Pinion Depth Adjustment

Pinion Depth Adjustment
Adjust the position of the pinion by increasing or decreasing the distance between the pinion head and the centerline of the ring gear. Decreasing the distance moves the pinion closer to the centerline of the ring gear. Increasing the distance moves the pinion farther away from the centerline of the ring gear.

Testing Procedure

1. Wipe clean the differential case, the ring gear and the axle housing of lubricant. Carefully clean each tooth of the ring gear.
2. Use a medium stiff brush in order to sparingly apply gear marking compound, GM P/N 1052351 (Canadian P/N 10953497) or equivalent, to all of the ring gear teeth.
3. Torque the bearing caps bolts to specification.

Important: Performing a test without loading the gears will not produce a satisfactory pattern.

4. Apply the park brake until a torque load of 14 Nm (10 ft. lbs.) is required in order to turn the pinion.

Important: Avoid turning the ring gear excessively.

5. Using a wrench, turn the drive pinion flange/yoke so that the ring gear rotates 3 full revolutions.
6. Turn the drive pinion flange/yoke in the opposite direction so that the ring gear rotates 3 full revolutions in the opposite direction.
7. Observe the pattern on the ring gear teeth. Compare the pattern with the following illustrations.

Correct Contact Pattern

Condition

The backlash and pinion depth is correct.

Correction
None required.

Service Hints
Loose bearings on the drive pinion or in the differential case may cause patterns that vary. If the contact pattern varies, inspect the following preload settings:
^ Total assembly
^ Differential case
^ Pinion If these settings are correct, inspect for damage or incorrectly assembled parts.

Drive Side Heel - Coast Side Toe Contact Pattern

Condition

The backlash is incorrect. The ring gear is too far away from the pinion.

Correction
Decrease the backlash. Move the ring gear closer to the pinion by adjusting the side bearing shim thickness or the adjuster sleeve(s).

Drive Side Toe - Coast Side Heel Contact Pattern

Condition

The backlash is incorrect. The ring gear is too close to the drive pinion.

Correction
Increase the backlash. Move the ring gear away from the pinion by adjusting the side bearing shim thickness or the adjuster sleeve(s).

Drive Side Heel - Coast Side Heel Contact Pattern

Condition

The pinion depth is incorrect. The pinion gear is too far away from the ring gear.

Correction
Increase the pinion depth. Move the pinion gear closer to the ring gear by increasing the pinion shim thickness.

Low Flank Contact Pattern

Condition

The pinion depth is incorrect. The pinion gear is too close to the ring gear.

Correction
Decrease the pinion depth. Move the pinion gear away from the ring gear by decreasing the pinion shim thickness.