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Torsen is a totally different animal. The below discussion clearly states:
"with an open or a locked diff". I am sitting on the sidelines and learning
as much as I can about the torsen stuff. I have no BTDT to add to the
torsen discussion. I do find it fascinating though!
<<Torque and 'torque split' are not related to the speed or relative
speeds of the two shafts with an open or a locked diff. The 'torque split' is
purely a function of the relative counterforce applied to each axle and this
is a function of the relative traction or lack of traction available at the
two road/tire interfaces on the axle in question. Equal traction = equal
torque split. Zero traction at one wheel = zero total torque and zero forward
vehicle acceleration/motion with an open diff. Zero traction at one wheel =
0/100 'torque split' with a locked diff with the 100% going to the wheel with
traction - exactly what you want if you want the vehicle to accelerate and
I've stayed out of the discussion as I haven't much experience with the
Torsen senses torque differences, and sends torque to the side with better
grip. It seems that the torque varies with numbers of factors: isn't torque a
function of power measured at a distance? (foot pounds = x pounds measured at
one foot, is not equal to that at two feet...)
Seems that you'd get differing front/rear torque as the distance at which the
force is applies varies:
1) weight transfer (acceleration, braking, turning) will "load" wheels on one
axle while unloading the wheels on the other axle, compressing the one set and
reducing their radius slightly, while decompressing the other set and
increasing their radius.
2) Weight transfer is probably greater in the nose-heavy (often softly
sprung) type 44's vs. the urQs, thus more torque differences.
3) variations in tire diameter will make the torsen see torque differences.
Doesn't Jeff (AudiDudi) run different rims front/back, with slightly different
tire radius/sidewall stiffness? It seems that differing tire pressures will
also affect the radius, such as higher pressure front to rear. Maybe these
cars aren't normally running a 50/50 split? How much difference is required
to start the torsen transfering power?
Seems like the above factors may tend to show torque differences between the
two sides of the torsen diff. Alone, these may not cause a torque split
difference, but it may be a partial cause (additive) of the reported "hunt" at
and above the limit in these cars. Or am I off base?
Chris Miller,Windham NH, firstname.lastname@example.org
'91 200q torsen center diff.