9.75 Inch Axle
Locking Differential Adjustment (9.75 Inch Axle)Tools Required
^ J7872 Magnetic Base Dial Indicator
Adjustment of the Differential
Important: If it is necessary to replace the left side gear cam unit and disc assembly, the right side gear and disc assembly, or the thrust block, the entire differential must be adjusted. The differential is adjusted using selective thickness thrust washers between the clutch disc assemblies and the case and/or different selective thickness thrust blocks.
When adjusting the differential, note the following:
^ Build up the clutch disc assemblies properly.
Proper clearance between parts is critical to the operation of the unit.
^ Adjust the backlash and thrust block clearance in the following order:
1. The left side gear backlash
2. The right side gear backlash
3. The thrust block clearance
Left Side Gear Backlash Adjustment
1. Install the original left side thrust washer into the left side or flange-end of the differential case.
2. Install the left side locking differential side gear cam unit and clutch disc assembly into the left side or flange-end of the differential case.
3. Install the differential pinion gears with the differential pinion gear thrust washers into the differential case.
Align the openings of the differential pinion gears and the differential pinion gear thrust washers to the pinion shaft opening in the differential case.
4. Install the pinion shaft. It may be necessary to press down on the side gear in order to align the pinion gear shaft opening with the pinion shaft opening in the differential case.
If the pinion shaft cannot be installed after pressing on the side gear, replace the locking differential clutch disc thrust washer with a thinner washer.
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.
5. Install the pinion shaft lock bolt.
Tighten the pinion shaft lock bolt finger tight.
6. Rotate the pinion gear closest to the lock bolt so that one of the teeth is pointing downward, perpendicular to the ring gear flange.
7. Install a brass drift between the side gear and the pinion shaft.
Press the brass drift in far enough in order to compress the clutch discs.
8. Measure the backlash of the pinion gear and the side gear by doing the following:
8.1. Install the J7872 (1) to the ring gear flange.
8.2. Loosely clamp the J8001-3 (2) onto the stem on the J7872 (1).
8.3. Place the contact pad of the J8001-3 on one of the teeth of the pinion gear closest to the pinion shaft lock bolt. Turn the dial of the J8001-3 until the needle and the dial face indicate ZERO.
8.4 Tighten the lock nut of the J8001-3 finger tight.
8.5. Pull the pinion gear firmly into the differential case seat.
8.6. Rotate the pinion gear back and forth.
8.7. Measure the backlash. Specification The backlash between the differential pinion gear and locking differential side gear should be between 0.279-0.432 mm (0.011-0.017 inch).
9. If the backlash is too large. install a thicker locking differential clutch disc thrust washer and recheck the backlash.
10. If the backlash is too small, install a thinner locking deferential clutch disc thrust washer and recheck the backlash.
Locking differential clutch disc thrust washers are available in the following sizes:
Washer Sizes
^ 0.56 mm (0.022 inch)
^ 0.69 mm (0.027 inch)
^ 0.81 mm (0.032 inch)
^ 0.91 mm (0.036 inch)
^ 1.02 mm (0.040 inch)
^ 1.12 mm (0.044 inch)
^ 1.22 mm (0.048 inch)
^ 1.32 mm (0.052 inch)
Right Side Gear Backlash Adjustment
1. If necessary, remove the following from the differential case:
1.1. The pinion lock shaft bolt
1.2. The pinion shaft
1.3. The differential pinion gears
1.4. The differential pinion gear thrust washers
1.5. The locking differential side gear cam unit and clutch disc assembly
2. Install the right side differential side gear shim into the right side or bell-end of the differential case.
3. Install the clutch disc assembly into the right side or bell-end of the differential case.
4. Install the locking differential side gear.
5. Install the differential pinion gears with the differential pinion thrust washers into the differential case.
Align the openings of the differential pinion gears and the differential pinion thrust washer to the pinion shaft opening in the differential case.
6. Press down on the locking differential side gear and install the pinion shaft.
If the side gear cannot be pressed down far enough to install the pinion shaft, replace the differential side gear shim with a thinner shim.
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.
7. Install the pinion shaft lock bolt.
Tighten the pinion shaft lock bolt finger tight.
8. Rotate the differential pinion gear so that one of the teeth is pointing downward, perpendicular to the ring gear flange.
9. Install a brass drift between the differential side gear and the pinion shaft.
Press the brass drift in enough in order to compress the clutch discs.
10. Measure the backlash of the differential pinion gear and the locking differential side gear by doing the following:
10.1. Install the J7872 (1) to the ring gear flange.
10.2. Loosely clamp the J8001-3 (2) onto the stem on the J7872 (1).
10.3. Place the contact pad of the J8001-3 on one of the teeth of the pinion gear closest to the pinion shaft lock bolt. Turn the dial of the J8001-3 until the needle and the dial face indicate ZERO.
10.4. Tighten the lock nut of the J8001-3 finger tight.
10.5. Pull the pinion gear firmly into the differential case seat.
10.6. Rotate the pinion gear back and forth.
10.7. Measure the backlash. Specification The backlash between the differential pinion gear and the locking differential side gear should be 0.051 - 0.203 mm (0.002 - 0.008 inch).
11. If the backlash is too large, install a thicker locking differential side gear shim and check the backlash.
12. If the backlash is too small, install a thinner locking differential side gear shim and check the backlash.
Differential side gear shims are available in the following sizes:
Shim Sizes
^ 0.25 mm (0.010 inch)
^ 0.38 mm (0.015 inch)
^ 0.51 mm (0.020 inch)
^ 0.64 mm (0.025 inch)
^ 0.76 mm (0.030 inch)
^ 0.89 mm (0.035 inch)
^ 1.02 mm (0.040 inch)
^ 1.14 mm (0.045 inch)
^ 1.27 mm (0.050 inch)
^ 1.40 mm (0.055 inch)
^ 1.52 mm (0.060 inch)
Thrust Block Clearance Adjustment
Important: The left and right side gear backlash measurements must be done before the thrust block measurement can be completed.
1. Install the locking differential clutch disc thrust washer into the left side or flange-end of the differential case.
2. Install the locking differential side gear cam unit and clutch disc assembly into the left side or flange-end of the differential case.
3. Install the right side differential side gear shim into the right side or bell-end of the differential case.
4. Install the right side locking differential side gear and clutch disc assembly into the right side or bell-end of the differential case.
5. Install the pinion shaft.
6. Install the pinion shaft bolt.
Tighten the pinion shaft bolt finger tight.
7. Install a brass drift between the left side gear and the pinion shaft.
Press the brass drift in far enough in order to compress the clutch disc assembly and hold the left side gear assembly in place.
8. Install a brass drift between the right side gear and the pinion shaft.
Press the brass drift in far enough in order to hold the right side gear assembly in place.
Important: Do not measure the distance between the side gear teeth.
9. Measure the distance between the side gear faces using a 25.4 - 50.8 mm (1 - 2 inch) telescoping gage.
10. Remove the telescoping gage.
11. Measure the telescoping gage with a micrometer.
Record the measurement.
12. Compare the measurement obtained in Step 11 to the thrust block sizes available. If the measurement is equal to one of the thrust blocks sizes available, then select that thrust block.
13. If the measurement obtained in Step 11 is not equal to one of the thrust blocks sizes available, then select the thrust block that is smaller than the measurement.
For example, if the measurement is 40.87 mm (1.609 inch), select the 40.79 mm (1.606 inch) thrust block.
Important: The backlash must be checked and adjusted to specification anytime the left and/or the right thrust washers are replaced.
14. If the measurement obtained in Step 11 is less than 40.49 mm (1.594 inch), then reduce the left side gear thrust washer or the right side gear shim thickness in order to increase the thrust block opening.
15. If the measurement obtained in Step 11 is greater than 41.20 mm (1.622 inch), then increase the left side gear thrust washer or the right side gear shim thickness in order to decrease the thrust block opening.
16. Check the left and/or right side gear backlash and adjust as necessary.
17. Check the thrust block clearance and adjust as necessary.
18. Assemble the differential.