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-   -   Dual Fuel, electric rear wheel drive, gasoline front wheel drive (

bucknmusky 01-21-2009 11:13 AM

Dual Fuel, electric rear wheel drive, gasoline front wheel drive
Since most of us are modding gasoline power cars or replacing gas engines with elec motors and batteries I had this concept. If it has already been invented please let me know where to get one, if not someone here should get on this and the profits are all yours.

Concept: traditional front wheel drive gas powered car has a rear axle which is really nothing more than a trailer axle. Small lightweight cars on the highway only need to overcome air and rolling resistance to move along at cruising speed so horsepower required is low, especially in well areomodded cars.

Replace the rear axle with either 2 motors, one mounted on each reat axle shaft (imagine the rear axle from an S-10) or one large motor mounted where a traditional driveshaft would enter the reat differential. This motor could even be mounted vertially as to put the motor in the trunk to reduce the amount of junk hanging below the vehicle.
place batteries in the car trunk to power the rear electric drive, use regen braking to recharge (maybe)

Car could be run in either mode by putting the front or rear systems in neutral and driving off your choice of power. using a plug in system at home and making short trips you may never have to run the gas motor. Since city driving kills overall mpg you could use elec mode for getting through the city and once on the freeway on ramp switch to gas power where your gas engine, geared high and run at constant speed would be more efficient and have all elec needs fed off of batteries (water pump, power steering) so the engine could be just for driving.

But for now lets start with the rear axle swap out could be just a bolt on system for most small cars, with a battery bank in the trunk, of course Ni-Cd or LiH batteries would be best for weight but the cost factor is still high.

Daox 01-21-2009 11:51 AM

UW Madison fuel mileage challenge team did that with an GM Equinox. Their largest problem with this setup was the regenerative braking only on the rear wheels doesn't let you recapture much juice compared to front wheel regen.

Its been thought up before, just never done by OEMs.

NachtRitter 01-21-2009 11:53 AM

Very similar concept as the XR3 (XR3 Hybrid: Personal Mobility Vehicle (PMV) Automotive Prototype Project)... though that is a "plan-built" vehicle. Diesel powered front wheel drive, electric powered rear wheel drive.

Cool idea!! :thumbup:

Clev 01-21-2009 11:56 AM

I like it, but using an AWD car (or one with an AWD variant) would be true "bolt-on." Looking at my Accord, it seems likely that cutting and/or fabrication would be involved. One way to keep the motor out of the sludge would be to have it facing down out of the trunk, and rotating the differential so the coupler is pointing up. Anybody see a problem with this?

Could be done with a RWD pickup too. Run the normal RWD gasoline drivetrain, and then put in a FWD differential and axle and direct-drive it. Like Daox said, you get better regen off the front (more weight transfer means more regen before skidding starts.)

MazdaMatt 01-21-2009 01:11 PM

There was a concept mitsu Eclipse that had gas front drive and electric rear drive... never went to market, of course. This was maybe around 2002-2004?

Clev 01-21-2009 01:14 PM

Dodge Durango Hybrid - Tech Stuff/Green Machines/Car Shopping/Hot Lists/Reviews/Car and Driver - Car And Driver

Dodge's "Through the Road" hybrid, never got to market. One cool feature was that the electric drivetrain could cover the hesitation while the automatic transmission shifted, resulting in smooth acceleration.

MetroMPG 01-21-2009 01:21 PM

VW Golf Twin Drive prototype pretty much matches the description:

MetroMPG 01-21-2009 01:28 PM

Details of the VW Golf Twin Drive:

VW Twin Drive Is German for Volt | Autopia from

It's an interesting setup.

NachtRitter 01-21-2009 07:36 PM

Cute!! Car's not bad either... ;)

Christ 01-21-2009 08:10 PM

So... Don't electric motors typically have two sides to the armature?

What would keep someone from mounting it between the rear hubs of an AWD car, and using a custom drive shaft on each side? I know that bench grinders (not enough power, I know) have dual shafts on them, and I can't see a reason why an armature could not be modded or a custom armature built by a machine shop that would allow for such a mod..

The cool thing is that if it were only used for acceleration assist it would only need little added weight from batteries... it's not like the engine won't be running, and producing power from the same fuel that it would be burning anyway is only logical, or at least using an alternator at idle to load the engine a little bit to help provide that power to reduce weight of batteries, but only using the alternator when the e-motor is working.

Conversely, using an e-motor of good size would limit the actual ICE power needed to keep the vehicle at a constant speed, or even to accelerate, so a smaller gas engine could be used.

Just tossing that other stuff out there, but primarily the idea that you could power the rear hubs of an AWD vehicle quite easily/cheaply (custom CV axles aren't THAT expensive.)

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