# Also wanting to convert a classic Mini



## mwalsh (Feb 7, 2020)

I haven't driven my OBCs (old British cars) for about 10 years now, more or less coincidentally with taking delivery of a Nissan LEAF in January 2011. Turns out that I'm just not that much into gasoline powered vehicles much anymore.

I have two Minis and a MGB. The Mins are standard saloon and Clubman Estate respectively and I'm thinking of converting the saloon. Minimum goal is 50-60mph top speed and approximately 40 miles of range. Usage would be city driving on nice days.

I was first thinking of stripping the top off the engine, just leaving the stock gearbox. Then mounting a DC motor to a blanking plate I'd have made up. Then I'd mate the two with a belt or chain going to the clutch housing.

Now I'm thinking I might do a pair of 72-96v Chinese hub motors at the rear and just pull everything out of the engine bay. The motors would mount to a custom swing arm which in turn would mount to a modified stock subframe or custom beam axle. 

The Chinese kit also comes with small hydraulic brake calipers, which would be fine because the OEM front discs would do most of the work, and then I would think that a pair of mechanical "puck" style calipers could substitute for the handbrake mechanisms in the original Mini rear drums. It also comes with a pair of motor controllers, a throttle pedal, and a display/speedometer. 

Not sure what the quality will be like, but most of the stuff I've gotten directly from China has been between excellent and "needs a little fettling but not bad". I've never received anything where the quality has been truly horrible.

So mechanically I feel pretty good, but I'm not clear on what I need battery wise to reach the stated goal. I would like to use LEAF battery cells, since I'm somewhat familiar with them and maybe could use the cells from my own LEAF when the time comes. Some advice there would be great.

Thanks in advance.


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## mwalsh (Feb 7, 2020)

So in doing a bit of site browsing, it looks like 72-96v might be unrealistic for what I'm trying to achieve. Fortunately, the vendor will customize the hub motors for up to 144v.So now I'm thinking either 120v or 144v would be a better choice? 

Oh, and the hydraulic brakes with the kit also incorporate a manual pull cable. 

While I'm having the factory customize the motors for me, I'll also be asking for a 101.6mm PCD so I can continue to use standard Mini 12" wheels (which I understand also need to be considered when it comes to maximum speed).


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## tylerwatts (Feb 9, 2012)

Sounds promising. If using LEAF parts why not drop a motor up front into the stock subframe and batteries in the boot? Depends on what space you want inside.

How much range are you after?

Sent from my moto g(7) plus using Tapatalk


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## mwalsh (Feb 7, 2020)

tylerwatts said:


> Sounds promising. If using LEAF parts why not drop a motor up front into the stock subframe and batteries in the boot? Depends on what space you want inside.
> 
> How much range are you after?





I thought a lot about dropping a motor into the front. A front runner (at least without making any measurements whatsoever) was the small Telsa Model S rear unit, which I think comes in at about 3'x2'1', married to a custom pair of half-shafts.

I really don't want to make any modifications to the passenger compartment at all (other than removing anything superfluous), if it can be helped. Even if that means I can't get the range I'm looking for (about 40 miles).


That's one of the reasons I was interested in the hub motors, because it would keep both the boot and the engine compartment available for battery modules and electronics. I am even more interested now I've found Cboy's electric chopper trike.


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## Emyr (Oct 27, 2016)

The rear motor-diff from Lexus hybrid 4wd RX and LS models might be a good option in something as light as a mini, driven by the inverter from a Prius or Yaris, including the boost converter to keep the required battery voltage manageable. Diff weighs about 40kg and is capable of 50kw (67bhp) which is about the same as the 1960s 1071cc/970cc Cooper S models, but will feel like much more due to the low-end torque.

With some mixed CV shafts you could mount the Lexus unit in the front with the battery pack split between the engine bay and somewhere in the back. This avoids re-engineering the suspension, and depending on your local laws, might avoid an intensive inspection to get it re-certified for road use.


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## Duncan (Dec 8, 2008)

Hub motors are an awful idea - OK for pushbikes

And a RWD drive mini is a travesty


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## tylerwatts (Feb 9, 2012)

Duncan said:


> Hub motors are an awful idea - OK for pushbikes
> 
> And a RWD drive mini is a travesty


I think a lightweight mini is probably a better candidate for hub motors and makes sense for the packaging constraints of the mini.

What's the possibility of fitting the small Lexus unit in the rear? Would mean chopping the boot out but it's light, you could use an already available rear drive subframe with trailing arm suspension and put all the weight of batteries up front. Also, the Lexus/Toyota boost converter would be really handy to say running some energy dense Tesla battery modules and still have a useful running voltage.

PS, that motor isn't in the LS, only the NX and RX SUVs and the Toyota RAV4 and CH-R.

Cheers
Tyler


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## brian_ (Feb 7, 2017)

tylerwatts said:


> What's the possibility of fitting the small Lexus unit in the rear? Would mean chopping the boot out but it's light, you could use an already available rear drive subframe with trailing arm suspension and put all the weight of batteries up front.


As I have said in previous discussions, I don't see the point of taking a front wheel drive car from an era in which almost everything was rear wheel drive, and completely ignoring everything about the original powertrain and suspension design to make it rear wheel drive. Just convert any other random small sports car, sedan, or hatchback. But it's your body shell... you can do what you want with it.



tylerwatts said:


> PS, that motor isn't in the LS, only the NX and RX SUVs and the Toyota RAV4 and CH-R.


Right, but to expand on this for clarity:

The Lexus GS and LS have a longitudinal engine layout. When fitting their hybrid system to vehicles with this layout, AWD is handled the same way as with a conventional transmission... by a transfer case.
The other listed models have a transverse engine layout. When fitting their hybrid system to vehicles with a transverse engine, the usual AWD hardware is not used; instead, the front drive is normal and there is a separate electric motor (with transaxle) driving the rear wheels.
It is that separate rear motor from the transverse system that Tyler is suggesting. It is small for driving an entire vehicle, but for a small car it could make sense. Honda has a similar system; their rear drive unit (front drive in the NSX) has separate left and right motors instead of one motor and a differential.

One issue is that this system has been used with at least three sizes of rear motor. In the original (the Highlander Hybrid) the rear motor is the same as the larger of the two motors in the hybrid system - about 50 kW output as Tyler mentioned earlier. In some cases the rear motor is smaller, and in some of the latest instances (the Prius eAWD) it is tiny. The Highlander and Lexus RX may be the only safe choices for the higher-power motor.

The C-HR isn't even available as a hybrid here in North America. It is available as a hybrid elsewhere, but I don't know if the AWD hybrid combination is available, let alone which rear motor it uses. For instance, in Australia there is a C-HR Koba hybrid, but only 2WD.


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## brian_ (Feb 7, 2017)

tylerwatts said:


> I think a lightweight mini is probably a better candidate for hub motors and makes sense for the packaging constraints of the mini.


While a very tightly packed car is a good candidate from a packaging viewpoint, a very light car is especially bad from a dynamic viewpoint to have extra-high unsprung weight.


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## brian_ (Feb 7, 2017)

mwalsh said:


> I thought a lot about dropping a motor into the front. A front runner (at least without making any measurements whatsoever) was the small Telsa Model S rear unit, which I think comes in at about 3'x2'1', married to a custom pair of half-shafts.


The Tesla Model S and X drive units (even the "small" ones, and even the one specifically for the front) won't fit in the front of a Mini. The motor is behind the axle, and would interfere with the firewall and steering. Some people are using the Leaf drive unit - it fits because (like nearly every other EV, and almost all transverse engines including the Mini) the motor is ahead of the axle line.


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## pickmeup (May 8, 2018)

Great to hear of another mini looking to become converted, as has previously been stated the choice of powertrain comes down to the packaging and in a mini there isn't much. Im doing a mini marcos so im limiting myself even more 

Ive looked at a lot of conversions from using the A series gearbox with a transfer case and the motor on top, using rover or Honda gearboxes with a custom subframe and Im now looking at more compact units (mitsubishi outlander)



The weapon of choice seems to be the leaf at the moment, with a few conversions from ESDI and others using a modified or bespoke front subframe and then having the batteries take up the boot or back seat.


Of course there is the Swind-E conversion https://swind.life/products/e-classic/ which is a drive in / out conversion starting at 79k.


And a couple others in France and the Netherlands http://electricmini.nl/
https://www.ian-motion.com/en/


I think you have a good idea on your range and speed requirements, theres a lot of information on here and Im still trying to read and learn as much as i can.


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## Tremelune (Dec 8, 2009)

Pick your poison.

1) Hub motors in the rear will require a lot of custom fabrication, and the end result will be a weak, untested drivetrain in a configuration the Mini wasn't designed for and may not like.

2) Mating a motor to the transmission will require some kind of custom belt/chain drive, and the end result will be limited by the torque handling of a transmission designed for...not much torque.

3) Mating a motor to a Honda transmission will require a $2k subframe and axles, a Honda transmission, and adaptor bits (which I _believe_ are available for purchase for motors that's the shape of a Warp 9). You'll have to trim the fenders a bit (this would be invisible with the bonnet closed).

4) A Leaf/Tesla motor up front will involve a custom front subframe and axles.

I'm going the latter route...It's likely to be the cheapest, stays pretty close to the factory design, and the power output will be only limited by the batteries.

My project: https://www.diyelectriccar.com/forums/showthread.php/nissan-leaf-into-rover-mini-129310-200007.html

You'll need approximately half a 24kW Leaf pack (200 lb) to get 40 miles. My research tells me the Leaf inverter might require a minimum of 240v, which is something like 300 lb of Leaf battery (if you choose to use the inverter instead of aftermarket bits). I'm still working on this.

I'm over $10k in, and I have yet to get the motor mounted. It has been interesting work, though, and I have high hopes in the final product being the perfect car for Los Angeles.


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## mwalsh (Feb 7, 2020)

Emyr said:


> The rear motor-diff from Lexus hybrid 4wd RX and LS models might be a good option in something as light as a mini, driven by the inverter from a Prius or Yaris, including the boost converter to keep the required battery voltage manageable. Diff weighs about 40kg and is capable of 50kw (67bhp) which is about the same as the 1960s 1071cc/970cc Cooper S models, but will feel like much more due to the low-end torque.
> 
> With some mixed CV shafts you could mount the Lexus unit in the front with the battery pack split between the engine bay and somewhere in the back. This avoids re-engineering the suspension, and depending on your local laws, might avoid an intensive inspection to get it re-certified for road use.



Interesting idea. Edit: But that wouldn't fit transverse, right? Edit 2: I might be able to make that work with a short body motor and/or sitting the assembly at a jaunty angle instead of forward or straight up.

What about the transfer case from a small 4wd vehicle?

No vehicle inspections in California, other than for emissions. And the Mini is old enough to be exempt even from those.

So I'm finding that I've an awful lot to learn before I even get started with this, so don't be surprised if I'm not back with any updates in a long, long while. I will spending much of my time trying to make it that I don't sound dumb when I do eventually get going.


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## Emyr (Oct 27, 2016)

mwalsh said:


> Interesting idea. Edit: But that wouldn't fit transverse, right? Edit 2: I might be able to make that work with a short body motor and/or sitting the assembly at a jaunty angle instead of forward or straight up.


It already is transverse, it sits where the rear diff normally would, but without a prop shaft in the nose.

Photo in post 2 of this thread: https://www.diyelectriccar.com/forums/showthread.php/toyota-mgr-first-spinup-170305.html


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## mwalsh (Feb 7, 2020)

Emyr said:


> It already is transverse, it sits where the rear diff normally would, but without a prop shaft in the nose.
> 
> Photo in post 2 of this thread: https://www.diyelectriccar.com/forums/showthread.php/toyota-mgr-first-spinup-170305.html



I didn't really express myself well. I meant that the motor couldn't be orientated transversely.


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## Emyr (Oct 27, 2016)

The motor is inside the diff...?


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## mwalsh (Feb 7, 2020)

Emyr said:


> The motor is inside the diff...?



Really? I must be finding the wrong things with my Google search.


Edit: So this? That's definitely interesting.


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## Emyr (Oct 27, 2016)

More info here: https://ecomodder.com/forum/showthread.php/hot-rodding-toyota-mgr-29878.html


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## mwalsh (Feb 7, 2020)

Emyr said:


> More info here: https://ecomodder.com/forum/showthread.php/hot-rodding-toyota-mgr-29878.html



I'm not sure about this one if it takes more than 300v to run it up properly. I was thinking I wouldn't go any more than 120v. 144v at the very most. Only got so much space in the Mini for LEAF cells without playing silly buggers with the passenger space!

Unless, between now and then, some other kind of cell comes which is much smaller but has the same kind of energy density. Oh, and they need to be cheap too.

Of course, I do have a trailer I could load up with LEAF cells too. I suppose I could do that at a pinch.


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## brian_ (Feb 7, 2017)

mwalsh said:


> I'm not sure about this one if it takes more than 300v to run it up properly. I was thinking I wouldn't go any more than 120v. 144v at the very most. Only got so much space in the Mini for LEAF cells without playing silly buggers with the passenger space!
> 
> Unless, between now and then, some other kind of cell comes which is much smaller but has the same kind of energy density. Oh, and they need to be cheap too.
> 
> Of course, I do have a trailer I could load up with LEAF cells too. I suppose I could do that at a pinch.


You don't need a different kind of cell, just a module configuration for higher voltage (more cells in series) at the expense of current capacity (cells in parallel). For instance, each traditional Leaf module has four cells, with two paralleled pair in series. If it were reconfigured (which is not easy and probably not worth the effort) to put all four cells in series, it would have twice the operating voltage

Plug-in hybrids have relatively small battery size (typically 8 kWh to 20 kWh), but the same overall voltage (~360V from 96 cells in series), by using smaller cells (of the same type as regular battery EVs), or configurations with fewer cells in series. Chevrolet Volt modules or the LG modules for the Chrysler Pacifica Hybrid are popular choices for higher voltage in smaller packages.


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## Greengearhead (Apr 21, 2015)

I bought a set of hub motors to convert a mini and never did it. I have the hub motors for sale if you are interested.


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## mwalsh (Feb 7, 2020)

Greengearhead said:


> I bought a set of hub motors to convert a mini and never did it. I have the hub motors for sale if you are interested.



Thanks, but I've sort of moved away from that idea now. Besides which, I would want a custom PCD (101.6mm) so I could continue to use stock Mini wheels.


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## Caspar (Dec 17, 2011)

Why not by a Norwegian Think Classic car and use as a donor? They are availeble for apr. 600 euro

https://youtu.be/8uG2PQk0OGM


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## mwalsh (Feb 7, 2020)

Caspar said:


> Why not by a Norwegian Think Classic car and use as a donor? They are availeble for apr. 600 euro
> 
> https://youtu.be/8uG2PQk0OGM



So far as Think availability in the USA... as they say in the UK - "rare as hen's teeth".


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## Emyr (Oct 27, 2016)

mwalsh said:


> I'm not sure about this one if it takes more than 300v to run it up properly. I was thinking I wouldn't go any more than 120v. 144v at the very most. Only got so much space in the Mini for LEAF cells without playing silly buggers with the passenger space!


I mentioned a boost controller in my earlier post; The standard battery in most Toyota/Lexus hybrids is only 288v, NiMH, usually about 1kWh behind the back seats. In the same casing as the inverter is a DC-DC boost controller. With Li-Ion cells you'll need 66S to get the same nominal voltage.

For a given power, halving the voltage means doubling the current, so you'll need much fatter cables to avoid dropping too many volts and wasting power as heat. You'll also need a third-party controller like a Kelly, which will need setting up and won't come cheap. With the Toyota MGR, you only need one of the two power stages of a Prius/Yaris inverter, and an open-source drop-in "brain board" to control it.


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## mwalsh (Feb 7, 2020)

I think I have an idea. Tell me if you think this sounds feasible:

Stock Mini differential mated to the electric motor via the stock final drive gears (with the pinion gear obviously on the end of the motor shaft). The motor sitting transversely in the Mini engine compartment on a custom mount.

There are a number of final drive ratios available for the Mini anywhere between 4.33/1 and 2.76. Most mild performance Minis have between 3.44/and 3.1/1. Later (1996-2000) Minis had the 2.76/1 and were a bit gutless through the mid-range. Might not be a problem with an electric motor though.

Considerations:

Problem: The Mini differential comes away in a half enclosure, with half of the circular hole for the output shaft bearings remaining with the gearbox case. This would obviously need to be recreated in a custom transfer case, which could otherwise be a fairly simple rectangular box. However, the engineering would need to be good because those gears would need to mate perfectly (*see comments below on helical gears vs. straight-cut).

Solution: Beyond my personal capabilities, other than maybe making a very rough mock up for proof of concept, but I know people who can do engineering and weld way better than I can, so not really a problem.

Advantage: Could use ALL original Mini running gear. Except maybe it would be good to switch the long and short half-shafts around so that more room is created on the side of the engine compartment where the motor would sit. 

In an enclosed box, the whole assembly could be run in a lightweight oil or transmission fluid bath, if a suitable oil seal could be found for where the motor shaft comes through.


Problem: With a motor mounted there might clearance issues with the one output shaft "pot joint" (not certain because no measurements have been made yet). Additionally, even a short motor might still be too long (again, not measured yet at all).

Solution: Maybe a pair of custom FD gears where the pinion gear that is larger than stock for more clearance? The problem here is the complexity of recreating the helical gearing. However, straight-cut gears have been a performance upgrade for the Mini for donkey's years, so not a problem other than higher cost. Probably quite expensive to have a custom straight-cut pinion gear matched and made too. 

HOWEVER, it seems to me that in my parts pile, I should have a Mini gearbox with a busted case that already has straight cut gears. That said, I failed to find it this morning when I took a quick look. I may have even already sold it.

Again, not measured anything yet, so maybe overthinking that.

So far as the length of the motor, there are plenty of opportunities to hack away at the inner wing if necessary. I wouldn't really want to do that, but there is really nothing up on that end, being as the radiator would have been there with the original engine.


Problem:

The weak spot of any performance Mini retaining a stock gearbox and diff is likely to be the diff pin. 

Solution:

There are several performance upgrades available. Price range is from expensive to ridiculous, but would negate diff disintegration. If I can find that one gearbox, it may well already have an upgraded cross-pin diff too, which is probably more than adequate. Heck, the stock diff could be fine too - won't know until I get the opportunity to make one explode.

Well, that's all I want to think about for right now. Let me know what you guys think?


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## pickmeup (May 8, 2018)

there's been a few conversions using the good old A series box, check out bdrive.ch on Instagram as his website isn't working at the moment.


Ive been looking seriously at using the A series box but I think its more economical and more reliable to go for something made for the job, hence a motor out of an OEM EV.

There's plenty of links on my website too, most are on ev album and on the search function on this forum.
https://www.electricclassicminis.com/index.php/useful-links


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## brian_ (Feb 7, 2017)

Unless you want and use the whole transmission, adapting the Mini's final drive (differential with final drive gearing) seems like a bigger hassle than assembling shafts to use a more suitable final drive with the Mini hubs.


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## keithy1 (Mar 17, 2020)

brian_ said:


> As I have said in previous discussions, I don't see the point of taking a front wheel drive car from an era in which almost everything was rear wheel drive, and completely ignoring everything about the original powertrain and suspension design to make it rear wheel drive. Just convert any other random small sports car, sedan, or hatchback. But it's your body shell... you can do what you want with it.
> 
> 
> Right, but to expand on this for clarity:
> ...


Good info here. Might be worth a try, they go for a few hundred US over on Ebay, they look small. I'm going to give them a crack at least in a 63 saloon. Wonder about 2 side by side? Thanks guys.


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## brian_ (Feb 7, 2017)

keithy1 said:


> Might be worth a try, they go for a few hundred US over on Ebay, they look small. I'm going to give them a crack at least in a 63 saloon. Wonder about 2 side by side?


I assume that this refers to two of Toyota's rear drive units (motor with reduction gearing and differential) from AWD hybrids. How would you use two of them side by side?


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