no drive to front wheels

[audis8tui]

Hi guys

My wife phoned me to say she has her car stuck in the snow so off I went with a tow rope in my S8 d3.
I got stuck too as I have no four wheel drive. The rear wheels work but nothing to the front. I have the slip control warning light on the dash when wheel spinning and also the management light flashed a few times
I have just put a complete engine in the car so I know all the drive shafts are there.
What is there to check?
I gave the gearbox a service and nothing there is nothing wrong with it, the gears change great.
The only problem I have with the car is a 014 defective abs unit according to vagcom but it worked ok when slipping in the snow

[Delboy]

Are you sure, the Audi Quattro needs a bit of juice to get all four seeking out grip, have you turned the traction control off and gave it beans?

[ainarssems]

If D3 is the same as D2 they are all open diffs without mechanical locks even if is torsen/limited slip and only 'locking' is that control unit slightly applies brakes to the spinning wheel in pulses. If 1 wheel loses grip completely or has very little grip you are moving nowhere, this is where old school quattros with manual rear and centre diff locks were much better, also having winter tyres helps a lot, most of the time FWD car with winter tyres will do better than quattro with summer tyres in the snow. I have even seen old Audi 80 with both diff locks engaged spinning 3 wheels and not going anywhere with summer tyres but there was not much problem for me right next to it with a front wheel drive Citroen XM with winter tyres I had at the time.

If you did not have drive to front wheels it would be the same as having no grip and you would not be driving at all. I actually had one of my friends quattros brake front driveshaft outer CV joint and it stopped moving, just spinning the broken drive shaft. They did actually disconnect the shaft from outer CV joint, secured to the body using rope at an angle so that it could not turn and were able to gently drive home. The reason your rear wheels spin is because the car is lighter in the rear so have less grip. Always keep you tank full and a couple of bodies in the boot in winter to have more weight and more balanced grip in snow

[snapdragon]

Sounds like the EDL is not operatig and so not slowing down the spinning wheels.

The centre diff is what I would call slightly self-locking if there is a torque bias between front and rear but probably not enough to overcome rears on very slippery surface and fronts on grippy surface (when the EDL is inoperative), but

try giving more power, as soon as you ease back, the locking limited-slip/ self-locking-function is greatly diminished.

[audis8tui]

Thanks guys, I have had the Ur Quattro with manual diff locks and I have had a A8 4.2tdi Quattro in the past and both pulled me up the same snow filled gravel track towing a car at the same yard. This time there was just nothing happening at the front end either setting off slow or with a bit of throttle. No noises at all.
I didn't know you could turn traction control off on the S8 but that seems to be the warning light that comes on when I had wheel spin at the rear.

Oddly though when the car was off the ground to carry out the auto fluid check all four wheels were turning.
Is there anything on the vcds I could look up?