GM Service Manual Online
For 1990-2009 cars only

Pinion Depth Adjustment 10.5 Inch Axle

  1. Install the differential, if necessary. Refer to Differential Replacement.
  2. Note: Measure and record the thickness of the pinion gear bearing retainer shim before any service procedures are performed to the pinion gear bearing retainer assembly.

  3. Install the original shim to the pinion bearing retainer. If the original shim is not available, install a 0.41 mm (0.016 in) shim to build pinion depth.
  4. Note: Do not apply sealant to the pinion gear bearing retainer at this time.

  5. Install the pinion gear bearing retainer.
  6. Caution: Refer to Fastener Caution in the Preface section.

  7. Install the pinion gear bearing retainer bolts and tighten to 88 N·m (65 lb ft)..
  8. Adjust the backlash. Refer to Backlash Adjustment.
  9. Perform a gear tooth pattern check on the pinion and the ring gear. Refer to Gear Tooth Contact Pattern Inspection.
  10. If the gear tooth contact pattern indicates a high or a low flank contact pattern, adjust the pinion depth by doing the following:
  11. 7.1. Remove the pinion gear bearing retainer bolts.
    7.2. Remove the pinion gear bearing retainer.
    7.3. Remove the shim.
       • If the gear tooth contact pattern shows a high flank contact pattern, install a shim one size larger.
       • If the gear tooth contact pattern shows a low flank contact pattern, install a shim one size smaller.
    7.4. Install the new shim to the pinion gear bearing retainer.
    7.5. Install pinion gear bearing retainer.
    7.6. Install pinion gear bearing retainer bolts and tighten to 88 N·m (65 lb ft)..
    7.7. Inspect the gear tooth contact pattern of the pinion and the ring gear. Refer to Gear Tooth Contact Pattern Inspection.
    7.8. If the gear tooth pattern is still incorrect, adjust the shim thickness as necessary and recheck the gear tooth pattern of the pinion and the ring gear.
  12. Inspect the backlash between the pinion and the ring gear and adjust, if necessary. Refer to Backlash Adjustment.

The pinion shims are available in the following sizes:

Shim Sizes

    • 0.15 mm (0.006 in)
    • 0.18 mm (0.007 in)
    • 0.20 mm (0.008 in)
    • 0.23 mm (0.009 in)
    • 0.25 mm (0.010 in)
    • 0.28 mm (0.011 in)
    • 0.30 mm (0.012 in)
    • 0.33 mm (0.013 in)
    • 0.36 mm (0.014 in)
    • 0.38 mm (0.015 in)
    • 0.41 mm (0.016 in)
    • 0.43 mm (0.017 in)
    • 0.46 mm (0.018 in)
    • 0.48 mm (0.019 in)
    • 0.51 mm (0.020 in)
    • 0.53 mm (0.021 in)
    • 0.56 mm (0.022 in)
    • 0.58 mm (0.023 in)
    • 0.61 mm (0.024 in)

Pinion Depth Adjustment 8.6, 9.5/9.5 LD and 11.5 Inch Axles

Special Tools

    • J 8001 Dial Indicator Set
    • J 21777-86 Side Bearing Disc Set
    • J 34925 Pinion Setting Gauge Set
    • J 44416 Pinion Setting Tool
    • J 45108 Gauge Plate

    Note: Make sure all of the tools, the differential side bearing bores, and the pinion bearing cups are clean before proceeding.

  1. Using the proper axle lubricant, lubricant the differential pinion bearings. Refer to Fluid and Lubricant Recommendations.
  2. Install the differential pinion bearings into the axle housing.

  3. Object Number: 651745  Size: SH
  4. Install the following special tools in the axle housing.
  5. • For the 8.6 inch axle, the J 21777-35 (1), the J 21777-43 (2), the J 21777-42 (3), and the J 21777-29 (4).
    • For the 9.5/9.5LD inch axles, the J 21777-8 (1), the J 21777-43 (2), the J 21777-42 (3), and the J 45108 plate  (4).
    • For the 11.5 inch axle, the J 44416-3 (1,4), the J 21777-43 (2), and the J 44416-2 (3).

    Note: 

       • Hold the J 21777-43 stationary while turning the torque wrench
       • Rotate the assembly several times in both directions in order to seat the pinion bearings

  6. Using an inch pound torque wrench and the J 21777-43, tighten the nut until a rotating torque of 1.7 N·m (15 lb in) is obtained.
  7. If the torque is less than 1.7 N·m (15 lb in), tighten the nut until a rotating torque of 1.7-2.3 N·m (15-20 lb in) is obtained.

  8. Object Number: 651746  Size: SH
  9. Install the following special tools in the differential carrier bores.
  10. • For the 8.6 inch axle, assemble the J 21777-45 (1, 2) to the J 21777-1 (3).
    • For the 9.5/9.5LD inch axles, assemble the J 21777-86 (1, 2) to the J 21777-1 (3).
    • For the 11.5 inch axle, assemble the J 44416-1 (1, 2) to the J 21777-1 (3).
  11. Install the bearing caps.
  12. Caution: Refer to Fastener Caution in the Preface section.

  13. Install the bearing cap bolts and tighten to 75 N·m (55 lb ft)..
  14. Note: The J 21777-1 must rotate back and forth freely within the discs. If the J 21777-1 does not rotate freely, disassemble the components, inspect for proper seating and/or mis-aligned components and re-assemble.

  15. Rotate the J 21777-1 within the J 21777-45, 8.6 inch axle, or the J 21777-86, 9.5/9.5LD inch axles, or the J 44416-1, 11.5 inch axle.

  16. Object Number: 670320  Size: SH
  17. Adjust the arbor of the J 21777-1 (1) to the gauge block setting of the J 21777-29 for the 8.6 inch axle, or the J 45108 plate , for the 9.5/9.5LD inch axles, or the J 44416-3, for the 11.5 inch axle (2).
  18. Install the J 8001 indicator to the J 21777-1 as follows:
  19. 11.1. Loosely clamp the J 8001 indicator onto the stem on the J 21777-1.
    11.2. Place the contact pad of the J 8001 indicator onto the mounting post of the J 21777-1.
    11.3. With the contact pad of the J 8001 indicator touching the mounting post of the J 21777-1, loosen the lock nut on the J 8001 indicator and push down on the J 8001 indicator until the needle the J 8001 indicator has turned 3/4 of a turn clockwise.
    11.4. Tighten the clamp on the J 8001 indicator finger tight.

    Note: The deflection is the point where the needle changes direction.

  20. Move the plunger of the J 21777-1 back and forth until the needle of the J 8001 indicator indicates the greatest deflection.

  21. Object Number: 670316  Size: SH
  22. At the greatest point of deflection, move the housing of the J 8001 indicator until the needle indicates zero.
  23. Move the plunger of the J 21777-1 back and forth again to verify the zero setting. Adjust the housing of the J 8001 Dial Indicator Set as necessary to set the needle to zero.
  24. Rotate the plunger of the J 21777-1 away from the J 21777-29, 8.6 inch axle, the J 45108 Gauge Plate , 9.5/9.5LD inch axles, or the J 44416-3, 11.5 inch axle, until it no longer touches the J 21777-29, the J 45108 plate , or the J 44416-3.
  25. The value indicated on the J 8001 indicator is the thickness of the shim needed in order to set the depth of the pinion.
  26. Select the shim that indicates the proper thickness. Measure the shim with a micrometer in order to verify that the thickness is correct.
  27. Remove the pinion depth setting tools.
  28. Remove the pinion bearings.
  29. Install the pinion shim between the pinion gear and the inner pinion bearing. Refer to Drive Pinion Bearings Replacement.