Limited slip differentials lock two wheels together while traveling in a straight line. While cornering it allows for the outside wheel to rotate faster than the inside by overcoming the tension of a clutch.
The clutch type differential is the most common and consists of two sets of multiple disc clutch packs located on each of the two side gears. These clutch packs consist of friction plates splined to the side gear interlaced with steel plates with tabs locking them to the differential case.
In order for the outside wheel to turn faster the wheel must overcome the tension of its side gears clutch pack. The more tension on the clutch packs the more resistance while cornering and the more torque while going forward.
The initial tension required to compress the clutch packs is provided by a spring. Shims are used to adjust the tension on these packs. This keeps the side gears and in turn the axles locked to the differential case. In order for a set of friction plates to slip this tension must be overcome.
The friction and steel plates wear in time and the fluid needs to be serviced at recommended intervals. Special fluids are used to compliment the engagement and release of the limited slip components. In time the friction material wears and sometimes the splines and tabs become rounded. Differentials are designed to provide smooth cornering. While cornering the symptoms of a worn or damaged differential become most apparent.
Chatter and vibration while cornering with a limited slip differential is often caused by servicing with the wrong type of fluid, but may also be caused by internal components. When the discs wear down the differential starts to behave more like an open or standard differential. The disc packs may be serviced. Soak the friction material for at least 30 minutes before installation and use a feeler gauge to measure the clutch pack. Use this measurement to determine the proper thickness of the preload shim.