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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1331 (Rear Drive Axle) >> Repair Instructions >> Differential Carrier Bearing Preload Adjustment (8.6 Inch Axle) >> Wedge Method

Wedge Method

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Special Tools

NOTE:
  • The differential side bearing preload adjustment must be completed before the backlash adjustment can be started.
  • In order to maintain the original backlash, adjust the differential case side bearing preload by changing the thickness of the left and the right side shim packs equally.
  • Measure the service shims and the spacers one at a time. Add the measurements together in order to obtain the total thickness of the left or the right side shim pack.
  • Do not use or reuse the original cast iron production shims. Use service shims and spacers instead.
  1. Install the drive pinion, if necessary. Refer to Drive Pinion and Ring Gear Replacement (8.6, 9.5/9.5 LD, and 11.5 Inch Axles)  or Drive Pinion and Ring Gear Replacement (10.5 Inch Axle) .
    2. NOTE: Record the measurement for re-assembly.
  2. Using an inch pound torque wrench, measure the rotating torque of the drive pinion, it should be 1.7-3.4 N.m (15-30 lb in) for new bearings or 1.1-2.3 N.m (10-20 lb in) for used bearings.
  3. If the rotating torque for the drive pinion bearings is not within specifications, adjust as necessary. Refer to Drive Pinion and Ring Gear Replacement (8.6, 9.5/9.5 LD, and 11.5 Inch Axles)  or Drive Pinion and Ring Gear Replacement (10.5 Inch Axle) .
    4. NOTE: Before installation of the differential assembly, ensure that the differential side bearing surfaces in the axle housing are clean and free of burrs. If the original differential side bearings are to be reused, the original differential side bearing cups must also be used.
  4. Install the differential assembly with the differential side bearings and differential side bearing cups into the axle housing.
  5. Insert one 4.318 mm (0.170 in) thick service spacer into the left side of the axle housing.
  6. Side the differential assembly towards the service spacer in order to hold the spacer in place.
    7. NOTE: The J 22779:  gage must be installed between the service spacer and the differential side bearing cup.
  7. Install the J 22779:  gage into the right side of the axle housing.
    8. NOTE: Over-tightening of the J 22779:  gage may spread the housing and result in incorrect shim selection.
  8. Tighten the knob on the J 25588:  installer until there is moderate drag when the J 22779:  gage is moved.
  9. Remove the J 22779:  gage.
  10. Remove the service spacer.
    11. NOTE: Record the measurement.
  11. Using a micrometer, measure the thickness of the service spacer.
    12. NOTE: Record the measurement.
  12. Using a micrometer, measure the thickness of the J 22779:  gage in 3 locations. Calculate the average of the 3 measurements.
  13. Add the thickness of the service spacer, measured in step 11 to the average thickness of the J 22779:  gage, measured in step 12. The resulting value is the total service shim thickness without preload for the axle.
  14. Insert one BENT 1.016 mm (0.040 in) service shim between the right side differential side bearing cup and the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
  15. Install the J 22779:  gage into the left side of the axle housing. The J 22779:  gage must be installed between the service spacer and the differential side bearing cup.
  16. While rotating the ring gear back and forth, tighten the knob on the J 22779:  gage until there is approximately 0.025-0.051 mm (0.001-0.002 in) of backlash between the ring gear and the drive pinion.
  17. Once the correct amount of backlash is obtained, remove the J 22779:  gage.
  18. Remove the differential assembly with the differential side bearings and the differential side bearing cups.
  19. Remove the BENT service shim.
  20. Using a micrometer, measure the thickness of the J 22779:  gage in 3 locations. Calculate the average of the 3 measurements. This value is the left side service shim thickness without preload.
  21. In order to determine the right side service shim thickness, subtract the service shim thickness for the left side of the axle, calculated in step 20, from the total service shim thickness, calculated in step 13. This value is the service shim thickness for the right side of the axle without preload.
  22. In order to preload of the differential side bearings and set the backlash to approximately 0.127-0.223 mm (0.005-0.009 in), take the value determined in step 21 and add 0.203 mm (0.008 in) service shim thickness to this amount.
  23. Assemble the left side shim pack using one 4.318 mm (0.170 in) service spacer and the appropriate amount of service shims equaling the thickness determined in step 20. Measure the service spacer and the service shims separately. Add the measurements together in order to determine the total shim pack thickness.
  24. Assemble the right side shim pack using one 4.318 mm (0.170 in) service spacer and the appropriate amount of service shims equaling the thickness determined in step 22. Measure the service spacer and the service shims separately. Add the measurements together in order to determine the total shim pack thickness.
  25. Install the differential assembly with the differential side bearings and the differential side bearing cups.
  26. Install the left side service spacer and service shim into the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
  27. Install the right side service spacer between the axle housing and the differential side bearing cup.
  28. Install the right side service shim into the axle housing using the J 25588:  installer, if necessary. The service shim must be installed between the service spacer and the differential side bearing cup.
    29. CAUTION: Refer to Fastener Caution .
  29. Install the differential bearing caps and the bolts and tighten to 75 N.m (55 lb ft).
  30. Rotate the pinion several times to ensure the drive pinion and differential side bearings have seated.
    31. NOTE: Record the measurement.
  31. Using an inch pound torque wrench, measure the rotating torque of the drive pinion and differential side bearings which should be 0.57-1.13 N.m (5-10 lb in) greater than the rotating torque of the drive pinion measured earlier.
  32. Calculate the differential side bearing preload by subtracting the drive pinion preload, measured in step 2, from the drive pinion and differential case bearing preload, measured in step 31. Multiply the value obtained by the axle ratio. The differential side bearing preload should be 1.7-4.0 N.m (15-35 lb in).
  33. If the differential side bearing preload is not within specifications, add or subtract shim thickness equally from each shim pack as necessary in order to increase/decrease the side bearing preload.
  34. Once the differential side bearing preload is correct, measure the backlash and adjust, if necessary. Refer to Backlash Adjustment (8.6 Inch Axle)  or Backlash Adjustment (10.5/11.5 Inch Axle)  or Backlash Adjustment (9.5 LD Axle) .
  35. Once the differential side bearing preload and backlash 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 .
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