Conversion to RWD

[audiman]

As a matter of interest - has anyone converted their quattro or coupe to rear wheel drive? Reasons are:

1) Drag racing
2) Drifting
3) less losses so more power available at the road
4) possibly less weight and better weight distribution

With the diff in the rear I am told it is a fairly easy conversion to do with a volvo 740 diesel gearbox but I was wondering if by removing the front driveshafts, this could be done with the existing gearbox....

The idea is remove the drive shafts and turn the centre diff lock to 1 position (so the empty drive shafts dont just turn without driving the car - hey this would make a good anti theft device!)

Would the car have any problems running like this full time? Would oil leak from the drive shaft holes so they need sealing up? Could you still run the rear diff lock without the Audi gearbox/centre diff?

Oh so many questions!

[Phil Payne]

> As a matter of interest - has anyone converted their quattro or coupe to rear wheel drive? Reasons are:

1) Drag racing
2) Drifting
3) less losses so more power available at the road
4) possibly less weight and better weight distribution

> With the diff in the rear I am told it is a fairly easy conversion to do with a volvo 740 diesel gearbox but I was wondering if by removing the front driveshafts, this could be done with the existing gearbox....

In theory, yes. You'd have to remove the driveshafts completely, which means pulling the hubs, then detach the hubs at the outer CV joint and replace them. There is no "hole" between the inner CV joint at the driven flange and the inside of the front differential, so nothing would leak out.

As far as drag racing is concerned, why not just lock the centre differential? And, as odd as it miht sound, the losses would go up and not down. Driven axles have lower rolling resistance than dragging ones.

There's a very learned article from Audi about it somewhere.

http://www.pistonheads.com/doc.asp?c=52&i=10065

"During testing, Audi also found another benefit: tyres generate less rolling resistance when driven gently than when rolling freely, more than enough to offset the additional frictional losses in the four-wheel-drive transmission. Prototypes delivered higher maximum speeds when driven by all four wheels than when the rear driveshafts were removed."

[JimH]

I would have thought that RWD conversion for drag racing would have to include some serious cutting to fit much wider tyres in the rear. Otherwise I think you'd loose too much time moving off the line compared to AWD.
I think a big advantage of the Dialynx car in those 0-60 challenges was quattro drive getting all the power down to the road.
My A4 has so much traction from a standing start that it feels impossible - nothing gives at all. Don't like to do that often as it feels that something's got to give eventually...

[puglife]

I was interested in this when a friend enquired bout fitting my 10v engine in the front on a 205gti for RWD
Are the front inner shaft hubs not held into the front diff?

[Ian Simmonds]

I know of a least a couple of quattro's (one of which was a 200t) that had the front hubs disconnected and run in RWD mode and the result has followed Phil's description to the letter, the cars have actually dropped off performance rather than benefited....Also, the initial 'take-up' of power over weight is a 'reducing equation' where the more power you have is off set against the reduced grip the tyres can provide.... Hence why 4WD is better for 'non-dragstrip-tyred cars'....

[BasilNZ]

I know a fellow who did this to his WRX by grinding down the splines for the front drive input shaft (butcher's method, I know). The car handles like a pig, instead of tidy oversteer it tank slaps everytime you touch the throttle on the mildest corner - nasty.

[Gazjen]

Originally Posted by puglife

Are the front inner shaft hubs not held into the front diff?

Yes by a 6mm or 8mm capscrew in the centre

[Phil Payne]

Originally Posted by puglife

I was interested in this when a friend enquired bout fitting my 10v engine in the front on a 205gti for RWD
Are the front inner shaft hubs not held into the front diff?

The flanges are - a single 6mm Allen stretch bolt. You leave them in place. The CV joint is held to the flange by six 8mm or 10mm (depends on the car) triple-squares - that's what you take off.

Once you've wiped out the grease that cannot be given to Swiss children, that's it.

[Phil Payne]

Originally Posted by BasilNZ

I know a fellow who did this to his WRX by grinding down the splines for the front drive input shaft (butcher's method, I know). The car handles like a pig, instead of tidy oversteer it tank slaps everytime you touch the throttle on the mildest corner - nasty.

The other problem is that the left leg of the rear subframe isn't strong enough to take all the torque all the time and would need reinforcing. Even stock 20Vs occasionally split this subframe going over wet white lines at full chat in the wet. It's part of my inspection routine.

The rear suspension is just not designed to take all the power.

[audiman]

thanks for the feedback - looks like I may as well stay in 4wd mode unless I get serious about drifting (although I did well in my old 90 Q drifting!)