Re: Torsen theory for Gary

[Fluhr <ejfluhr@austin.ibm.com>]

Gary,

Here is an idea that you can evaluate for your brainstorming list...

First, let us assume that the torsen does allocate more torque rearward
as the car is cornering.  It seems to me, perhaps incorrectly, that
the effect of this rearward torque bias would depend on the initial
attitude of the car in question.

If I recall correctly, Phil and Dave both feel that the torsen improves
the balance of the car as it navigates the turn.  This would seem to
be the case if the car is understeering badly, and the application of
more power to the rear wheels should cause the car to handle more
neutrally.

Scott, however, feels that the torque shift can cause the driver to lose
control because the car oversteers when the driver is not expecting it.
Now let us suppose, for whatever reason, that the car is perfectly
neutral (or very close to it) while driving through the turn.  Then it
would be upset by a torque shift to the rear wheels, causing the car
to oversteer while in the middle of a turn.  At this point, if the
driver lifts, the car will spin and the driver will have been "bitten."

Scott, however, feels that the torque shift can cause the driver to lose
control because the car oversteers when the driver is not expecting it.
Now let us suppose, for whatever reason, that the car is perfectly
neutral (or very close to it) while driving through the turn.  Then it
would be upset by a torque shift to the rear wheels, causing the car
to oversteer while in the middle of a turn.  At this point, if the
driver lifts, the car will spin and the driver will have been "bitten."

Now, this whole arguement depends on several factors:
(1) Does the torsen in fact redistribute torque to the rear wheels
    when powering through a turn?
(2) Assuming #1 is true, how much does the rearward torque shift 
    affect the attitude of the car?  (i.e. large or only small affect)
(3) What is the attitude of the car in relation to the affect of
    question #1?  (No matter the effect, the the car needs only
    to understeer slightly more than or equal to the effect for
    it to balance the car, while even a small effect can toast you
    when balanced at the absolute limit of traction.)
(4) Does the setup and/or line and/or method used by Scott put the
    car at just about a neutral position through the turn, and liable
    to be adversely affected by power shift?
(5) Does the setup and/or line and/or method used by Phil and Dave
    cause the car to understeer initially, generally transitioning
    to neutral as the power shifts rearward?



If I assume that my analysis is correct, then I would qualify for
question #4 of my hypothesis.  I certainly follow the race line as
best as I can, but I know the car is understeering pretty badly
throughout the turn (A4 1.8tq, Texas World Speedway), hence I have
never been bitten despite some pretty hard driving.  However,
I have been in situations where the car is so precariously balanced
that any increase in oversteer, no matter how slight, would have
cause me to spin.  Since my driving talent and experience is not
nearly enough to convince me that you cannot run a stock quattro
into/through a turn at close to a neutral attitude (much less a car
set up for more neutral handling), I have to assume that you can
do #3.

So, in summary, perhaps both Phil and Dave and Scott and Jeff are
all correct, and it boils down to driving technique as to whether
or not you are bitten. 

Personally, I think that tagging our cars with a big Q sticker will
NOT give us any extra horsepower, as another lister lamented, **BUT**
painting them YELLOW must certainly yield 5hp per sticker!


Later,
Eric
---
Eric J. Fluhr                                Email:  ejfluhr@austin.ibm.com
High End Processor Design                    Phone:  (512) 838-7589
IBM Server Group                             Austin, TX