RE: Torsen 201

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

no scott this is simply not true.  you do not understand how a locked
differential works.  once it is locked, the differential *because* it does
not allow shaft speed differences, cannot control torque distributed to
either shaft.  so torque is entirely dependent upon tractive forces
(front/rear slip).  think of a "locker" quattro with the front driveshaft
disconected - all torque will go to the back.  with the front on ice, *most*
of the torque will go to the back.  ditto in turns where the forced slip
front/rear caused by vehicle dynamics (weight transfers, etc) cause the same
effects.

freemans paper "4wd powertrain models" describes the torque proportioning
effects of a locked centre diff in detail, including showing what happens on
traction loss at the rear sending torque to the front.  ditto jeff daniels
book which i've referenced before...

because you do not grasp these points, you fail to understand the
similarities between the torsen and the locker.  and hence why 2 people on
the list can experience the spider bite in locker quattros.

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

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

Date: Tue, 2 Nov 1999 10:16:26 EST
From: QSHIPQ@aol.com
Subject: RE:  Torsen 201

Dave writes:
>i have stated (again, and again, and again), that both the locked
>differential and the torsen are torque *proportioning* devices.  the
methods
t>hat 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.

No, not exactly.  What you describe above, means that a locker *can't*
resist
output speed shaft differences.  Physically it's impossible.  I think you
need to spend more time on this to figure out what that means in a turn.
There is no friction or *allowance* for one shaft to rotate faster than the
other in a locker.  The effect in both cases is exactly NOT the same.  You
can *only* argue this in a straight line acceleration with no traction
variable.

 >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.

I say it happens before the bias ratio.  A .2% forced slip between axles
quoted in 885140 with a 62r/38f would be documentation of that.  How much
forced slip between axles does a locker have?