thanks for all the resources. Looks like I have a heap more reading ahead. 
I have to get the car out again this weekend for another motorkhana so hopefully I will get a chance to measure the springs then. For motorkhana really hard rear is a good thing as it is better for getting the rear loose. So even after I soften the rear I will swap back to the harder springs for motorkhana. 


I'll keep you informed how it all progresses.


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## Duncan (Dec 8, 2008)

Hi Galderdi

Another big mistake I made - I made my own front suspension for the front of my "mini" - based on Lancia bits 

The lancia's used steering rack with the steering arms coming out of the middle - this means that they are quite insensitive to rack height

Unfortunately that does not mean insensitive! - the car was awful - my mate showed me that if he bounced up and down on the front subframe the wheels steered 

Bump steer!

I had to lower the rack by 70 mm to get it to stop doing that!

I got very paranoid about bump steer after that! - 

Have you checked front and rear?


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## galderdi (Nov 17, 2015)

The rear bump steer is fully adjustable. For faster events I wind it up to neutralise the bump steer. For the slower events I wind it down to introduce significant bump steer. Theoretically it steers the rear out slightly under load. But in reality it doesn't lean enough to work the way I would like. But it will be better with a softer rear (every man's dream).


The front is about right. I do have an action in my list to check it accurately. But under normal conditions (without jacking it up and disconnecting the spring) I don't notice an issue. Once I test it accurately I can allow for any minor imperfections using spacers. Or worse case if spacers aren't enough I can re-make my ackerman angle brackets.


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## brian_ (Feb 7, 2017)

galderdi said:


> The photos you refered to are out of date in terms of the front design. I have replaced those shocks with longer units which has rotated the pivots about 30 degrees. The result is a longer pull rod and better movement through the compression arc. It still isn't ideal as you mentioned but it is an improvement.


Good to hear


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## galderdi (Nov 17, 2015)

Oh sorry Brian. I just realised I forgot to respond to your question about spring rate labels.


The original springs on the car were labelled (950Lbs) stamped on the spring.


The others aren't labelled. I am only referring to the details from Ebay.
Search "motorbike shock 700Lbs" or "motorbike shock 800Lbs" or "motorbike shock 950Lbs" in Ebay and you'll see what I mean.


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## brian_ (Feb 7, 2017)

galderdi said:


> The original springs on the car were labelled (950Lbs) stamped on the spring.
> 
> 
> The others aren't labelled. I am only referring to the details from Ebay.
> Search "motorbike shock 700Lbs" or "motorbike shock 800Lbs" or "motorbike shock 950Lbs" in Ebay and you'll see what I mean.


I do see what you mean. My guess would be that the "poundage" is intended to be the force compressing the unit under normal load (as you were thinking, but based on force on the spring not weight of the vehicle), or perhaps the force to fully compress it. Since the spring is usually working at a mechanical disadvantage, this value (or the total for two springs on a traditional two-shock bike rear suspension) would need to be substantially greater than the load on the bike's rear wheel. Some are listed for ATVs - the basic non-independent rear ATV suspensions had a single rear spring-shock, working at substantial mechanical disadvantage, so the load on the spring would be much higher than the total weight on the ATV's rear tires.

Some of the eBay ads list a diameter for the spring wire (e.g. 12 mm), and you can easily count the number of turns, but to complete the spring rate calculation you need the diameter of the coil. That's not all that hard to measure, so you could plug the numbers into the formula or the online calculator which Duncan linked. For an example, one unit listed on eBay as "800 pound" had 10 mm wire, 67 mm outside diameter, and 11 free turns, which would have a spring rate of 49 N/mm or 280 lbs/inch... not so extreme when used with a less than 1:1 ratio in this car's suspension... maybe roughly 200 lb/in at the wheel. A really rough guess at free length produced a maximum load of 950 pounds in the calculator, so perhaps 800 pounds could be either the normal load or the fully compressed load. The problem with free length for these things is that they are normally compressed a bit even when the shock is not installed; the preload collar changes how much.

Those "motorcycle shocks" in eBay certainly are inexpensive!


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## galderdi (Nov 17, 2015)

Hi everyone. Appologies for not posting for a while. It has been a heck of a journey (not implying it is over).


The car is coming along nicely. But it still isn't competitive. I seem to be hovering around the mid field in most results. Not bad in itself as I am usually up against some seasoned competitors in some goo cars. So as I usually say I am happy but not content.


The second last event of 2018 was the Noosa Hill Climb. It was only my second time at the event and I improved by 4 seconds. The car was still understeering but was managable. But the understeer prevents me from gaining too much confidence and holding corner speed. So I am still focused on improving that aspect of the car. Here is a video from that event:


https://www.youtube.com/watch?v=O0FDh_p_rbk


The last event of 2018 was an autocross/khanacross. But it was very very wet which emphasised the understeer to the point where is was not managable. I don't have a video for that event.


I started with a check of all the suspension geometry including Castor, camber, king pin inclination, roll centres, toe in and Ackerman angle. 
Castor was about right on the driver side but significantly more aggressive on the passenger side. This will be resolved as I complete the new front contro...l arms. 
Camber, king pin inclination and roll centres were about where they need to be. 
Toe in was correct but will need to be adjusted again as it will be impacted by all the other changes. 
Ackerman angle was a little out on the passenger side but not enough to warrant a change in the short term. The driver side was out by a bit more and I have now replaced the adaptor plate to bring it in line with the passenger side. 
I have made some solid progress on a second nose for the car. The first nose is for lower speed events where it is an advantage for the tyres to be in front of the nose. The new nose is sleeker, and will include a wing for additional downforce (maybe). The two noses are interchangeable depending on the upcoming types of events. The nose and wing are structurally complete and just need the panels to be added. 
I have created some ballast in the form of a 10kg lump of lead. This can be added or removed depending on conditions. I intend to only include it in wet weather where the understeer characteristics seemed to be pronounced. 
I have made new front control arms. These are designed to address the inequality in caster from left to right. They are also designed with a slight bend in the front bar of each arm. The bend is to improve the angle of the rose joint attaching to the chassis mount. I was concerned about the bend creating a weak point in the control arm. So you can see I added some significant reinforcing to ensure it can handle the forces. 
I am also part way through a modification of the hydraulic handbrake setup. The existing setup has a single master cylinder serving both rear wheels equally. The braking capacity was insufficient to overcome the grip of the rear tyres. The new setup will have dual master cylinders opposing each other with a handle in between the cylinders. Pushing the handle forward will operate the right rear brake and pulling it back will operate the left rear brake. Operating one of the rear brakes at the same time as some mild acceleration should enable the car to perform very tight turns when required (one of the requirements it has struggled to satisfy in the past). The car will retain the cable handbrake for parking and as an emergency brake. I have created the adaptor brackets required for the modification but I will need a full weekend to install system, rerun all the hydraulics and bleed the system.


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## Duncan (Dec 8, 2008)

That looks like so much fun!

I haven't been able to get out in my machine for ages - just driving to the shops

Not sure why you would have so much understeer - the left front wheel appears to slow down in the video - about 1 min 14 - is it possible that you have the front so stiff that it was actually lifting off the ground?

How much droop do you have available? - is it enough


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## galderdi (Nov 17, 2015)




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## galderdi (Nov 17, 2015)

Yeah, It certainly has something to do with it. I'm not sure how to increase the droop. I do have one more suspension ration setting to try so we'll see how that goes. Otherwise I might need to drill some new holes in the pivot to gain some more leverage.


The understeer is mostly due to the weight distribution. Hence why I am trying to add a little more weight up in the nose for wet days.


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## Duncan (Dec 8, 2008)

Hi
Not sure I would blame the wt distribution
But I WOULD blame the lack of droop!

The front is effectively far too stiff in roll so it does all of the work and lets the rear grip like crazy

You need less pre-load on those springs - when you lower the car onto its wheels they have got to compress the springs

If you do have less weight on the front then you also need softer springs - and stiffer ones on the back to balance

Your picture looks as if the wheel with the entire front of the car on it is only about 2 inches displaced from the one on full droop


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## galderdi (Nov 17, 2015)

Suspension and handling is a black art. Everyone pushes you in a different direction. Since the previous post I have realised the left wheel is not fully drooped. I can tell because in the fully drooped position the top control arm is horizontal. So either the wheel is mid bounce off a bump or the front sway bar is pulling the left off the ground.


I ran the car without a front sway bar for many events but received some advice to add it to the mix. 


Over the weekend I also realised I had softened the shocks to their softest setting in an effort to gain fromt grip. But I think if anything I have gone too far with the shocks and not far enough with the spings.


So I have now softened the front springs but brought the shocks back from #1 to #4. As a result the car is now sitting too low in the nose and I will need to make an adjustment to bring it back up by around 20mm.


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## Duncan (Dec 8, 2008)

Front sway bar 
What I would call a front anti-roll bar!

I have provision for a front and rear anti-roll bar - the Subaru uses both
But neither is fitted to my device
The damn thing does not seem to roll much at all

If I had understeer the quick solution is increase the REAR roll stiffness

Oversteer - increase the FRONT roll stiffness 

Sounds like you were more correct without the front sway bar


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## galderdi (Nov 17, 2015)

Oh also, After checking the Ackerman angle I found it was significantly out. So I am confident this was part of the problem too. Effectively the front wheels have been fighting each other mid corner. This theory is supported by the following facts.


In high speed corners where one wheel lifts the car handled fairly well. 
In very low speed / tight corners the car would totally understeer.
In wet cornering the car would totally understeer.


So I think the ackerman angle adjustment will go some way to resolving the issues.


The higher speed handling in the dry is quite managable. But I do wonder how much faster I can go if the handling was maximised.


In hindsight I somewhat regret making the car rear engined. I think knowing what I do now I would have gone with a clubman / lowcost style design to help achieve near perfect weight distribution. But that would have resulted in some extra weight due to the addition of a diff and driveshaft.


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## Duncan (Dec 8, 2008)

galderdi said:


> In hindsight I somewhat regret making the car rear engined. I think knowing what I do now I would have gone with a clubman / lowcost style design to help achieve near perfect weight distribution. But that would have resulted in some extra weight due to the addition of a diff and driveshaft.


Your rear engined machine is much more compact than my Device
Almost certainly better for your events


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## galderdi (Nov 17, 2015)

Here are a couple of photos from my last event last weekend. The handling si startign to come good. This event was a bit odd in that it had both high and low speed components so I stuck with a setup that was better for the high speed components. The new handbrake setup was a handful while I came to terms with the new driving style but by the end of the day I was starting to get the idea. I can now aim just to the side of a flag, hit the handbrake on the same side as the flag, hold the accelerator and the car swings the back around until I release the handbrake. Happy days!!!


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## galderdi (Nov 17, 2015)

Here is a video of the higher speed test: 


https://www.youtube.com/watch?v=QhmS7OiK_t4


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## galderdi (Nov 17, 2015)

and here is a video of the lower speed test demonstrating the handbrake setup:


https://www.youtube.com/watch?v=tigUI8hdGmU


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## galderdi (Nov 17, 2015)

I had a great day at the 2019 Interclub motorkhana. The car was fairly good. I am starting to get the hang of driving the car in this latest format. The new hydraulic handbrake in particular takes some practice. I also think it works best once warm. I did have some issues knocking my switches in the heat of battle resulting in a loss of power. So I will make a cover to avoid this in future. I am waiting for the calculation of the final results but I am hopeful of a solid result, possibly my best ever. 


I did capture some video but I am trialling a new camera and the results are not worth posting. I will need to do some more testing before the next event.


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## galderdi (Nov 17, 2015)

Well the results are in. I managed 7th from 44 entries. Not quite as good as I was expecting. Still respectable. I also managed 2nd in class, again behind the same competitor. I would have been 6th if I hadn't loaned my car to the 3rd place getter when his car died. The car is heading in the right direction and I have a few ideas for improvements. The next event is the Noosa Hill Climb early June so I won't be facing the same challenges.


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## galderdi (Nov 17, 2015)

I had a great day at the Mt Cotton Hill climb on Saturday. My results were not all that impressive but quite respectable for a first attempt. I did end up in the Macadamia nuts (quite an effective safety barrier) on my second run. This event has made me realise the "understeer" issue I had been trying to resolve is gone and what I am suffering from now is actually a brake bias issue. On the successful runs during the day I was forced to brake very early for the tight corners and enter at rather conservative speeds. On the second run I left the braking too late for the brakes to handle and as a result continued straight ahead into the nuts. There was no damage to the car or driver apart from some dents to the ego. All in all it was a very successful day as I now know what is required to make the car more competitive. Here are a few photos from the day.


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## Duncan (Dec 8, 2008)

Brake bias issue?
So are you locking up one end long before the other?

Do you have a dual master cylinder set-up?


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## galderdi (Nov 17, 2015)

Yes the front is locking up LONG before the rear. In fact I can't lock the rear no matter how hard I try. No I only have a single master cylinder. Although I may need to alter the master cylinder so it can provide enough pressure to run bigger brakes.


At the moment I have a single master cylinder with two bias adjustment knobs. But even with the knobs turned to send maximum pressure to the back it is not even close to enough. It kinda makes sense in hindsight as the rear brakes I have are meant for a front wheel drive car where all the weight is up front. I have exactly the opposite.


Citroen C5 front brakes seem like a good option. They are big, modern and have a cable handbrake included.


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## Duncan (Dec 8, 2008)

Hi
I'm using two of the Trojan cylinders for braked trailers - cheap and simple

I think that you need a dual system so that you can alter the brake bias as you mess about with a circuit car

My system is quite simple - and I would make another of the balance bars to alter the balance

I can still lock the front up - JUST - and I'm a bit happier about it that way around 

I have two brake light switches! - one for the lights and the other one shorts out the throttle 

I went for bottom mounted pedals as they are said to be the "best" - I'm not convinced - I may go for pendant mount next time!


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## galderdi (Nov 17, 2015)

I see.


I do prefer the floor mounting. It is easier in a home built chassis to achieve a solid mount (imho). That is it allows the re-use of the floor as the mounting platform rather than building new structure above the feet.


When you say balance are you refereeing to the engagement sequence? When I say balance I mean amount of hydraulic pressure to each end of the car. I am not sure how the balance bar you have described would/could alter the pressure to either end?


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## Duncan (Dec 8, 2008)

Hi

It's a lever, the two master cylinders are the pivots - if you push in the middle then the two cylinders see equal forces

If you push 1/3rd of the way along then one cylinder sees twice the force of the other

If you lose pressure on one side then that cylinder moves to it's end stop and you can still keep pushing on the other

You can also use two different sized cylinders so get different pressures even with the same forces

The bar in my picture has two holes - so I could use two different ratios - I seem to have guessed about right but making more levers would be easy

You can do that with a threaded rod - and that means that you can have a cable to a knob in the cockpit to adjust it while driving

http://www.robcollingridge.com/kitcar/design/brakes/index.html

About half way down this page you can see one like that

Looking at those pictures I think I have slightly overdone the brackets for the brake pedal and the cylinders


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## galderdi (Nov 17, 2015)

Thanks Duncan, That makes sense and I will probably adopt some of that approach. 


Your system works because you are needing to achieve something close to balanced between front and rear. My situation is different because I need to unbalance the pressure to send way more to the back. I think the key difference is that regardless how much pressure I put on the back they are not strong enough to take their share of the load. So even if I had your setup it wouldn't solve the problem.


I think it will work if I have your system plus bigger back brakes.


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## galderdi (Nov 17, 2015)

Here are some videos from Saturday:



https://youtu.be/4_37IdY2G5E
https://youtu.be/EH-VH4-v8Lk
https://youtu.be/tg7KLp6S7XU


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## Duncan (Dec 8, 2008)

What I would do is fit a smaller master cylinder for the rear!

Brake "size" is to do with heat dissipation and is not a problem for us (despite my picture with an apparently orange disc)

Your rear brakes will be more than big enough - you just need to get a lot of pressure into your rear brakes while putting a lot less pressure into the front

A smaller master cylinder will give you more pressure for the brakes at the expense of more brake travel 

My brakes feel rock solid - a bit "heavy" - but solid so I could change both master cylinders for smaller ones to reduce the pedal force if I wanted to

Trojan appear to do a 3/4 and a 7/8 master cylinder
So areas - 0.5625 and 0.765 = one is 36% larger than the other

So you could fit a 7/8th cylinder for the front brakes and a 3/4 for the rear brakes which would give you 36% more at the rear before you started messing with the balance bar

I built mine over 8 years ago - but I'm fairly sure that I have two 3/4 cylinders and my balance bar is at 40/60 - which gives me 50% more rear pressure than front pressure

The Subaru the brakes came off was heavier at the front and would have got more weight transfer - I'm 45% front 55% rear

When I brake very hard on the track I do still lock the front first - but it feels like it's only just

Going to larger rear brakes may not solve your problem as it's the hydraulic pressures that are at issue


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## Duncan (Dec 8, 2008)

Damn that track looks like fun!
Looks like a kart track


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## brian_ (Feb 7, 2017)

galderdi said:


> Your system works because you are needing to achieve something close to balanced between front and rear. My situation is different because I need to unbalance the pressure to send way more to the back.


No, the system with two separate master cylinders and a balance bar can create any front:rear ratio that you desire... one reason that it is the standard method for dedicated competition vehicles. Even if you had identical components front and rear, you could still massively bias the braking effect with the balance bar. The only reasons to use one master cylinder (although presumably a tandem cylinder for dual circuits) in a racing vehicles are restrictions of rules (requiring production parts, not applicable in this case), effort to mount in a production firewall and pedal assembly (not applicable in this case), and cost.

The fundamental brake bias is determined by a balance bar system, differently sized front and rear cylinders (master and slave/caliper), and different effective brake radius. The other methods used to adjust front:rear balance work by limiting hydraulic pressure. A hydraulic "proportioning valve" is not for fixing a fundamental imbalance - it is for reducing rear pressure at higher brake effort, to adjust to the changing front-to-rear balance needed because of dynamic load transfer. Get the balance right for the static weight distribution with the fundamental design factors (disk and cylinder sizes), tune it with a balance bar, and adjust for load transfer with a proportioning valve.

You can build your own balance bar system, but the easiest (not least expensive) is to just buy a complete pedal assembly (separately or as part of an accelerator/brake/clutch cluster) from any racing brake supplier. The balance bar in these is normally set up as a threaded rod so that the balance can be adjusted by just turning it, and a cable to place the adjustment knob within reach of the driver (so it can be adjusted during test sessions, or adjusted to compensate for weight bias changes due to fuel consumption during the race) is a routine option.
example: Wilwood Tru-Bar Pedal Assemblies


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## galderdi (Nov 17, 2015)

Ok thanks for the clarification. It sounds like I will need to wait for the Christmas break to implement the upgrade then. There is no way I am willing to redo the entire braking system in between events.


I think I will opt for the home grown version. Parts like that are not readily available here. Which means I would have to deal with freight, exchange rates and import duties if I were to buy them off the shelf.


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## brian_ (Feb 7, 2017)

galderdi said:


> I think I will opt for the home grown version. Parts like that are not readily available here. Which means I would have to deal with freight, exchange rates and import duties if I were to buy them off the shelf.


You might consider used racing parts. Race cars get retired so there must be parts (although I have no idea how commonly or at what price), and buying rebuild kits new must be more reasonable than buying all of the components new, even if the kits must be imported.

If you were starting from scratch an alternative to get suitable balance might be to use the full set of coordinated components (from master cylinder to calipers and rotors... or rotors of the same size) from a car of similarly rear-biased proportions... but with the Toyota MR2 gone that mostly leaves large components from relatively exotic (or at least overpriced) vehicles.


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## galderdi (Nov 17, 2015)

Thanks, yes those are good options. I specifically considered the MR2. There are probably still enough around to find a donor. But I suspect their weight distribution is not quite as rear biased as mine. I am also considering Citroen C5 front calipers. This would give the size I desire but also the C5 had front operated cable handbrake. 
I will still need to redo most of the brake lines to accommodate the changes to the master cylinders and pedals. There isn't much room to work in there so it will be time consuming and frustrating. So I need to leave it until I have multiple weeks between events. So that means it will be Nov/Dec.


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## Duncan (Dec 8, 2008)

About Brian's suggestion - using MR2 bits

Toyota are probably more switched on than Fiat/Lancia but I remember back in the day the Mid engined Lancia - The MonteCarlo did NOT have the correct brake bias !

The most common tuning mod was to add a brake booster (servo) in the rear line only

So I would not assume that a production car even with the same weight balance has the right front rear brake balance


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## brian_ (Feb 7, 2017)

Duncan said:


> Toyota are probably more switched on than Fiat/Lancia but I remember back in the day the Mid engined Lancia - The MonteCarlo did NOT have the correct brake bias !
> 
> The most common tuning mod was to add a brake booster (servo) in the rear line only


While I assume there was some reason for this insanity, and the fix is an interesting approach, it is truly bizarre. Just using the right components - either at the factory or as a mod - would have been a more obvious solution.

According to some quick online research, it appears that the Montecarlo braking may have been balanced under heavy braking, but was definitely too front-biased under lesser braking effort; if this was due to component sizing, it should have been more rear-biased, and compensated for heavy braking with a proportioning valve. Early examples were also over-boosted, and later ones just left out the booster (servo); from some online comments and drawings, it appears that the original had a servo only for the front (which seems idiotic), causing the problem. There's no need for any builder to be as incompetent as Lancia was in this case.



Duncan said:


> So I would not assume that a production car even with the same weight balance has the right front rear brake balance


I agree that an assumption would not be safe, but it's reasonably straightforward to check cylinder sizes and rotor effective diameters to see what the balance would be, for any given vehicle.


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## galderdi (Nov 17, 2015)

Here are some videos from the Noosa Hill climb over the weekend


https://www.youtube.com/watch?v=kH1hjenP-fY
https://www.youtube.com/watch?v=8FtAjdIk0wE
https://www.youtube.com/watch?v=tGrP3-eylks


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## Duncan (Dec 8, 2008)

Looks fun
Just first for take-off - then second??

It's probably safer than my machine with the front roll cage but I think I feel more "inside the car" and safer - even if I'm not

Definitely jealous of the track


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## galderdi (Nov 17, 2015)

I get what you are saying and I agree. I think it looks worse than it is. I am 6foot 4 so I do tend to spill out of the car a little. But even so the photos make it look more like I am sitting on the car rather than in it. But it feels more like I am in the car. Risk wise, it is not made to handle risk of impacts from other cars as all the driving I do is one car at a time. The main reasons for the full cage are to add support to the frame in case of an impact, deflect wire or a fence over my head if I run way off a course, roll over, deflect a wheel if I hit a barrier and it rips a wheel off. The main risk which remains largely unmitigated is a tree or pole from the right side. But short of adding another 100KG of bar work there are no guarantees. I am fairly comfortable with the level of risk.

I like to think about how much safer we are compared to those guys racing high speed gokarts and lawn mowers. If they flip there is a real risk of spinal injuries.


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## galderdi (Nov 17, 2015)

Here are some videos from my event yesterday:

https://www.youtube.com/watch?v=FtQh6y_HUW4
https://www.youtube.com/watch?v=2Iel9kCvx_4
https://www.youtube.com/watch?v=lBh2q-moqPA
https://www.youtube.com/watch?v=kjLND2U10TQ


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## dkubus (Oct 10, 2019)

Damn!! That looks like a blast!!!! I think I'd get lost. Amazing machine 👍👍

Mike.


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## dkubus (Oct 10, 2019)

After reading through this thread and enjoying your videos I'm starting to think I should build my Hillclimb project EV with a lot less bodywork! Reminds me of my first Hillclimb racing in my VW beach buggy. (I also discovered with that car that no front sway bar was best)... 🤘👍👍 

I'm glad Duncan sent me here! Cheers NZ mate! 

Mike. 



galderdi said:


> Here are some videos from my event yesterday:
> 
> https://www.youtube.com/watch?v=FtQh6y_HUW4
> https://www.youtube.com/watch?v=2Iel9kCvx_4
> ...


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## galderdi (Nov 17, 2015)

Thanks mate,

Yeah it has been a hoot and sooooo rewarding.
unfortunately I am totally blocked at the moment.
The governing body here has had a hissy fit because they are clueless. So I can't compete in that car until they sort themselves out.
The don't have a criteria or process to approve an electric vehicle to compete.
They have no idea what to do about it.

For example they introduced a rule that electric vehicles must have twice the dry powder extinguisher capacity as any other car.....Dry powder is useless on a lithium fire so it is twice the uselessness.
And yet they have not addressed the basics like insulation, fuses, contactors.

Anyhow, sorry to turn this into a rant, but it is frustrating to make it this far only to be blocked from any further progress.

I highly recommend giving it a go.


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## Duncan (Dec 8, 2008)

Hi
My son had a demon idea for your problem
Stick a tailpipe on it 
If anybody comments say how quiet today's engines are
Every other car there has a starter motor and battery - your car just takes a bit more starting 
You could stick a chainsaw motor on somewhere


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