# Building an Electric TR3



## Moltenmetal (Mar 20, 2014)

HI, and welcome! 

Beautiful car- perfect conversion target! Love the panels- they look gorgeous! Very jealous- I love my Spitfire conversion but started with a car in bad shape and regret that now- the car is so much fun I wish I'd started with one in much better condition! Yours looks awesome...

Take a look at my E-Fire build thread, but think about used Leaf or Volt batteries instead- you'll save a lot of money relative to what I spent.

Randy at CanEV was great to deal with. Or talk to HPEVS and see who they recommend as a distributor- they're great guys making a great product- powerful enough and reliable, and their Curtis implementation is very functional and versatile and easy to work with. I would use the AC50 again with no hesitation.

I would not go direct drive with the AC 50 or AC51. You need at least two speeds. More speeds aren't necessary but give options for more fun and come free with a 4spd. I used a Toyota 5 spd tranny, Baratong used a Ford in his '79 Spitfire IIRC, there are many choices if the TR3 box isn't up to the job or is hard to get parts for. Making a transition driveshaft is easy. If you buy a CanEV tranny adapter, it just drops on- took about an hour to mount my motor to the tranny, all in, with zero alignment problems. You don't really need the clutch but do need it if you use the CanEV adapter- it's handy and easier on the synchros and gives you fast reliable shifting.

You'll like the regen braking- it's like power brakes which gives you lower brake wear, a 10-15% range boost etc. as a side benefit. I turn mine off in wet weather to avoid locking up the rear wheels, and miss it every time.

Ask questions and post lots of pics! You'll get lots of help here. You are going to love the result!


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## Duncan (Dec 8, 2008)

Hi
AC is definitely more "sophisticated" and fits well with Molten's Spitfire- but I'm not sure that is appropriate for a TR3

The TR's were hairy chested brutes compared to the more civilized Spitfire

IMHO a DC motor would be more "fitting" as well as a LOT more powerful


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## Moltenmetal (Mar 20, 2014)

Depends just how much grunt you want out of the car when you step on the pedal. DC definitely gives you more grunt for the dollar, in return for more maintenance and no regen braking. To each their own, but if you're going to drive it, AC is better. If performance off the line is your key goal, DC is better for the buck.

Again I definitely would NOT go direct drive, either way, but especially with the AC50/51. But I think you'd still be satisfied with the AC50 as long as you keep the clutch and install a decent tranny.

Note that the AC51 and higher voltage 1239 Curtis controller give you less torque than the AC50/1238 lower voltage combination, because the 144V 1239 controller is limited to 500A vs the 1238's 650 A. Makes a bit of a difference.


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## ponobill (May 29, 2014)

So which transmission do people recommend most? I've been thinking Toyota 22R five speed, but I'm not settled on that. Is there something better. more compact, more robust??

This will definitely be a driver. Not looking for max performance, just similar to stock will be fine. I live in Hood river, Oregon which is a hilly town, so it seems like regen will be a good thing. It will be mostly short haul, generally with a stand up paddle board on a rack. A way to leave my F350 diesel parked and still carry a board.


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## Duncan (Dec 8, 2008)

I will put a vote in for direct drive,
I can spin my rear tires just by pressing the throttle and I have 55% of the weight on the back and an LSD

The real advantage of direct drive with a car like the TR is packaging - you can put the motor where the gearbox normally lives which leaves all of the "engine bay" for your batteries
Battery space is important - they do take up a lot of space and I am paranoid about keeping that weight as low as possible 
You will be using Volt or Leaf cells - these come in modules of fixed sizes so getting them all in your space can be fun

But you do need a grunty motor/controller setup 

I will expand that - if you have enough grunt a gearbox is redundant and you can use the space
If you don't have enough grunt then a gearbox is needed

http://www.diyelectriccar.com/forum...dubious-device-44370p13.html?highlight=duncan


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## Karter2 (Nov 17, 2011)

Direct drive is effective as you say , but there are reasons to be wary.
Over on ES, a smart guy with a AC drive kart did some data collection using different gear ratios and a set speed.
Using a higher drive ratio for better accelleration, He recorded 50% more power needed at the same cruise speed (100km/hr) because the motor ran 1200 rpm faster....that is a huge difference.
So the indication is you need to be very careful selecting the final drive ratio to suit the motor and type of driving, speed, range , etc, that you require


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## Duncan (Dec 8, 2008)

Hi karter

50% more is a HUGE amount - I would question his measurements -

It will take the same amount of actual mechanical power to travel at the same speed so he is basically saying that his motor efficiency drops so much that 50% more power is needed at 1200rpm higher 

So if it was 90% efficient at condition 1 then it would be 60% efficient 1200rpm higher? 
Sounds like too big a change


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## onegreenev (May 18, 2012)

ponobill said:


> So which transmission do people recommend most? I've been thinking Toyota 22R five speed, but I'm not settled on that. Is there something better. more compact, more robust??
> 
> This will definitely be a driver. Not looking for max performance, just similar to stock will be fine. I live in Hood river, Oregon which is a hilly town, so it seems like regen will be a good thing. It will be mostly short haul, generally with a stand up paddle board on a rack. A way to leave my F350 diesel parked and still carry a board.


Sent you a private message. (more info in the message)

Stock tranny with a performance pressure plate will be good.


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## Karter2 (Nov 17, 2011)

Duncan said:


> Hi karter
> 
> 50% more is a HUGE amount - I would question his measurements -
> 
> ...


Yes, i was shocked also, but he has very comprehensive data logging and the result was repeated.
Apparently its a feature of some AC motors/controllers that are optomised for certain rpm ranges.
I guess you just have to make sure you know the performance characteristics of the system you are using and match your gearing to suit.
..last few posts on this page..
https://endless-sphere.com/forums/viewtopic.php?f=34&t=68543&start=50


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## Duncan (Dec 8, 2008)

Hi karter

I think the magic words are - "field weakening" - apparently 

"In fact yes.. at about 4kRPM the sevcon goes into Field Weakening witch is less efficient."

Sounds like an unusual sort of thing - which may be why I can't remember seeing that sort of efficiency drop on any motor curves


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## ponobill (May 29, 2014)

I'm interested in direct drive, I can use the space that putting the motor into the transmission tunnel would provide. But it looks like getting the ratio I'd expect would yield reasonable speed and performance would require gear reduction beyond just the available rear end reduction (4.1:1 is about the max for the stock TR3 rear end). 

I've looked at some reduction gears, but they are quite expensive. Not outside the realm of possibility, especially if I can save a few bucks on the battery by using one salvaged from a Volt or Leaf. 

I'm looking at the ev-torque Box http://www.torquetrends.com/ which is $3500. It looks extremely stout and well designed. It looks like the plate mount on the gearbox will support both it and the motor weight. Might be a pretty elegant solution. The total reduction available would be in the range of 8:1, which looks pretty reasonable compared to the power/torque curve of either the AC51 or AC50 motor. 

Any other ideas?


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## Moltenmetal (Mar 20, 2014)

Again, I would strongly recommend that you NOT do direct drive with an AC50 or AC51. The car will feel gutless- I guarantee it. You NEED two speeds and would benefit from having a 3rd plus reverse. A tranny in my view is definitely required if you go with these AC motors. The clutch you can do without, but it's handy to keep it, and keeping it reduces the alignment worries somewhat when making a motor/gearbox mating arrangement.

I can't comment on the re-use of the existing tranny so I won't, other than to say that if it's in good condition and you're not after hard acceleration, it is probably up to the job. But you'd be on your own to make a mating flange and hub to connect it to your motor, and that is a precision job that a lot of people seem to think is trivial but I certainly did not- I was very glad to be able to buy a precision-made solution, which CanEV offered for my Toyota tranny, and just have it all bolted together in less than an hour with zero alignment concerns. Making a transition driveshaft and mounting a different tranny is easy in comparison. I have no experience under the tranny cover of a TR3 so can't comment on what else might be in the way of you doing so though.

If you're worried about the viability of the Triumph drivetrain, you can always dial the torque back by setting current limits in the Curtis controller, or by setting gentler acceleration parameters too. You can really baby the old Triumph drivetrain components if you want to.

Direct drive with DC is feasible, but again I wouldn't recommend it for a daily driver unless you're not going to drive it often AND you really need to save the money by building a kit motor controller- none of that sounds like your situation. 

Brakes on my Spitfire are harsh- they take a lot of legwork. Having regen is like having power brakes, with the benefit of putting energy back into your battery. Not having to worry about brushes, carbon dust and potential commutator damage is a huge plus for me- the thought of driving my car with what amounts to a huge cordless drill is not very appealing, even though the torque must feel delightful!

The tranny I have is a W50 "steel case" 5 spd which was coupled to a 20R Toyota 2.2L 4 cylinder out of a 1980 Celica. It's very a solid gearbox, which was also used in some of their light trucks.

$3500 sounds like a lot for a gear reduction, but then again, I'm cheap! And your car is beautiful- don't cheap out: do exactly what you want!


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## ponobill (May 29, 2014)

Thanks for the quick response. I'm not sure I understand why a single speed reduction would be gutless if the ratio is correct. Maybe I'm misunderstanding the distinction--I wouldn't expect directly driving the rear end to work well, 4.1:1 is much too tall for getting off the line. First gear in a TR3 is 3.38 so a 4:1 reduction box would give a little more torque off the line. I don't expect to be driving the thing over 60. I'm comfortable with high speed on a race track, but I'm a little old blue-haired lady on the street. 

Do DIY conversions use an electric reverse? Seems like a simple thing to do. Just change the phase order. Don't motor controllers include that? That's got to be a total newb question. 

The WD50 transmission and similar Toyota boxes are the ones I'm considering, for exactly the reason you mention. I planned on looking for a good W58 box, which is what some Triumph racers use with a conversion bell housing. If I decide on this direction I will definitely use a clutch. 

I am settled on AC, and either the AC50 or 51. 

I'm not too worried about fabrication issues for mounting, I have a fair level of skill in bending, machining and welding steel and aluminum, but no, I don't want to make my own adapter. One more reason to NOT use a Triumph gearbox.


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## Karter2 (Nov 17, 2011)

Duncan said:


> Hi karter
> 
> I think the magic words are - "field weakening" - apparently
> 
> ...


Yup !..Duncan...aparently it is not uncommon.
From Wiki....Field Weakening...


> Operation of the motors above rated nameplate speed (base speed) is possible, but is limited to conditions that do not require more power than the nameplate rating of the motor. This is sometimes called "field weakening" and, for AC motors, means operating at less than rated V/Hz and above rated nameplate speed. Permanent magnet synchronous motors have quite limited field-weakening speed range due to the constant magnet flux linkage. Wound-rotor synchronous motors and induction motors have much wider speed range. For example, a 100 HP, 460 V, 60 Hz, 1775 RPM (4-pole) induction motor supplied with 460 V, 75 Hz (6.134 V/Hz), would be limited to 60/75 = 80% torque at 125% speed (2218.75 RPM) = 100% power.[18] At higher speeds, the induction motor torque has to be limited further due to the lowering of the breakaway torque[a] of the motor. Thus, rated power can be typically produced only up to 130-150% of the rated nameplate speed. Wound-rotor synchronous motors can be run at even higher speeds. In rolling mill drives, often 200-300% of the base speed is used. The mechanical strength of the rotor limits the maximum speed of the motor.


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## Moltenmetal (Mar 20, 2014)

Yes, you could do electric reverse, easily with the Curtis controller. It simply runs the drive motor in reverse at some adjustable current and accel settings so you don't get yourself in trouble...

If you had a clutch but only one gear reduction (ie the motor tied directly to a differential with the correct ratio), performance might not be an issue. But my Spitfire would need at very least two speeds (two different gear ratios) to be driveable without a clutch- and who wants to burn a clutch during takeoff anyway?). Driving mine locked in 3rd gear without a clutch would be possible, but really boring (embarrassing) off the line and with a limited top speed a little too low for my liking. 2nd would not get me to highway speed. So 2nd and 4th would do, but to get those ratios I get 1st, 3rd, 5th and reverse for nothing.

So yes, a tranny is strongly recommended. Pick one CanEV has an adapter plate on the shelf for- he has one for a couple different Toyota engines including my R series.

Keep the questions coming until you're satisfied- and let us know what you choose.


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## Duncan (Dec 8, 2008)

Hi
Molten is right you do need a powerful motor for direct drive,

The way to look at this is how much torque and rpm do I need,
Your TR3 is about 1000kg with maybe 40% on the rear wheels - 400Kg 
Normal tires have a friction coefficient of about 0.8 - so 400 x 0.8 = 320Kg will slip the rear tires
The wheels are about 2ft in diameter - so 320kg x 2.2 = 704 - so 704ftlbs torque will spin the rear tires
Your diff will be about 4.2:1 (?) so 167ftlbs of propshaft torque will spin the rear tires
(Please re-do these calcs with your actual numbers)

So if your motor can produce 167ftlbs then you don't need a gearbox


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## ponobill (May 29, 2014)

I was planning to use a single speed reduction gear that's 4:1 plus the rear end of 4.1:1 gives about 8.1:1 = 86 ft/lbs to spin the tires. the AC51 motor offers 107 ft/lbs. I'll aim at a 50/50 weight distribution, but it seems the low end would be fine. Top speed is probably more the issue. 

I have rear end ratios of 3.5, 3.7, 3.9 and 4.1. The reduction gear I'm looking at offers 3.5 to 4. So at the high geared end I have 7:1. Using your numbers that's 100 ft/lb to spin the tires -- still there unless I get the rear end heavier--or the entire car. Given these calculations, I'd probably get the reduction gear at the high end (3.5) and use the rear end ratios to tune. Swapping the gearing out is a PITA, requiring that the rear axle be completely removed from the car, but it's something I'm very used to with my race car. I'll have to simplify the rear axle installation, assuming I'd be fiddling with this some. 

At 7 to 1, turning the motor at 8000 rpm, the rear axle will spin at 1140 rpm or 19 RPS. With a 205 50/15 tire the circumference is 72 inches = 6 feet so it's 114ft/sec= 78MPH. 

That sounds reasonable assuming that an AC51 is happy at 8000 RPM. TR3's have about the same aerodynamics as a garage door. I assume I'd be burning energy like crazy at 70 mph. 

I'm going back and forth with this. I can certainly use an unencumbered engine compartment. The reduction gear and motor would fit entirely within the gearbox tunnel. Helps with weight distribution and moment of inertia as well. 

Thaks so much, this was helpful. I'm still contemplating a transmission, but I have measurements to make to figure this all out. At least I know it's feasible within certain boundaries.


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## Duncan (Dec 8, 2008)

Hi ponobill

If you have a 4:1 drive and another 4:1 drive the total is 16:1

So a 3.5:1 + a 3.5:1 gives 12.25:1
A 4.1:1 + 4:1 gives 16.4:1

You need about 7:1 - I don't think its that easy to get

I'm using 4.1:1 - but with a big DC motor


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## piotrsko (Dec 9, 2007)

On the old style trannies 2nd was around 2:1. So with a 3.5 diff you get 7:1.

IMHO use the 4.1 and adjust tire size for top end. If you have a multiple speed trans use it.

Your aero has to be better than my ranger. I average 425 wh /mile on the local freeways on the flatlands, the hills kill that. I still comfortably go 40 miles on. A Volt pack


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## ponobill (May 29, 2014)

Duncan said:


> Hi ponobill
> 
> If you have a 4:1 drive and another 4:1 drive the total is 16:1


Ah, of course. Duh.


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## ponobill (May 29, 2014)

Back and forth. I'm generally an excessively decisive guy, but I want to get this right. 

Some people have asked why I don't want to use the stock transmission. The stock TR3 transmission has a number of well-known weak points. All racers and most restorers use a TR4 or better yet a TR6 transmission--when they can get them. Parts for rebuilding are expensive and of indifferent quality. There are dog box gearsets available from Quaife with bearing designs that fix most issues , but they are very expensive and not easy to set up. The transmission shortage is critical enough for racing that many vintage organizations permit replacement with a modern transmission. There are bolt-on bell housing that enable a Toyota W5X transmission to bolt onto a TR3-6 motor. If I do use a transmission it will definitely not be a triumph one, though I have quite a few at hand. I'm not concerned about the engineering or fabrication necessary to swap a transmission into the car. I'm familiar with the universal joint alignment requirements for swaps. 

One of the benefits of 20+ years of vintage racing is that I have several 7" multiplate clutches kicking around, I'll probably turn a stock flywheel down to suit the clutch and lighten what's left. I'll have to look at the clutches I have and see what the splines are. I can get plates to suit available tranmissions or get an adapter to suit the plate spines--whichever is more readily available. I generally replace Triumph clutch actuators with Saab concentric actuators and throwout bearings. I have a few of those handy as well, though I'll probably have to make a new adapter plate for a Toyota W58 transmission. 

Like most cars with frames that I've worked on, the Triumph engine/transmission is supported at the output shaft end with a flex mount and at the motor faceplate with flex frame mounts. How are people supporting the motor end of adapted transmissions? Do you build a cradle to support the motor or do you support everything at the motor/transmission joint and rely on the adapter plate to support the motor?


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## Baratong (Nov 29, 2012)

It's nice to see another vintage Triumph conversion. There are number of Spitfire and a few TR and MG builds here. They make for a nice little EV.



ponobill said:


> Back and forth. I'm generally an excessively decisive guy, but I want to get this right.


I know what you mean. When I started my Spitfire, It took me quite a while to decide the path forward. There are a lot of decisions to make.



ponobill said:


> Some people have asked why I don't want to use the stock transmission. The stock TR3 transmission has a number of well-known weak points.


There are a number of examples, some here on the forums, of the Spitfire stock transmission getting trashed by the instant torque of the electric motor. At first I was planning on going transmission-less because of this.



ponobill said:


> ... I generally replace Triumph clutch actuators with Saab concentric actuators and throwout bearings. I have a few of those handy as well, though I'll probably have to make a new adapter plate for a Toyota W58 transmission.


I ended up choosing a Borg Warner T5/WC transmission. It is larger than stock, but with modifications to the tunnel (i.e. cut it out and make a new one), it worked out nicely. 



ponobill said:


> Like most cars with frames that I've worked on, the Triumph engine/transmission is supported at the output shaft end with a flex mount and at the motor faceplate with flex frame mounts. How are people supporting the motor end of adapted transmissions? Do you build a cradle to support the motor or do you support everything at the motor/transmission joint and rely on the adapter plate to support the motor?


On my build, the Warp9 motor is supported by a cradle, and the rear of the transmission is supported. From what I've seen in the forums this seems to be the primary method -- with the exception of the VW builds.


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## ponobill (May 29, 2014)

I've been reading your build thread Baratong, very interesting. I'm also reading MoltenMetals thread. Both really useful for me. 

I also have a reasonably strong general electronics and embedded systems background, but not professionally--just hobby stuff. I like the idea of separate modules for each cell, but I suspect with cells from a chevy volt and BMS connectors on each battery array that the most practical way is to use an existing commercial BMS for the voltage of each battery assembly. 

I'd be very interested to hear your take on that. I've built some lithium batteries for my bicycles and trike using 18550 cells and Besttech BMS boards. So far, so good, though my criteria for success might be a bit on the low side--no fires, and the batteries are well balanced, are charged to the voltage I specify, and don't discharge below my limit. I suspect doing a really fast charge with tiny balancing wires might vaporize more than a few or result in poorly balanced cells. I have a lot to learn about this aspect.


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## Baratong (Nov 29, 2012)

ponobill said:


> I've been reading your build thread Baratong, very interesting. I'm also reading MoltenMetals thread. Both really useful for me.


Glad it could be of help. In the beginning I read several Spitfire conversion threads (ClintK, and Bottomfeeder) and found them very helpful. MoltenMetal started his build just a little before mine and we exchanged a lot of info during our builds. 



ponobill said:


> I also have a reasonably strong general electronics and embedded systems background, but not professionally--just hobby stuff. I like the idea of separate modules for each cell, but I suspect with cells from a chevy volt and BMS connectors on each battery array that the most practical way is to use an existing commercial BMS for the voltage of each battery assembly.


Yes, the distributed method for BMS that I used is rather specific to prismatic cells (primarily based on physical size) and probably would not be applicable to the Volt/Leaf/Tesla type packs.

I am accumulating parts now for my next build which will be based on a kit-car rolling chassis. I'll be using an AC51/Curtis AC setup and am looking at Leaf or Volt packs instead of prismatic cells. I'll be building a centralized BMS to manage these for that build. 




ponobill said:


> I'd be very interested to hear your take on that. I've built some lithium batteries for my bicycles and trike using 18550 cells and Besttech BMS boards. So far, so good, though my criteria for success might be a bit on the low side--no fires, and the batteries are well balanced, are charged to the voltage I specify, and don't discharge below my limit. I suspect doing a really fast charge with tiny balancing wires might vaporize more than a few or result in poorly balanced cells. I have a lot to learn about this aspect.


Personally, I wouldn't use LiPo cells (18650, Tesla, etc) simply because their potential for thermal runaway. My decades of experience in product development has given me a wariness of reliance on the fortitude of built-in safety systems to prevent disaster. 

On balancing via a centralized BMS, the design of the BMS should be to limit the total shunting current during the balancing operation to less than the point of voltage sag on the connecting wires. i.e. take into account the wire resistance in the design. So I wouldn't think that would be much of a problem except for perhaps limiting the amount of load that could be placed on the cell to bring down it's voltage to match the rest of the pack.


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## ponobill (May 29, 2014)

I like the idea of using a 356 Speedster kit. I almost bought one of the Beck Spyders back when they were a bit cheaper. They're just cool looking and they have a lot of space for batteries given the small size of the car.

I'm equally concerned about thermal runaway, which is why my homebrew LiPo battery contraptions live outside the garage. I've never had a problem, but then again I've never won the lottery either. though I guess I'd have to actually buy a ticket for that analogy to be useful. I don't think the Tesla chemistry is actually LiPo. There are a lot of 18550 batteries with more stable chemistries. My trike has two 40Ah, 48V battery packs made of 18550-format LiFe. 

I think the Volt batteries are Lithium Nickel Manganese Cobalt Oxide. They should be pretty stable as long as they aren't shorted.


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## ponobill (May 29, 2014)

I like the idea of using a 356 Speedster kit. I almost bought one of the Beck Spyders back when they were a bit cheaper. They're just cool looking and they have a lot of space for batteries given the small size of the car.

I'm equally concerned about thermal runaway, which is why my homebrew LiPo battery contraptions live outside the garage. I've never had a problem, but then again I've never won the lottery either. though I guess I'd have to actually buy a ticket for that analogy to be useful. I don't think the Tesla chemistry is actually LiPo. There are a lot of 18550 batteries with more stable chemistries. My trike has two 40Ah, 48V battery packs made of 18550-format LiFe. 

I think the Volt batteries are Lithium Nickel Manganese Cobalt Oxide. They should be pretty stable as long as they aren't shorted.


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## Moltenmetal (Mar 20, 2014)

My W50 tranny is supported near the rear with the original tranny rubber mount. The mount bracket was cut out of the Celica and just welded to the underside of the Spitty's frame. We did this back when we dropped the 20R engine + W50 tranny into the Spitty in the early '90s, and I just kept the rear mount the way it was.

The tranny bell housing is bolted to the AC50 motor using CanEV's plate.

The other i.e. frontmost end of the AC50 motor is mounted via a face-mounting bracket, via flat rubber mounts directly to the frame. The front end of the motor therefore takes the weight of the motor and the front of the tranny. 

8,400 miles and counting- no issues on the motor or tranny so far. 

I did blow up a diff, but it was the last major Leyland drivetrain component left in my build so I suspect it blew up just out of pure spite. I've renewed both rear UJs and the diff, and will probably have to do the prop shaft UJs this winter just for fun. The new diff, which is a spare I had laying around, is surprisingly not leaking any oil yet, and it still makes quite a racket at highway speed. We'll see how long it lasts...it may be the weak link in my build. The quick reversals between drive and regen braking may be something they aren't happy with long term. I would engine brake a bit with the Spitfire when it had its original 1500 engine, but nowhere nearly as much reversal of torque when engine braking as you get with 200A of regen current I'd imagine.

Now the rear end of your TR3 is of some interest. Is it up to the job, long term? It's got the rotoflex connection on the half shafts between the tranny and the rear wheels, right? Rubber donuts instead of UJs? I have no experience with those so can't comment, other than to say that they seem a bit Mickey Mouse from a distance. Or did you upgrade those, given it sounds like you've raced these things? Duncan probably has a thing or two to say about those, given his history with classic British cars which is very extensive.


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## ponobill (May 29, 2014)

Moltenmetal said:


> My W50 tranny is supported near the rear with the original tranny rubber mount. The mount bracket was cut out of the Celica and just welded to the underside of the Spitty's frame. We did this back when we dropped the 20R engine + W50 tranny into the Spitty in the early '90s, and I just kept the rear mount the way it was.
> 
> The tranny bell housing is bolted to the AC50 motor using CanEV's plate.
> 
> The other i.e. frontmost end of the AC50 motor is mounted via a face-mounting bracket, via flat rubber mounts directly to the frame. The front end of the motor therefore takes the weight of the motor and the front of the tranny.


Cool. That's pretty much what I plan to do. I plan to make a thick plate mount for the rear of the motor--probably get it water jet cut from aluminum plate. 




Moltenmetal said:


> Now the rear end of your TR3 is of some interest. Is it up to the job, long term? It's got the rotoflex connection on the half shafts between the tranny and the rear wheels, right? Rubber donuts instead of UJs? I have no experience with those so can't comment, other than to say that they seem a bit Mickey Mouse from a distance. Or did you upgrade those, given it sounds like you've raced these things? Duncan probably has a thing or two to say about those, given his history with classic British cars which is very extensive.


No--TR3s are solid axle. the rear ends are very stout. They tend to break axles, but not gearsets. When you break an axle on a racing TR3 the wheel falls off, unfortunate at 120mph, which is when it usually happens. There is a conversion for this which uses larger, stronger axles and a bearing retaining system. I've installed one of these in the diff I'm going to use. I've also installed a Quaife rear end, which is a pretty gentle semi-posi rear end.


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