Rear wheel drive conversion guide.
"Convert your front wheel drive car to a rear wheel drive setup."
Why would anyone want to try to carry this mod out? Some people just like a challenge or want a project to inspire others. But there are some practical reasons you might want a rear wheel drive conversion.
Power delivery through a RWD setup means you can run much higher power figures.
The maximum power output through a FWD setup is around 225bhp, and with some clever differentials you might be able to go higher.
Are RWD conversions easy?
As the front wheels control the steering and weight is pushed to the back of the car on acceleration is is quite hard to get traction.
For this reason, most high power cars and motorsport cars have rear wheel drive setup.
Even front engined street cars tuned for competitions are converted with either a mid mounted engine and rear wheel drive or just a rear wheel drive setup.
Why go rear wheel drive?
Cars are more fun to drive when the power is to the back wheels.
It also removes the grip based power limit from front wheel drive, typically around 225hp, unless you have a well designed front end and differential where you might get away with around 300hp.
Any more power than this will be unusable as the wheels will just scrabble for grip as the weight transfers to the rear wheels and the front lifts.
Rear wheel drive also makes for lots of oversteer rather than the safer and more predictable understeer manufacturers build into FWD cars.
Is this something you can do on your car to maximise your performance and driver enjoyment?
Problems you'll need to solve:
- Engine could be mounted in the wrong orientation
- Added weight to the car and loss of cabin space
- High project costs, with lots of additional custom fabrication required
- Lack of off the shelf parts
- Gearbox and driveshaft connections
- Managing traction control and ABS sensing
- Mating a FWD engine to a RWD transmission
Transverse (sideways) and Longitudinal (Inline) engines
Does your engine face left to right or front to back, the output to the gearbox/driveshaft makes a difference to how easy this is to convert to rear wheel drive.
Most small FWD cars have the engine mounted sideways so the driveshaft takes power to the front wheels. To get this power to the back you'll need to reroute the driveshaft which is a big problem.
Some drivers will mount the engine inline and choose a different gearbox setup, but this often means losing some space in the cars cabin as the engine and gearbox will need more room.
Otherwise you'll need a differential to take the power to the rear of the car through a propshaft.
Shortcuts to RWD conversions.
If your FWD car model has a four wheel drive option it makes the conversion process a lot simpler - think A3 Quattro for example.
Generally speaking a rear wheel drive setup can be made from the four wheel drive parts which are readily available but modified without the power going to the front wheels.
That said you might just as well run a four wheel drive setup, this will give better traction, but if you want the car for drifting or have other needs to go rear wheel drive then stay with the RWD concept.
In these four wheel drive cars you'll also usually have a driveshaft tunnel running the length of the car and a rear axle diff and gearbox that copes with the RWD setup.
FWD only car models and conversions to RWD
If your car model is only available in FWD format then the challenge is that you'll need to get a driveshaft from the front of the car to the rear.
This will generally mean cutting into the cars cabin as ground clearance prevents an external drive shaft on most cars, unless you lift the cars suspension!
The brake lines, fuel line, spare wheel housing and exhaust pipes will all conspire to frustrate your plans to mount a driveshaft the length of the car.
Some car makers offer a RWD option or AWD option that would be compatible with your chassis/engine bay (usually larger executive cars such as the Passat 4motion, Quattro or surprise limited editions like the Clio V6, although this had a rear mounted engine!).
This can provide suitable parts to convert your car to rear wheel drive, planning makes a big difference.
Much older cars can also offer suitable parts for your project and can often be used to make a Frankenbuild.
For example the MX5, most BMW models and early Ford models are ripe for part picking.
A mark 1 Ford escort was rear wheel drive and the drive train fits nicely with the powerful Cosworth engine.
Dropping the modern engine into your car and using the running gear from the Mk1 will save a lot of custom fabrication.
The shortcut route to RWD conversions
We have seen some people convert an old RWD chassis, engine and gearbox to look like a FWD by shortening it and adding the FWD cars body.
This is more converting an old RWD to look like a modern FWD car but it does achieve the RWD feel and retains a modern cars appearance.
Wheelbase can be a problem, and you should try and match the wheelbase or you'll have lots of additional fabrication to carry out.
The MX5, Passat and A4 quattro, Volvo and BMW would be suitable for sourcing RWD parts you could use on your car's chassis, but expect much cutting and fabricating to get it to fit and work.
Kits are around which will help but be prepared to source a new engine, gearbox and fabricate custom mounts as this is generally easier than getting your current engine and gearbox to drive the rear wheels.
After you've achieved this engineering feat, you'll need to alter the suspension to cope with the difference in handling and alter the braking.
The front driveshafts and hubs will need to be modified as they are no longer driving the front wheels. On most cars this.
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One Response to “Converting a FWD to a RWD”
interesting option… almost tempted to take this route with my u13 sss attesa limited. but it would be sacrilege. there is however a bellhousing adaptor kit for a ford c4/c9/c10 and a powerglide…. might just need a little bit more time to find another factory 5 speed