Back in 2022 I published a blog post exploring rear wheel drive EV conversion motor options. My conclusion was that the ideal solution would be to use a Tesla Small Drive Unit (SDU) but that was not feasible for this car due to the required independent rear suspension (IRS).
I ended that blog post with two options to explore further:
- See if the Lexus L110 fits the Volvo Amazon in therms of weight and space
- Further work on modifying a Tesla small drive unit to drive the driveshaft and keep the rear axle
Does a Lexus L110 fit in a Volvo Amazon?
Let’s start with the easy one. When comparing the original Volvo Amazon M40 gearbox side by side with the L110 I already had my doubts.
If I’d align the prop shaft flanges then the L110 would fit into the tunnel by approximately 40 cm. Then the subframe would be where the marker is on the below picture.
So it would take up even more space than the Siemens motor with original gearbox did. The weight should be OK for the Volvo Amazon. The L110 itself weighs around 128 kg and the inverter adds another 18 kg. So in total that is 146 kg.
The setup with the Siemens 1PV5135 + DMOC645 + gearbox was around 155 kg so that would be a bit less.
So while the output of 250 kW is appealing I’d rather improve in terms of weight and size compared to the previous setup. As a result I decided the L110 is not an option for me. The kW to Euro ratio is amazing. So for a slightly bigger car this still is a great option. I gathered a complete set of L110, oil pump + controller, inverter and control connectors which is for sale. Contact me if you are interested.
Modifying a Tesla SDU to drive the driveshaft
The Tesla small drive unit (SDU) is an awesome package. Motor output of 220 kW and torque of 330 Nm. To be able to use the SDU directly an independent rear suspension is required. But what if we could eliminate the differential and use only one reduction?
This is what EVshop offers with their Tesla Small Drive Unit Modified package. That brings up the question: “Why reinvent the wheel and not just get one of those?”
Well, they use the Tesla front small drive unit as that one is the easiest to modify. Furthermore they replace the original Tesla logic board with an aftermarket Openinverter one.
I’d like to maintain the original Tesla logic board and control it with a suitable VCU since then one retains all Tesla R&D and functional safety aspects. However this is only possible with the Tesla rear small drive unit. As a result I’d either have to buy a rear SDU as well and drop the logic board into the EVshop solution or alternatively modify a rear Tesla SDU.
The yellow lines in the photo of the opened Tesla small drive unit indicate where I’d have to cut the casing. Upon closer inspection many challenges have to be overcome:
- There is no suitable face / plane to seal it off again
- One of the alignment pins need to be moved
- The oil pump would no longer work/fit
- Bringing the axis out is not trivial
- Moving the inverter would make it no longer justifiable to refer to ‘comes from a Tesla’ to prove meeting EMC requirements
Plus even after modifying the SDU it would be a challenge to fit it into the Amazon. So I dropped this option as well.
In the next blogpost I will go into detail of what I did choose: an Engiro motor.
