Operation CHARM: Car repair manuals for everyone.

Pinion Depth Adjustment

^ Tools Required:
- J 8001 Dial Indicator Gauge Set
- J 21777-1 Arbor
- J 21777-8 Rear Pilot Washer
- J 21777-42 Front Pilot Washer
- J 21777-43 Stud Assembly Bolt
- J 21777-85 Gauge Plate
- J 21777-86 Side Bearing Disc

1. Clean all gauge parts.
2. Lubricate the front and rear pinion bearings with axle lubricant.
3. Place the bearings into the pinion bearing cups.





4. Install J 21777-8, J 21777-42, J 21777-85, and J 21777-43 to the pinion bore.
5. Hold the stud stationary at the flats of the stud.
- Tighten stud nut to 2.2 Nm (20 inch lbs.).
6. Rotate the gauge plate and bearings several complete revolutions to seat the bearings.
7. Tighten the stud nut until a torque of 1.6 to 2.2 Nm (15 to 25 inch lbs.) is obtained to keep the gauge plate in rotation.





8. Assemble J 21777-86, J 21777-1, and J 8001 to the differential bearing bore.
- The bearing bores must be clean and burr free.
9. Install the side bearing caps.
- Tighten bolts to 74 Nm (55 ft. lbs.).
10. Rotate the gauge plate until the proper gauging area is parallel with the disks.
11. Position the gauge shaft assembly in the carrier so the dial indicator rod is centered on the gauging area of the gauge block.





12. Set the dial indicator at zero. Push the indicator down on the indicator shaft until the needle rotates approximately 3/4 of a turn to the right. Tighten the dial indicator in this position.
13. Rotate the gauge shaft slowly back and forth until the dial indicator reads the greatest deflection (when the indicator needle is centered between movement to the left and to the right).
14. At the point of greatest deflection, set the dial indicator to zero. Repeat the rocking action of the gauge shaft to verify the zero setting.
15. Rotate the gauge shaft until the dial indicator rod does not touch the gauge block.
16. Record the actual number on the dial indicator and not the number which represents how far the needle travels. This is the nominal pinion setting. EXAMPLE: If the indicator needle moved counterclockwise 1.70 mm (0.067 inch) to a dial reading of 0.84 mm (0.033 inch) as shown, record the dial reading of 0.84 mm (0.033 inch), not 1.70 mm (0.067 inch).
17. All drive pinions are manufactured to a nominal depth. There are no markings on the drive pinion relating to depth. The dial indicator reading is used for shim selection.
18. Remove bearing caps and depth gauging tools.
19. Install the correct pinion shim to the pinion according to this procedure

NOTICE: Proper pinion depth setting is a two step procedure.
1. Setup dimension arrived at with the indicator to be considered a starting point.
2. Gear tooth pattern check is necessary to "fine tune" the pinion depth and may indicate additional shim changes to the pinion stem. Both procedures must be performed to ensure proper axle performance and prevent system damage.