# The best motor position



## CroDriver (Jan 8, 2009)

One big motor for the rear wheels









One medium sized motor for the RWD and two small ones for FWD

One motor for every wheel (or two for FWD or RWD)


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## Telco (Jun 28, 2008)

I say 2 motors, RWD. Two smaller motors will package easier than one large motor, you can likely fit the two motors inside the trans tunnel with a little work freeing the entire engine bay for batteries or genset depending on your plans. Having two motors will also allow you to wire them into a series/parallel setup, which will give the effect of a 2 speed transmission. When in series you get loads of torque to get moving, then you switch to parallel to get more speed once you are moving. It'll take a little extra work to set it up to switch between the two modes safely, but it'll act as a 2 speed transmission.


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## CroDriver (Jan 8, 2009)

Telco said:


> I say 2 motors, RWD. Two smaller motors will package easier than one large motor, you can likely fit the two motors inside the trans tunnel with a little work freeing the entire engine bay for batteries or genset depending on your plans. Having two motors will also allow you to wire them into a series/parallel setup, which will give the effect of a 2 speed transmission. When in series you get loads of torque to get moving, then you switch to parallel to get more speed once you are moving. It'll take a little extra work to set it up to switch between the two modes safely, but it'll act as a 2 speed transmission.


Very interesting! This would be perfect! You are talking about DC motors, right?


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## bblocher (Jul 30, 2008)

CroDriver said:


> Very interesting! This would be perfect! You are talking about DC motors, right?


Technically AC or DC would be fine. There are quite a few discussions on any direct drive approach around these forums if you search a bit. There are a few main concerns to be aware of. First the motors need enough torque to accelerate the car at a reasonable speed. Second they also need to support high enough RPMs to meet your required top speed and the last thing I can think of is proper cooling. You'll probably want a water cooled motor since the high amp low rpm conditions of low speed acceleration would cool well with an internal fan motor.

You'd want to figure out your circumferance of the wheels on the car and then do the math to find what the motor requirements are.


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## sunworksco (Sep 8, 2008)

bblocher said:


> Technically AC or DC would be fine. There are quite a few discussions on any direct drive approach around these forums if you search a bit. There are a few main concerns to be aware of. First the motors need enough torque to accelerate the car at a reasonable speed. Second they also need to support high enough RPMs to meet your required top speed and the last thing I can think of is proper cooling. You'll probably want a water cooled motor since the high amp low rpm conditions of low speed acceleration would cool well with an internal fan motor.
> 
> You'd want to figure out your circumferance of the wheels on the car and then do the math to find what the motor requirements are.


 Here are some images of limited slip differentails for front or rear axle shafts independent suspension.These can be set up using belt or chain drive.


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## JRP3 (Mar 7, 2008)

The most efficient and easiest setup will be a single motor, probably connected to a rear limited slip differential.


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## 1clue (Jul 21, 2008)

I think 2 motors in back, or possibly one on each wheel.

However, I don't want a wheel motor, or even direct drive. A modest reduction with a toothed belt or gears will get the motor size down significantly, and as long as the motor has enough guts to get you started and enough RPM to carry you down the road well enough there is no need for a shiftable transmission. If you use a gear belt you have the additional advantage of having isolation between the motor and the road, torque wise.

If you need to shift, then suddenly the multiple motors no longer seem attractive. The chances that one tranny will stick makes that sort of thing dicey I think.


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## azninferno (Nov 12, 2008)

if youre planning on converting an e30 M3 i will have your babies for a ride.


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## sunworksco (Sep 8, 2008)

1clue said:


> I think 2 motors in back, or possibly one on each wheel.
> 
> However, I don't want a wheel motor, or even direct drive. A modest reduction with a toothed belt or gears will get the motor size down significantly, and as long as the motor has enough guts to get you started and enough RPM to carry you down the road well enough there is no need for a shiftable transmission. If you use a gear belt you have the additional advantage of having isolation between the motor and the road, torque wise.
> 
> If you need to shift, then suddenly the multiple motors no longer seem attractive. The chances that one tranny will stick makes that sort of thing dicey I think.


Check out this link for drive systems and 3 or 4 wheels.
http://www.clevislauzon.qc.ca/Professeurs/Mecanique/ethierp/3-wheels/class3.htm


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