Center differential in Subaru automatic transmission
A center differential is a transmission mechanism that distributes torque between the front and rear axles of a vehicle.
Design and operating principle
Subaru automatic transmissions use a Torsen differential, also known as an LSD (limited slip differential). It consists of:
* Differential housings
* Bevel gears (satellites)
* Spur gears (crown)
The differential housing is attached to the transmission housing and contains the bevel gears. The bevel gears, in turn, mesh with spur gears, which are connected to the output shafts for the front and rear axles.
When the speed of the input and output shafts differs, the worm gears slide against each other, creating friction. This friction distributes torque between the axles, directing more torque to the axle with the best traction. However, the Torsen differential also allows some slip between the axles to compensate for speed differences when cornering.
Advantages of a Torsen differential
* Improved grip on slippery surfaces
* Increased maneuverability in corners
* Reduced tire wear
Types of Torsen differentials used in Subaru automatic transmissions
Subaru uses different types of Torsen differentials in its automatic transmissions, depending on the model and year of manufacture:
* Torsen T-2: Distributes torque from 75:25 to 45:55 in standard conditions and up to 80:20 when one of the wheels slips.
* Torsen T-3: Distributes torque from 80:20 to 25:75 in standard conditions and up to 90:10 when one of the wheels slips.
Differential service
To ensure optimal performance of the center differential, the transmission and differential oil should be changed regularly. Refer to your vehicle’s owner’s manual for recommended replacement intervals. It is also important to regularly check the differential for leaks or damage.