RE: Torsen 201

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

i have stated (again, and again, and again), that both the locked
differential and the torsen are torque *proportioning* devices.  the methods
that they use to proportion torque are of course, entirely different.  as i
have also stated, the torsen uses internal friction (worm gears) to resist
output shaft speed differences in order to allow a torque difference between
those shafts.  the locker just locks the shafts together. the effect in both
cases is exactly the same.  both output shafts are locked together which
allows torque to be apportioned according to tractive forces front and rear.
the torsen continues this behaviour until it reaches a pre-determined torque
proportioning limit (the bias ratio), at which point it allows output shaft
speed differences while holding the bias ratio of torque.

what you fail to understand in the (fabled) 885140, is that it is the forced
slip front/rear in the torsen which forces the torsen worm gears to do their
thing and torque to be differentiated between the output shafts.  in the
absence of front/rear slip, the torsen is a 50:50 torque proportioning
device.  unlike the locker.  with the locker (not modelled in 885140), the
inputs are also only front/rear slip based on either turn dynamics or weight
dynamics or both.

much as you might like not like to think so scott, the above are facts, and
are not really discussion points.  there are a number of sources (so quoted)
which explain them in more detail.

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

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

Date: Mon, 1 Nov 1999 08:11:16 EST
From: QSHIPQ@aol.com
Subject: RE:  Torsen 201

Dave E writes:
>well scott, as i understand it, you're saying that:-
>1) no locked-diff quattro can oversteer.  this is certainly not my
>experience.  very interested that it is your claim.  i agree that
understeer
>is more likely.  just as it is with the torsen.  by design with both
>technologies.  as i've explained.2) that torque doesn't follow weight
shift.
>really, we are still at the basics here scott.  you are failing to
>understand/comprehend the following points:
>1) the torsen operates as a locked diff does only *until* the bias ratio of
>torque difference between the output shafts.  there is no magic here scott.
>until the torque bias ratio is reached, the output shafts of the torsen are
>effectively locked together.  just like the locked diff.  the effect in
>torque distribution dynamics is the same as is directly proportional to
>weight distribution and wheelbase and roll characteristics.

OK, so dave, if the above is true, then in 885140, then please explain the
statement "however, the front wheels follow a wider radius than the rear
wheels on a circular course, so that .2% of forced slip occurs between the
two axles, which reduces the slip under traction at the front wheels, and
increases the slip at the rear wheels.  This results in the tractive forces
being redistributed towards the rear wheels, so that the tractive force
distribution is 38/62."  Where is the weight distribution variable here?
How
does weight distribution change more rear with a tighter radius turn giving
75r/25f?  With the same acceleration rate, wouldn't a higher given side load
actually reduce the rear weight distribution during acceleration?