Chevrolet Silverado / GMC Sierra. Service manual — part 1390

22. Install the front drive axle actuator.

Apply sealant to the threads of the front axle actuator. Use the correct sealant. Refer to
Sealers, Adhesives, and Lubricants.

Tighten: Tighten the front drive axle actuator to 20 N.m (15 lb ft).

Fig. 237: Installing Lower Differential Carrier Assembly Bushing Using J 21474-18,
Thrust Bearing, J 36616-2, J 36616-1, & Forcing Screw
Courtesy of GENERAL MOTORS CORP.

NOTE:

Refer to Component Fastener Tightening Notice .

IMPORTANT: The following service procedures are for the 9.25 inch axle

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

23. Install the lower differential carrier assembly bushing by performing the following steps:

1. Install the J 21474-18 (1), the thrust bearing (2), the J 36616-2 (3), the J 36616-1 (4),

and the forcing screw (5) as shown.

2. While holding the forcing screw, slowly tighten the J 21474-18 until the bushing has

stopped against the step on the bushing and is centered within the differential carrier
assembly bushing bore.

Fig. 238: Installing Upper Differential Carrier Assembly Bushing J 21474-18, Thrust
Bearing, J 36616-2, J 36616-1, & Forcing Screw
Courtesy of GENERAL MOTORS CORP.

ONLY.

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

24. Install the upper differential carrier assembly bushing by performing the following steps:

1. Install the J 21474-18 (1), the thrust bearing (2), the J 36616-2 (3), the J 36616-1 (4),

and the forcing screw (5) as shown.

2. While holding the forcing screw, slowly tighten the J 21474-18 until the bushing has

stopped against the step on the bushing and is centered within the differential carrier
assembly bushing bore.

25. Install the differential carrier assembly. Refer to Differential Carrier Assembly

Replacement (1500 FWD) or Differential Carrier Assembly Replacement (2500
4WD).

GEAR TOOTH CONTACT PATTERN INSPECTION

The contact pattern check is not a substitute for adjusting the pinion depth and backlash. Use this
method in order to verify the correct running position of the ring gear and the drive pinion. Gear
sets which are not positioned properly may be noisy and/or have a short life. A pattern check
ensures the best contact between the ring gear and the drive pinion for low noise and long life.

Gear Tooth Nomenclature

IMPORTANT: The following service procedures are for the 9.25 inch axle

ONLY.

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 239: Defining Gear Tooth Nomenclature
Courtesy of GENERAL MOTORS CORP.

The side of the ring gear tooth which curves outward, or is convex, is the drive side (4). The
concave side is the coast side (3). The end of the tooth nearest the center of the ring gear is the toe
end (2). The end of the tooth farthest away from the center is the heel end (1).

Adjustments Affecting Tooth Contact

The following 2 adjustments affect the tooth contact pattern:

Backlash adjustment

Pinion depth adjustment

2008 Chevrolet Silverado 1500

2008 Driveline/Axle Front Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado