Transfer Case Description and Operation: Notes

WARNING: This page is about a different car, the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Cadillac Escalade EXT, 2011 Cadillac Escalade ESV, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

The Borg Warner (BW) model 4485, RPO NR3 transfer case is a 1-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 40/60 torque split, front/rear, full time. This means both axles are constantly being driven for maximum traction in all conditions.

The transfer case external type planetary differential functions the same as a typical rear axle differential. The transfer case differential pinion gears function as the spider gears, and the sun gears function as the side gears.

The following actions occur because of the planetary differential:

If the vehicle is on a hoist, the front propeller shaft can be rotated by hand.
The vehicle cannot be driven if 1 propeller shaft is removed.
Operating the vehicle on the hoist can damage the differential pinion gears, by over-spinning.
Operating the vehicle with 1 propeller shaft removed causes over-spinning of the differential pinion gears.

The BW 4485 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.

The BW 4485 case halves are high-pressure, die-cast magnesium. Ball bearings support the input shaft, the front output shaft, and the rear output shaft. The transfer case requires DEXRON®VI Automatic Transmission Fluid (ATF) GM P/N 88861003 (Canadian P/N 88861004), which is red in color.