Quote:
Originally Posted by Ultramaroon
I think this is at the root of my disagreement with your position on the basic operation of the torsen and any variant.
Do we agree that when the outputs are being driven equally (no differentiation) that a component of the input thrust vector places an axial load on the worm gears? I think yes.
This is where the friction comes into play. Under load, at the onset of differentiation, those gear teeth do rub relative to each other. They are not involutes. (edit: They do have that component in their shape but they are somewhere in between worm and spur in operating principle.)
It is that very same friction on which the torsen relies. The only time a torsen truly behaves like an open diff is when there is zero torque applied to the input.
Without any statement to consequence of continuous operation, do we agree on these points academically?
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I'm afraid not. I'm also disappointed that nobody has yet jumped on the error in my post. So, either nobody in this thread understands how their T 2 Torsen diff works or everyone who does isn't interested in clarifying it for others.
Torque biasing differentials are engineered to differentiate exactly as open bevel gear differentials do. They are not speed sensitive, they react only to torque. They bias torque by exploiting the internal frictional forces generated by helical worm gearsets and, more importantly, the frictional forces generated by the ends of (or faces of the side gears in the case of T1 and the new split gear types) the worm gears when they engage the diff case.
Torsen bias torque delivered at the crown and pinion, transferred through the "carrier" which is the Torsen part. They can only bias torque by reacting to uneven torque resistance at the output shafts. Furthermore, unlike an LSD they cannot limit slip to the output shaft experiencing the lesser reaction torque. Understanding why that is so allows one to understand how a Torsen works, that it isn't really an LSD and why using a space saver or other tire of even significantly different rolling circumference cannot wear the torque biasing components of the Torsen. Despite what the lawyers who write owner's manuals might say.
There are some good reasons not to run different sized tires on the drive axles of a car but differential wear isn't one of them.