driving in rain and snow (Re: 4000 Quattro Question

[Eliot Lim <eliot@u.washington.edu>]

On Sun, 13 Nov 1994, Bruce Bell wrote:

> >address.  First, a few years back while I was in Germany a friend of mine
> >who owned a Quattro coupe, would routinely lock the center differential
> >when driving at moderately high speeds (approx. 120-140 km/h) on a WET
> >autobahn.  This, he claimed, settled the car down and improved braking at
> >higher speeds in the wet. 

> The car has 4 wheel brakes whether or not the center differential is locked.
> 4 Wheel drive, Audi's nor anyone elses, does not help braking. 

if the center diff is locked, braking loads are redistributed over the
two axles, thus influencing the braking characteristics of the car.  i
don't know if it actually *improves* braking, but it will most
certainly be different over a 2wd or unlocked diff quattro.

i also recall that the victorious quattro racing drivers (hans stuck,
hurley haywood) also said that because of quattro they had a braking
advantage over their competitors.

>Driving at
> that speed on a wet highway puts the car in danger of hydroplaning.

it is always dangerous to over generalize.  i punted a v8 on a wet
race track once at speeds in excess of 100 mph in complete confidence.
after that the skip barber instructor took the wheel to show us how to
drive a quattro and went even faster than that.  i think that tires
make a big difference on what speed is safe.  there is no one safe
speed that applies to all conditions and all cars.

> If the
> car hydroplanes at that speed no brake is going to stop you. The Audi owners
> manual has a warning about quattro drive and hydroplaning. Seems the 4 wheel
> drive makes you think all is well until the last wheel floats. 

yes, this is very true.  i think the key to uninhited quattro motoring
is to always use the right tires for the conditions.  using bald
tires in snow is asking for trouble.. you may be able to pull off
but you won't be able to steer or stop.
 
> I do use the center diff when ever the roads start getting slick. I have
> found the Quattro drive really helps to stabilise the car at speed on a
> slick surface but as above I use it with the knowledge it won't help me brake. 

the first year i owned a 4000q i took it to the mountains for skiing
and found that the impressive traction really led one into a false
sense of security about how grippy the road was when in fact it was
butt-busting slippery.  :)

after that i got studded snow tires for it and i must say that driving
in the snow in a quattro with these things is one of the purest, most
heavenly experiences one could have on earth.  if you guys can afford
it, buy a set!  how would you like to be able to put down 200+ bhp
onto a snowy road with 4 rooster tails with the car simply charging
straight ahead in complete stability? (real handy for blasting past
long lines of struggling traffic) immense stopping power where even
the abs does not activate... sluuurp!  :) a quattro in winter with the
proper tires is as grippy as a snowmobile.  my M+S rated dunlop all
season tires suck rocks in comparison.

eliot