Limited Slip Differentials
When a vehicle is turning, the outside wheel is spinning faster than the inside wheel. This is because the outside path of a turn has a greater distance to travel than the inside path does. To compensate, a differential allows one wheel to spin faster than the other. This is accomplished through the use of a pinion gear assembly.
Open differentials power the wheel with the least resistance. This causes a tire that has broken loose and started to spin to spin even faster. This is not good, because it leaves the other tire with little or no torque. A limited slip differential provides a limited connection between the two axles, providing torque to both wheels, even when one has begun to slip or break loose.
There are different types of limited slip differentials and some are not serviceable. Most are though and contain a series of friction disks and steel plates held under a constant, but limited amount of spring pressure. Some contain a viscous clutch with a thick sticky fluid that gets thicker as it heats up. This unit is typically replaced when the fluid wears.
Special Fluid: These units require a special type of fluid typically recommended by the manufacturer. Failure to do so can result in slippage and chatter around corners.