[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: Torsen post for Gary

Eric writes:
>To borrow a line from Scoobie Doo, rut-roh! It seems we have a 
>_major_ inconsistency here. I've suspected this ever since 
>reading the hearsay about the above document, and now that 
>Orin's provided the direct quote my suspicions are confirmed. 
>The above makes you think that as a Torsen center car is 
>turning, it gradually and progressively allocates more torque 
>to the rear, until at some point (slow, tight turn) it reaches 
>the max torque split.Now take a look at section 5.2 of Stan the Man's paper 
>"A torque division between drive axles at the bias ratio is a 
>precondition for differentiation under all circumstances of operation."
>According to Stan, if the front and rear axles are spinning 
>at different rates then you are already _at_the_bias_ratio_. 
>To put it another way, if a Torsen diff is differentiating, 
>then the max torque will be sent to the slower driveshaft.
>Either I'm missing something, or we've got a big problem with 
>two of the primary sources of information on this topic. Which do we believe?

Both.  Eric, understand that the torsen should have axle slip built into the 
design,  Stans point (or how could you take a turn in a rear diff rwd car?)  
However, further testing shows that that slip is *not* universal, more 
specifically, isn't constant thruout chassis application (audi really should 
have more torsens for their cars).  We could see that in a 80q the radius is 
"significant" to torsen allocation and is measureable at 40m and 15m at a 
given rate of accel and other given conditions

Reread Jeff's interview, Stan explicity admitted to Jeff, that slip angle 
differences can and do fool a torsen (assuming we believe jeff's version).  
His issue is that this won't affect chassis dynamics/control under the 
majority of conditions.  He's right.  That would mutually exclude most of us 
here that have fun with are quattros.

Again, you have traction and slip angle as torsen inputs.  Stan address the 
traction argument in his paper only (It's in the title), 885140 addressed 
both, they have to,  since they address the influence of torsen on Handling 
(it's in the title).  When you read the 80q paper, you will find that the 
intrinsic argument is that this relative slip torque allocation is a good 
thing.  I argue it *can* be, but isn't necessarily.  What causes that to 
change, suddenly/and at maximum BR?  A traction argument.  That's expressly 
stated in 885140.  And is by Stan too,  further down in the second paragraph 
of 5.2.

Stan dedicated one small paragraph to centerbox application, with no data.  
Wasn't the object or purpose of his paper.  

Best to read both thoroughly, they are complements, IMO.

Scott Justusson