GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 7872 Magnetic Base Dial Indicator

Adjustment of the Differential

If it is necessary to replace the cam gear, the right hand side gear, or the thrust block, the entire differential must be adjusted. The differential is adjusted using selective thickness thrust washers behind each side gear, and the selective thickness thrust washers between the thrust blocks.

When adjusting the differential, note the following:

    • Build up the differential properly.
        The proper clearance between parts is critical to the operation of the unit.
    • Adjust the backlash and thrust block clearance in the following order:
        1. The left side gear backlash
        2. The right side gear backlash
        3. The thrust block clearance

Left Side Gear Backlash Adjustment

   • 
  • Install the cam unit and the side thrust washer to the flange end of the differential case.
  •    • 
  • Install the pinion gears and the side gear thrust washer into the differential case.
  • Align the openings of the pinion gears and the side thrust washer to the pinion shaft opening in the differential case.

       • 
  • Press down on the side gear and install the pinion shaft.
  • If the side gear cannot be pressed down far enough to install the pinion shaft, replace the side gear thrust washer with a thinner washer.

       • 
  • Install the pinion shaft lock bolt.
  • Tighten the pinion shaft lock bolt finger tight.

       • 
  • Rotate the pinion gear closest to the lock bolt so that one of the teeth is pointing downward (perpendicular to the ring gear flange).
  •    • 
  • Insert a large tapered tool, such as a screwdriver, firmly between the side gear and the pinion shaft.
  •    • 
    Object Number: 7531  Size: SH
  • Measure the backlash of the pinion gear and the side gear by doing the following:
  • 0.1. Install the J 7872 to the ring gear flange.
    0.2. Loosely clamp the J 8001-3 onto the stem on the J 7872 .
    0.3. Place the contact pad of the J 8001-3 on one of the teeth of the pinion gear closest to the pinion shaft lock bolt.

    Turn the dial of the J 8001-3 until the needle and the dial face indicate zero.

    0.4. Tighten the lock nut of theJ 8001-2 finger tight.
    0.5. Pull the pinion gear firmly into the differential case seat.
    0.6. Rotate the pinion gear back and forth.
    0.7. Measure the backlash.

    Record the measurement.

    0.8. Measure the backlash for the opposite pinion gear.
    0.9. Add the measurements together.

    Specification
    The backlash for the pinion gears should be 0.051-0.243 mm (0.002-0.010 in).

    0.10. If the backlash is too large, install a thicker side gear thrust washer and measure the backlash again.
    0.11. If the backlash is too small, install a thinner side gear thrust washer and measure the backlash again.

    Right Side Gear Backlash Adjustment

    1. Assemble the clutch plates.
    2. Alternate the plates.

    3. Assemble the guide clips to the plates.
    4. Use grease in order to hold the clips in place on the plates.

    5. Install the side gear thrust washer, the clutch plate assembly and the right side gear to the differential case.
    6. Install the pinion gears and the side gear thrust washers into the differential case.
    7. Align the openings of the pinion gears and the pinion gear thrust washers to the pinion shaft opening in the differential case.

    8. Press down on the side gear and install the pinion shaft.
    9. If the side gear cannot be pressed down far enough to install the pinion shaft, replace the side gear thrust washer with a thinner washer.

    10. Install the pinion shaft lock bolt.
    11. Tighten the pinion shaft lock bolt finger tight.

    12. Rotate the pinion gear closest to the lock bolt so that one of the teeth is pointing downward (perpendicular to the ring gear flange).
    13. Insert a large tapered tool, such as a screwdriver, firmly between the side gear and the pinion shaft.

    14. Object Number: 7531  Size: SH
    15. Measure the backlash of the pinion gear and the side gear by doing the following:
    16. 9.1. Install the J 7872 to the ring gear flange.
      9.2. Loosely clamp the J 8001-3 onto the stem on the J 7872 .
      9.3. Place the contact pad of the J 8001-3 on one of the teeth of the pinion gear closest to the pinon shaft lock bolt.

      Turn the dial of the J 8001-3 until the needle and the dial face indicate zero.

      9.4. Tighten the lock nut of the J 8001-2 finger tight.
      9.5. Pull the pinion gear firmly into the differential case seat.
      9.6. Rotate the pinion gear back and forth.
      9.7. Measure the backlash.

      Record the measurement.

      9.8. Measure the backlash for the opposite pinion gear.
      9.9. Add the measurements together.

      Specification
      The backlash for the pinion gears should be 0.051-0.243 mm (0.002-0.010 in).

    17. If the backlash is too large, install a thicker side gear thrust washer and measure the backlash again.
    18. If the backlash is too small, install a thinner side gear thrust washer and measure the backlash again.

    Thrust Block Clearance Adjustment

    1. Install the left side gear thrust washer into the differential case.
    2. Install the left side cam unit assembly into the differential case. Refer to Locking Differential Cam Unit Assemble .
    3. Install the right side thrust washer into the differential case.
    4. Assemble the right side clutch plates.
    5. Alternate the clutch plates.

    6. Assemble the guide clips to the plates.
    7. Use grease in order to hold the clips in place on the plates.

    8. Install the right side clutch plates into the differential case.
    9. Install the right side gear into the differential case.
    10. Install the pinion shaft.
    11. Install the pinion shaft bolt.
    12. Tighten the pinion shaft bolt finger tight.

    13. Insert a large tapered tool, such as a screwdriver, firmly between the side gears and the pinion shaft.
    14. Important: Do not measure the distance between the side gear teeth.

    15. Measure the distance between the side gear faces using a 1-2 in telescoping gage.
    16. Remove the telescoping gage.
    17. Measure the telescoping gage with a micrometer.
    18. Record the measurement.

    19. Measure the original thrust block with a micrometer.
    20. Record the measurement.

    21. Subtract the thrust block measurement from the telescoping gage measurement.
    22. Specification
      The difference between the thrust block measurement and the telescoping gage measurement should be 0.000-0.1524 mm (0.000-0.006 in).

    23. If the difference between the thrust block measurement and the telescoping gage measurement is greater than 0.1524 mm (0.006 in), reduce the distance by doing the following:
    24. 16.1. Select a new thrust block of the correct size in order to obtain the 0.000-0.1524 mm (0.000-0.006 in) clearance.
      16.2. If a thrust block of the correct size is not available, increase or reduce the left and/or right thrust washers thickness in order to reduce the distance.

              Important: The backlash must be rechecked and adjusted to specification anytime the left and/or the right thrust washers are replaced.

      16.3. If the thrust washers were replaced, recheck the backlash.