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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 45 (Rear Drive Axle) >> Repair Instructions >> Differential Carrier Bearing Preload Adjustment (9.5 Inch Axle) >> Shim Method

Shim Method

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:

Do not re-use the old pinion nut. Stake the NEW pinion nut after the final rotating torque is achieved. If the pinion nut is not staked after the final rotating torque is achieved, the nut may lose retention causing loss of vehicle propulsion.

NOTE:
  • The differential side bearings must have preload 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 service 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 service spacers instead.
  1. Install the drive pinion, if necessary. Refer to Drive Pinion and Ring Gear Replacement (10.5 Inch Axle) , or Drive Pinion and Ring Gear Replacement (9.5 Inch Axle) .
    2. NOTE:

    Record the measurement.

  2. Using an inch pound torque wrench, measure the rotating torque of the drive pinion which 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 (10.5 Inch Axle) , or Drive Pinion and Ring Gear Replacement (9.5 Inch Axle) .
  4. GM4886706
    NOTE:

    Nut MUST be staked for 9.5/9.76 Inch LD Axles.

    Use a hammer and punch to stake two sides of the drive pinion nut lip to the corresponding grooves (1) in the drive pinion gear.

    5. NOTE:

    Before installation of the case assembly, 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.

  5. Install the differential assembly with the differential side bearings and bearing cups into the axle housing.
  6. Insert one BENT 1.016 mm (0.040 in) thick service shim into the right side axle housing. Side the differential assembly towards the bent service shim in order to hold the shim in place.
  7. While holding the differential assembly against the bent service shim, install one 4.575 mm (0.180 in) thick SERVICE SPACER into the left side axle housing.
  8. Move the differential assembly to the right until the ring gear contacts the drive pinion. Once the ring gear contacts the drive pinion, continue to move the ring gear towards the drive pinion to until all backlash is removed.
  9. While holding the ring gear against the drive pinion, insert progressively larger service shims between the service spacer and the differential side bearing cup until a moderate resistance can be felt.
  10. Once the largest service shim has been determined, measure the thickness of the shim using a micrometer. Measure the service shim in 3 locations. Calculate the average of the 3 measurements. Use the average as the thickness for the shim. Record the measurement.
  11. Install the service shim that was just measured back into the left side of the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
  12. Remove the BENT shim from the right side of the axle housing.
  13. Insert one 4.575 mm (0.180 in) thick SERVICE SPACER into the right side axle housing.
  14. Move the differential assembly towards the left side of the axle housing. While holding the differential assembly against the left side shim pack, insert progressively larger service shims between the service spacer and the differential side bearing cup until a moderate resistance can be felt.
  15. Once the largest service shim has been determined, measure the thickness of the shim using a micrometer. Verify the thickness of the service shim. Measure the service shim in 3 locations. Calculate the average of the 3 measurements. Use the average as the thickness for the shim. Record the measurement.
  16. In order to preload the differential side bearing and set the initial backlash to approximately 0.127 mm (0.005 in), adjust the thickness of left and right side shims by doing the following:
    1. Subtract 0.152 mm (0.006 in) from the measurement recorded for the left side shim in step 9. Record the measurement.
    2. Add 0.356 mm (0.014 in) to the measurement recorded for the right side shim in step 14.
    17. NOTE:

    Using a micrometer, verify the thickness of the service shim. Measure the service shim in 3 locations.

  17. Select the correct service shim thickness for each side corresponding to the measurements determined above. Calculate the average of the 3 measurements. Use the average as the thickness for the shim.
    18. NOTE:

    The service shim must be installed between the service spacer and the differential side bearing cup.

  18. Install the left side service spacer and shim into the axle housing.
  19. Move the differential assembly towards the left side of the axle housing.
  20. Install the right side service shim.
    1. Using a brass drift or rod, install the right side service spacer into the axle housing.
    21. CAUTION:

    Refer to Fastener Caution .

  21. Install the differential bearing caps and bolts and tighten to:
    1. First pass at 60 N.m (44 lb ft).
    2. Final pass an additional 30 degrees
  22. Rotate the pinion several times to ensure the bearings have seated.
  23. Using an inch-pound torque wrench, measure the rotating torque of drive pinion and differential case 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.
  24. Calculate the differential side bearing preload by subtracting the drive pinion preload, measured in Step 2, from the drive pinion and the differential case bearing preload, measured in Step 22. 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).
  25. 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.
  26. Once the differential side bearing preload is within specifications, measure the backlash between the ring gear and the drive pinion and adjust, if necessary. Refer to Backlash Adjustment (9.5 Inch Axle) , or Backlash Adjustment (10.5 Inch Axle) .
  27. Once backlash and differential side bearing preload is within specifications, 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 .
Part Name Metric Width Tolerance English Width Tolerance
    Plus/Minus   Plus/Minus
Spacer 4.575 mm 2.5 mm 0.180 in 0.0098 in
Shim 1.016 mm 0.013 mm 0.040 in 0.0005 in
Shim 1.067 mm 0.013 mm 0.042 in 0.0005 in
Shim 1.118 mm 0.013 mm 0.044 in 0.0005 in
Shim 1.168 mm 0.013 mm 0.046 in 0.0005 in
Shim 1.219 mm 0.013 mm 0.048 in 0.0005 in
Shim 1.27 mm 0.013 mm 0.050 in 0.0005 in
Shim 1.321 mm 0.013 mm 0.052 in 0.0005 in
Shim 1.372 mm 0.013 mm 0.054 in 0.0005 in
Shim 1.422 mm 0.013 mm 0.056 in 0.0005 in
Spacer 4.575 mm 2.5 mm 0.180 in 0.0098 in
Shim 1.473 mm 0.013 mm 0.058 in 0.0005 in
Shim 1.524 mm 0.013 mm 0.060 in 0.0005 in
Shim 1.575 mm 0.013 mm 0.062 in 0.0005 in
Shim 1.626 mm 0.013 mm 0.064 in 0.0005 in
Shim 1.676 mm 0.013 mm 0.066 in 0.0005 in
Shim 1.727 mm 0.013 mm 0.068 in 0.0005 in
Shim 1.778 mm 0.013 mm 0.070 in 0.0005 in
Shim 1.829 mm 0.013 mm 0.072 in 0.0005 in
Shim 1.88 mm 0.013 mm 0.074 in 0.0005 in
Shim 1.93 mm 0.013 mm 0.076 in 0.0005 in
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