Originally Posted by 4carl
I ROTATED ONE REAR WHEEL THE OTHER WHEEL ROTATED IN THE OTHER DIRECTION THE SAME AS A OPEN DIFFERENTIAL DOES.
Not here too...
This pops up over and over on the Miata forum.
Originally Posted by MyElise
Watch "My Cousin Vinny".
That only works for American made/GM cars equipped with a clutch pack differential.
There are different types of Limited Slip Differentials.
The typical American car usually has a clutch pack type of differential - there are spring loaded clutches that "lock" one axle to the other side. If you turn one wheel, the other will turn in the same direction. One wheel will not turn without the other unless you can apply a lot of force (like the weight of a heavy car turning sharply). There is very limited slip. They have a tendency to wear out over time as the clutch packs wear.
Torsen type of limited slips do not use clutches. They have a series of worm gears inside the differential. They "lock" the two axles together when there is force being applied from the input of the differential - when power is being applied. When there is no power being applied, a Torsen behaves like an open differential. One other quirk is that if one wheel completely looses traction (is raised in the air), the Torsen will no longer "limit the slip" - all the "power" goes out the spinning wheel, and you essentially have an open differential. Torsen differentials do not wear out, they work by mechanical forces, not friction forces (that wear).
There are also Viscous Limited Slips what have the two sides connected by a sealed container of very viscous fluid - as differential rotation occurs, the viscous fluid heats up, and "locks" the two side together. The downsides are that the viscous LSD tend to wear out, and they don't do much limiting in the first place.
There are other types of Limited Slip Differentials, but but the main ones of interest are the ones above.
The Elise has a Torsen Limited Slip Differential.
There is specific tests to determine that a Torsen LSD exists, but it requires careful measurement of the forces exerted when compared to a specified turning force.
Many people can simply "feel" the handling with/without the Torsen. Some can tell by it's behavior during a tight turn. But the only real way that I know of to really demonstrate the existence of a Torsen LSD is to stop your car on the side of the road. One wheel on drive pavement. The other wheel on sand/grass/dirt. Rev up the engine and dump the clutch. If both wheels spin, you most likely have a Torsen. If only one wheel (the one on the pavement), you most likely have an open differential. If neither wheel spins, you did try hard enough - rev the engine more, and/or dump the clutch quicker. Anything that happens as a result of the ECU dump is not my problem.