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Discussion Starter #1
Is this feasible?

I'm looking to convert a 2 seater (probably an SLK so about 1300Kg) the only gear reduction would be the diff.

No gearbox would allow the motor to fit lower and further back and would simplify things a lot I feel as I'd just need to couple to the prop-shaft.

You can probably tell I'm new to this, so any input would be appreciated.
 

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You might not be able to get a high enough final drive ratio, so you'll end up with poor torque at the wheel, geared for 200mph but without the power to get there.
 

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Discussion Starter #3
Yes that kind of confirms what I was afraid of.

The highest ratio diff is 3.91 (slk200) which is about 1/2 the geardown on the leaf if what I've read is correct. So I'd get poor acceleration with a ridiculous theoretical top speed :(.

I which case if I want a rear drive two seater with no gearbox an MR2 might be better suited then.
 

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Yes that kind of confirms what I was afraid of.

The highest ratio diff is 3.91 (slk200) which is about 1/2 the geardown on the leaf if what I've read is correct. So I'd get poor acceleration with a ridiculous theoretical top speed :(
Right... half the Leaf's torque to the wheels, so half the acceleration with the same mass of vehicle.

Another way to think of this is that the Leaf motor needs to turn about 2800 rpm or higher to produce its maximum power; while that corresponds to a reasonable speed with the correct gearing, with this gearing it would mean that you would have less than 80 kW at anything short of highway speed.

I which case if I want a rear drive two seater with no gearbox an MR2 might be better suited then.
Are you thinking of an MR2 with a complete Leaf drive unit (motor plus transaxle, so it has the stock Leaf gearing) replacing the Toyota engine and transaxle? Yes, that would make sense. :)

Another alternative would be to put the motor in the SLK's transmission tunnel, but put a compact single-speed reduction box on the output of the motor. The ev-Torquebox is an example (although it is relatively expensive and larger than necessary).
 

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Discussion Starter #5

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Nice idea about a single speed reduction box, I hadn't though of that. That EV torquebox is insanely expensive, maybe something like this https://www.ebay.co.uk/itm/Motovario-Reduction-Gearbox-71-Flange-Input-80-Flange-Output-4-2-1-Reduction/163334976282?epid=677990372&hash=item260785f31a:g:P~oAAOSwKEFb0dAp would work?
Yes... although I don't know about the torque and speed ratings of that one, or how well the offset would package in the car. Someone else was planning to use a very similar unit (sorry, I can't remember who, so no link to their thread).
 

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Is this feasible?

I'm looking to convert a 2 seater (probably an SLK so about 1300Kg) the only gear reduction would be the diff.

No gearbox would allow the motor to fit lower and further back and would simplify things a lot I feel as I'd just need to couple to the prop-shaft.

You can probably tell I'm new to this, so any input would be appreciated.
Why a Leaf motor?
That would be an ideal application for a DC series motor
 

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Discussion Starter #8
Yes... although I don't know about the torque and speed ratings of that one, or how well the offset would package in the car. Someone else was planning to use a very similar unit (sorry, I can't remember who, so no link to their thread).
That was just the first thing I found. I need to do more research.
 

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Why a Leaf motor?
That would be an ideal application for a DC series motor
A DC motor is an alternative, and probably would be cheaper overall. I'd need to find a manual and keep the gearbox, manual SLKs are fairly thin on the ground and it cuts down choice considerably.

Leafs are readily available as scrap now, so for an AC motor it seems the obvious choice.
 

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Reverse is obtained by running the motor backwards - I'm using the reversing contactor out of an old forklift
 

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Discussion Starter #13
Thanks Duncan. I'd read elsewhere that reversing contactors weren't great, but I've re-read your device thread and it seems that it's certainly not the weak link. I may have to re-consider my options (in a good way :)).
 
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