Transfer Case Description and Operation: Notes

WARNING: This page is about a different car, the 2004 GMC Yukon XL and 2004 GMC Yukon. However, it is still accessible from the selected car via links, so may be relevant.

The Borg Warner (BW) model 4482 NR4 transfer case is a two-speed, full time 4WD, transfer case. The transfer case has an external planetary type differential, which has two different sets of pinion gears. The planetary differential provides a 40/60 torque split front/rear full time. This means the front and rear propeller shafts are constantly being driven for maximum traction in all conditions.

While in the 4HI mode, 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, and in the 4HI mode, the front propeller shaft can be rotated by hand.
The vehicle cannot be driven in the 4HI mode if one propeller shaft is removed.
Operating the vehicle on the hoist, in the 4HI mode, can damage the differential pinion gears, by over-spinning.
Operating the vehicle with one propeller shaft removed, in the 4HI mode, causes over-spinning of the differential pinion gears.

The BW 4482 design of the planetary differential allows 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. A high/low planetary carrier assembly provides the high and low ranges, which is a 4-pinion gear, sun gear, and annulus gear arrangement, giving a 2.64 low range reduction ratio.

The BW 4482 case halves are high-pressure die-cast magnesium. Ball bearings support the input shaft, the front output shaft, and the rear output shaft. A needle roller bearing is located inside of the input shaft gear to support the front of the mainshaft. The rear of the mainshaft is supported by a bronze bearing inside the rear output shaft. The transfer case requires DEXRON®III ATF Fluid GM P/N 12346143 (Canadian P/N 10952622), which is red in color. An oil pump pumps the fluid through the mainshaft oil gallery to the gears and bearings.