Chevrolet Silverado / GMC Sierra. Manual - part 928
Fig. 296: Measuring Wear Surface Thickness On 1-2-3-4 Clutch Backing Plate
Courtesy of GENERAL MOTORS CORP.
1. Measure the wear surface thickness of the 1-2-3-4 clutch backing plate (1) at dimension A
IMPORTANT: Measure as described below at a minimum of 3 locations.
Replace the 1-2-3-4 clutch backing plate if the specifications
are not met.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
for minimum thickness.
2. Refer to the 1-2-3-4 clutch backing plate table in Selective Components Specifications
for the correct size backing plate.
Fig. 297: Measuring Cone Of 1-2-3-4 Clutch Backing Plate
Courtesy of GENERAL MOTORS CORP.
3. Measure the cone of the 1-2-3-4 clutch backing plate (1) at dimension A.
4. Replace the backing plate (1) if any cone is measured.
1-2-3-4 CLUTCH PISTON INSPECTION
IMPORTANT: Check the backing plate for coning on a level surface.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Fig. 298: Locating Orifice
Courtesy of GENERAL MOTORS CORP.
1. Inspect 1-2-3-4 clutch piston (1) for damage. Replace the piston if damage is present.
2. Make sure that the orifice in the 1-2-3-4 clutch piston is not restricted. Clean any debris that
is restricting the orifice.
3. Measure the orifice in the 1-2-3-4 clutch piston for the specified size. Replace the piston if
the specification is not met.
Specification: The 1-2-3-4 clutch piston orifice size is 0.85-1.15 mm (0.033-0.045 in).
1-2-3-4 CLUTCH PISTON HOUSING INSPECTION
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Fig. 299: Locating Orifice
Courtesy of GENERAL MOTORS CORP.
1. Inspect the 1-2-3-4 clutch housing (1) for damage. Replace the housing if damage is present.
2. Make sure that the orifice in the 1-2-3-4 clutch housing is not restricted. Clean any debris
that is restricting the orifice.
3. Measure the orifice in the 1-2-3-4 clutch housing for the specified size. Replace the housing
if the specification is not met.
Specification: The 1-2-3-4 clutch housing orifice size is 0.85-1.15 mm (0.033-0.045 in).
FIBER 4-5-6 CLUTCH PLATE INSPECTION
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado