Physics is....

[QSHIPQ <QSHIPQ@aol.com>]

Orin writes:

>I say neither.  Torsen resists one shaft turning faster than the other
>up to its maximum torque split, at which point, one shaft
>will start turning faster, with max torque still going to the
>slower shaft.
>We are getting bogged down in Torsen marketing... it's really a dumb
>device.  The fancy gearing pushes the friction surfaces against
>each other when driven from the ring gear and allows different
>characteristics when not driven, eg under engine braking/coasting.

It is dumb, too dumb to know the difference between Slip and Traction.  They
are the same to the Center Torsen, Constant to a rwd/fwd Torsen, and
variables, by definition to the physics of a center torsen.  Nothing was
changed in the design of the Center Torsen to change them.  But those Relative
Slip and Slip Angles become a set of variables, viewed by a Torsen, as
traction, period.  It can't see them any other way.  By the very definition of
the above paragraph 1, I can have the rear tires spinning and no tshift
forward.  My only point, and is consistent with Orins here.  The reality of
the 'bite' is that all these tshifts happen before you have spinning tires.
By the time the tire spins you are already tshifting torque.  My mistake for
the example of a 'spinning' rear tire.  That was to illustrate that Slip and
Traction are the same to that dumb Torsen.

I sent this synopsis privately, might help here.....

Slip Angle is constant to a Torsen.  It is in section 5.2 of the paper.  That
presents fwd/rwd.  Nothing was changed in the design of the Torsen to make a
Center Torsen think that Slip Angle is still not a constant.  Except the fact
that you moved the Torsen from 'an' end to between two ends.  Making Slip
Angle and Relative Slip Angle both variables, by definition.  A Torsen assumes
them to be tractive forces (reread 5.2) only and ALWAYS constant to each set
of drive wheel.  It can't see them ANY other way.  It's defined IN the paper.
We don't need more information, they give it to you.

And I don't care what the "actual" numbers are.  Audi chassis understeer at
50/50 f/r.  That is a given, we know that to be true, ask any locker dude.  We
can safely say then, that more that 50 front is MORE understeer, less than 50
front is LESS understeer.  At what point does that "LESS" become OVERSTEER?
Somewhere between 50f/50r and 78r/22f.  I claim only that you can get
oversteer in a Torsen center, and based on f&r Slip Angle, Traction, cf, and
Trg, it can happen anywhere in that range.  As soon as all these "collective"
torque transfers and variables put you back to 50/50f> you have UNDERSTEER.  

Way too much "need more information" thoughts here.  You don't need more
information.  By the above definition, regardless of wheel lift, and all the
'other' points y'all made, at 50/50 we know that audi awd chassis understeer.
We all seem to agree that a throttle up oversteer is possible with a Torsen
Center.  Understand that is ALL Jeff and I need to make the argument that you
can have Understeer, Oversteer, Understeer in the SAME corner.  

HTH

Scott Justusson
QSHIPQ@aol.com