Quote:
Originally Posted by CeeforCitroen
Hi, anyone investigated the feasibility of installing a small electric motor on one of the back wheels of a front wheel drive car? The back wheels of my car freewheel independently of any power train. I'm wondering if anyone has designed a sprocket that bolts on behind the wheel and goes to a small electric motor driven on a chain to drive the car at speeds between 5 and 10 mph in heavy traffic in an "engine off coast" situation. Ideally the sprocket will have a freewheel or overrun clutch just to protect the motor at high speeds where it's not needed. A solar panel on the roof could charge the battery. You probably wouldn't need more than a kilowatt motor just to get the car moving in low speed stop and go, where a petrol engine is puttering along doing next to nothing and the car is not moving fast enough to make use of the engine's minimum fuel consumption. It seems there is little point in making the car extremely heavy just to get it slightly better at handling traffic jams, so a small motor and battery would suffice - maybe even an e-bike battery or two.
I thought of the idea when in really low speed traffic jams I could just open the car door and scoot the thing along with my foot, rather than having the engine puttering along all the time or turning it off and on an excessive amount of times. But due to the angle of my leg I can't get much power down, not to mention it looks ridiculous.
I'm wondering how feasible it is. It seems like an easy mod if you can custom design a sprocket to go on the rear wheel with a built in overrun clutch. Clearances might be an issue though depending on the car. I'm a complete mechanic novice so it's unlikely I'd be trying it but it's an interesting concept IF you can get the chain not to rub against sprocket parts. Otherwise a specially designed rear wheel with gear teeth on an inside rim that also freewheels might be needed.
As for the freewheel, I'm assuming the car does not need to be reversed at excessive speeds which could damage the motor.
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I've read of AWD vehicles, in which the driveshaft was interrupted to the rear wheels, and an electric motor added to power that axle, independent of the remaining FWD. Probably mated directly to the yoke on a cradle attached to the differential.