[s-cars] G35x debate

[Keith Maddock]

alexander witham <alexander_witham at yahoo.com> wrote:
> Although quattro is supposed to be
> a true all wheel drive system, in that the power is
> split 25% to all 4 wheels @ its natural state, I sense
> that it has a front wheel bias that I suspect is due
> to the additional weight up front.

Your statement is true but rarely truly realized in our cars.  In the
"natural state" (equal torque capacity/traction Front vs Rear which
for low acceleration in a straight line requires 50/50 F/R weight
distribution) Torsen-Quattro is indeed 50/50 front/rear split (and
then by nature each axle is split 50/50 unless locked for 92-95 or a
torsen rear has been retrofitted).  So this natural state will pretty
much only occur unless you have the car on a hoist, or if you're
accelerating at a brisk pace (which our cars are indeed capable of :-D
 )

However your sense and suspicion is also true: the nose-heavy nature
of the Torsen-Quattro cars means that you almost always have more
torque capacity/traction at the front end, which means that the center
Torsen diff will react and proportion the Front/Rear torque split
accordingly biased to the front.  So if the car has a 65/35 Front/Rear
weight distribution while accelerating at 0.1g, then the Torsen will
be locking up enough to allow 65 percent of the torque to go to the
front, and 35 percent to the rear.  (up to the limit of the bias
ratio, generally 75-80% IIRC)

Cheers,
Keith