Differential Side Gear Backlash Adjustment

1. Remove the following from the differential case:
   1. The pinion shaft lock bolt
   2. The pinion shaft
   3. The pinion gears
   4. The pinion gear thrust washers
   5. The locking differential side gear
   6. The locking differential side gear thrust washer
Fig 1: Differential Side Gears & Thrust Washers
Courtesy of GENERAL MOTORS CORP.
2. Install the differential side gear thrust washer into the bell-end of the differential case.

   If the original differential side gear thrust washer is not available, install a 1.000 mm (0.039 in) thrust washer.

3. Install the differential side gear into the bell-end of the differential case.
Fig 2: Identifying Differential Pinion Gears & Thrust Washers
Courtesy of GENERAL MOTORS CORP.
4. Install the differential pinion gears by doing the following:
   1. Position both pinion gears and each thrust washer into each side of the differential window.

      Place the pinion gears 180 degrees across from each other.

   2. Rotate the differential side gears until both pinion gears are directly opposite the opening in the differential case.

      Line up the pinion shaft opening in each of the pinion gears with the pinion shaft opening in the differential case.

Fig 3: View Of Differential And Pinion Shaft
Courtesy of GENERAL MOTORS CORP.
5. Install the pinion shaft.
6. If the pinion shaft cannot be installed, remove the pinion gears and thrust washers, the locking differential side gear and differential thrust washer.
7. Install a smaller differential side thrust washer and re-install the locking differential side gear, the pinion gears and thrust washers and the pinion shaft.
Fig 4: View Of Pinion Shaft Lock Bolt
Courtesy of GENERAL MOTORS CORP.
8. Install the pinion shaft lock bolt.

   Do not torque the pinion shaft lock bolt at this time.

Fig 5: Measuring Backlash Of Pinion Gear Closest To Pinion Shaft Lock Bolt & Differential Side Gear
Courtesy of GENERAL MOTORS CORP.
9. Measure the backlash of the pinion gear closest to the pinion shaft lock bolt and the differential side gear by doing the following:
   1. Rotate the pinion gear so that one of the teeth is perpendicular to the ring gear flange.
   2. Install a brass drift between the locking differential side gear and the pinion shaft in order to prevent the side gear from moving.
   3. Install the J 7872  (1) to the ring gear flange. See Special Tools .
   4. Loosely clamp the J 7872-2 (2) and the J 8001-3  (3) onto the stem on the J 7872  (1). See Special Tools .
   5. Install the J 7872-3 (4) to the J 8001-3  (3).
   6. Place the contact pad of the J 7872-3 (4) onto one of the teeth of the pinion gear closest to the locking differential side gear.

      Preload the dial of the J 8001-3  approximately 3/4 of a turn clockwise.

   7. Tighten the lock nut of the J 7872-2 (2) finger tight.
   8. Turn the dial of the J 8001-3  until the needle and the dial face indicate ZERO.
   9. Pull the pinion gear firmly into the differential case seat.
   10. Rotate the pinion gear back and forth.
   11. Measure the backlash.

       Specification:  The backlash between the locking differential side gear and the pinion gears should be 0.051-0.076 mm (0.002-0.003 in).

10. If the backlash is too large, disassemble the differential, install the next larger size side gear thrust washer, re-assemble the differential and recheck the backlash.
11. If the backlash is too small, disassemble the differential, install next smaller size side gear thrust washer, re-assemble the differential and recheck the backlash.

Differential side gear thrust washers are available in the following sizes:

Washer Sizes: 

• 0.750 mm (0.030 in)
• 0.800 mm (0.031 in)
• 0.850 mm (0.033 in)
• 0.900 mm (0.035 in)
• 0.950 mm (0.037 in)
• 1.000 mm (0.039 in)
• 1.050 mm (0.041 in)
• 1.100 mm (0.043 in)
• 1.150 mm (0.045 in)
• 1.200 mm (0.047 in)
• 1.250 mm (0.049 in)