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Re: Physics is....

> >Given this, I think we can remove any quantitative treatment of
> >speed differential and say if there is any speed differential,
> >max torque is going to the slower turning shaft.

> The torsen is not a binary switch. The amount of torque shift 
> depends upon how much the two driveshafts resist turning, and 
> the difference between the two.

Quite true, it is not a binary switch, what you say is absolutely
correct _if the shafts are turning at the same speed_.

I said 'if there is any speed differential'... for there
to be a speed differential, all the friction surfaces must in
the torsen must be slipping, therefore all frictional forces must
be at their maximums, therefore torque split is at the maximum.

If then max torque split is more than one shaft can take, it spins of course
and speeds up to the speed of the faster axle.  Once it reaches that
speed, then torque will probably go to the other axle.

I believe that a consequence of 
> shifting torque is that the driveshaft with less traction is forced 
> to spin faster than the other. Scott says that it works the other 
> way -- that the torsen "reads" the driveshaft speeds to determine 
> torque split.

I say neither.  Torsen resists one shaft turning faster than the other
up to its maximum torque split, at which point, one shaft
will start turning faster, with max torque still going to the
slower shaft.

We are getting bogged down in Torsen marketing... it's really a dumb
device.  The fancy gearing pushes the friction surfaces against
each other when driven from the ring gear and allows different
characteristics when not driven, eg under engine braking/coasting.