RE: Torsen 201

[QSHIPQ@aol.com]

Dave writes:
>i have stated (again, and again, and again), that both the locked
>differential and the torsen are torque *proportioning* devices.  the methods
t>hat they use to proportion torque are of course, entirely different.  as i
>have also stated, the torsen uses internal friction (worm gears) to resist
>output shaft speed differences in order to allow a torque difference between
>those shafts.  the locker just locks the shafts together. the effect in both
>cases is exactly the same. 

No, not exactly.  What you describe above, means that a locker *can't* resist 
output speed shaft differences.  Physically it's impossible.  I think you 
need to spend more time on this to figure out what that means in a turn.  
There is no friction or *allowance* for one shaft to rotate faster than the 
other in a locker.  The effect in both cases is exactly NOT the same.  You 
can *only* argue this in a straight line acceleration with no traction 
variable.

 >both output shafts are locked together which
>allows torque to be apportioned according to tractive forces front and rear.
>the torsen continues this behaviour until it reaches a pre-determined torque
>proportioning limit (the bias ratio), at which point it allows output shaft
>speed differences while holding the bias ratio of torque.

I say it happens before the bias ratio.  A .2% forced slip between axles 
quoted in 885140 with a 62r/38f would be documentation of that.  How much 
forced slip between axles does a locker have?

>what you fail to understand in the (fabled) 885140, is that it is the forced
>slip front/rear in the torsen which forces the torsen worm gears to do their
>thing and torque to be differentiated between the output shafts.  in the
>absence of front/rear slip, the torsen is a 50:50 torque proportioning
>device.  unlike the locker.  with the locker (not modelled in 885140), the
>inputs are also only front/rear slip based on either turn dynamics or weight
>dynamics or both.

Not consistent with earlier posts you made.  You indicated that a locker 
follows the same character as a torsen in a straight line.  Is that *now* not 
true?  A locker can't have forced slip between axles, can it?  

>much as you might like not like to think so scott, the above are facts, and
>are not really discussion points.  there are a number of sources (so quoted)
>which explain them in more detail.

Again, when we discuss a torsen, we don't *need* to discuss a locker.  We 
aren't there yet.  I appreciate your interpretation of the *facts*.  Can't we 
stick to the *facts* about the torsen?  The locker scenarios as you present 
them defy simple logic.  

What I think needs discussion, is the concept of an oversteering locking 
center differential.  However, since this is a torsen discussion, can we keep 
it there.   Bottom Line:  I disagree with your presentation of a locked 
center diff in terms of chassis dynamics Dave.  I'm happy to explore why, 
after the torsen discussion is complete.

"not really discussion points" means that we don't need to discuss them.  
Let's not.  How bout that torsen bite presentation?  Please address that 
specifically.  IN that presentation, I make *no* claims of a locked center 
diff.  Therefore, bringing a locked diff argument to the table seems 
irrelevent.

My .02

Scott Justusson