8.6 Inch Axle
Differential Side Bearing Preload Adjustment (8.6 Inch Axle)Wedge Method
Tools Required
^ J22779 Side Bearing Backlash Gage
^ J25588 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.
2. Measure the rotating torque of the drive pinion using an inch-pound torque wrench. Record the measurement.
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.
3. If the rotating torque for the drive pinion bearings is not within specifications, adjust as necessary.
Important: Before installation of the differential assembly, ensure that the differential side bearing surfaces in the axle housing are clean and free of burrs. If the original differential side bearings are to be reused, the original differential side bearing cups must also be used.
4. Install the differential assembly with the differential side bearings and differential side bearing cups into the axle housing.
5. Insert one 4.318 mm (0.170 inch) 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 J22779 into the right side of the axle housing.
The J22779 must be installed between the service spacer and the differential side bearing cup.
Important: Over-tightening of the J22779 may spread the housing and result in incorrect shim selection.
8. Tighten the knob on the J22779 until there is moderate drag when the J22779 is moved.
9. Remove the J22779.
10. Remove the service spacer.
11. Using a micrometer, measure the thickness of the service spacer. Record the measurement.
12. Using a micrometer, measure the thickness of the J22779 in 3 locations. Calculate the average of the 3 measurements. Record the measurement.
13. Add the thickness of the service spacer, measured in Step 11 to the average thickness of the J22779, measured in Step 12. The resulting value is the total service shim thickness without preload for the axle.
14. Insert one BENT 1.016 mm (0.040 inch) service shim between the right side differential side bearing cup and the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
15. Install the J22779 into the left side of the axle housing. The J22779 must be installed between the service spacer and the differential side bearing cup.
16. While rotating the ring gear back and forth, tighten the knob on the J22779 until there is approximately 0.025 - 0.051 mm (0.001 - 0.002 inch) of backlash between the ring gear and the drive pinion.
17. Once the correct amount of backlash is obtained, remove the J22779.
18. Remove the differential assembly with the differential side bearings and the differential side bearing cups.
19. Remove the BENT service shim.
20. Using a micrometer, measure the thickness of the J22779 in 3 locations. Calculate the average of the 3 measurements. This value is the left side service shim thickness without preload.
21. In order to determine the right side service shim thickness, subtract the service shim thickness for the left side of the axle, calculated in step 20, from the total service shim thickness, calculated in step 13. This value is the service shim thickness for the right side of the axle without preload.
22. In order to preload of the differential side bearings and set the backlash to approximately 0.127 - 0.223 mm (0.005 - 0.009 inch), take the value determined in step 21 and add 0.203 mm (0.008 inch) service shim thickness to this amount.
23. Assemble the left side shim pack using one 4.318 mm (0.170 inch) service spacer and the appropriate amount of service shims equaling the thickness determined in step 20.Measure the service spacer and the service shims separately. Add the measurements together in order to determine the total shim pack thickness.
24. Assemble the right side shim pack using one 4.318 mm (0.170 inch) service spacer and the appropriate amount of service shims equaling the thickness determined in step 22. Measure the service spacer and the service shims separately. Add the measurements together in order to determine the total shim pack thickness.
25. Install the differential assembly with the differential side bearings and the differential side bearing cups.
26. Install the left side service spacer and service shim into the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
27. Install the right side service spacer between the axle housing and the differential side bearing cup.
28. Install the right side service shim into the axle housing using the J25588, if necessary. The service shim must be installed between the service spacer and the differential side bearing cup.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
29. Install the differential bearing caps and the bolts.
Tighten the differential bearing cap bolts to 75 Nm (55 ft. lbs.).
30. Rotate the pinion several times to ensure the drive pinion and differential side bearings have seated.
31. Measure the rotating torque of the drive pinion and differential side bearings using an inch-pound torque wrench. Record the measurement.
The rotating torque of the drive pinion and differential side bearings should be approximately 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.
32. 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.
The differential side bearing preload should be 1.7 - 4.0 Nm (15 - 35 inch lbs.).
33. 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.
34. Once the differential side bearing preload is correct, measure the backlash and adjust, if necessary.
35. 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.
Shim Method
Tools Required
^ J25588 Side Bearing Shim Installer
Important:
^ The differential side bearings must have preload 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 service 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 service spacers instead.
1. Install the drive pinion, if necessary.
2. Measure the rotating torque of the drive pinion using an inch-pound torque wrench. Record the measurement.
The rotating torque for the drive pinion bearings 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.
3. If the rotating torque for the drive pinion bearings is not within specifications, adjust as necessary.
Important: Before installation of the case 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 differential side bearings and bearing cups into the axle housing.
5. Insert one BENT 1.016 mm (0.040 inch) thick service shim into the right side axle housing. Side the differential assembly towards the bent service shim in order to hold the shim in place.
6. While holding the differential assembly against the bent service shim, install one 4.318 mm (0.170 inch) thick service spacer into the left side axle housing.
7. Move the differential assembly to the right until the ring gear contacts the drive pinion. Once the ring gear contacts the drive pinion, continue to move the ring gear towards the drive pinion to until all backlash is removed.
8. While holding the ring gear against the drive pinion, insert progressively larger service shims between the service spacer and the differential side bearing cup until a moderate resistance can be felt.
9. Once the largest service shim has been determined, measure the thickness of the shim using a micrometer. Measure the service shim in 3 locations. Calculate the average of the 3 measurements. Use the average as the thickness for the shim. Record the measurement.
10. Install the service shim that was just measured back into the left side of the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
11. Remove the BENT shim from the right side of the axle housing.
12. Insert one 4.318 mm (0.170 inch) thick service spacer into the right side axle housing.
13. Move the differential assembly towards the left side of the axle housing. While holding the differential assembly against the left side shim pack, insert progressively larger service shims between the service spacer and the differential side bearing cup until a moderate resistance can be felt.
14. Once the largest service shim has been determined, measure the thickness of the shim using a micrometer. Verify the thickness of the service shim. Measure the service shim in 3 locations. Calculate the average of the 3 measurements. Use the average as the thickness for the shim. Record the measurement.
15. In order to preload the differential side bearing and set the initial backlash to approximately 0.127 mm (0.005 inch), adjust the thickness of left and right side shims by doing the following:
15.1. Subtract 0.152 mm (0.006 inch) from the measurement recorded for the left side shim in Step 9. Record the measurement.
15.2. Add 0.356 mm (0.014 inch) to the measurement recorded for the right side shim in Step 14.
16. Select the correct service shim thickness for each side corresponding to the measurements determined above. Using a micrometer, verify the thickness of the service shim. Measure the service shim in 3 locations. Calculate the average of the 3 measurements. Use the average as the thickness for the shim.
17. Install the left side service shim into the axle housing. The service shim must be installed between the service spacer and the differential side bearing cup.
18. Move the differential assembly towards the left side of the axle housing.
19. Install the right side service shim into the axle housing using the J25588, if necessary. The service shim must be installed between the service spacer and the differential side bearing cup.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
20. Install the differential bearing caps and bolts.
Tighten the differential bearing cap bolts to 75 Nm (55 ft. lbs.).
21. Rotate the pinion several times to ensure the bearings have seated.
22. Measure the rotating torque of drive pinion and differential case side bearings using an inch-pound torque wrench.
The rotating torque of the drive pinion and differential side bearings should be 3.9 - 6.2 Nm (30 - 55 inch lbs.) for new bearings or 2.8 - 5.6 Nm (25 - 50 inch lbs.) for used bearings.
Record the measurement.
23. Determine the preload for the differential side bearings by performing the following calculation:
23.1. Subtract the drive pinion rotating torque, measured in Step 2, from the drive pinion and differential case side bearing rotating torque, measured in Step 22.
23.2. Multiply the value obtained by the axle ratio. This value equals the preload for the differential side bearings.
The differential side bearing preload should be 1.7 - 4.0 Nm (15 - 35 inch lbs.).
24. 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.
25. Once the differential side bearing preload is within specifications, measure the backlash between the ring gear and the drive pinion and adjust, if necessary.
26. Once backlash and differential side bearing preload is within specifications, perform a gear tooth contact pattern check in order to ensure proper alignment between the ring and pinion gears.