[Asaszn]

Does anyone run direct drive? I'm working on a custom sand rail project and it was suggested I try to run two transwarp 7/9 motors directly to the half shafts.

Anyone have experience here or any thoughts?

 

[kixGas]

I am not because I haven't built my EV yet. However I have been doing a lot of research into because I think it has some advantages. However, I do not think that you would be successful attaching a motor directly to a VW half shaft. You will need some sort of gear reduction. My current thought is to attach a motor (or two) to the pinion of a IRS differential. I will likely use a sequential belt. This will allow it to be fairly compact and the motors do not have to travel with the suspension causing a lot of unsprung weight.

 

[Asaszn]

Kixgas,

Can you tell me a bit more about this? Where are your getting your trans, I'll also be running rear IRS.

Asaszn

 

[kixGas]

Get one from an existing car. 4wd Honda CV, Ford Escape, Isuzu Rodeo are some examples. The hot rodder favorite is one out of a Jaguar XJ12. It has it's own cage so everything comes out in one complete unit. The disc brakes also are attached to the half shafts on the differential side which further decreases unsprung weight (but makes maintenance a PITA).
IIRC the Isuzu has an aluminum housing for the Dana 44 differential which would work fairly well in a medium powered EV.

 

[major]

Does anyone run direct drive? I'm working on a custom sand rail project and it was suggested I try to run two transwarp 7/9 motors directly to the half shafts.

Anyone have experience here or any thoughts?

Hi again Asaszn,

Direct drive means coupling the motor to the driveline with one ratio, as opposed to a multiple ratio transmission. Some will argue this and say it means having the motor turn at wheel speed. Convention for the past 30 or so years has "direct drive" including a single ratio, including 1 to 1. And, direct drive generally infers the absence of a clutch.

Connecting motors directly to the half shafts without any gear reduction is a bad idea. Wheel speed is too low. And the torque from reasonable sized motors at reasonable current is too low. A gear reducer (or belt or chain) will get the motor speed up and multiply motor torque to the wheel.

DC motors have excellent torque at low speeds and can do well in direct drive. Compared to the same motor with a multispeed tranny, the direct drive systems generally run a higher current limit for more torque off the line and up-hill. Once up to top speed, direct drive is equivalent to the multigear system in hi gear.

Regards,

major

 

[Mastiff]

Check out the EVAlbum:
www.evalbum.com

You most likely will find a few direct drive EVs and you might be able to E-mail the owners and ask for their experience.