Differential Side Bearing Preload Adjustment

Differential Side Bearing Preload Adjustment

Tools Required
^ J22779 Side Bearing Backlash Gage
^ J25588 Side Bearing Shim Installer
^ J25025 Guide Pins
^ J8001 Dial Indicator Set

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 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.
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 Nm (15 - 30 inch lbs.) for new bearings or 1.1 - 2.3 Nm (10 - 20 inch lbs.) for used bearings.
Record the measurement.
3. Determine the total service shim thickness for the axle without preload by doing the following:

Important: Before installation of the case assembly, ensure that the side bearing surfaces in the carrier are clean and free of burrs. If the original bearings are to be reused, the original bearing cups must also be used.

3.1. Install the differential case with the side bearings and bearing cups.
3.2. Insert one 4.318 mm (0.170 inch) thick service spacer on the left side or ring gear side of the case.
3.3. Install the J22779 between the differential case and the axle housing on the right side.

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

3.4. Tighten the knob on the J22779 until there is moderate drag when the J22779 is moved.
3.5. Remove the J22779 and the service spacer.
3.6. Measure the J22779 in 3 locations.
3.7. Calculate the average of the 3 measurements.
Record the measurement.
3.8. Measure the service spacer. Record the measurement.
3.9. Add the thickness of the service spacer to the average thickness of the J22779. The resulting value is the total service shim thickness without preload for the axle.
4. Determine the service shim thickness for the left side of the axle without preload by doing the following:
4.1. Insert one 1.016 mm (0.040 inch) service shim between the differential case and right side axle housing.
4.2. Insert one BENT 1.016 mm (0.040 inch) service shim between the differential case and the service shim.
4.3. Install the J22779 on the left side of the differential case.
4.4. Tighten the knob on the J22779 until there is slight amount of backlash between the ring and pinion gears.
4.5. Install the J25025-1 onto the differential housing.
4.6. Install the J8001-3 onto the J25025-1.
4.7. Position the button of the J8001-3 against the ring gear.
4.8. Preload the dial of the J8001-3.
Align the needle and the dial face of the J8001-3 to ZERO.
4.9. While holding the drive pinion stationary, measure the backlash between the drive pinion and the ring gear. Specification The backlash between the drive pinion and the ring gear should be 0.0254 - 0.0508 mm (0.001 - 0.002 inch).
4.10. If the backlash is not within specification, tighten or loosen the knob on the J22779 as necessary until the proper backlash is obtained.
4.11. Remove the J8001-3.
4.12. Remove the J25025-1.
4.13. Remove the J22779 and measure the thickness in 3 locations.
4.14. Calculate the average of the 3 measurements.
This value is the left side service shim thickness without preload.
5. Remove the differential case with the differential side bearings and the bearing cups.
6. Subtract the service shim thickness for the left side of the axle (calculated in step 4.14)from the total service shim thickness (calculated in step 3.9).
This value is the service shim thickness for the right side of the axle without preload.
7. In order to initially set the preload of the differential case bearings and the backlash to approximately 0.127 - 0.2286 mm (0.005 - 0.009 inch), take the value determined in step 6 and add 0.2032 mm (0.008 inch) service shim thickness to this amount.
8. Assemble the left and right side shim packs using one 4.318 mm (0.170 inch) service spacer on each side and the appropriate amount of service shims.
Measure the service spacer and the service shims separately.
Add the measurements together in order to determine the total shim pack thickness.
9. Install the differential case with the differential side bearings and the bearing cups.
10. Install the left side service spacer between the axle housing and the differential case.
11. Install the right side service spacer between the axle housing and the differential case.
12. Install the left side service shim or shims using the J25588, if necessary.
The service shim or shims must be installed between the service spacer and the differential bearing cup.
13. Install the right side service shim or shims using the J25588, if necessary.
The service shim or shims must be installed between the service spacer and the differential bearing cup.

Notice: Refer to Fastener Notice in Service Precautions.

14. Install the differential bearing caps and bolts.
Tighten the differential bearing cap bolts to 75 Nm (55 ft. lbs.).
15. Measure the drive pinion and differential case side bearing preload using an inch-pound torque wrench.
Rotate the pinion several times to ensure the bearings have seated.
Specification
The rotating torque of the drive pinion and differential case bearings should be 3.9 - 6.2 Nm (30 - 55 inch lbs.) for new bearings or 2.8 - 5.1 Nm (25 - 45 inch lbs.) for used bearings. Record the measurement.
16. 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 15. Multiply the value obtained by the axle ratio.
Specification
The differential case side bearing preload should be 1.7 - 4.0 Nm (15 - 35 inch lbs.).
17. If the differential case 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.
18. Once the differential side bearing preload is correct, measure the backlash and adjust, if necessary.