Shim Selection

Rear Axle - 286RBI
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, if necessary.
4. Install dummy side bearings D-346 on differential case.
5. Install differential case in the housing.





6. Install the marked bearing caps in their correct positions. Install and snug the bolts (Fig. 11).








7. Using a dead-blow hammer, seat the differential dummy bearings to each side of the housing (Fig. 12) and (Fig. 13).





8. Thread Pilot Stud C-3288-B into rear cover bolt hole below ring gear (Fig. 14).
9. Attach a dial indicator C-3339 to pilot stud. Position the dial indicator plunger on a flat surface between the ring gear bolt heads (Fig. 14).





10. Push and hold differential case to pinion gear side of the housing and zero dial indicator (Fig. 15).





11. Push and hold differential case to ring gear side of the housing and record dial indicator reading (Fig. 16).
12. Add 0.254 mm (0.010 inch) to the zero end play total. This total represents the thickness of shims to preload the new bearings when the differential is installed.
13. Rotate dial indicator out of the way on the pilot stud.
14. Remove differential case and dummy bearings from the housing.
15. Install the pinion gear in axle housing. Install the pinion yoke, or flange, and establish the correct pinion rotating torque.
16. Install differential case and Dummy Bearings D-346 in the housing (without shims), install bearing caps and tighten bolts snug.
17. Seat ring gear side dummy bearing (Fig. 12).
18. Position the dial indicator plunger on a flat surface between the ring gear bolt heads. (Fig. 14).





19. Push and hold differential case toward pinion gear (Fig. 17).
20. Zero dial indicator face to pointer (Fig. 17).





21. Push and hold differential case to ring gear side of the housing and record dial indicator reading (Fig. 18).
22. This is the thickness shim required on the ring gear side of the differential case to achieve proper backlash.
23. Subtract the backlash shim thickness from the total preload shim thickness. The remainder is the shim thickness required on the pinion side of the housing.
24. Rotate dial indicator out of the way on pilot stud.
25. Remove differential case and dummy bearings from the housing.
26. Install side bearing shims on differential case hubs.
27. Install side bearings and cups on differential case.
28. Install spreader W-129-B on the housing and spread housing enough to install differential case.

CAUTION: Do not spread over 0.50 mm (0.020 inch). If the housing is over-spread, it could be distorted or damaged.

29. Install differential case in the housing.
30. Remove spreader from the housing.
31. Rotate the differential case several times to seat the side bearings.





32. Position the indicator plunger against a ring gear tooth (Fig. 19).
33. Push and hold ring gear upward while not allowing the pinion gear to rotate.
34. Zero dial indicator face to pointer.





35. 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 (Fig. 20).
36. 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.After the proper backlash is achieved, perform Gear Contact Pattern Analysis procedure.