# Planning classic mini conversion



## Kevin Sharpe (Jul 4, 2011)

jjc839 said:


> It seems as though the classic mini isn't ideal because of the original integral engine/gearbox and lack of room to fit a different gearbox.


What are the overall dimensions of the mini engine and gearbox?

The Tesla front motor/inverter/gearbox/differential from the all wheel drive Model S is surprisingly small at just ~500mm long 

At ~85kg the Tesla is also around half the weight of the mini engine/gearbox according to a quote I found - "a mini engine and gearbox is about 330lbs according to my (very old) Haynes book so about 150kg". 

Here are some photos showing the front motor/inverter/gearbox/differential from a Tesla Model S 85D... >200HP would also make this a rather interesting conversion


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## jjc839 (Sep 1, 2017)

Thanks for that. I think the Tesla motor is quite a bit more powerful so alot bigger. The AC-34motor bolted up to the reduction gearbox should be about 110lbs and 18x9x15"


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## Kevin Sharpe (Jul 4, 2011)

jjc839 said:


> I think the Tesla motor is quite a bit more powerful so alot bigger.


I've just checked a 'small' Tesla rear motor which is almost identical in size/weight to the 'small' Tesla front motor. It weighs 190lbs and is 24" long, 24" wide, and 12" high including the motor mounts. Remember this package includes the motor, gearbox, inverter, and differential. If it would fit in the space occupied by the current ICE, gearbox, clutch, diff, then you'd be saving ~140lbs that you could 'spend' on battery weight.


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## jjc839 (Sep 1, 2017)

Thanks, I've also just found an 8.75:1 gearbox from an electric Smart ForTwo, which may also work and already have an appropriate output for CV joints.


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## Kevin Sharpe (Jul 4, 2011)

For future reference it looks as if a Tesla 'small' motor will fit into the space occupied by the ICE and gearbox in a 'classic' mini 

Here are some rough dimensions for a Honda B16 engine according to the 16V Mini Club Forum;

"crankshaft pulley to end of gearbox is 850mm

top of cam cover to bottom of sump is 550mm

from the front exhaust heat shield to rear of diff is 600mm"

http://www.16vminiclub.com/showpost.php?p=54701&postcount=4


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## brian_ (Feb 7, 2017)

The complete motor and transaxle (transmission with differential) from any common modern production EV is a possibility: all or nearly all of them are configured similarly to the Tesla unit, with a transverse motor, single-speed reduction gearbox, and differential. Of course you want a small one... the Smart ForTwo ED has already been mentioned, and the Mitsubishi i-MiEVis also smaller than most.

Any of these setups will require custom half-shafts, with Mini outer joints and the inner joints which work with the transaxle.

If the original motor is used, a suitable AC inverter/controller will be needed; if a different motor is used, mounting the motor to the transaxle might be a challenge.


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## brian_ (Feb 7, 2017)

jjc839 said:


> - reduction drive mated directly to only one wheel via one CV joint, or possibly both wheels via a dual output 90* gearbox.


I strongly suggest not trying either of these. One-wheel drive would be bad at the rear, and nearly undriveable at the front. Driving both wheels without a differential to allow them to turn at different speeds will also make the car almost undriveable, since it will be unable to turn without substantial scrubbing.

You need either a differential (which is included in any transaxle), or separate left and right motors (which also means separate left and right transmissions).


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## jjc839 (Sep 1, 2017)

What are the implications of only driving one wheel at the front? Torque steer? 

Aside from physical fitment, are there other major factors to consider for running 2 small motors/reduction drives, one for each wheel? Can you run two ac motors from a single controller?


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## brian_ (Feb 7, 2017)

jjc839 said:


> What are the implications of only driving one wheel at the front? Torque steer?


Yes - torque steer is the direction of the car changing as drive torque is increased and decreased, and you would have lots of that.

Also, it will pull to one side all of the time, so it will go down the road slightly sideways (called "dog tracking", because dogs often run twisted to one side so their front and rear paws don't hit), with compensating steering needed all the time, and extra drag.

Motorcycles with sidecars do drive a driven wheel on only one side, but it's hard on tires and the car would be worse.


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## brian_ (Feb 7, 2017)

jjc839 said:


> Aside from physical fitment, are there other major factors to consider for running 2 small motors/reduction drives, one for each wheel? Can you run two ac motors from a single controller?


The major issue would be cost. It saves a differential, but requires two of everything else (controllers, motors, transmissions), and two small ones is always more expensive than one big one.

Control complexity is the other. One controller won't work for AC, but I noticed a feature in the Curtis controllers that is designed for coordinating two controllers, one for each motor... exactly for this purpose. From the _Dual Drive_ feature description of the Curtis Model 1239E web page:


> Most Curtis AC controllers have Dual-Drive functionality built into the operating system as a standard feature. This feature is required for vehicles with dual fixed axle drive motors and a steered wheel or axle, such a 3-wheel counterbalance trucks. The traction controllers must provide an electronic 'differential' effect which prevents excess tire wear and allows the trucks to smoothly execute tight turns. The Dual-Drive function allows the traction controllers (one master, one slave) to proportionally reduce the relative speed of the inside wheel and increase the speed of the outside wheel as the truck corners. As the steering angle increases, the direction of the inside wheel is reversed, giving the truck the smallest possible turning circle. Curtis Dual-Drive provides smooth and efficient control of vehicle speed, acceleration and motor current while turning, and ensures safe operation in the event of a fault with either of the motors, controllers, or the steering angle feedback sensor.


You won't turn anywhere near tight enough for tightest turn feature (it's not a forklift), but otherwise this looks like the required functionality.

Separate left and drive motors is quite unusual in road vehicles, but there are some production examples... so far in exotics and in hybrids.


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## MalcolmB (Jun 10, 2008)

Hi Jeff,
I did a Mini conversion a few years ago using a pair of small series-wound DC motors to drive the front wheels independently through a chain drive reduction to each drive shaft. The motors were powered by a single controller. This worked well with the motors wired in series at the low power level I was limited to with an Alltrax 7245 controller.

I didn't get round to trying higher power levels as I felt the chain drive solution was a bit "agricultural" and was likely to require regular maintenance, which I'd like to eliminate. I'm now looking for a neater solution, so I've taken a more conventional approach this time round and bought a small transverse gearbox from a VW. The issue then is finding a motor that's short enough to fit without requiring major surgery on the subframe. 

Kevin's suggestion of using the Tesla drive unit would be great, and it's crossed my mind a couple of times, but the critical dimension for fitting a different gearbox/drive unit to the Mini is the distance from the drive output centreline to the back of the diff casing. This is very small in the Mini since it's limited by the steering rack, which is right behind the diff. The maximum dimension is about 100 mm. If you increase this significantly the drive shafts will be at an excessive angle. Looking at the photo of the Tesla unit I estimate this distance is around 120 mm. Any chance you could measure this Kevin?

Malcolm


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## jjc839 (Sep 1, 2017)

Great info guys, thanks. I'm a few hours away from the car right now but once I get under the hood I'll have a much better idea of what kind of space there is to work with. Also going to investigate FWD diffs and see what the smallest is out there.

Jeff


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## jjc839 (Sep 1, 2017)

Hmm...just browsing around...anyone consider an ATV diff? Very compact, with gear ratios in the mid 3's. I would think a diff from a newer 700+cc ATV would be plenty strong for what I have in mind.

So, AC motor at 7500rpm with reduction drive of 2:1, driving a 3.50:1 diff, 19.5" tires, top speed of 62mph.

Still need to take some measurements.


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## Kevin Sharpe (Jul 4, 2011)

MalcolmB said:


> Any chance you could measure this Kevin?


I'm not sure exactly which dimension you are looking for... any chance you have a picture showing the critical dimensions in the mini drivetrain?

I'll see if I can find someone with a 3D scanner so that we can easily record the critical dimensions from the Tesla motors


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## brian_ (Feb 7, 2017)

Two motors (for separate drive to each wheel) on on controller works with DC motors, but not with AC. AC synchronous motors must be driven in synch with the rotor position, AC induction motors are driven at a frequency closely related to the motor speed, and the point of separate motors is to allow them to run a different speeds for turning corners.


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## brian_ (Feb 7, 2017)

MalcolmB said:


> Kevin's suggestion of using the Tesla drive unit would be great, and it's crossed my mind a couple of times, but the critical dimension for fitting a different gearbox/drive unit to the Mini is the distance from the drive output centreline to the back of the diff casing. This is very small in the Mini since it's limited by the steering rack, which is right behind the diff.


This will typically be a challenge in any front-wheel-drive car with a transverse engine (the layout which the Mini popularized and is now the most common), because except in rare cases they have the engine just ahead of the axle line, so the steering rack ends up just behind it.

The Tesla Model S drive assemblies (motor and transmission) for both front and rear place the motor behind the axle line. Most recent EVs emulate the layout of a gas-engined model and place the motor at or ahead of the axle line; examples include the Nissan Leaf, Mitsubishi i-MiEV, and presumably the VW eGolf, Ford Focus EV, etc.



MalcolmB said:


> The maximum dimension is about 100 mm. If you increase this significantly the drive shafts will be at an excessive angle. Looking at the photo of the Tesla unit I estimate this distance is around 120 mm.


That sounds like the front of the Tesla differential housing. The motor on the back will extend much further from the axle line than this... to the point that interference with the firewall (not just the steering rack) is a concern.

If only the steering rack is an issue, it may be feasible to convert the Mini to front-steer (rack ahead of the axle line). The steering column may be able to get past the Tesla hardware on the right-hand side (driver's side in the UK), because the motor is offset to the left and the smaller inverter is on the right; however, with the narrow track and narrow engine space of the Mini I suspect that it will need a shorter right-side shaft, bringing the motor and inverter to the centre and blocking steering shaft access.

For illustration, I have attached a helpful photo from Kevin showing the Tesla Model S drive unit, mocked up with a VW van (aftermarket) rear suspension... seen from the _front_ (from Kevin's VW van thread), plus an overhead view of the dual-motor Tesla Model S motor/transaxle units in position relative to the axles (from Tesla).

The Tesla unit in Kevin's photo has the motor to the vehicle's left side, which means it is a rear motor - the front drive unit puts the motor on the right-hand side of the car.


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## brian_ (Feb 7, 2017)

jjc839 said:


> Also going to investigate FWD diffs and see what the smallest is out there.


Keep in mind that in a normal front wheel drive (or rear-engine rear-drive) configuration, the differential is integrated with the transmission (so the combination is a transaxle) so you can't reasonably use just the diff - you would use the transmission gearing as well.



jjc839 said:


> Hmm...just browsing around...anyone consider an ATV diff? Very compact, with gear ratios in the mid 3's. I would think a diff from a newer 700+cc ATV would be plenty strong for what I have in mind.
> 
> So, AC motor at 7500rpm with reduction drive of 2:1, driving a 3.50:1 diff, 19.5" tires, top speed of 62mph.


This makes sense to me. You could use a chain or belt drive from the motor to the final drive (diff) input, which would place the motor longitudinally (assuming a longitudinal shaft drive in the ATV). The motor could be above the diff, and to one side to keep it lower. The rear diff from an ATV with independent suspension would put the input shaft and chain or belt on the front side, which you would need to avoid steering rack (and firewall) interference.

The rear final drive (diff) of any front-engined vehicle with independent rear suspension - and rear-drive or all-wheel-drive - would be similar, but of course most of them would be a heavy. They can also be surprisingly long. The Mazda Miata/MX5 has one of the shorter and lighter ones, because of the way the front of it is mounted and the low weight of the car. You would want to avoid electronically-controlled clutch-based units used in some AWD cars.


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## jjc839 (Sep 1, 2017)

brian_ said:


> This makes sense to me. You could use a chain or belt drive from the motor to the final drive (diff) input, which would place the motor longitudinally (assuming a longitudinal shaft drive in the ATV). The motor could be above the diff, and to one side to keep it lower.


This is just what I was thinking, motor on top, longitudinally, except using a front diff so your belt/chain drive would be on the firewall side, hopefully with enough clearance from the steering components.


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## brian_ (Feb 7, 2017)

jjc839 said:


> This is just what I was thinking, motor on top, longitudinally, except using a front diff so your belt/chain drive would be on the firewall side, hopefully with enough clearance from the steering components.


A front final drive from an ATV might be small enough for this work; however, some of them do not contain a differential - they just have a bevel gear drive. This works on dirt (especially since these things can usually be disengaged to make it a rear-wheel-drive vehicle), but not on a hard surface. Early ATVs didn't even have a diff in the rear axle, and some still don't!

While the rear diff from an ATV seems suited to the load, I would wonder about a front diff handling all of the torque needed to move the Mini; an ATV front end is pretty light.

The front diff from any front-wheel-drive car will be integrated with the transaxle, so there's no potential there. The front diff from a more traditionally laid out four wheel drive (truck, SUV, or car) is a separate unit, but the input shaft is probably too long to avoid conflict with the steering rack.


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## MalcolmB (Jun 10, 2008)

Kevin Sharpe said:


> I'm not sure exactly which dimension you are looking for... any chance you have a picture showing the critical dimensions in the mini drivetrain?


I can't find a relevant photo, but if you imagine the Tesla unit installed in the front of a Mini, it would be the distance from the rotational axis of the differential to the rearmost point on the differential casing.



brian_ said:


> The rear final drive (diff) of any front-engined vehicle with independent rear suspension - and rear-drive or all-wheel-drive - would be similar, but of course most of them would be a heavy. They can also be surprisingly long. The Mazda Miata/MX5 has one of the shorter and lighter ones


A Landrover Freelander rear diff is surprisingly short and light as well.


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## brian_ (Feb 7, 2017)

MalcolmB said:


> A Landrover Freelander rear diff is surprisingly short and light as well.


That's a good example of an all-wheel-drive system. But watch which one you get: the Freelander 1 (1997-2006) unit is compact, but the Freelander 2 (2006-2014, plus later related models) is a completely different vehicle and the rear final drive unit has a bulky housing on the input side for the Haldex clutch unit which you don't want (the equivalent part was mounted separately on the Freelander 1).

Freelander 1 rear final drive (seen from the right side, so input to the right; this unit is probably also upside-down):









Freelander 2 rear final drive (seen from the left side, so input to the left):









The Honda CR-V is the same type of vehicle, but its rear final drive unit has the same problem as the Freelander 2. At least some Ford Escape variants have a similar issue. The Toyota RAV4 looks okay.


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## brian_ (Feb 7, 2017)

MalcolmB said:


> I can't find a relevant photo, but if you imagine the Tesla unit installed in the front of a Mini, it would be the distance from the rotational axis of the differential to the rearmost point on the differential casing.


But since the motor is behind the axle, it would be the distance to the rearmost point on the motor or inverter housing. Right?


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## brian_ (Feb 7, 2017)

This video tour of a Tesla Model S P85D shows the mounting and size of the front motor assembly quite clearly. The motor is behind the axle line, on the right-hand side of the vehicle, and quite high (because it extends over the thick front part of the battery pack).
https://www.youtube.com/watch?v=KVCi8GicPck

I can't see this fitting in the front of a Mini.


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## MalcolmB (Jun 10, 2008)

Nice video, but it looks feasible to me if you turn the Tesla drive unit around so it's in front of the drive shafts, and drive it in reverse (assuming the drive shaft angle is not too extreme). Is there some other problem I've overlooked – is the gear train unsuitable for sustained operation in reverse?

Being realistic though, a Tesla unit in the front of a Mini would be overkill (but fun). Front wheel drive obviously sets a limit on the maximum useable torque and I get the impression Jeff isn't looking for high performance.

Looking at the idea of a motor mounted above a differential: is there any particular reason why you don't want the drive chain/belt at front of the engine bay, rather than at the back? If not, a Curtis AC34/35 above a lightweight RWD diff seems like a fairly easy solution if you're comfortable with chain/belt drive.


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## brian_ (Feb 7, 2017)

MalcolmB said:


> Nice video, but it looks feasible to me if you turn the Tesla drive unit around so it's in front of the drive shafts, and drive it in reverse (assuming the drive shaft angle is not too extreme). Is there some other problem I've overlooked – is the gear train unsuitable for sustained operation in reverse?


Quite possibly, yes. If the gear motion is what moves oil around the transaxle, it won't do that properly in reverse. Even if there is a lube pump, it will deliver oil to the locations suited to forward rotation. It might be possible to fix this... but why?



MalcolmB said:


> Being realistic though, a Tesla unit in the front of a Mini would be overkill (but fun). Front wheel drive obviously sets a limit on the maximum useable torque and I get the impression Jeff isn't looking for high performance.


I agree. The Tesla components would be interesting, but don't seem to me like the logical choice for this size of car.


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## Kevin Sharpe (Jul 4, 2011)

One other variable to consider... Tesla currently make two 'small' motor variants (one for the front axle and one for the rear) and the driveshafts are in different locations in relations to the motor (they are lower on the front motor - see photo)... for lubrication purposes I think you'll need to keep the motors horizontal and running in the correct direction (iirc they use a simple oil splash mechanism in the transmission).

I'll try to get some dimensioned drawings produced 

For those who are interested Doug Yip produced a great video showing the insides of the transmission of the 'large' motor variant... clearly we need to open up the small one soon


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## jjc839 (Sep 1, 2017)

MalcolmB said:


> Being realistic though, a Tesla unit in the front of a Mini would be overkill (but fun). Front wheel drive obviously sets a limit on the maximum useable torque and I get the impression Jeff isn't looking for high performance.
> 
> Looking at the idea of a motor mounted above a differential: is there any particular reason why you don't want the drive chain/belt at front of the engine bay, rather than at the back? If not, a Curtis AC34/35 above a lightweight RWD diff seems like a fairly easy solution if you're comfortable with chain/belt drive.


Correct, not looking for anything more than stock performance that came with the 34hp 998. So the AC34/35 or maybe even an AC20 would suit. As for the drive being at the front or rear of the engine bay, I was just thinking for the right direction of rotation of the axles if using a front diff, but I suppose it really doesn't matter as the motor will happily turn either direction.

Going to do some more searching to find the smallest diff out there. Maybe something like an early corolla rwd unit.


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## brian_ (Feb 7, 2017)

jjc839 said:


> Going to do some more searching to find the smallest diff out there. Maybe something like an early corolla rwd unit.


That would be a live beam axle, not usable in an independent suspension unless you're up to building a housing for it... and I don't see any point in doing that!


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## brian_ (Feb 7, 2017)

Kevin Sharpe said:


> One other variable to consider... Tesla currently make two 'small' motor variants (one for the front axle and one for the rear) and the driveshafts are in different locations in relations to the motor (they are lower on the front motor - see photo)...


Good point Kevin - the front motor is placed up over the battery pack, but the rear motor is as low as it can be (under the cargo area floor). While the high position of the front motor might be useful for clearance in some cases (to clear a subframe structure?) the lower rear motor would lower the centre of mass, and allow more space above the motor.

Of course, none of them suit this Mini...


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## evmini1973 (Dec 20, 2012)

I've been working through 1973 Austin 1000 conversion for about 4 years now. Here is my blog:  http://austinmini1973.blogspot.com/



I went with a Motenergy ME0913 motor and Kelly KHB 700A 72V controller. Top speed 65 MPH, kept the original Mini gear box and adapted the motor to it.


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## brian_ (Feb 7, 2017)

Kevin Sharpe said:


> One other variable to consider... Tesla currently make two 'small' motor variants (one for the front axle and one for the rear) and the driveshafts are in different locations in relations to the motor (they are lower on the front motor - see photo)... for lubrication purposes I think you'll need to keep the motors horizontal and running in the correct direction (iirc they use a simple oil splash mechanism in the transmission).
> ...
> For those who are interested Doug Yip produced a great video showing the insides of the transmission of the 'large' motor variant... clearly we need to open up the small one soon
> 
> https://www.youtube.com/watch?v=mHT1ET9Elhs&t=100s


I realize that this is now old, but in case anyone is reading it while looking for information about Tesla drive units...

In the video the gear oil pump, which is driven by a narrow black gear engaged with the ring gear, is visible inside the gear case; it's actually visible below the intermediate shaft gears in the snapshot used for the YouTube video. A similar pump is shown more clearly in images of the internals of the small drive units. It turns out that all Tesla drive units have these gear oil pumps.


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## steveclunn (Sep 5, 2011)

I did a 67 Austin MK1100... its on my web page.. I have been converting for over 20 years.. Greenshedconversions.com


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## tylerwatts (Feb 9, 2012)

Hello folks
If you want to use an OEM unit the i-MIEV is almost perfect for your build. The motor sits in front of axle line and controller and charger, cooling pump, almost everything attaches to a single subframe that can easily be adapted to bolt into stock motor mounts in the mini.
Here are some pics (I have an entire i-MIEV powertrain in my garage) for your reference. Remember, these came in 3 iterations, i-MIEV, C-Zero and Ion, so should be decent options for donors.


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## Tremelune (Dec 8, 2009)

Piling on to this dead thread in case anyone is looking to electrify a classic Mini...

The folks at MiniTec (known for various Honda conversions) build a rear subframe for AWD conversions:

http://www.superfastminis.com/AWD_CRV_KIT.htm

Seems like it would eliminate the complexity of a FWD solution. It uses a Honda CRV differential and Miata axles...you just need to hook a motor up to that pumpkin:


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## tylerwatts (Feb 9, 2012)

Very cool kit, but why's a FWD conversion complicated. It's the opposite and exactly what the mini pioneered with outright success! Plus most donors are FWD...

AWD mini is insane though!


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## brian_ (Feb 7, 2017)

Tremelune said:


> The folks at MiniTec (known for various Honda conversions) build a rear subframe for AWD conversions:
> 
> http://www.superfastminis.com/AWD_CRV_KIT.htm
> 
> Seems like it would eliminate the complexity of a FWD solution. It uses a Honda CRV differential and Miata axles...you just need to hook a motor up to that pumpkin...





tylerwatts said:


> Very cool kit, but why's a FWD conversion complicated. It's the opposite and exactly what the mini pioneered with outright success! Plus most donors are FWD...


I agree - this seems like the combination of worst features: making car designed to FWD into RWD, using parts which naturally work better FWD, while dealing with an old body from an era in which most cars were RWD.

I can almost see making a readily available modern FWD small car into a RWD EV, because RWD is more desirable and few inexpensive small RWD cars are now available; however, even then the front is the wrong end of the car for the motor.


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## Tremelune (Dec 8, 2009)

The Mini's gearbox is more like an oil pan, which makes it difficult to attach an electric motor to it. It's also a pretty crappy gearbox. I would expect most people would want _no_ gearbox at all. This seems easiest to accomplish by going RWD.

The Mini was "designed" to be FWD because it was designed to be 120" long and have a back seat. That's pretty much it.

Most people who are converting classic Minis aren't asking "What should I convert to an electric car?" they're asking "How can I convert this classic Mini into an electric car?" It's a naturally poor candidate, due in no small part to the unique engine/transmission mating.


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## brian_ (Feb 7, 2017)

Tremelune said:


> The Mini's gearbox is more like an oil pan, which makes it difficult to attach an electric motor to it. It's also a pretty crappy gearbox.


Yes, the original Mini's drivetrain layout is antiquated and undesirable. The obvious solution is to use a more modern (i.e. 50 year old) configuration of transverse FWD drivetrain.



Tremelune said:


> I would expect most people would want _no_ gearbox at all. This seems easiest to accomplish by going RWD


You still have gearing. If you mean eliminating the multi-ratio feature, that's most directly accomplished with a suitable reduction ratio by using an EV's transaxle... since every volume production EV uses a transverse motor on a transaxle.

The front motor and RWD approach makes it difficult to put any useful battery volume in both the rear and the front, which seems like a undesirable thing in a small car. Of course, one can just replace the rear seat with a battery pack, but that pack would still need to work around a propeller shaft.



Tremelune said:


> Most people who are converting classic Minis aren't asking "What should I convert to an electric car?" they're asking "How can I convert this classic Mini into an electric car?" It's a naturally poor candidate, due in no small part to the unique engine/transmission mating.


I get that, but by the time the entire chassis is replaced, all that's left is the body... and none of the car's character.


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## brian_ (Feb 7, 2017)

Tremelune said:


> The Mini was "designed" to be FWD because it was designed to be 120" long and have a back seat. That's pretty much it.


I agree. But why do a Mini if you want something very different? If you are sentimentally attached to the Mini but want RWD, a well-designed RWD EV - which would have a rear motor - would pay tribute to Issigonis' design approach.


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## Tremelune (Dec 8, 2009)

brian_ said:


> I agree. But why do a Mini if you want something very different?


It looks cool.

I basically want a Smart Fortwo Electric Drive (the perfect city car) that looks as good as a classic Mini.


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## brian_ (Feb 7, 2017)

Tremelune said:


> I basically want a Smart Fortwo Electric Drive (the perfect city car) that looks as good as a classic Mini.


Okay, so you realize that you have defined the solution: complete Smart ForTwo ED components in a classic Mini body... which would be RWD, but not with the motor in the front. The layout would be more Smart Roadster than Smart ForTwo (because the Mini's front seats need to be on the floor instead of over battery, but it would likely work.


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## pickmeup (May 8, 2018)

Swindon Powertrain in the UK have developed a kit for the mini, i had a good look around it last week but unfortunately didnt drive it.


https://www.pressreader.com/uk/autocar/20180912/284374085269616


It uses a large battery box in a t shape which has to cut into the floor pan, not sure on the powertrain details yet, but its a very tidy conversion.


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## brian_ (Feb 7, 2017)

pickmeup said:


> Swindon Powertrain in the UK have developed a kit for the mini, i had a good look around it last week but unfortunately didnt drive it.
> 
> 
> https://www.pressreader.com/uk/autocar/20180912/284374085269616
> ...


The article contains a mention of returning the gearbox to GKN due to a noise, which means it is a single-speed transaxle from GKN's electric driveline range, and typical of modern EV transaxles. There's not much information about the motor, but Swindon doesn't make motors so it will be something off-the-shelf; it may be a complete GKN eDrive module (drive unit), with Swindon just installing it and the rest of the electric gear in the Mini. There is little detail available to the public for any of the GKN hardware, since they sell their eDrive line to OEMs, not retail customers.


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## pickmeup (May 8, 2018)

they seemingly worked with SDT drive technology, Im having a look at the website but cant find a suitable motor.


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## Caspar (Dec 17, 2011)

https://youtu.be/8uG2PQk0OGM

This car is built with donorparts fron a Think Classic.


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## CraigB77 (Jan 25, 2019)

any further developments in this area? keen to do this with my mini....


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## Tremelune (Dec 8, 2009)

The i-MiEV motor seems promising...Might just need to bolt it to a subframe and get some axles made...?

Might be some ideas here, but it seems they fabbed a lot of custom stuff:

https://greenshedconversions.com/converting-a-1967-austin-to-electric/

I wonder if there is any benefit (besides a modern suspension and brakes) to starting with a subframe designed for Honda motor/transaxle setup. How rare are conversions of Hondas to electric...? These kits are for swapping Honda motors into classic Minis:

Honda D motor - http://www.superfastminis.com/MTD KIT.html

Honda B motor - http://www.superfastminis.com/MTB2 KIT.html

Honda K motor (requires longer nose) - http://www.superfastminis.com/MTKKIT.htm










Some info on the B transmission:

http://www.performanceforum.com/wesvann/honda/trans/trans.html


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## brian_ (Feb 7, 2017)

Tremelune said:


> I wonder if there is any benefit (besides a modern suspension and brakes) to starting with a subframe designed for Honda motor/transaxle setup. How rare are conversions of Hondas to electric...?


I think this makes a lot of sense, allowing the use of a more conventional (by current standards) transaxle that would be easier to work with than the original Mini transaxle, as well as the suspension and brakes.

The oddball thing about most Honda vehicles (the old S2000 being a notable exception) is that the engine is on the opposite side of the car from conventional practice, and so turns the opposite direction. This is challenge for engine swaps, but doesn't matter to an electric conversion (since the motor can rotate whichever direction is desired), unless a brushed DC motor is used and the brushes have a preferred rotation direction.

I can't think of any reason to chose Honda rather than another brand for an EV conversion of a Mini, except that these kits are available for Honda powertrains. Presumably the engine swappers like Honda because they have reasonably small and light but powerful engines with lots of aftermarket performance support, none of which matters to an EV conversion.

If swapping out the transmission and having to fabricate a bunch of structure and suspension yourself (not using one of these kits), it would make more sense to me to use a complete drive unit from a similarly configured (transverse front motor, front wheel drive) production EV such as a Leaf (or several others). A Smart ED or Mitsubishi i-MiEV drive unit would likely fit as well, since they place the motor ahead of the axle line.


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## Tremelune (Dec 8, 2009)

Here's a better shot of how the front wheels are driven...It sure looks like you would just need to adapt a motor to the transmission with a plate, and the rest is just mounting components anywhere there's space:










You wouldn't need to start out AWD (though that is what's in the photo—I believe it's from a RAV4, which I assume mates up to the same motor as the FWD transmission), though if one day you scored a Tesla battery pack and decided to put all the torque in the world in a tiny car, you would have options...


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## brian_ (Feb 7, 2017)

Tremelune said:


> Here's a better shot of how the front wheels are driven...It sure looks like you would just need to adapt a motor to the transmission with a plate, and the rest is just mounting components anywhere there's space...


Yes, that's the advantage of one of these kits: mounting the motor to the transaxle is relatively straightforward, and routinely done in EV conversions. It's not just an adapter "plate" (which is not just a flat plate) to mount the motor housing to the transaxle case: you also need the shaft coupler to connect the motor output to transaxle input. And the transaxle won't hold the motor up using just the single original transaxle mount to the vehicle structure: there are usually two engine mounts (on the end opposite the transaxle, and at the front or rear) - visible in the conversion kit images - which would need brackets to the motor.



Tremelune said:


> You wouldn't need to start out AWD (though that is what's in the photo—I believe it's from a RAV4, which I assume mates up to the same motor as the FWD transmission), though if one day you scored a Tesla battery pack and decided to put all the torque in the world in a tiny car, you would have options...


This appears to be the AWD kit discussed earlier. The donor would be a Honda CR-V, not a Toyota RAV4. Even without the previous discussion or other information about the kit, it's apparent that it is Honda because the engine is on the left side of the vehicle (driver's side where we drive on the right hand side of the road).

Yes, the transaxles in vehicles like this mount to the car the same way, and mate to the engine the same way, regardless of whether they are FWD or AWD. The FWD and AWD transaxles are mostly identical, with only a case extension on the back and some extra components to tap drive off for the rear.

No production AWD EV uses one motor and a complex mechanical system to get drive to both axles - they all use separate front and rear motors, so no shaft is required between front and rear, and torque distribution between the axles is easily controlled. Running a modern AWD system without the all of the same computers used in the original vehicle could be a challenge... and of course the EV conversion doesn't have the engine computer.


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## Tremelune (Dec 8, 2009)

Correct on all counts. here's some more info on the Honda AWD, which seems way more complicated than, say, the Dana setup in an old Jeep:

https://www.awdwiki.com/en/honda/

I don't mean to harp too much on the AWD aspect, as it's not really a goal of mine (or many, I would expect), but I still find myself wondering if it wouldn't make as much sense to mate the motor directly to this driveshaft to the rear diff (or even directly to the rear diff, though you'd have to cut out parts of the car to put the motor where the rear seat is). A RWD Mini with improved weight distribution would be fun indeed.

Seems like maybe the FWD solution is a solved problem with the above...The only thing left to do is all the work!


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## brian_ (Feb 7, 2017)

Tremelune said:


> Correct on all counts. here's some more info on the Honda AWD, which seems way more complicated than, say, the Dana setup in an old Jeep:
> 
> https://www.awdwiki.com/en/honda/


The Honda system doesn't really have more major parts (although it does have hydraulics), just more sophisticated control. Since that particular system has no electronic control (unlike current systems) it might be a good choice for a DIY AWD conversion.


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## Tremelune (Dec 8, 2009)

Stumbled on this thread where someone converted a classic Mini using the original transmission and a Leaf motor:

https://www.diyelectriccar.com/forums/showthread.php?t=196386


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## brian_ (Feb 7, 2017)

Tremelune said:


> Stumbled on this thread where someone converted a classic Mini using the original transmission and a Leaf motor:
> 
> https://www.diyelectriccar.com/forums/showthread.php?t=196386


That one uses the Leaf transaxle, not the original Mini transaxle.


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## Tremelune (Dec 8, 2009)

Right again—I must have misread! I was staring at those photos trying to figure out where the Leaf motor ended and the Mini transmission began!

That seems like a solid solution right there. Custom subframe/motor mounts and axles, Leaf drivetrain...I wonder where the software is for integrating the Leaf parts. How much do you still need to "trick" the Leaf drivetrain when it's in another car?

With 20" vs 25.5" tires, the gearing is significantly shorter in a Mini than a Leaf, and the weight of the Mini is less by like 1,000lb (factoring in an extra 500lb for batteries). I bet a classic Mini with a Leaf motor and battery pack would move. In a classic Mini with the Leaf 7.91 gear reduction, it looks like maximum efficiency would be from 15mph (2700 RPM) to just under the top speed of 75mph (10,000 RPM).


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## brian_ (Feb 7, 2017)

Tremelune said:


> Right again—I must have misread! I was staring at those photos trying to figure out where the Leaf motor ended and the Mini transmission began!
> 
> That seems like a solid solution right there. Custom subframe/motor mounts and axles, Leaf drivetrain...


It can be hard to pick individual components out of the maze of parts, especially when so much of it is generic raw cast aluminum in appearance.

Even without the discussion (which wasn't really clear), the key in the case of a classic Mini conversion is that the transaxle is at the end of the motor (as has been the most common practice for about 45 years) rather than below the motor, so the diff housing is near the motor-transmission interface rather than sticking out the middle of the assembly as it does from the Mini engine and transaxle.

In the Leaf the motor-transaxle housing junction is roughly centred in the vehicle, with the motor on the right side and so the transaxle is on the left, with free space between the transaxle and the left side of the compartment. Since the Mini is substantially narrower than the Leaf, the whole unit is effectively offset to the left when transplanted into the Mini; it still fits, but without the extra space. 

This would be similar for most drive units, since they are generally placed in the stock vehicle to keep the differential reasonably centred, rather than putting the mass of the whole thing on centre (e.g. i-MiEV, ForTwo ED, e-Golf, Soul EV, Focus Electric, 500e, Ioniq, Kona, i3, etc. The challenge with some of them might be that the left-side output is too far left in the stock configuration (copying the position of the corresponding gas-engine model with its longer engine and further-left transaxle), then shifting the whole thing left might make the left-side axle shaft too short; the Kona Electric drive unit looks like a likely example of this, although it might be fixable with a different inner CV joint assembly. Planning in detail is important. 

The exception would be drive units which run one output concentric with the motor shaft, such as the Chevrolet Spark and Chevrolet Bolt; those might be expected to generally centre the whole assembly, and might have an issue with axle shaft length on both sides (too short) in a narrow car like the Mini, because the outputs are so widely spaced (because the whole motor and gearbox are between them).



Tremelune said:


> I wonder where the software is for integrating the Leaf parts. How much do you still need to "trick" the Leaf drivetrain when it's in another car?


Lots of work, unless you replace the Leaf controller (as Alex did in that other conversion), then it's different work. 



Tremelune said:


> With 20" vs 25.5" tires, the gearing is significantly shorter in a Mini than a Leaf, and the weight of the Mini is less by like 1,000lb (factoring in an extra 500lb for batteries). I bet a classic Mini with a Leaf motor and battery pack would move. In a classic Mini with the Leaf 7.91 gear reduction, it looks like maximum efficiency would be from 15mph (2700 RPM) to just under the top speed of 75mph (10,000 RPM).


I agree that this is a nice match, although fitting in enough battery (360 volts is needed to maintain performance to the top speed) is a challenge.


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## brian_ (Feb 7, 2017)

pickmeup said:


> Swindon Powertrain in the UK have developed a kit for the mini, i had a good look around it last week but unfortunately didnt drive it...


I looked for updates on this today (since this thread is still active) and found a bunch of coverage of the introduction of this as a limited-production vehicle (100 units) last month, as the "Swind E Classic". If you search for "Swindon electric mini" you'll find lots of articles from 2019 Feb 14 and a few days after that. None of the articles that I found says anything not found on the Swind.life website. I didn't find any photos of the drive unit configuration (which will not be anything interesting anyway) or the battery pack.

It's not especially quick (0-60 mph in 9.2 seconds) but has usable range (125 miles), corresponding to the battery capacity (24 kWh) and small size (720 kg, only 80 kg over stock). Of course it's insanely expensive, as all commercial conversions are: £79,000 ($138K CAD).


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## Tremelune (Dec 8, 2009)

Random thread I stumbled on discussing adapting a Leaf motor to a Warp 9 bolt pattern (and then to a Honda Civic transmission):

https://www.diyelectriccar.com/forums/showthread.php?t=188962&highlight=leaf


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## Tremelune (Dec 8, 2009)

Another thread I stumbled on with a very detailed conversion:

http://www.theminiforum.co.uk/forums/topic/320098-electrifying-trogdor/

He used an AC50, Smart batteries, and a Suzuki G10 transmission (which required a fair amount of customization of the subframe and axles).


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## Tremelune (Dec 8, 2009)

Stumbled on an unfinished Mini project that has some interesting bits:

https://www.diyelectriccar.com/forums/showthread.php/grant-electric-mini-71039


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## Cali Symz (Jun 17, 2019)

I stumbled on this thread by accident, but if you did fancy popping an IMiEV power unit into the back of a 1960's city car, don't forget the humble Hillman Imp. Imps are rear engine, rear wheel drive. I am considering embarking on such an adventure with my Imp Californian (the coupe shaped Imp), I'm have been thinking of fitting the whole drive train - diff, half shafts, hubs, brakes, rear suspension in, as the track is within 40mm of perfect.


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## Tremelune (Dec 8, 2009)

Another random classic Mini conversion I stumbled upon in New Zealand:

https://carrott.org/emini/Main_Page

It's an old conversion, and...apparently quite involved, but it seems to have come through with success. It uses an 80s Mitsubishi transaxle...


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## BrianMacZA (Apr 30, 2021)

Has anybody ever used the existing Mini gearbox/clutch/driveshaft setup and simply swapped the ICE engine part for an electric motor? The ICE already connects to the gearbox via a chain, so it may be the simplest engineering solution.


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## pickmeup (May 8, 2018)

Yes the original conversions done by bmc in the sixties incorporated the motor on top of the gearbox.
There is an up to date conversion on the go in Europe. Have a look at the g.o.s.h carborg project on Facebook. Or have a look at my Instagram electricclassicminis for more pics.


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## schelle63 (Jan 3, 2018)

@BrianMacZA:

There is this conversion also mentioned in page #2 of this thread:





__





1973 Austin Mini


A journey of rebirth for a 1973 Austin Mini named Jane.




austinmini1973.blogspot.com






I happen to know a guy in Hamburg, who did this also. He uses a belt drive. Have a look at sven_grimpe in instagram. (By the way, the other electric Mini (with the Gulf-Racing outfit) is my project. I preferred to skip the Mini-gearbox.)
Regards,
Markus


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## schelle63 (Jan 3, 2018)

BrianMacZA said:


> The ICE already connects to the gearbox via a chain, so it may be the simplest engineering solution.


By the way, it is a set of gears which make the primary drive in the original Mini, not a chain.

Reards,
Markus


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## brian_ (Feb 7, 2017)

schelle63 said:


> By the way, it is a set of gears which make the primary drive in the original Mini, not a chain.
> 
> Reards,
> Markus


Good catch.
The gear set are apparently called the "drop gears" or sometimes"transfer gears" in Minis, and are a set of three: small gears on the transmission input shaft and at the engine (called the "primary" gear), plus a larger idler gear connecting them. 

A conversion should be able to use the gear on the input shaft (it's on the splined end of the shaft), and could provide a bracket and bearings to support the outboard end of the idler gear (which has an integral shaft, and runs in the gearbox case on the inboard end). The one at the engine is a more complex setup, because the it is connected to the crankshaft through the clutch), but if it can be modified to work the resulting gear drive would be efficient and reliable.

Does that sound right, Markus?


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## schelle63 (Jan 3, 2018)

Exactly.
Concerning reliability, it should be mentioned that the primary drive, especially the mentioned idler connecting gear, is a weak point of the Mini drivetrain. It becomes worse, of course, when the engine gets more power; there are straight-cut gears available which do better, but their sound is deafening!
In addition, what appears to be "the simplest engineering solution" (BrianMcZA) is not that easy to realize, as you will need to cover the entire gearbox, and keep the primary drive lubricated (gears or chain), or to seal the input shaft (belt drive).


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## brian_ (Feb 7, 2017)

schelle63 said:


> ...
> In addition, what appears to be "the simplest engineering solution" (BrianMcZA) is not that easy to realize, as you will need to cover the entire gearbox, and keep the primary drive lubricated (gears or chain), or to seal the input shaft (belt drive).


Another good point that I had missed: the classic Mini gearbox is lubricated by engine oil. It seems likely that it will lubricate properly without the engine's oil pump (as most traditional transmissions don't have a pump, but just pick up oil with the gears), but since the cover on the drive end presumably retains the oil, an input shaft seal would be needed with a belt drive. Keeping the gear drive implies lubricating those gears with oil and retaining some version of the cover (so no new input shaft seal would be needed), but it also implies a possible need to pump oil for the idler shaft and perhaps for the drop/transfer gears. Maybe if you're lucky even the drop/transfer gear system would work without a pump.


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## schelle63 (Jan 3, 2018)

To be honest, I find only one reason to retain the heavy, bulky MINI-gearbox:
- there is absolutely no other option available.
Better keep things simple.
Markus


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