Differential Bearing Preload Adjustment

Standard Rear Axle Assembly:

Rear Axle Assembly With Traction Control (Acceleration Slip Regulation):

The differential bearing preload adjustment is to be made before installing the drive pinion gear (23). If drive pinion gear (23) is installed, remove ring gear (20). Refer to "DIFFERENTIAL CASE."

Differential bearing preload is adjusted by changing the thickness of both the right and left bearing shims (24) by an equal amount.

By changing the thickness of both bearing shims (24) equally, the original backlash will be maintained.

Production bearing shims (24) are cast iron and vary in thickness from 5.33 mm to 6.91 mm (0.210 inch to 0.272 inch) in increments of 0.05 mm (0.002 inch).

Standard service bearing spacers (25) are 4.32 mm (0.170 inch) thick and steel service bearing shims (24) are available from 1.02 mm to 2.08 mm (0.040 inch to 0.082 inch) in increments of 0.05 mm (0.002 inch).

Important:
- Do not attempt to reinstall the production bearing shims (24) as they may break when tapped into place.
- If service bearing shims (24) were previously installed, they can be reused, but whether using new or old differential bearings (32), adhere to the following procedure in all cases. If differential bearings (32) are used again, they must have original outer races in place.

Adjust
1. Determine the approximate thickness of bearing shims (24) needed by measuring each production bearing shim (24) or each service bearing spacer (25) and bearing shim pack.





- In addition to the service bearing spacer (25), service bearing shims (24) will be needed. Select a starting point in service bearing shim thickness.
2. Place differential case (33) with differential bearing outer races in position in the rear axle housing (16).
3. Slip the service bearing spacer (25) between each differential bearing race and rear axle housing (16) with chamfered edge against rear axle housing (16).

NOTICE: Install the left side bearing cap loosely so the differential case may be moved while checking adjustments. Another differential bearing cap bolt/screw can be added in the lower right side differential bearing cap hole. This will prevent the case from dropping while making shim adjustments.

4. Select one or two bearing shims (24) totaling the amount shown in the right-hand column of the chart and position between the right side differential bearing race and service bearing spacer (25).
- Be sure left side differential bearing race and bearing spacer (25) are against left side of the rear axle housing (16).
5. Insert progressively larger feeler gage sizes 0.25 mm, 0.30 mm, 0.36 mm, etc. (0.010 inch, 0.012 inch, 0.014inch, etc.) between the right bearing shim (24) and service bearing spacer (25) until there is a noticeable increase in drag.
6. Push feeler gage downward until end of gage makes contact with rear axle housing bore to obtain a correct reading.
- The point just before additional drag begins is the correct feeler gage thickness.
7. Rotate differential case (33) while using feeler gage to ensure an even reading.
- The original light drag is caused by weight of differential case (33) against rear axle housing (16) while additional drag is caused by differential bearing preload.
- By starting with a thin feeler gage, a sense of "feel," is obtained so the beginning of preload can be recognized to obtain zero clearance.
- It will be necessary to work differential case (33) in and out and to the left in order to insert feeler gage.
8. Remove left side differential bearing cap (22) and bearing shim (24) from rear axle housing (16).
9. The total bearing shim pack needed, with no preload on differential bearings (32), is the feeler gage reading found in step 7 plus the thickness of bearing shims (24) installed in step 4.
10. Select two bearing shims (24) of approximately equal size whose total thickness is equal to the value obtained in step 9.
- These bearing shims (24) will be installed between each differential bearing race and service bearing spacer (25) when differential case (33) is installed in rear axle housing (16).
- The preload will not be added until differential case (33) is installed.
11. If drive pinion gear is in position, install ring gear. Refer to "DIFFERENTIAL CASE."