The Torsen Mentality of Slip Angle

[QSHIPQ <QSHIPQ@aol.com>]

>i understand what you are saying about slip angles, i just have no
information
>about how they would affect the operation of the torsen.  by definiton they
>affect the torque reaction of the wheels, and so would affect torque
>distribution.  but by how much?  on dry roads, not much at all (relative f:r
>split), although on snow, it could be more.  the same factor affects the open
>or locked centre diff...
NO.  Not correct.  Slip Angle to a fixed diff is 50/50, to an open diff, it
becomes 100 front.  Both defined as understeer.  Remember, no wheels have left
the ground, so a fixed diff is fixed at 50/50.  Why? Because of the same
"equalizing" effect you describe with wheel lift.  If cf is constant on all 4
wheels and they are grounded, you will have 50/50.  With an open diff, the
fronts will spin before the rears, and more torque sent forward (lift and
absolute traction are the same thing).  So, we can say that understeer will
stay with the above two scenarios, both over and understeer will occur in the
Torsen Center.  

Understand Dave, the difference between your "loss of traction" definition and
the Torsens interpretation.  The Center Torsen is looking ONLY for torque
indicators in the front and rear driveshaft, it isn't looking at traction per
say.  Slip Angle is traction to a Torsen.  You are looking for forward
rotation, doesn't need to be.  To us lay folk, a tire sliding sideways has
"lost traction".  To a Center Torsen, a tire sliding side is a tire that has
GAINED traction.  Less Slide to relative to opposing wheels (slip angle) =
Less Traction.  Absolutely opposite of reality.  Specifically, to a Center
Torsen,  if the front is sliding sideways less than the back (like steering
with a slide around an apex), the rear has more traction.  Reread that.  To
your definition that is false, to the Torsen it will transfer torque Tmax to
exactly your axle with LESS traction (as you defined it).  See any problems
with that?  Are you sure you want to put that in the lower percentile?  Want
to look at cf first?  I don't think you need to based on my experiences...

Go to fwd/rwd, the above doesn't apply.  Why?  Cuz slip is independent
(constant) to the fwd/rwd axle.  It could care less what you are doing with
the steering or throttle.  Since Slip Angle between what it is measuring
torque from is EXACTLY the same.  And if the fronts steering more than the
rears, or opposite, still irrelevent to the operation of the Torsen.  No bite
in fwd and rwd cars, and a proven advantage in both.

I can say I have experience with the effect of Slip Angles on a Torsen,
"information" would require that I know when it occurs and why.  I think I
know why, by physics, the when part seems to have eluded my scrutiny.  

>it will be interesting to hear the results of jeff's discussions with the
>gleason folk on this issue..

Agreed.  The torsen makes a lot of sense to me, except this part between
absolute traction equations.

HTH

Scott Justusson
QSHIPQ@aol.com