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Chevrolet Silverado / GMC Sierra. Manual - part 1480
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.
Fig. 262: Axle Nut Retaining Ring
Courtesy of GENERAL MOTORS CORP.
9. Install the retaining ring.
10. Install the axle shaft. Refer to Rear Axle Shaft and/or Gasket Replacement.
11. Inspect the lubricant level and add, if necessary. Refer to Rear Axle Lubricant Level
Inspection (11.5 Inch Axle) or Rear Axle Lubricant Level Inspection (8.6, 9.5 LD
Axle) or Rear Axle Lubricant Level Inspection (10.5 Inch Axle).
12. Lower the vehicle.
BACKLASH ADJUSTMENT (8.6 INCH AXLE)
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Tools Required
J 8001 Dial Indicator Set
J 25025 Guide Pins. See Special Tools.
J 25588 Side Bearing Shim Installer. See Special Tools.
Adjustment
Fig. 263: Measuring Ring Gear Backlash
Courtesy of GENERAL MOTORS CORP.
1. Install the J 25025-1 and the J 8001 to the axle housing as shown. See Special Tools.
2. Place the indicator stem of the J 8001-3 at the heel end of a gear tooth. See Special Tools.
3. Set the J 8001-3 so that the stem is aligned with the gear rotation and perpendicular to the
tooth angle. See Special Tools.
4. Preload the dial of the J 8001-3 . See Special Tools.
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Align the needle and the dial face of the J 8001-3 to ZERO. See Special Tools.
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).
9. If the backlash is too small, increase the backlash using the following procedure:
1. Remove the bearing cap bolts and the bearing caps.
Mark the bearing caps left or right.
2. Remove the differential case assembly with the bearing cups and the shims.
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).
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Mark the bearing cups and the shims left or right.
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.
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.
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.
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.
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.
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:
1. Remove the bearing cap bolts and the bearing caps.
Mark the bearing caps left or right.
2008 Chevrolet Silverado 1500
2008 Driveline/Axle Rear Drive Axle - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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