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RE: A New Look at Torsens (torsen tech 101)
scott, a fundamental understanding of the torsen is required before you can
understand how it works in a vehicle. it's finally starting to become clear
where your misunderstandings are:
1) bias ratio. you completely misunderstand this. the bias ratio is not a
variable, it's a given for a particular differential design (set of gears).
it is the maximum ratio of torque bias the diff will support between shafts.
hence your statement "bias ratio [sic] rear varies with every turn" is plain
wrong (and nonsensical). bias ratio is a *constant*, not a variable as you
state. in a torsen, bias ratio is determined by the respective worm gear
"interfaces" which also govern the degree and rapidity of locking behaviour.
much like the setup of a vc where different silicones change the speed of
locking. anyway, i digress...
2) you state that "bias ratio [sic] rear varies with every turn" with the
torsen. incorrect as stated. replacing "bias ratio" with "torque", then
this is correct. up to the bias ratio of torque split.
3) the torsen distributes torque on the *basis* of front/rear slip
differences. until the bias ratio limits torque proportioning. ditto the
locker, except that the locker will continue to proportion torque to 100%
either way (i.e. no bias ratio). you should understand this point. each
differential uses the *same* inputs. in other words, the *only* thing which
causes the torsen (and the locker) to proportion torque is the *differences*
between front and rear slip. ok?
these points are really torsen 101 scott. btw, if you actually had the audi
sae torsen paper you reference so often, you see this in the tests.
once you have agreed to these points, we can move on to torsen behaviour at
the bias ratio.
'88 mb 2.3-16
Date: Mon, 18 Oct 1999 07:30:32 EDT
Subject: RE: A New Look at Torsens
Bias Ratio rear varies with EVERY turn, and with every slide or skid. Lets
clear here, the maximum (what you mean to say above) Bias Ratio doesn't have
to be acheived to get O. Nor does the maximum Bias Ratio front have to be
acheived to get U. The torsen *might* have less understeer than a gen 1, it
might have *more*. Depends on a bunch of factors. How, when and where you
turn is included. Variables that just don't create U-O-U while turning
Dave has indicated that my conclusions (scenarios, answers, and truisms)
mean I misunderstand torsen and locker operation.
Fire away boys, I've put a lot of ammo up for ya. Right now, you both
even in agreement.