Differential Side Bearing Preload Adjustment

ADJUSTMENT
Perform the differential bearing preload adjustment before installing the drive pinion gear.
If the drive pinion gear is installed, remove the ring gear.
Change the thickness of both the right and the left bearing shims by an equal amount in order to adjust differential bearing preload.
Changing the thickness of both of the bearing shims equally will ensure that the original backlash remains constant.
Production bearing shims are cast iron. Production bearing shims (1) vary in thickness from 5.33-6.91 mm (0.210-0.272 inch) in increments of 0.05 mm (0.002 inch).
Steel service bearing shims are available from 1.02 - 2.08 mm (0.040 - 0.082 inch) in increments of 0.05 mm (0.002 inch).
Standard service bearing spacers are 4.32 mm (0.070 inch) thick.

IMPORTANT:
^ Do not reinstall the production bearing shims.
The production bearing shims may break when tapped by a hammer.
^ Service bearing shims are reusable.
The differential bearings must have the original outer races in place when the bearings are reused.

1. Determine the approximate required thickness of the replacement bearing shims.
Measure each production bearing shim (1) or each service bearing spacer and each bearing shim pack.
2. Determine the necessary service bearing shims.
Select a starting point in service bearing shim thickness.

3. Position the following components into the rear axle housing:
^ The differential case
^ The differential bearing outer races

4. Slip the correct service bearing spacer between each differential bearing race and the rear axle housing.
Ensure that the chamfered edge of the service bearing spacer is placed against the rear axle housing.

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.

5. Select one or two bearing shims.
6. Position the shims between the right side of the differential bearing race and the service bearing spacer.
^ The right side of the differential bearing race
^ The service bearing spacer
Ensure that the left side differential bearing race and the bearing spacer are against the left side of the rear axle housing.

7. Insert progressively larger feeler gauge sizes between the right bearing shim and service bearing spacer until a noticeable increase in drag exists.
The following measurements are examples of progressively larger feeler gauge sizes:
^ 0.25 mm (0.010 inch)
^ 0.30 mm (0.01 inch)
^ 0.36 mm (0.01 inch)
8. Push a feeler gauge downward until the end of the gauge touches the rear axle housing bore. This position will ensure an accurate reading.
Correct feeler gauge thickness exists at the point just before additional drag begins.
9. Rotate the differential case (9) while using the feeler gauge in order to ensure an even reading.
^ The weight of the differential case against the rear axle housing (10) causes the original light drag.
Differential bearing preload causes the additional drag.
^ Starting with a thin feeler gauge obtains a sense of feel that is necessary in order to recognize the beginning of the preload.
Recognizing the beginning of the preload is necessary in order to obtain zero clearance.
^ Work the differential case (9) in, out and to the left in order to insert the feeler gauge.
10. Remove the following components from the rear axle housing:
^ The left side differential bearing cap
^ The left side bearing shim
11. Add the following measurements in order to obtain the size of the total shim pack that is needed with no preload on the differential bearings (3)
^ The feeler gauge reading measured in Step 7.
^ The thickness of the bearing shims that were installed in Step 4.
12. Select two bearing shims of approximately equal size. The total thickness of the two shims must be equal to the value obtained in Step 9.
When installing the differential case into the rear axle housing, install the above bearing shims (1) between the following components:
^ Each differential bearing race
^ Each service bearing spacer
The additional preload will be added after the differential case is installed.
13. Install the ring gear if the drive pinion gear is in position.