Content .. 1481 1482 1483 1484 ..
Chevrolet Silverado / GMC Sierra. Manual - part 1483
1. Measure the rotating torque of the drive pinion and differential assembly using an inch-
pound torque wrench.
Specification: The rotating torque of the drive pinion and differential assembly should be
2.3-4.5 N.m (20-40 lb in) for new bearings or 1.7-3.4 N.m (15-30 lb in) for used bearings.
2. If the rotating torque is too low, tighten the differential bearing adjuster nut in 1 slot
increments until the specified rotating torque is obtained.
3. If the rotating torque is too high, loosen the differential bearing adjuster nut in 1 slot
increments until the specified rotating torque is obtained.
4. If the specification for the rotating torque of the drive pinion and differential assembly
cannot be obtained by adjusting the differential bearing adjuster nut, remove the differential
assembly, measure the rotating torque of the drive pinion and adjust as necessary. Refer to
Differential Replacement (8.6, 9.5/9.5LD Inch Axles) or Differential Replacement
(10.5 Inch, 11.5 Inch Axle) and Drive Pinion Bearings Replacement (8.6, 9.5, 11.5
Inch Axle) or Drive Pinion Bearings Replacement (10.5 Inch Axle).
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Fig. 269: Measuring Ring Gear Backlash
Courtesy of GENERAL MOTORS CORP.
5. Install the J 25025-1 and the J 8001-3 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 approximately 3/4 of a turn. 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).
13. If the backlash is not within specifications, adjust the backlash by performing the following
procedure:
1. Remove the differential bearing adjuster nut retainer bolt.
2. Remove the differential bearing adjuster nut retainer.
3. Loosen the bearing cap bolts.
14. Do not remove the bearing cap bolts.
1. Loosen the differential bearing adjuster nut using the J 24429 . See Special Tools.
2. Remove the differential side bearing shim.
3. Measure the thickness of the shim.
15. Calculate the average of the 3 measurements.
16. Record the measurement.
If the backlash is too small, select a smaller shim than the one that was removed. For
example, to increase the backlash by 0.05 mm (0.002 in), select a shim that is 0.10 mm
(0.004 in) thinner than the shim that was removed.
If the backlash is too large, select a larger shim than the one that was removed. For
example, to increase the backlash by 0.05 mm (0.002 in), select a shim that is 0.10 mm
(0.004 in) thicker than the shim that was removed.
IMPORTANT: Increasing or decreasing the shim thickness by 0.05 mm
(0.002 in) will change the backlash adjustment approximately
0.03 mm (0.001 in).
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Install the shim.
17. Tighten the differential bearing adjuster nut using the J 24429 until the differential bearing
adjuster nut is seated against the bearing cup. See Special Tools.
18. Once the differential bearing adjuster is seated against the differential bearing, tighten the
differential bearing adjuster nut using the J 24429 the following additional amounts:. See
Special Tools.
Tighten:
For used bearings, tighten the differential bearing adjuster nut an additional 2 slots.
For new bearings, tighten the differential bearing adjuster nut an additional 3 slots.
19. Tighten the differential bearing cap bolts.
Tighten: Tighten the bearing cap bolts to 85 N.m (63 lb ft).
20. Recheck the backlash following the steps above to verify that the backlash is within
specifications.
21. Install the differential bearing adjuster nut retainer.
22. Install the differential bearing adjuster nut retainer bolt.
Tighten: Tighten the differential bearing adjuster nut retainer nut bolt to 26 N.m (19 lb ft).
23. Measure the drive pinion and differential case side bearing preload and adjust, if necessary
following the steps above.
24. 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.
GEAR TOOTH CONTACT PATTERN INSPECTION
Pattern Evaluation (Ring Gear)
NOTE:
Refer to Fastener Notice .
Drive Side
Coast Side
Pattern
Condition
Corrective Action
Heel Toe
Toe Heel
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Content .. 1481 1482 1483 1484 ..