RE: Torsen 201/103 and some 101

[QSHIPQ@aol.com]

Dave E writes
>if the torsen is at the bias ratio power-on in a turn, then there is *more*
>tractive potential at rear of the vehicle than is being used.  why?  because
>by definition the bias ratio means that the the torsen has *stopped*
>allocating torque rearwards.  if it hadn't stopped shifting torque, even
>more would be going to the rear.  

It's not at the bias ratio power on in a turn.  Remember it "... is 
presupposed that the torque split limits of the differential are not 
exceeded, so that it is not called up on to compensate for different wheel 
speeds"  Your above is not correct as stated, more importantly, not relevent. 
 For ease of discussion, can't we presuppose (just like your 885140), that 
torque allocation doesn't include wheel speed differences.  Remember, a 
torsen allocates torque before wheel speed differences occur.  

>in other words the realive traction inputs
>to the differential from the fronts and rears means that the fronts would in
>reality accept *less* torque than the torque bias ratio dictates, and the
>rears would accept *more*.  to put it another way, if we're alking about the
>locker, it could have a torque bias of (for example) 85% rear 15% front in
>the same turn.

Not with you here.  Can't we stick to torsens?  I'm happy to compare a 
locker, let's wait on that please.  We haven't gotten to the chassis dynamics 
part of torsens yet.

>hence, at the bias ratio in a turn you are already seeing increased front
>slip due to torque inputs vs tractive feedback.  and the torque ratio is
>fixed until tractive inputs front and rear change.  so your scenario of loss
>of traction at the rear causing oversteer is hypothetical in the extreme.

Hardly.  Remember, as you turn in the real world, you can oversteer a given 
radius while adding power, which can overload the rear tractive ability.  You 
are assuming a given rate of acceleration.  What happens if that increases or 
cf decreases.

>again, you need to re-think your scenarios scott.  if you think through a
>power oversteer scenrio with a torsen, you will understand how unlikely it
>is in reality.
>also, reading the information from various sources, it is clear that the
>designers have striven to avoid oversteer at all times.  and guys like georg
>kacher from "car" are complaining about it....

Change cf or raise hp.  I'm having difficulty swapping between your sources 
and your claims.  Most torsen owners that have been to steamboat, can easily 
argue that a torsen oversteers, I can argue that it does on dry pavement as 
well.  Is that now *not true*  Given that 885140 indicates that speed and 
radii can get torque transmission to the rear (without a weight shift 
argument), can't we reasonably draw the conclusion at a certain radii, and 
rate of acceleration, oversteer is the chassis dynamic?  

I'm all for making the step to chassis dynamics.  I'd like to keep the 
discussion simple and relevent.  To do so, we need to put aside torque bias 
ratios beyond 75%.  885140 did (albiet explaning what happens).  Besides 
bringing torque bias ratios back into the BR of the torsen, only requires a 
wheel spinnning (delaying torsen input as it were), instead of just slipping.

I went thru 101, specifically Scott Fishers post.  Scott, get the paper.  If 
you read it, you will find that my relative slip angle statements are valid.  
I think what you are missing is that the paper refers to axle slip, but 
remember, there are two differentials and more axles before 'axles connected 
to the torsen' sees traction, slip, or relative slip angles.  It is expressly 
stated that it's the radius that forces the axles to slip, allocating torque. 
 The *result* is indeed wheel slip.  We use slip angles to address the 
chassis dynamics of O and U while turning, since, per your post, loading 
torque on a given tire indeed will affect that chassis dynamic.  Then can't 
we reasonably conclude that a 75r/25f car oversteers, and a 75f/25r 
understeers?   Isn't O and U why you calculate slip angles to begin with?  
Can't we indeed make a slip angle chart on the 80q in the paper which would 
indicate O and U?  Doesn't that change at a given radius, on a given cf, with 
a given wheelbase with a given Trg?  If torsens varies torque between 4 
tires, isn't that loading affecting U and O?  

Scott Justusson