Shimming Procedures

Tools Required

• J 7079-2  Universal Driver Handle - Non-Threaded. See Special Tools .
• J 44385  Differential Bearing Race and Seal Installer. See Special Tools .
• J 44388  Final End Checking Fixture. See Special Tools .

Fig 1: Inspecting Bearings
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: Remove all of the old shims before performing the Shimming Procedures.
1. Make sure the bearings are fully seated in the case.
Fig 2: Ensuring Bearing Seating
Courtesy of GENERAL MOTORS CORP.
2. Position the transaxle on a bench so that the bearings are resting on a flat surface.
3. Using a rubber mallet, tap lightly on the case mating surface to ensure the bearings are fully seated.
Fig 3: Installing J 44388-1
Courtesy of GENERAL MOTORS CORP.
4. Measure the distance of the transaxle case parting surface to the output shaft gear thrust washer surface using the J 44388-1.
5. Place the J 44388-1 on the case parting surface.
6. Extend the gage rod on the J 44388-1 until it is bottomed on the output shaft gear thrust washer.
7. Tighten the thumbscrew on the J 44388-1 to retain the gage rod.
Fig 4: Measuring Length Of Gage Rod Protruding From Gage Bar
Courtesy of GENERAL MOTORS CORP.
8. Measure and record the length of the gage rod protruding from the gage bar (measurement A).
Fig 5: View Of Differential Bearing Race
Courtesy of GENERAL MOTORS CORP.
9. Make sure the left differential bearing race is fully seated into the transaxle case using the J 7079-2  (1) and the J 44385  (2). See Special Tools .
Fig 6: Installing J 44388-2
Courtesy of GENERAL MOTORS CORP.
10. Install the J 44388-2 into the left differential side bearing race. Ensure that the J 44388-2 is fully seated into the left differential side bearing race.
Fig 7: Identifying J 44388-2 & J 44388-1
Courtesy of GENERAL MOTORS CORP.
11. Remove the gage rod from the J 44388-1 (2).
12. Place the bar of the J 44388-1 (2) onto the gage rod of the J 44388-2 (1).
13. Tighten the thumbscrew on the J 44388-1 (2) to retain the J 44388-2 (1) gage rod.
Fig 8: Measuring Height Of J 44388-1 & J 44388-2
Courtesy of GENERAL MOTORS CORP.
14. Measure the overall height of the J 44388-1 (1) and J 44388-2 (2) (measurement B).
Fig 9: Measuring Height Of J 44388-1
Courtesy of GENERAL MOTORS CORP.
15. Measure the height of just the J 44388-1 (measurement C).
16. Subtract the height of the J 44388-1 (measurement C) from the overall height of the J 44388-1 and J 44388-2 (measurement B) and record (measurement D).
Fig 10: Placing Differential Assembly Onto J 44388-4
Courtesy of GENERAL MOTORS CORP.
17. Place the differential assembly onto the J 44388-4 to provide a steady measuring surface.
Fig 11: Installing J 44388-1 To Differential Assembly
Courtesy of GENERAL MOTORS CORP.
18. Install the rod back into the J 44388-1 (1).
19. Place the J 44388-1 (1) across the face of the ring gear.
20. Center the gage rod of the J 44388-1 (1) over the land for the left differential side bearing shim.
21. With the gage rod of the J 44388-1 (1) fully seated on the shim land for the left differential side bearing shim, tighten the thumbscrew on the J 44388-1 (1).
Fig 12: Measuring Length Of Gage Rod Protruding From Gage Bar
Courtesy of GENERAL MOTORS CORP.
22. Measure and record the length of the gage rod protruding from the J 44388-1 (measurement E).
Fig 13: View Of VSS Ring & Differential Pinion Shaft
Courtesy of GENERAL MOTORS CORP.
23. Remove the vehicle speed sensor (VSS) ring.
IMPORTANT: Both retaining rings must be removed from the pinion shaft to ensure proper removal of the differential pinion shaft.
24. Remove and discard both the differential pinion shaft retaining rings and remove the differential pinion shaft.
Fig 14: Inserting J 44388-3
Courtesy of GENERAL MOTORS CORP.
25. Insert the J 44388-3 (1) through the center of the differential until it rests firmly on the J 44388-4 (2).
Fig 15: Measuring Distance From Top Surface Of J 44388-3 To Land Of Right Differential Side Bearing Shim
Courtesy of GENERAL MOTORS CORP.
26. The distance from the top surface of the J 44388-3 (1) to the land of the right differential side bearing shim is measured and recorded (measurement F).
27. Subtract measurement F from 127 mm (5 in) (measurement G).
Fig 16: View Of Left & Right Differential Side Shims
Courtesy of GENERAL MOTORS CORP.
28. To obtain shim size for left differential side shim (1) use the following formula:

    Shim (1) = E - A + D - 19.036 mm (0.749 in).

29. To obtain shim size for right differential side shim (2) use the following formula:

    Shim (2) = 94.65 mm (3.726 in) - G - shim (1).