[Biturbos4] Wheel spin - Thread Hijack - Wheel Spin

Keman keman at interwolf.net
Thu Apr 14 10:07:15 EDT 2005

> to say that the car is not full-time AWD based on this phenomenon is
> simply incorrect.  To say that the B5 S4 is rear-biased is even more
> preposterous.

And here I was thinking "An Audi tech who feels that the quattro system
isn't a full time AWD system" ... preposterous isn't the term that came to
my mind. :P

If you want to get technical, the general difference between a "part time"
and a "full time" 4WD system is that with a part time system, you have no
center differential. And if you try to make the car turn on any surface
that isn't slippery enough, the tires will be forced to spin at speeds
which do not match the road's surface. They'll drag, skid, bind up,
chatter, and in worst case scenarios- break an axle. If you've driven a
4WD truck with a part time 4WD system on pavement, you know what this
feels like. A full time 4WD system has a center differential. It can be
the locking variety (as with the older Audi's), a limited slip say- a
viscous coupling, it can be a haldex clutch setup, it can be a torsen. It
can be open. In any event, it allows the front and rear wheels to be
driven at different velocities. A torsen is generally regarded as the best
non-electronic mechanical differential, because it works smoothly and
reliably. But as I said in my prior post, anything times 0 is still 0, so
if there's no hint of resistance on the rear wheels, the torsen has
nothing to work with to multiply and send to the front tires. So a
driveshaft that's disconnected will render it useless.

If it were a part time 4WD system, this would not be the case.

What is probably the case is that audi tech has worked on older audi's,
and on those with the locking center and rear differentials, if you push
the button to lock them then yes, even with the rear driveshaft
disconnected you could still theoretically drive the car. To say it would
drive like crap is an understatement though. :P

- Keman

> -Ti
> --
> Ti Kan
> http://www.amb.org/ti
> Vorsprung durch Technik

More information about the Biturbos4 mailing list