Backlash Adjustment

Backlash Adjustment

^ Tools Required
- J 8001 Dial Indicator
- J 23409 Dial Indicator Extension
- J 25588 Side Bearing Shim Installer





1. Install the differential case with the bearing cups into the rear axle.
2. Determine the differential side bearing preload.

Notice: Refer to Fastener Notice in Service Precautions.

3. Install the differential bearing caps and the bolts.
^ Tighten the bolts to 75 Nm (55 lb ft).
4. Rotate the case several times in order to seat the bearings.
5. Install the J 8001 and the J 23409 to the axle housing as shown.
6. Place the indicator stem of the J 8001 at the heel end of a gear tooth.
7. Set the J 8001 so that the stem is aligned with the gear rotation and perpendicular to the tooth angle.
8. While holding the pinion stationary, move the ring gear back and forth. Measure and record the backlash.
9. 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).
10. 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
11. 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).

Important:
^ Do not use the original cast iron production shims to adjust the backlash. Use service shim 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 inch) of shim thickness from one side of the differential to the other will change the backlash adjustment by 0.03 mm (0.001 inch).

12. If the backlash is too small, increase the backlash using the following procedure:
12.1. Remove the appropriate amount of thickness from the left side shim pack. For example, to increase the backlash by 0.10 mm (0.004 inch), subtract 0.20 mm (0.008 inch) of thickness from the left side shim pack.
12.2. Add the 0.20 mm (0.008 inch) of shim thickness to the right side shim pack.
12.3. Recheck the backlash and adjust as necessary.
13. If the backlash is too large, decrease the backlash using the following procedure:
13.1. Remove the appropriate amount of thickness from the right side shim pack. For example, to decrease the backlash by 0.10 mm (0.004 inch), subtract 0.20 mm (0.008 inch) of thickness from the right side shim pack.
13.2. Add the 0.20 mm (0.008 inch) of shim thickness to the left side shim pack.
13.3. Recheck the backlash and adjust as necessary.





14. When you have correctly adjusted the backlash, remove the bearing caps and the shim packs.
15. Select a shim 0.10 mm (0.004 inch) thicker than the one removed from the left side. Insert this shim between the spacer and the left bearing race.
16. Install the left bearing cap and bolts. Do not tighten.
17. Select a shim 0.10 mm (0.004 inch) thicker than the shim removed from the right side. Insert the shim between the spacer and the right bearing race. Drive the shim into place using the J 25588.
18. Install the right side bearing cap and bolts.
^ Tighten the bolts to 75 Nm (55 lb ft).
19. Recheck the backlash and adjust as necessary.
20. Once backlash is correct, perform a gear tooth contact pattern check in order to ensure proper alignment between the ring and pinion gears.