Pinion Depth Adjustment
Pinion Depth Adjustment^ Tools Required
- J3289-20 Holding Fixture Base
- J3289-21 Holding Fixture
- J37769 Differential Holding Fixture Adapters
- 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 Gage Plate
Setting Pinion Depth
Pinion depth is the distance from the face of the pinion gear to the center line of the ring gear. Pinion depth is critical to all differentials. Each ring and pinion gear set is matched so as to produce the best tooth contact pattern. Pinion depth is controlled by placing the proper selective shim between the pinion gear and the inner bearing. Pinion depth is set with the J21777-B pinion setting gage set which provides a nominal or 0 as a gaging reference to find the pinion center. If the original ring and pinion gears and pinion bearings are reused, the original size selective shim will set the proper pinion depth.
1. Lubricate both the inner and the outer pinion bearings with wheel bearing lubricant GM P/N 1051344, or equivalent.
2. Assemble the gauge plate and the stud assembly.
3. Place the inner pinion bearing (1) into the differential carrier and install the J21777-102, the J23597-12, the J21777-43 and the J21777-42.
4. Place the outer pinion bearing into the differential carrier and install the J21777-102, the J23597-12, the J21777-43 and the J21777-42.
Notice: Refer to Fastener Notice in Service Precautions.
5. Hold the J21777-43 stationary.
^ Tighten the J21777-43 jam nut to 2 Nm (18 inch lbs.).
6. Rotate J21777-102 25 revolutions in order to ensure the pinion bearings (1) are fully seated.
^ Tighten the J21777-43 jam nut to 2 Nm (18 inch lbs.).
7. Install the J21777-101 in the side bearing bores with the J23597-1 through both of the J21777-101.
8. Rotate the J21777-102 (1) until both gage 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.
10. Install the J8001 to the J23597-1 and position the J8001 plunger over the spring loaded plunger extension and slightly load the J8001.
11. Rotate the J8001 adjustable face so that the needle indicates 0.
12. Slowly rotate the J23597-1 back and forth so that the spring loaded plunger extension sweeps back and forth across the J21777-102 while observing the J8001.
13. Stop the J23597-1 at the J8001 greatest point of deflection.
14. Without disturbing the J8001 needle setting, rotate the J8001 adjustable face so that the needle indicates 0.
15. Slowly rotate the J23597-1 until the spring loaded plunger extension is no longer making contact with the J21777-102.
Important: This reading indicates the selective shim required for the correct pinion depth.
16. Record the deflection reading on the J8001.
17. Remove the J8001 and the spring loaded plunger extension from the J23597-1.
18. Remove the J23597-1 and the 2 J21777-101 from the differential carrier.
19. Remove the J21777-102, the J3289-21, the J21777-43 and the J21777-42 from the differential carrier.
20. Remove the inner pinion bearings from the differential carrier.
21. Remove the outer pinion bearing from the differential carrier.