8.6 Inch Axle
Differential Side Bearing Preload Adjustment (8.6 Inch Axle)^ Tools Required
- J 22779 Side Bearing Backlash Gauge
- J 8001 Dial Indicator Set
^ 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.
2. Measure the rotating torque of the drive pinion using an inch-pound torque wrench.
^ The rotating torque of the drive pinion should be 1.7 - 3.4 Nm (15 - 30 inch lbs.) (new bearings) or 1.1 - 2.8 Nm (10 - 25 inch lbs.) (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 outer bearing cups must also be used.
3.1. Install the differential case.
3.2. Insert a 4.318 mm (0.170 inch) thick service spacer on the left side of the case (ring gear side).
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 J 22779 until there is moderate drag when the J 22779 is moved.
3.5. Remove the J 22779 and the service spacer.
3.6. Measure the J 22779 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 J 22779. The resulting value is the total service shim thickness (without preload) for the axle.
4. Determine the thickness of the left side service shims (without preload) by doing the following:
4.1. Insert one 1.016 mm (0.040 inch) service shim against the right side axle housing and insert one BENT 1.016 mm (0.040 inch) service shim against the right side differential case bearing.
4.2. Install the J22779 on the left side of the differential case.
4.3. Install a J 8001 against the ring gear.
4.4. Tighten the knob on the J22779 until there is approximately 0.0254 - 0.0508 mm (0.001 - 0.002 inch) backlash between the ring and pinion gears.
4.5. Measure the backlash in 8 locations.
4.6. Remove the J 8001.
4.7. Remove the J 22779 and measure the thickness in 3 locations.
4.8. Calculate the average of the 3 measurements. This value is the left side service shim thickness (without preload).
5. Remove the differential case.
6. Subtract the left side service shim thickness (calculated in step 4.8) from the total service shim thickness (calculated in step 3.9). This value is the right side service shim thickness (without preload).
7. In order to properly set the preload of the differential case bearings and set 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. Install one service spacer against the axle housing on each side of the differential case.
Add service shims in order to complete the total shim thickness for each side.
9. Install the J 8001 to the ring gear.
10. Measure the backlash in 8 locations.
11. If the backlash is not between 0.127 - 0.2286 mm (0.005 - 0.009 inch), remove the appropriate amount of shim thickness from one side and transfer the shim thickness to the other side (maintaining total shim thickness).
Moving 0.0508 mm (0.002 inch) of service shim thickness will change the backlash by 0.0254 mm (0.001 inch).
In order to increase backlash, subtract 0.0508 mm (0.002 inch) from the left side for each 0.0254 mm (0.001 inch) increase in backlash. Add this value to the right side.
In order to decrease backlash, subtract 0.0508 mm (0.002 inch) from the right side for each 0.0254 mm (0.001 inch) reduction in backlash. Add this value to the left side.
Notice: Refer to Fastener Notice in Service Precautions.
12. Install the differential bearing caps.
^ Tighten the differential bearing caps to 75 Nm (55 lb ft).
13. Measure the drive pinion and differential case side bearing preload using an inch-pound torque wrench.
^ The rotating torque of the drive pinion and differential case bearings should be 3.9 - 6.2 Nm (30 - 55 inch lbs.) (new bearings) or 2.8 - 5.6 Nm (25 - 50 inch lbs.) (used bearings).
Record the measurement.
14. 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 13). Multiply the value obtained in step 14 by the axle ratio.
^ The differential case side bearing preload should be 1.7 - 4.0 Nm (15 - 35 inch lbs.).
15. Once the specified torque is obtained, rotate the pinion several times to ensure the bearings have seated. Recheck the rotating torque and adjust if necessary.
16. Perform a gear tooth contact pattern test.