Backlash Adjustment (9.75, 10.5, 11.5 Axles)

Backlash Adjustment (9.75, 10.5, 11.5 Axles)
^ Tools Required
- J 8001 Dial Indicator Set
- J 24429 Side Bearing Backlash Spanner
- J 25025 Guide Pins

Important:
^ 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 using an inch-pound torque wrench.
The rotating torque of the drive pinion and differential assembly should be 3.4 - 6.2 Nm (30 - 55 lb in) for new bearings or 2.8 - 5.1 Nm (25 - 45 lb in) for used bearings.
2. If the rotating torque is too low, tighten the differential bearing adjuster nuts in 1 slot increments until the specified rotating torque is obtained.
3. If the rotating torque is too high, loosen the differential bearing adjuster nuts in 1 slot increments until the specified rotating torque is obtained.
4. If the specification for the rotating torque of the drive pinion and differential assembly cannot be obtained by adjusting the differential bearing adjuster nut, remove the differential assembly, measure the rotating torque of the drive pinion and adjust as necessary.





5. Install the J 25025-1 and the J 8001 to the axle housing as shown.
6. Place the indicator stem of the J 8001-3 at the heel end of a gear tooth.
7. Set the J 8001-3 so that the stem is aligned with the gear rotation and perpendicular to the tooth angle.
8. Preload the dial of the J 8001-3. Align the needle and the dial face of the J 8001-3 to ZERO.
9. While holding the drive pinion stationary, move the ring gear back and forth. Measure and record the backlash.
10. Repeat the measuring procedure at eight points around the ring gear.
The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 inch).
11. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 inch), inspect for the following conditions:
^ Burrs
^ A distorted case flange
^ Uneven bolting
12. If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be:
The backlash between the ring gear and the drive pinion should be between 0.08 - 0.25 mm (0.003 - 0.010 inch) with a preferred backlash of 0.13 - 0.18 mm (0.005 - 0.007 inch).





13. If the backlash is not within specifications, adjust the backlash by performing the following steps:
1. Remove the differential bearing adjuster nut retainers bolts.
2. Remove the differential bearing adjuster nut retainers.
3. Remove the bearing cap bolts.
4. Remove the bearing caps. Mark the bearing caps left and right.
5. If the backlash is too small, increase the backlash by turning the left differential bearing adjuster in one slot and the right differential bearing adjuster out one slot using the J 24429 until the correct backlash is obtained.
6. If the backlash is too large, decrease the backlash by turning the right differential bearing adjuster in one slot and the left differential bearing adjuster out one slot using the J 24429 until the correct backlash is obtained.
14. Install the bearing caps.

15. Install the bearing cap bolts.
^ Tighten the bearing cap bolts to 185 Nm (136 lb ft) (10.5 inch axle).
^ Tighten the bearing cap bolts to 207 Nm (153 lb ft) (11.5 inch axle).

Notice: Refer to Fastener Notice.

16. Recheck the backlash following the steps above to verify that the backlash is within specifications.
17. Install the differential bearing adjuster nut retainers.
18. Install the differential bearing adjuster nut retainer bolts.
^ Tighten the differential bearing adjuster nut retainer nut bolts to 27 Nm (20 lb ft).
19. Measure the drive pinion and differential case side bearing preload and adjust, if necessary following the steps above.
20. 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.