The S4 twin turbo is Slow

[Dave Eaton]

no, when there is the traction available, the rears can and will receive
100% of the engine's torque and the fronts 0%.

remember that when the haldex is locked, it is operating as a "solid shaft"
(think locked centre diff).  you cannot control torque distribution with a
solid shaft.

this is a common misconception.  with a traditional open diff, torque is
split 50% at all times, regardless of traction.  with a locked diff, torque
can and will vary according to traction, from 0:100%.  many people think
that the opposite is true...

the big advance with the haldex is that the leakdown valve controls the rate
at which the haldex clutch will slip, allowing the computer to decide the
torque distribution.  the weakness is that it requires slip in order to
generate the hydraulic pressure to work in the 1st place.  however, all that
would be required to make it "active", is a hydraulic pump.

btw, autocar reports that the new a8q (due 2003) will have 4 haldex
clutches.

hth,
dave
'95 rs2
'90 ur-q
-----Original Message-----
From:	Per Lindgren [mailto:lindgre at online.no]
Sent:	22 July 2001 11:06 PM
Subject:	Re: The S4 twin turbo is Slow

As long as the front wheels have 0% traction it is normal for the rear
wheels to
have 100% traction. But even if they got 100% traction, they still only
receive
50% of the engine's power! The other 50% is constantly linked to the front
axle,
and that is what makes it spin in the first place. This is what this TT
owner
didnt understand.

Dave Eaton wrote:

> actually, he is right.  front with no traction, a haldex clutch, and the
> rear will get 100%.  and if he disconnects the front, he will get 100% to
> the rear (it's just that you can't disconnect the front)...torque will be
> continually distributed front to rear 0:100% as required.