Subaru Impreza 2002 Service Manual page 56

B: MECHANISM OF VISCOUS COUPLING
The viscous coupling consists of a number of alternately arranged inner and outer plates and air-
and-silicone oil mixture filled into a sealed space that is formed by the center differential case and
the rear side gear of the differential gear set. The inner plates have their inner perimeters splined
to the side gear and the outer plates have their outer perimeters splined to the center differential
case. The outer plates are held apart by spacer rings. There are no spacer rings between the inner
rings, so the inner rings are movable slightly in axial directions. X-section rings are used to prevent
leakage of silicone oil which would otherwise occur if the oil is pressurized due to large difference
in front and rear axle speeds.
(1) X-section ring
(2) O-ring
(3) Spacer ring
(4) Outer plate
CENTER DIFFERENTIAL
6MT-17
Manual Transmission and Differential
(5) Inner plate
(6) X-section ring
(7) Side gear (rear)
NF0612