Kai M. Radicke wrote:
> What are the various differences between different types of differentials?
>
> a) Posi-Drive
"Posi-Drive" is not a differential at all, but the trade name of a type of
screw head - similar to a phillips head - that you'll find used all over TRs
and Healeys. The abbreviation "Posi" is sometimes used in car advertisements
as shorthand for "Positraction", which is (I think) a Chevrolet-made limited
slip that's been around in various forms since the late fifties.
> b) Locked
There's a differential called the "Detroit Locker" which (as I understand
it) is an "in or out" type rear end - when the speed differential between
the two rear wheels reaches a specified point, the differential locks so
that both wheels get equal torque. I've never used one of these so I could
be WAY off . . . There's also a REAL "locked" differential that's made by
just welding up the rear end gears so that you effectively have a solid rear
axle.
> c) Limited Slip
Someone will provide you with an elegant description of how both the Torsen
and Quaife type limited slips work, but suffice it to say that a "limited
slip" differential is just that - the wheel with less traction (the inside
wheel on a fast turn, the wheel sitting on an icy or wet surface, etc) is
only allowed a limited amount of slip as compared to the other rear wheel.
Clutches are used to prevent the lightly loaded wheel from excessive wheel
slip.
Generically speaking, locked differentials are almost impossible to drive on
the street (especially around tight corners) and are tricky to use but fast
on the race track in the hands of a competent driver.
Limited slip differentials (like the ubiquitous--albeit expensive--Quaife)
are much more user friendly.
Jim Hill
Madison WI
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