Shim Selection
SHIM SELECTION / Front Axle - 186FIANOTE: 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. Install ring gear on differential case and tighten bolts to specification.
3. Install Dummy Bearings D-348 on differential case.
4. Install differential case in the housing.
5. Record the thickness of Dummy Shims 8107. Insert the shims between the dummy bearings and the differential housing (Fig. 14).
6. Install the bearing caps in their correct positions and snug the bolts (Fig. 15).
7. With a dead-blow hammer, seat the differential dummy bearings to each side of the axle housing (Fig. 16) and (Fig. 17).
8. Thread Pilot Stud C-3288-B into rear cover bolt hole below ring gear.
9. Attach a Dial Indicator C-3339 to the Pilot Stud. Position the dial indicator plunger on flat surface between the ring gear bolts.
10. Push and hold differential case to pinion gear side of the housing and zero dial indicator (Fig. 18).
11. Push and hold differential case to ring gear side of the housing and record dial indicator reading (Fig. 19).
12. Add 0.152 mm (0.006 in.) 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.
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 the housing. Install the pinion yoke and establish the correct pinion rotating torque.
16. Install differential case and Dummy Bearings D-348 in the housing.
17. Install a single dummy shim in the ring gear side. Install bearing caps and tighten bolts snug.
18. Seat ring gear side dummy bearing (Fig. 17).
19. Position the dial indicator plunger on a flat surface between the ring gear bolt heads.
20. Push and hold differential case toward pinion gear and zero dial indicator (Fig. 20).
21. Push and hold differential case to ring gear side of the housing and record dial indicator reading (Fig. 21). Add dummy shim thickness to this reading. This will be the total shim thickness to achieve zero backlash.
22. Subtract 0.076 mm (0.003 in.) 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.
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 axle 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 bearings and cups on differential case.
27. Install spreader W-129-B with Adapter Set 6987 on the housing and spread axle opening enough to receive differential case.
CAUTION: Never spread the differential housing over 0.34 mm (0.013 in.). If the housing is overspread, it could be distorted or damaged.
28. Place the bearing preload shims in the axle housing, against the axle tubes.
29. Install differential case into 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. 22).
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 in.) and 0.20 mm (0.008 in.). If backlash is not within specifications transfer the necessary amount of shim thickness from one side of the housing to the other (Fig. 23).
36. Verify differential case and ring gear runout by measuring ring to pinion gear backlash at eight locations around the ring gear. Readings should not vary more than 0.05 mm (0.002 in.). 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.