The Borg Warner (BW) model 4476, transfer case is a one-speed, full time, all wheel drive (AWD), transfer case. The transfer case provides power to both axles through an external planetary type differential, which has 2 different sets of pinion gears. The planetary differential provides a 50/50 torque split, front/rear, full time. This means both axles are constantly being driven for maximum traction in all conditions. The BW 4476 design of the planetary differential allows the use with the vehicle stability enhancement system (VSES) vehicles. The VSES takes use of the planetary differential by applying braking to a tire that has less traction and dividing the engine torque to the other axle.
Reduced driveline backlash is achieved through press fit interfaces of the lower sprocket, sun gear, and input shaft assembly.
The BW 4476 case halves are high-pressure, die-cast aluminum. Ball bearings support the input shaft, the front output shaft, and the rear output shaft. The transfer case requires manual transmission fluid GM P/N 88861800 (Canadian P/N 88861801), which is red in color.
Design updates in the service replacement assemblies provided in 2007 and later include the following:
| • | Replacing the BW 4476 with the BW 4479 design |
| • | Replacing the BW 4476 50/50 carrier with the BW 4479 40/60 carrier |
| • | Revising the cover to require a 850 ml (0.90 quart) oil fill |
When servicing a transfer case or carrier that has been replaced with a BW 4479, refer to the 2006 SRX Transfer Case Unit Repair Manual.
