Many LSDs use friction material to transfer the torque
applied to a slipping wheel to the one with traction. Those
that use a clutch pack (Figure 58-29) have two sets (one
for each side gear) of clutch plates and friction discs to
prevent normal differential action. The friction discs are
steel plates with an abrasive coating on both sides. These
discs fit over the external splines on the side gears'hub.
The clutch plates are also made of steel but have no friction
material bonded to them. The plates are placed between
the friction discs and fit into intemal splines in the
differential case. Pressure is kept on the clutch packs by
either an S-shaped spring or coil springs.