For 1990-2009 cars

## Differential Carrier Bearing Preload Adjustment 8.0, 8.6 Inch Axle

#### Tools Required

• | J 22779 Side Bearing Backlash Gage

• | J 25588 Side Bearing Shim Installer

Important:

• | 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.
2. Measure the rotating torque of the drive pinion using an inch-pound torque wrench.

Specification
The rotating torque of the drive pinion 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. Record the measurement.

Important: Before installation of the differential 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.

4. Install the differential assembly with the side bearings and 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. Install the J 22779 between the right side differential side bearing cup and the axle housing.

Important: Over-tightening may spread the housing and result in incorrect shim selection.

8. Tighten the knob on the J 22779 until there is moderate drag when the J 22779 is moved.
9. Remove the J 22779 .
10. Remove the service spacer.
11. Using a micrometer, measure the thickness of the J 22779 in 3 locations.
12. Calculate the average of the 3 measurements.

Record the measurement.

13. Using a micrometer, measure the thickness of the service spacer.

Record the measurement.

14. Add the thickness of the service spacer to the average thickness of the J 22779 .

The resulting value is the total service shim thickness without preload for the axle.

15. Insert one 1.016 mm (0.040 in) service shim between the right side differential side bearing cup and the axle housing.
16. Insert one BENT 1.016 mm (0.040 in) service shim between the right side differential side bearing cup and the service shim.
17. Install the J 22779 on the left side of the differential assembly.
18. While rotating the ring gear back and forth, tighten the knob on the J 22779 until there is approximately 0.025-0.051 mm (0.001-0.002 in) of backlash between the ring gear and the drive pinion.
19. Once the amount of backlash is obtained, remove the J 22779 .
20. Remove the differential case with the differential side bearings and the bearing cups.
21. Remove the service shims.
22. Using a micrometer, measure the thickness of the J 22779 in 3 locations.
23. Calculate the average of the 3 measurements.

This value is the left side service shim thickness without preload.

24. Subtract the service shim thickness for the left side of the axle, calculated in step 23, from the total service shim thickness, calculated in step 14.

This value is the service shim thickness for the right side of the axle without preload.

25. In order to initially set the preload of the differential side bearings and the backlash to approximately 0.013-0.023 mm (0.005-0.009 in), take the value determined in step 24 and add 0.0203 mm (0.008 in) service shim thickness to this amount.
26. Assemble the left side shim pack using one 4.318 mm (0.170 in) service spacer and the appropriate amount of selective service shims equaling the thickness determined in step 23.

Measure the service spacer and the service shims separately.

Add the measurements together in order to determine the total shim pack thickness.

27. Assemble the right side shim pack using one 4.318 mm (0.170 in) service spacer and the appropriate amount of selective service shims equaling the thickness determined in step 25.

Measure the service spacer and the service shims separately.

Add the measurements together in order to determine the total shim pack thickness.

28. Install the differential assembly with the differential side bearings and the differential side bearing cups.
29. Install the left side service spacer between the axle housing and the differential assembly.
30. Install the left side selective service shim or shims.

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

31. Install the right side service spacer between the axle housing and the differential assembly.
32. Install the right side selective service shim or shims using the J 25588 , if necessary.

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

Notice: Refer to Fastener Notice in the Preface section.

33. Install the differential bearing caps and the bolts.

Tighten
Tighten the differential bearing cap bolts to 75 N·m (55 lb ft).

34. Measure the drive pinion and differential side bearing preload using an inch-pound torque wrench.

Rotate the pinion several times to ensure the differential side bearings have seated.

Specification
The rotating torque of the drive pinion and differential side bearings should be 3.9-6.2 N·m (30-55 lb in) for new bearings or 2.8-5.1 N·m (25-45 lb in) for used bearings.

35. Record the measurement.
36. 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 33.

Multiply the value obtained by the axle ratio.

Specification
The differential case side bearing preload should be 1.7-4.0 N·m (15-35 lb in).

37. 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.
38. Once the differential side bearing preload is correct, measure the backlash and adjust, if necessary. Refer to Backlash Adjustment.
39. 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.