RE: Spider Bite II

[QSHIPQ@aol.com]

Dave E et. al.: 
Here is a reprint of my post: Torsen Spider Bite described, per my review of 
SAE 885140.  After further discussion and review, IMO, this paper would 
indicate that my summary, and description in my spider bite scenario is 
exactly *possible*.  Sticking to this scenario only, please feel free to 
present any *errors* in my thinking, OR errors in the data, facts, and/or 
presentation of 885140.  To date, no lister has proposed my presentation of 
the scenario as *wrong*, only that all my other thinking *might* be (I'm 
happy to accept that for now).  That's still a "yes" to the last question in 
my following scenario:

------------------------------------------------------------
>To summarize:  A torsen center diff chassis, in a turn, *can* suddenly and 
without >prediction, shift from an oversteer to an understeer to an oversteer 
(ad infinitum) >condition in a single turn.  This phenomenon I refer to as 
The Spider Bite (tm -sj) >and is a nature of the torsen center differential.  
This creates a 'challenge' in >controlling a center torsen vehicle in a high 
performance - high cf environment or a >low performance - low cf environment. 
 I come to this conclusion based on my >research into how a torsen 
differential operates.

>Definition of Spider Bite (as I understand the device, based on my research 
and >Dave E's):
>Torsen center diff car enters a given turn, turning radius fools torsen into 
allocating >torque rearward -O-, which (depending on all the variables in 
885140) *can* overload >the rear tractive ability, which then changes the 
variable affecting torque shift from a >slip angle one (turning radius) to a 
tractive variable (traction at the rear wheels), >which per 885140, is 
"independent of the forced slip resulting from the vehicles >circular path", 
and this shifts torque forward, causing -U-. which then *can* regain 
>tractive force rear, which results in -O-, because once tractive force rear 
is regained, >torque shifts rearward due to turning radius.  This scenario 
*can* cycle several times >in a single turn.

>This assumes all variables the same as 885140 except accleration(Trg)=cf 
(they are >the same variable for all intents and purposes).  Changing *any* 
variable, *can* i>ncrease or decrease the chances of Bite, but can't 
eliminate it.

>Single yes/no question Dave (/others):  Looking at the above scenario v your 
>research, isn't the definition of bite as I presented above, possible (I 
didn't ask: >*likely*)?  After the answer, you(/others) are welcome to 
address the errors of my >thinking.

>thinking.------------------------------------------------------------------------------------------

For the sake of simplicity, could we address the above only in reference to 
TORSEN operation.  Since 885140 expressly *lacks* any claims or data of 
locked center differentials, any reviews should also lack locked center diff 
content, as they are irrelevent to the torsen operation.  

I'm intrigued by the chasing of tangents, when the above would appear to be 
simple to critique line by line.   I'm happy to correct or even <delete> the 
above, based on the outcome of rebuttals.

Thanks to those who are donning nomex to reach a "torsen unification theory" 
(tm - Dave L) in deference to  the phlogistications (tm - Phil P).

Scott Justusson

P.S.  I have subscribed to the torsen list, FWIW.  The word "outstanding" 
comes to mind :)