Rear Drive Axle: Adjustments Chevrolet Silverado 2500

Adjustment Procedure

Tools Required: J 2222-C Wheel Bearing Nut Wrench

Scheme 43

Scheme 44

1. Raise the vehicle.
2. Remove the axle shaft. Refer to «Rear Axle Shaft And/Or Gasket Replacement»(ref-177218-S25603339872005052500000) .
3. Remove the hub adjuster nut retaining ring.
4. Remove the adjuster nut lock key.
5. Tighten the wheel bearing adjusting nut using the J 2222-C . Rotate the hub in the opposite direction to the way the adjuster nut is turning. Ensure the inner bearing and the seal seats against the spindle shoulder. Tighten the adjusting nut to 70 N.m (52 lb ft).
6. Turn the adjusting nut counterclockwise until the nut is loose using the J 2222-C.
7. Turn the adjusting nut clockwise until the nut contacts the bearing cone. Torque on the nut must be zero to finger tight.
8. Insert the adjusting nut lock key into the keyway using one of the following procedures: If the adjusting nut slot is in alignment with the keyway in the axle spindle, insert the adjusting nut lock key into the keyway in the axle spindle. Important: Do not turn the adjusting nut more than one slot counterclockwise in order to align the adjusting nut slot with the keyway in the axle spindle. If the adjusting nut slot is not aligned with the keyway in the axle spindle, turn the adjusting nut counterclockwise until the adjusting nut slot is in alignment with the keyway in the axle spindle and insert the adjusting nut lock key.
9. Install the retaining ring.
10. Install the axle shaft. Refer to «Rear Axle Shaft And/Or Gasket Replacement»(ref-177218-S25603339872005052500000) .
11. Inspect the lubricant level and add, if necessary. Refer to «Lubricant Level Check (11.5 Inch Axle)»(ref-177218-S41021371622005052500000) .
12. Lower the vehicle.

Backlash Adjustment (All Except 9.75 Inch Axle)

Tools Required

1. J 8001 Dial Indicator Set
2. J 25025 Guide Pins
3. J 25588 Side Bearing Shim Installer

1. Install the J 25025-1 and the J 8001 to the axle housing as shown.
2. Place the indicator stem of the J 8001 at the heel end of a gear tooth.
3. Set the J 8001 so that the stem is aligned with the gear rotation and perpendicular to the tooth angle.
4. Preload the dial of the J 8001 . Align the needle and the dial face of the J 8001 to ZERO.
5. While holding the drive pinion stationary, move the ring gear back and forth. Measure and record the backlash.
6. Repeat the measuring procedure at eight points around the ring gear. Specification The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).
7. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in), inspect for the following conditions: Burrs A distorted case flange Uneven bolting
8. If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be: Specification The backlash between the ring gear and the drive pinion should be between 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in). Important: Do not use the original cast iron production shims to adjust the backlash. Use service shims and spacers instead. Adjust the thickness of the shim pack on each side of the differential in equal amounts. This will maintain the correct axle side bearing preload. Moving 0.05 mm (0.002 in) of shim thickness from one side of the differential to the other will change the backlash adjustment approximately 0.03 mm (0.001 in).
9. If the backlash is too small, increase the backlash using the following procedure: 9.1. Remove the bearing cap bolts and the bearing caps. Mark the bearing caps left or right. 9.2. Remove the differential case assembly with the bearing cups and the shims. Mark the bearing cups and the shims left or right. 9.3. Measure the thickness of left side shim pack. Measure the production shim or the shim and service spacer in 3 locations. Measure each shim separately. 9.4. Calculate the average of the 3 measurements for each shim. Add the average of each of the shim measurements together. Record the measurement. This is the thickness for the left side shim pack. 9.5. Assemble a new left side shim pack by decreasing the appropriate amount of thickness from the original left side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in), remove 0.10 mm (0.004 in) of thickness from the left side shim pack. 9.6. Measure the thickness of right side shim pack. Measure the shim or the shim and service spacer in 3 locations. Measure each shim separately. Calculate the average of the 3 measurements for each shim. Add the average of each of the shim measurements together. Record the measurement. This is the thickness for the right side shim pack. 9.8. Assemble a new right side shim pack by increasing the appropriate amount of thickness to the original right side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in), add 0.10 mm (0.004 in) of thickness to the right side shim pack.
10. If the backlash is too large, decrease the backlash using the following procedure: 10.1. Remove the bearing cap bolts and the bearing caps. Mark the bearing caps left or right. 10.2. Remove the differential case assembly with the bearing cups and the shims. Mark the bearing cups and the shims left or right. 10.3. Measure the thickness of left side shim pack. Measure the production shim or the shim and service spacer in 3 locations. Measure each shim separately. 10.4. Calculate the average of the 3 measurements for each shim. Add the average of each of the shim measurements together. Record the measurement. This is the thickness for the left side shim pack. 10.5. Assemble a new left side shim pack by increasing the appropriate amount of thickness to the original left side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to increase the backlash by 0.05 mm (0.002 in), add 0.10 mm (0.004 in) of thickness to the left side shim pack. 10.6. Measure the thickness of right side shim pack. Measure the shim or the shim and service spacer in 3 locations. Measure each shim separately. 10.7. Calculate the average of the 3 measurements for each shim. Add the average of each of the shim measurements together. Record the measurement. This is the thickness for the right side shim pack. 10.8. Assemble a new right side shim pack by decreasing the appropriate amount of thickness to the original right side shim pack. If the original shim is cast iron production shim, assemble the shim pack using a service spacer and service shims. For example, to decrease the backlash by 0.05 mm (0.002 in), remove 0.10 mm (0.004 in) of thickness to the right side shim pack.
11. Install the differential case assembly with the bearing cups.
12. Install the left side service spacer between the axle housing and the differential case.
13. Install the right side service spacer between the axle housing and the differential case.
14. Install the left side service shim using the J 25588, if necessary. The service shim must be installed between the service spacer and the differential bearing cup.
15. Install the right side service shim using the J 25588, if necessary. The service shim must be installed between the service spacer and the differential bearing cup.
16. Install the bearing caps and bolts. Tighten the bolts to 75 N.m (55 lb ft).
17. Recheck the backlash and adjust, if necessary.
18. Once backlash is correct, perform a gear tooth contact pattern check in order to ensure proper alignment between the ring and pinion gears. Refer to «Gear Tooth Contact Pattern Inspection»(ref-177218-S06211448232005052500000) .

Backlash Adjustment (9.75 Inch Axle)

Tools Required

1. J 25025 Guide Pins
2. J 8001 Dial Indicator

1. Determine the differential side bearing preload and initial backlash. Refer to «Differential Side Bearing Preload Adjustment (9.75 Inch Axle)»(ref-177218-S01875057052005052500000) .
2. Install the J 25025 (1) and the J 8001 (2, 3) to the axle housing as shown.
3. Place the indicator stem of the J 8001 at the heel end of a gear tooth.
4. Set the J 8001 so that the stem is aligned with the gear rotation and perpendicular to the tooth angle.
5. While holding the pinion stationary, move the ring gear back and forth. Measure and record the backlash.
6. Repeat the measuring procedure at eight points around the ring gear. Specification The difference between the backlash at all of the measuring points should not vary by more than 0.05 mm (0.002 in).
7. If the difference between the backlash at all of the measuring points varies by more than 0.05 mm (0.002 in), inspect for the following conditions: Burrs A distorted case flange Uneven bolting
8. If the difference between all the measuring points is within specifications, the backlash at the minimum lash point measured should be: Specification The backlash between the ring gear and the drive pinion should be between 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.20 mm (0.005-0.008 in). Important: Adjust the thickness of the shim pack on each side of the differential in equal amounts. This will maintain the correct axle side bearing preload.
9. If the backlash is not within specifications, adjust the backlash by doing the following: 9.1. Remove the differential side bearings. Refer to «Differential Side Bearings Replacement (9.75 Inch Axle)»(ref-177218-S12782626112005052500000) . 9.2. If the backlash is too small, increase the backlash using the following procedure: Important: Moving 0.05 mm (0.002 in) of shim thickness from one side of the differential to the other will change the backlash adjustment by 0.03 mm (0.001 in). 9.2.1. Remove the appropriate amount of thickness from the left side shim pack. For example, to increase the backlash by 0.10 mm (0.004 in), subtract 0.20 mm (0.008 in) of thickness from the left side shim pack. 9.2.2. Add the 0.20 mm (0.008 in) of shim thickness to the right side shim pack. 9.3. If the backlash is too large, decrease the backlash using the following procedure: Important: Moving 0.05 mm (0.002 in) of shim thickness from one side of the differential to the other will change the backlash adjustment by 0.03 mm (0.001 in). 9.3.1. Remove the appropriate amount of thickness from the right side shim pack. For example, to decrease the backlash by 0.10 mm (0.004 in), subtract 0.20 mm (0.008 in) of thickness from the right side shim pack. 9.3.2. Add the 0.20 mm (0.008 in) of shim thickness to the left side shim pack.
10. Install the left and right shim packs onto the differential case.
11. Install the differential side bearings. Refer to «Differential Side Bearings Replacement (9.75 Inch Axle)»(ref-177218-S12782626112005052500000) .
12. Recheck the backlash and adjust as necessary.
13. Once backlash is correct, perform a gear tooth contact pattern check in order to ensure proper alignment between the ring and pinion gears. Refer to «Gear Tooth Contact Pattern Inspection»(ref-177218-S06211448232005052500000) .

Adjustments Affecting Tooth Contact

The following 2 adjustments affect the tooth contact pattern

1. Backlash adjustment
2. Pinion depth adjustment

The effects of bearing preloads are not readily apparent on hand-loaded tooth contact pattern tests. However, bearing preloads should be within specifications before proceeding with backlash and pinion depth adjustments.

Backlash Adjustment

The backlash can be adjusted by either varying the thickness of the side bearing shims from side to side or by moving the adjuster sleeve(s) in or out, or both. By adjusting the shim thickness or moving the adjuster sleeve(s), the case and ring gear assembly will move closer to or further away from the pinion. In most cases, adjusting the backlash will correct an abnormal contact pattern. This adjustment will also be used to set the side bearing preload.

1. If the thickness of the right shim is increased or the adjuster sleeve is moved in (if applicable), along with an equal decrease in the thickness of the left shim or the adjuster sleeve is moved out (if applicable), the backlash will increase.
2. If the thickness of the left shim is increased or the adjuster sleeve is moved in (if applicable), along with an equal decrease in the thickness of the right shim or the adjuster sleeve is moved out (if applicable), the backlash will decrease.

Pinion Depth Adjustment

Adjust the position of the pinion by increasing or decreasing the distance between the pinion head and the centerline of the ring gear. Decreasing the distance moves the pinion closer to the centerline of the ring gear. Increasing the distance moves the pinion farther away from the centerline of the ring gear.

Scheme 45

1. Wipe clean the differential case, the ring gear and the axle housing of lubricant. Carefully clean each tooth of the ring gear.
2. Use a medium stiff brush in order to sparingly apply gear marking compound, GM P/N 1052351 (Canadian P/N 10953497) or equivalent, to all of the ring gear teeth.
3. Torque the bearing caps bolts to specification. Important: Performing a test without loading the gears will not produce a satisfactory pattern.
4. Apply the park brake until a torque load of 14 N.m (10 lb ft) is required in order to turn the pinion. Important: Avoid turning the ring gear excessively.
5. Using a wrench, turn the drive pinion flange/yoke so that the ring gear rotates 3 full revolutions.
6. Turn the drive pinion flange/yoke in the opposite direction so that the ring gear rotates 3 full revolutions in the opposite direction.
7. Observe the pattern on the ring gear teeth. Compare the pattern with the following illustrations.