Rear wheel drive EV conversion motor options

Improve the driving experience of Voltvo

Back in 2015 when I decided to use the Siemens 1PV5135 motor the common way forward was to keep the original gearbox. This was mainly due to the fact that there were no other options available for rear wheel driven cars. I decided to upgrade the original Volvo Amazon M40 gearbox to a freshly rebuild M400 from a Volvo 164 to be able to handle the high level of torque.

Let’s have a look at the options we have nowadays that would be interesting for this car. I’m focussing on high voltage systems. In case I missed an interesting option, please let me know!

Possibilities for rebuilding Voltvo

Probably the quickest fix to driving again would be to install the combustion engine again, but that is not going to happen. So I have five options in my mind:

1. Using the Siemens 1PV5135 again ->
2. A Nissan Leaf motor ->
3. Lexus L110 motor/gearbox from a GS450h ->
4. Tesla Small Drive Unit (SDU) ->
5. Engiro 260W ->

1. Siemens 1PV5135

From the list of electric motors using a or even this Siemens motor again is the easiest one. The chances are that the motor still works and perhaps even the inverter and maybe even the vehicle control unit (VCU). Then I could just repair and replace what is needed and implement the same setup again in terms of drivetrain.

2. Nissan Leaf motor

A very popular option nowadays is a EM57 motor from a Nissan Leaf or e-NV200. The motor+inverter found in the Leaf (2013-2017) and e-NV200 (2014+) have 80 kW power and 254 Nm torque. This setup has the Gen2 inverter. The 2018+ Nissan Leaf has a Gen 3 inverter and still the same EM57 motor. That setup has 110 kW power and 320 Nm of torque. The 62 kWh 2019+ Nissan Leaf E+ has a 160 kW inverter which outputs 340 Nm of torque.

The output (in kW and Nm) is similar to the Siemens, but the advantage of the Nissan motor is that the weight of the motor + inverter is much less than the Siemens + DMOC.

Adopting this approach certainly is low hanging fruit since as EVcreate I am already developing the adapter plate and a coupler. The coupler will have Leaf splines on one end and Volvo splines on the other. So it will result in a setup without flywheel and intended to be fixed in third gear.

3. Lexus L110 motor/gearbox from a GS450h

This one was recommended to me by a friend from an ‘EV conversion brains’ working group. It’s an interesting piece of engineering. The Lexus L110 is a two speed gearbox and has two integrated motors (MG1 and MG2). Together these motors output 147 kW and 275 Nm. However, the most interesting part is the reduction. In low rear the reduction gear ratio is 1 : 3,90 so this is comparable with the first gear of the M400. In high gear the reduction ratio is 1 : 1,90 so still comparable with second gear.  So this would result in a very fast and powerful car.

There is a catch however, the motor/gearbox is big and heavy. Around 125 kg excluding the inverter which is another 15 to 20 kg.

4. Tesla Small Drive Unit (SDU)

Another very interesting and promising motor is the Tesla Small Drive Unit. During our trip in Sweden, after the fire we visited Tom and his family (Tom is building an electric Volvo by putting an Amazon wagon body on top of a Tesla). I was allowed to drive his Tesla and got convinced that that is how EV’s were supposed to be: power directly delivered to the wheels. A Tesla Large Drive Unit would be way to big, but an SDU isn’t that huge.

Only main challenge is: then I need to convert the Amazon wagon to independent rear suspension (IRS) to be able to drive the wheels directly.

The unit only weighs 88 kg and outputs 220 kW and peak torque of 330 Nm, imagine that!

5. Engiro 260W

Perhaps the most beautiful motor of my shortlist is the Engiro 260W series. The 400V model has a peak power of 192 kW and continuous power of 116 kW. But the most impressive part is the peak torque of 830 Nm. Imagine that, 830 Nm from zero RPM.

That profile is good enough to completely skip the gearbox. At the same time the top RPM is sufficient to drive fast as well. The 700V version just is insane.

Unfortunately also this option has its downsides. Building on some hands on experience when picking one up for an EVcreate customer I can tell it is rather large and quite heavy. The inverter is not by the way. But the main issue is: it is expensive.

Selection criteria & shortlist

First one is budget so that’s an easy one. I’ll have to take the Engiro motor out. So then we have four candidates left.

To be honest, when the car was finished I was slightly disappointed with the driving experience. The two main reasons are:

1. The drivetrain could not handle the ideal level of regenerative braking for smooth one pedal drive
2. The noise coming from the M400 gearbox in third gear was disturbing

Rebuilding this car for me is about further innovation, learning, challenges and improving the car. So using the Siemens again is not an option. I’m committed to dropping the gearbox and the clutch!

Motors remaining: Lexus L110 & Tesla SDU and maybe Leaf

Two or maybe three motors are thus remaining.

Nissan Leaf with fixed reduction box

I am aware of a plug and play fixed reduction gearbox for the Nissan motor that will become available on the market. Recently I had a look at the reduction box and it feels well made.

Still awaiting further information on availability, pricing and first hand test experiences. Will it be silent enough?

Tesla small drive unit

Is Volvo Amazon wagon independent rear suspension (IRS) feasible?

So ideally I’d like to use the Tesla small drive unit and directly drive the wheels. I’ve done some research on that and believe that a BMW E30 rear end would be adaptable to the Amazon. However, after discussing this with my friend Ben this seems not the best approach in this case. My car has front damage and it would require cutting up the rear end. So it still is the ultimate goal but not feasible for rebuilding my car.

Trick for using the Tesla small drive unit anyway?

Perhaps I’ll do the rear end mod on another project (already have some thoughts on that). There might be a way to use the Tesla motor in my car anyway. It can be modified by removing the differential and its reduction. I’ll share thoughts on that in a next blogpost. It certainly is an interesting option.

Lexus L110 in a Volvo Amazon wagon?

In terms of ‘readiness’ the L110 is perhaps the best option. People are using it in rear wheel driven conversions already and it performs great. So the main question is: Will it fit? The L110 is significantly bigger than the original M40.

Only one way to find out! My philosophy is learning by making so I am about to get some stuff to try if/how it would work out. To be continued!

Wrap up / summary

So to wrap things up: I’m committed to improving the driving experience of the car and drop the gearbox and the clutch. I’ve got the following things on my action list:

• Explore using BMW E30 independent rear suspension for a Volvo Amazon in a separate project
• Further work on modifying a Tesla small drive unit to drive the driveshaft and keep the rear axle
• See if the Lexus L110 fits the Volvo Amazon in therms of weight and space

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