RE: Torsen defined

[QSHIPQ@aol.com]

Dave E writes:
>scott, drive your new bmw rwd and you will find understeer most of the time,
>despite 100% rear torque bias.

Understand "Most of the time" isn't what I, or others bitten are referring to 
at all dave.

 > likewise it is perfectly possible to have
>oversteer with 75% torque at the front of a torsen or locker quattro.  

On the same cf?  Please help us understand that.  I don't agree.  How and 
when?

>100%
>torque to the front of a fwd car and you can have oversteer (btdt on all of
>the above).

On throttle, or is that LTO.  I think you are stretching things some here 
Dave.  

>these statements you make about 75% torque front meaning understeer and 75%
>torque rear meaning oversteer are so prone to error and misinterpretation as
>to be totally meaningless.

I think you should reread Scott Fishers post.  Relative slip angles are 
relevent and expressly used to figure U and O.  Wheel torque is a significant 
variable affecting slip angle.  What is prone to error?  Understand how this 
is plotted dave.  You can plot out a given radius turn and the variables per 
885140 to figure O and U.  There is no error or misinterpretation, either the 
chassis O (in which case it takes out the apex cone), or it U (in which case 
it travels away from the apex cone) or it's N (steering angle of front wheels 
= actual direction of travel).  There is no misinterpretation of data.  For a 
set of given conditions in 885140, we can easily and without error or 
misinterpretation, declare U or O as a chassis dynamic.  This isn't theory, 
it's the practical application and conclusions of (relative) slip angles.

>with regards to your claim of the bite being referenced in the 885140 paper,
>i am still at a complete loss to find this reference.  however,
>you say that "the turning radius fools the torsen into allocating more
>torque rearwards... overloading the rear tractive ability".
>you are correct in that if the torsen is in a turn, it will allocate more
t>orque rearwards.  as will the locker.  by design.

Dave, let me, for the sake of YOUR arguments, conditionally accept and agree 
with  *ALL* your claims of lockers for now.  Is the torsen Bite scenario, as 
I described it possible?  

>given the torsen is not at the bias ratio, it is not allowing output shaft
>speed differences.  to clear up your misunderstanding, the paper says when
>measuring the dynamics of a 80q in a turn that "0.2% of forced slip occurs
>between the 2 axles which reduces the slip under traction at the front
>wheels and increases the slip at the rear wheels.  this results in tractive
>forces being redistributed towards the rear wheels".

This happens because forced slip between axles, means that torque shifts 
which changes relative front to rear slip angles, which results in 
measureable oversteer or understeer chassis dynamic for the given torque 
bias.  

>scott, this means that the *tyres* compensate for this slip *not* the axles
>speeds.  you misunderstand this.  the torsen at this point (before the bias
>ratio) has locked the output shaft speeds.  

No forced slip indicates that the shaft speeds are *not* equal.  

>it is operating as a locked
>differential would. 

No.  Not with you here.  Torsen diff only please.  There can be no forced 
slip between a locked diff axles, because a locked diff isn't a frictionally 
locked device, it's a mechanically locked device.

> hence any "claim" you make for the torsen at this
>point, you have to also make for the locker.
>btw, the torsen will not allow any axle to "spin up" until it is at the bias
>ratio.  this is a function of torque inputs or tractive forces at the tyres
>or both.i really don't know how i can make this any clearer...

What you can make clearer, is that my torsen bite scenario *is* possible.  
I'm reading that into all your posts to date.  You want to say "yes, but..."  
 Dave, what would make a relevent torsen discussion clearer, is if you just 
said "yes", because I'm not making *ANY* claims of what a locker can or can't 
do.  THEN you can present your locker arguments to show that the torsen bite 
scenario is the same as a "locker bite scenario" (tm - DE).  This won't get 
easier, nor "any clearer" until you answer only the question I posed.

Scott Justusson