Subaru impreza 2002 Service Manual page 59

3. DRIVING ON ROUGH OR SLIPPERY ROADS
D
When front wheels are on a slippery surface
When the front wheels begin to spin, the resulting speed difference between the front and rear
drive shafts causes the viscous coupling to generate significant amount of shear torque. As a re-
sult, the torque distributed to the rear wheels becomes much larger than that distributed to the
spinning front wheels. The traction and driving stability are thus ensured on a rough or slippery
road.
D
When rear wheels are on a slippery surface
When the vehicle is accelerated quickly from a standing start with the rear wheels on a slippery
surface, the distribution of the vehicle weight on the front and rear wheels changes and the rear
wheels start spinning. Due to the resulting speed difference between the front and rear drive
shafts, the viscous coupling generates a significant amount of shear torque, now in the direction
opposite to that generated when the front wheels are on a slippery surface. As a result, the torque
distributed to the front wheels becomes much larger than that distributed to the rear wheels.
CENTER DIFFERENTIAL
6MT-21
Manual Transmission and Differential
NF0615
NF0616