Shim Selection

NOTE: It is difficult to salvage the differential side bearings during the removal procedure. Install replacement bearings if necessary.

1. Remove differential side bearings from differential case.
2. Remove factory installed shims from differential case.
3. Install ring gear on differential case and tighten bolts to specification.
4. Install dummy side bearings D-348, or equivalent on differential case.
5. Install differential case in axle housing.





6. Install the marked bearing caps in their correct positions. Install and snug the bolts.








7. Using a dead-blow type mallet, seat the differential dummy bearings to each side of the axle housing.





8. Thread guide stud C-3288-B, or equivalent into rear cover bolt hole below ring gear.





9. Attach a dial indicator C-3339, or equivalent to guide stud: Position the dial indicator plunger on a flat surface between the ring gear bolt heads.
10. Push and hold differential case to pinion gear side of axle housing.
11. Zero dial indicator face to pointer.





12. Push and hold differential case to ring gear side of the axle housing.
13. Record dial indicator reading.
14. Add 0.008 inch (0.2 mm) to the zero end play total. This new total represents the thickness of shims to compress, or preload the new bearings when the differential is installed.
15. Rotate dial indicator out of the way on the guide stud.
16. Remove differential case and dummy bearings from axle housing.
17. Install the pinion gear in axle housing. Install the pinion yoke and establish the correct pinion rotating torque.
18. Install differential case and dummy bearings D-348, or equivalent in axle housing (without shims), install bearing caps and tighten bolts snug.
19. Seat ring gear side dummy bearing.
20. Position the dial indicator plunger on a flat surface between the ring gear bolt heads.
21. Push and hold differential case toward pinion gear.





22. Zero dial indicator face to pointer.





23. Push and hold differential case to ring gear side of the axle housing.
24. Record dial indicator reading.
25. Subtract 0.002 inch (0.05 mm) from the dial indicator reading to compensate for backlash between ring and pinion gears. This total is the thickness shim required to achieve proper backlash.
26. Subtract the backlash shim thickness from the total preload shim thickness. The remainder is the shim thickness required on the pinion side of the axle housing.
27. Rotate dial indicator out of the way on guide stud.
28. Remove differential case and dummy bearings from axle housing.
29. Install side bearing shims on differential case hubs.
30. Install side bearings and cups on differential case.
31. Install spreader W-129-B, utilizing some items from Adapter Set 6987, or equivalents, on axle housing and spread axle opening enough to receive differential case.
32. Install differential case in axle housing.
33. Remove spreader from axle housing.
34. Rotate the differential case several times to seat the side bearings.





35. Position the indicator plunger against a ring gear tooth.
36. Push and hold ring gear upward while not allowing the pinion gear to rotate.
37. Zero dial indicator face to pointer.





38. Push and hold ring gear downward while not allowing the pinion gear to rotate. Dial indicator reading should be between 0.12 mm (0.005 inch) and 0.20 mm (0.008 inch). If backlash is not within specifications transfer the necessary amount of shim thickness from one side of the axle housing to the other.
39. Verify differential case and ring gear runout by measuring ring to pinion gear backlash at several locations around the ring gear. Readings should not vary more than 0.05 mm (0.002 inch). If readings vary more than specified, the ring gear or the differential case is defective.

NOTE: After the proper backlash is achieved, perform Gear Contact Pattern Analysis procedure.