Chevrolet Silverado / GMC Sierra. Service manual — part 2830

Fig. 88: View Of Transfer Case Drain Plug
Courtesy of GENERAL MOTORS CORP.

34. Apply pipe sealant GM P/N 12346004 (Canadian P/N 10953480) to the threads on the

drain plug and fill plug.

35. Install the drain plug and the fill plug.

Tighten: Tighten the drain plug and fill plug to 25 N.m (18 lb ft).

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 89: Installing J 43484 To J 8092
Courtesy of GENERAL MOTORS CORP.

36. Using the J 43484 (2) and the J 8092 (1), install the front output shaft seal. See Special

Tools.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 90: Installing Input Shaft Seal Using J 42738
Courtesy of GENERAL MOTORS CORP.

37. Using the J 42738 , install the front input shaft seal. See Special Tools.

38. Remove the transfer case from the J 45759 . See Special Tools.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

DESCRIPTION AND OPERATION

TRANSFER CASE DESCRIPTION AND OPERATION

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.

Power Flow

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - BW 4485-NR3 - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado