Drive Pinion Shim Selection

Tools Required

• J 42168-1  Differential Centerline Cylinder. See Special Tools and Equipment .
• J 42168-2  Shim Gage Assembly. See Special Tools and Equipment .
• J 42168-9  Holding Strap. See Special Tools and Equipment .
• J 42168-11  Pinion Housing Centering Spacer. See Special Tools and Equipment .
• J 42173  Differential Holding Fixture. See Special Tools and Equipment .

Fig 1: J 42173 & Differential Assembly
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: The pinion depth adjustment procedure and shim selection must be performed prior to pinion shaft and housing assembly.
1. Install the differential assembly (1) onto the J 42173  (2). See Special Tools and Equipment .
NOTE: Refer to Fastener Notice in Cautions and Notices.
2. Install 4 M8 x 1.25 bolts (3).

   Tighten:  Tighten the bolts to 25 N.m (18 lb ft).

Fig 2: Left Bearing Race Bore & J 42168-1 Removed
Courtesy of GENERAL MOTORS CORP.
3. Install the J 42168-1  into the left bearing race bore of the differential housing. See Special Tools and Equipment .
Fig 3: Thumbscrew & J 42168-9 Removed
Courtesy of GENERAL MOTORS CORP.
4. Install the J 42168-9  and thumbscrew to the J 42168-1  . See Special Tools and Equipment . Tighten the thumbscrew until snug.
Fig 4: Bearing Races & Components
Courtesy of GENERAL MOTORS CORP.
5. Install the bearing races into the pinion housing/cage (4). Refer to Drive Pinion Assemble .
6. Install the J 42168-11  (2), bearings (3 and 6), spacer (5), J 42168-2  (7), and bolt (1) to the pinion housing/cage (4). See Special Tools and Equipment . Tighten the bolt until sung.
Fig 5: Differential Housing & Pinion Housing/Cage Assembly
Courtesy of GENERAL MOTORS CORP.
7. Install the pinion housing/cage assembly (1) into the differential housing.

   The use of M8 x 1.25 dowels or long bolts will ease in pinion housing installation and alignment.

Fig 6: Pinion Housing/Cage Bolts
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: ALL of the pinion housing/cage bolts must be installed in order to obtain an accurate measurement and correct shim selection.
8. Install the pinion housing/cage bolts (1).

   Tighten:  Tighten the bolts to 25 N.m (18 lb ft).

Fig 7: Feeler Gage
Courtesy of GENERAL MOTORS CORP.
9. Using a feeler gage, measure the distance between the J 42168-2  and the J 42168-1  . See Special Tools and Equipment . Record the dimension as B1.
10. Subtract the B1 value from a B nominal value of 5 mm (0.197 in). Record that calculation as B2.

    Refer to the applicable calculation tables in Spacer and Shim Specifications .

Fig 8: Locating A1 Value & A2 Value On Side Of Ring Gear
Courtesy of GENERAL MOTORS CORP.
11. Locate the A1 value (1) on the side of the ring gear.
IMPORTANT: The A1 value is a manufacturing variation between the ring gear and pinion. The A1 value may be higher, lower, or equal to 103.00 mm (4.055 in) nominal value. When subtracting the A nominal value from the A1 value, the B3 calculation may compute to a positive, negative, or zero total.
12. Subtract the A nominal value of 103.00 mm (4.055 in) from the A1 value. Record the calculation as B3.
13. Add the B2 value to the B3 value for the proper pinion housing shim thickness. The B3 value may be a positive, negative, or zero value.
14. Select shims equal to the calculated value. It may be necessary to round the shim or shims total to obtain the proper size shim pack. If the shim thickness calculation is past the midpoint value, round the number higher to the next decimal value.

    Refer to Rear Axle Specifications .