# Lightweight Differential for FWD?



## PhantomPholly (Aug 20, 2008)

Ok the CVT thread I started has gone it's own way, but the conclusion I got was that they work and are available if I decide go down this path, and I can count on about a 3:1 low end through 1:1 high end ratio from the CVT.

That still leaves a problem in that FWD cars don't usually have a differential which is separate from the transmission - so I would have to adapt a small differential in order to obtain about a 4:1 step-down to make best use of the CVT output shaft speed.

Has anyone done a direct-drive on a FWD using some kind of differential, probably adapted from a RWD?


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## Woodsmith (Jun 5, 2008)

I suppose you could look at some of the light weight 4x4 cars that have a longitudinal engine for a front diff, shafts and overall suspension set up or just using something like a rear diff from a BMW or similar, and adpating the inner CV joints toy your FWD shafts, might be fine. The question would be how to mate the diff to the CVT and keeping it compact.


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## PhantomPholly (Aug 20, 2008)

Woodsmith said:


> I suppose you could look at some of the light weight 4x4 cars that have a longitudinal engine for a front diff, shafts and overall suspension set up or just using something like a rear diff from a BMW or similar, and adpating the inner CV joints toy your FWD shafts, might be fine. The question would be how to mate the diff to the CVT and keeping it compact.


Yes, the mating (diff to pto; diff to axels) will clearly be the hard part. My assumption is that since a CVT is little more than two pulleys I should be able to locate a "driven pulley" shaft that can be mated to the diff. input.

My original plan to use LiIon for a 100 mile range may have been optimistic from a budget perspective. [email protected] with A/C running is my minimum goal, so that may actually be a 100mi car at slower speed. I may look for a diff. with greater than 4:1 to limit my propensity to drive too fast and to improve the torque advantage of the motor.


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