Chevrolet Silverado / GMC Sierra. Service manual — part 1482

Fig. 266: Measuring Ring Gear Backlash
Courtesy of GENERAL MOTORS CORP.

5. Install the J 25025-1 and the J 8001 to the axle housing as shown. See Special Tools.

6. Place the indicator stem of the J 8001-3 at the heel end of a gear tooth. See Special Tools.

7. Set the J 8001-3 so that the stem is aligned with the gear rotation and perpendicular to the

tooth angle. See Special Tools.

8. Preload the dial of the J 8001-3 . See Special Tools.

Align the needle and the dial face of the J 8001-3 to ZERO. See Special Tools.

9. While holding the drive pinion stationary, move the ring gear back and forth.

Measure and record the backlash.

10. Repeat the measuring procedure at eight points around the ring gear.

2008 Chevrolet Silverado 1500

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

Specification: The difference between the backlash at all of the measuring points should
not vary by more than 0.05 mm (0.002 in).

11. If the difference between the backlash at all of the measuring points varies by more than

0.05 mm (0.002 in), inspect for the following conditions:

Burrs

A distorted case flange

Uneven bolting

12. If the difference between all the measuring points is within specifications, the backlash at

the minimum lash point measured should be:

Specification: The backlash between the ring gear and the drive pinion should be between
0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007
in).

2008 Chevrolet Silverado 1500

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

Fig. 267: Turning Adjusters Using J 24429
Courtesy of GENERAL MOTORS CORP.

13. If the backlash is not within specifications, adjust the backlash by performing the following

steps:

1. Remove the differential bearing adjuster nut retainers bolts.

2. Remove the differential bearing adjuster nut retainers.

3. Remove the bearing cap bolts.

4. Remove the bearing caps. Mark the bearing caps left and right.

5. If the backlash is too small, increase the backlash by turning the left differential

bearing adjuster in one slot and the right differential bearing adjuster out one slot using
the J 24429 until the correct backlash is obtained. See Special Tools.

6. If the backlash is too large, decrease the backlash by turning the right differential

bearing adjuster in one slot and the left differential bearing adjuster out one slot using
the J 24429 until the correct backlash is obtained. See Special Tools.

14. Install the bearing caps.

15. Install the bearing cap bolts.

Tighten:

Tighten the bearing cap bolts to 185 N.m (136 lb ft) (10.5 inch axle).

Tighten the bearing cap bolts to 207 N.m (153 lb ft) (11.5 inch axle).

16. Recheck the backlash following the steps above to verify that the backlash is within

specifications.

17. Install the differential bearing adjuster nut retainers.

18. Install the differential bearing adjuster nut retainer bolts.

Tighten: Tighten the differential bearing adjuster nut retainer nut bolts to 27 N.m (20 lb ft).

19. Measure the drive pinion and differential case side bearing preload and adjust, if necessary

following the steps above.

20. Once the backlash and bearing preload is correct, perform a gear tooth contact pattern

check in order to ensure proper alignment between the ring and pinion gears. Refer to Gear
Tooth Contact Pattern Inspection.

NOTE:

Refer to Fastener Notice .

2008 Chevrolet Silverado 1500

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

BACKLASH ADJUSTMENT (9.5 LD AXLE)

Special Tools

J 8001 Dial Indicator Set

J 24429 Side Bearing Backlash Spanner. See Special Tools.

J 25025 Guide Pins. See Special Tools.

Adjustment

Fig. 268: Measuring Pinion Rotating Torque
Courtesy of GENERAL MOTORS CORP.

IMPORTANT:

Ensure that the side bearing surfaces in the axle housing are
clean and free of burrs. If the original bearings are to be
reused, the original bearing cups must also be used.

The differential side bearings must be initially preloaded in
order to determine the backlash of the gear set. After the
backlash is set, the final bearing preload is set.

2008 Chevrolet Silverado 1500

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