Backlash Adjustment 9.5 LD Axle

Special Tools

Note: 

1. Measure the rotating torque of the drive pinion and differential assembly. Refer to Drive Pinion Bearings Replacement



2. Install the J 25025 pins and the J 8001 indicator to the axle housing.

Note: Preload the dial of the J 8001-3 approximately ¾ of a turn and zero the gauge.

3. Set the J 8001-3 so that the stem is aligned with the gear rotation and square to the tooth angle.
4. Hold the drive pinion stationary, move the ring gear back and forth.
5. Repeat the measuring procedure at eight points around the ring gear.
6. The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).
7. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in) , inspect for burrs, a distorted case flange or uneven bolting.
8. If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in).
9. If the backlash is not within specifications, remove the differential bearing adjuster nut retainer bolt and retainer.
10. Loosen, but DO NOT remove the bearing cap bolts.
11. Using the J 24429 spanner , loosen the differential bearing adjuster nut.
12. Remove the differential side bearing shim and measure the thickness of the shim.

Note: Increasing or decreasing the shim thickness by 0.05 mm (0.002 in) will change the backlash adjustment approximately 0.03 mm (0.001 in).

13. Calculate the average of the 3 measurements.

Note: 

•	If the backlash is less than, select a smaller shim than the one that was removed. For example, to increase the backlash by 0.05 mm (0.002 in) , select a shim that is 0.10 mm (0.004 in) thinner than the shim that was removed.

•	If the backlash is larger than, select a larger shim than the one that was removed. For example, to increase the backlash by 0.05 mm (0.002 in) , select a shim that is 0.10 mm (0.004 in) thicker than the shim that was removed.

14. Install the selected shim.
15. Using the J 24429 spanner , tighten the differential bearing adjuster nut until the differential bearing adjuster nut is seated against the bearing cup.
16. With the differential bearing adjuster nut is seated against the differential bearing, use the J 24429 spanner tighten the differential bearing adjuster nut the following additional amounts.

•	For used bearings, turn the differential adjuster nut an additional 2 slots.

•	For new bearings, turn the differential adjuster nut an additional 3 slots.

Caution: Refer to Fastener Caution in the Preface section.

Note: Recheck the backlash following the steps above to verify that the backlash is within specifications.

17. Tighten the differential bearing cap bolts to 85 N·m (63 lb ft).
18. Install the differential bearing adjuster nut retainer.
19. Install the differential bearing adjuster nut retainer bolt and tighten to 26 N·m (19 lb ft).
20. Measure the drive pinion and differential case side bearing preload and adjust, if necessary following the steps above.
21. Once the backlash and bearing preload 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.

Backlash Adjustment 8.6 Inch Axle

Note: 

•	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.

•	The differential side bearings must be initially preloaded in order to determine the backlash of the gear set. After the backlash is set, the final bearing preload is set.

1. Measure the rotating torque of the drive pinion and differential assembly. Refer to Drive Pinion Bearings Replacement



2. Install the J 25025 pins and the J 8001 indicator to the axle housing.

Note: Preload the dial of the approximately ¾ of a turn and zero the gauge.

3. Set the J 8001 indicator so that the stem is aligned with the gear rotation and square to the tooth angle.
4. Hold the drive pinion stationary, move the ring gear back and forth.
5. Repeat the measuring procedure at eight points around the ring gear.
6. The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).
7. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in) , inspect for burrs, a distorted case flange or uneven bolting.
8. If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in)..

Note: 

•	Do not use the original cast iron production shims to adjust the backlash. Use service shims and spacers instead.

•	Adjust the thickness of the shim pack on each side of the differential in equal amounts. This will maintain the correct axle side bearing preload.

•	Moving 0.05 mm (0.002 in) of shim thickness from one side of the differential to the other will change the backlash adjustment approximately 0.03 mm (0.001 in).

9. If the backlash is too small, increase the backlash using the following procedure:

Note: Mark the bearing caps left or right.

9.1.	Remove the bearing cap bolts and the bearing caps.

Note: Mark the bearing cups and the shims left or right.

9.2.	Remove the differential case assembly with the bearing cups and the shims.

Note:     •  Measure the production shim or the shim and service spacer in 3 locations.    •  Measure each shim separately.

9.3.	Measure the thickness of left side shim pack.

Note:     •  Add the average of each of the shim measurements together.    •  Record the measurement. This is the thickness for the left side shim pack.

9.4.	Calculate the average of the 3 measurements for each shim.

Note:  If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in) , remove 0.10 mm (0.004 in) of thickness from the left side shim pack.

9.5.	Assemble a new left side shim pack by decreasing the appropriate amount of thickness from the original left side shim pack.

Note: Measure each shim separately.

9.6.	Measure the thickness of right side shim or the shim and service spacer in 3 locations.

Note:     •  Add the average of each of the shim measurements together.    •  Record the measurement. This is the thickness for the right side shim pack.

9.7.	Calculate the average of the 3 measurements for each shim.

9.8.

Assemble a new right side shim pack by increasing the appropriate amount of thickness to the original right side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in) , add 0.10 mm (0.004 in) of thickness to the right side shim pack.

10. Use the following procedure to decrease the backlash if the backlash is too large, :

Note: Mark the bearing caps left or right.

10.1.

Remove the bearing cap bolts and the bearing caps.

Note: Mark the bearing cups and the shims left or right.

10.2.

Remove the differential case assembly with the bearing cups and the shims.

Note:     •  Measure the production shim or the shim and service spacer in 3 locations.    •  Measure each shim separately.

10.3.

Measure the thickness of left side shim pack.

Note:     •  Add the average of each of the shim measurements together.    •  Record the measurement. This is the thickness for the left side shim pack.

10.4.

Calculate the average of the 3 measurements for each shim.

10.5.

Assemble a new left side shim pack by increasing the appropriate amount of thickness to the original left side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in) , add 0.10 mm (0.004 in) of thickness to the left side shim pack.

Note:     •  Measure the shim or the shim and service spacer in 3 locations.    •  Measure each shim separately.

10.6.

Measure the thickness of right side shim pack.

Note:     •  Add the average of each of the shim measurements together.    •  Record the measurement. This is the thickness for the right side shim pack.

10.7.

Calculate the average of the 3 measurements for each shim.

10.8.

Assemble a new right side shim pack by decreasing the appropriate amount of thickness to the original right side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to decrease the backlash by 0.05 mm (0.002 in) , remove 0.10 mm (0.004 in) of thickness to the right side shim pack.

11. Install the differential case assembly with the bearing cups.
12. Install the left side service spacer between the axle housing and the differential case.
13. Install the right side service spacer between the axle housing and the differential case.




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

14. Using the J 25588 installer , install the left side service shim or shims.

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

15. Using the J 25588 installer , install the right side service shim or shims.

Caution: Refer to Fastener Caution in the Preface section.

16. Install the bearing caps and bolts and tighten to 75 N·m (55 lb ft).
17. Recheck the backlash and adjust, if necessary.
18. Once 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.

Backlash Adjustment 10.5/11.5 Inch Axle

Note: 

1. Measure the rotating torque of the drive pinion and differential assembly. Refer to Drive Pinion Bearings Replacement.



2. Install the J 8001 indicator and the J 25025 pins to the axle housing.
3. Place the indicator stem of the J 8001 indicator at the heel end of a gear tooth.

Note: Preload the dial of the J 8001 indicator approximately a turn and zero the gauge.

4. Set the J 8001 indicator so that the stem is aligned with the gear rotation and square to the tooth angle.
5. Hold the drive pinion stationary, move the ring gear back and forth.
6. Repeat the measuring procedure at eight points around the ring gear.
7. The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).
8. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in). , inspect for burrs, distorted case flange or uneven bolting.
9. If the difference between all the measuring points is within specifications, the backlash at the between the ring gear and the drive pinion should be between 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in) at the minimum lash point.



10. If the backlash is not within specifications, remove the differential bearing adjuster nut retainers bolts.
11. Remove the differential bearing adjuster nut retainers.
12. Remove the bearing cap bolts.

Note: Before removing the bearing caps, mark the bearing caps left and right.

13. Remove the bearing caps.
14. If the backlash is less than, use the J 24429 spanner to increase the backlash by turning the left differential bearing adjuster in one slot and the right differential bearing adjuster out one slot until the correct backlash is obtained.
15. If the backlash is greater than, use the J 24429 spanner to decrease the backlash by turning the right differential bearing adjuster in one slot and the left differential bearing adjuster out one slot until the correct backlash is obtained.
16. Install the bearing caps.

Caution: Refer to Fastener Caution in the Preface section.

17. Install the bearing cap bolts and tighten to 185 N·m (136 lb ft). for the 10.5 inch axle, or 207 N·m (153 lb ft). for the 11.5 inch axle.
18. Recheck the backlash following the steps above to verify that the backlash is within specifications.
19. Install the differential bearing adjuster nut retainers.
20. Install the differential bearing adjuster nut retainer bolts to tighten to 27 N·m (20 lb ft).
21. Measure the drive pinion and differential case side bearing preload and adjust, if necessary following the steps above.
22. Once the backlash and bearing preload 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.