Subaru 2002 Impreza Service Manual page 270

CENTER DIFFERENTIAL
Manual Transmission and Differential
3. Center Differential
A: CONSTRUCTION
The center differential consists of a set of bevel gears and a viscous coupling.
The center differential has the following two functions: distributing the engine torque to the front
and rear wheel drive shafts and absorbing the difference in rotating speed between the front and
rear wheels.
The engine torque enters the center differential case from the transmission's driven shaft. The
torque is then distributed through the bevel gear set directly to the drive pinion shaft and via the
transfer drive and driven gears to the rear drive shaft.
The viscous coupling limits the bevel gear set's differential action when either front or rear wheels
spin so that adequate torques are transmitted to the front and rear wheels and proper traction is
obtained.
Transfer driven gear
(4)
Center differential assembly (with viscous
Transfer drive gear (5) Drive pinion shaft
Viscous coupling (6) Driven shaft
NF0120
coupling)
MT-10