RPO M41

Pinion Depth Adjustment

^ Tools Required
- J8001 Dial Indicator Set
- J23597-1 Arbor
- J23597-12 Pilot Washer
- J21777-42 Pilot Washer
- J21777-43 Stud Assembly
- J21777-101 Side Bearing Discs
- J21777-102 Gauge Plate Setting Pinion Depth
Pinion Depth (the distance from the face of the pinion gear to the center line of the ring gear) is critical to all differentials. Each ring and pinion gear set is matched so as to produce the best tooth contact pattern. This relationship (pinion depth) is controlled by placing the proper selective shim between the pinion gear and the inner bearing. If the original ring, pinion gears and pinion bearings are reused, the original ring size selective shim will set the proper pinion depth. Pinion depth is set with a Pinion Setting Gage Set which provides a nominal or zero as a gaging reference to find the pinion center.
1. Lubricate both inner and outer pinion bearings with wheel bearing lubricant GM P/N 1051344, or equivalent.





2. Assemble the gauge block and stud.





3. Place the inner pinion bearing into the differential carrier and install a J21777-102 with the Differential Dummy attachment, a J23597-12, a J21777-43 and a J21777-42.

Notice: Refer to Fastener Notice in Service Precautions.





4. Hold the J21777-43 stationary and tighten the jam nut.
^ Tighten the jam nut to 2 Nm (18 inch lbs.).
5. Rotate the J21777-102 25 revolutions with the differential dummy attachment to ensure the pinion bearings are fully seated.
6. Retighten the jam nut.
^ Tighten the jam nut to 2 Nm (18 inch lbs.).





7. Install the J21777-101 in the side bearing bores with J23597-1 through both side bearing discs.
8. Rotate the J21777-102 with -the differential dummy attachment until both gauging levels are parallel with the J21777-101.





9. Install the dial indicator spring loaded plunger extension through the J23597-1 and position over the 97 mm level of the J21777-102 with the differential dummy attachment.





10. Install a J8001 to the J23597-1.
11. Position the gauge plunger over the plunger extension and slightly load the indicator.
12. Rotate the J8001 adjustable face so that the 0 is aligned with the dial indicator, needle.





13. Slowly rotate the J23597-1 back and forth so that the spring loaded plunger tension sweeps back and forth across the 97 mm level of the J21777-102 while observing the dial indicator.
14. Stop the J23597-1 at the dial indicator's greatest point of deflection.
15. Without disturbing the J8001 needle setting, rotate the J8001 adjustable lace so that 0 is aligned with the dial indicator needle.
16. Slowly rotate the J23597-1 one way until the spring loaded plunger extension is no longer making contact with the J21777-102.
17. Record the deflection reading on the J8001.
18. This reading indicates the selective shim size required for the correct pinion depth.
19. Remove the J8001 and spring loaded plunger extension from the J23597-1.
20. Remove the J23597-1 and the 2 J21777-101 from the differential carrier (6).
21. Remove the J21777-102 and with the J23597-12, the J21777-43 and the J21777-42 from the differential carrier.
22. Remove both inner and outer pinion bearings from the differential carrier (6,1.