RE: A New Look at Torsens

["Dave Eaton" <Dave.Eaton@clear.net.nz>]

no, while the torsen starts with a static 50% front/rear bias ratio (not
true for the locked centre - see below), the torsen will progressively shift
torque to the rear until the bias ratio is reached and then increased slip
will be rewarded by wheel spin.  don't forget that the accelerating vehicle
has a rearwards weight bias as well, so the torsen will result in
significantly less understeer than a generation 1 car.

the open centre will fix torque split @50% and when (front) traction is lost
(spinning inside wheel), the torque to the rear will decrease to the amount
supported by the front (i.e. keeping the 50% front/rear distribution).

the fixed centre will have a static front/rear torque split mirroring the
weight distribution (fr audi's usually 60% front, 40% rear) resulting in
more initial understeer but, as weight is transferred backwards, so is
torque.  it mirrors the torsen quite closely until the point where
front/rear slip differences becaome enough to cause the torsen to hit the
bias ratio.  at this point the locker has no option by terminal understeer.
the torsen will not allocate any more torque rearwards at this point, and so
has less understeer than the locker.

a fundamental misunderstanding in this debate is that the locker supports
100% torque shift, wheras the torsen will limit torque shift to around 75%
(depending upon design).  the open centre can't shift torque at all, but is
locked at 50% to each driveshaft.

hth,
dave
'95 rs2
'90 ur-q
'88 mb 2.3-16

-----Original Message-----

Date: Sat, 16 Oct 1999 12:14:53 EDT
From: C1J1Miller@aol.com
Subject: RE:  A New Look at Torsens

OK, please clarify something for me.
Take a track corner, assume a perfect surface, repeatable line, steering
angle, etc.
As you go through the corner, the torsen will distribute torque at some
ratio
between the front and rear axles.
In a straight line, equal distribution front rear.
while taking the corner, what will the ratio be?
Must it be either 50/50, or 25/75, or 75/25? or can it be in between?
Is it a three-state device (rear 75/25 front, or front 75/25 rear, or equal
50/50), or does it continuously vary the ratio?  My understanding was that
the ratio would vary, and only on a full-lock turn would there be enough
difference between front and rear wheels to go to full bias ratio...
If you take the same line at the same speed, same steering wheel angle, will
the ratio always be the same?
chris miller, windham nh, c1j1miller@aol.com