Section 1586 (G56 Manual Transmission - (Service Information) - 2500 Hd): Inspection
Minor corrosion, nicks, or pitting can be smoothed with 400 grit emery and polished out with crocus cloth.
Bearings: Inspect for worn, chipped, cracked, flat-spotted or brinnelled.
Gears: Inspect for worn, chipped or cracked teeth. Inspect bearing surfaces for wear or flat-spotted.
Mainshaft: Inspect for worn splines, snap ring grooves and threads.
Countershaft: Inspect all gears for worn, chipped or cracked teeth (1). Inspect all bearings (2) and bearing surfaces for ware or flat-spotted. The countershaft is serviced as an assembly, except for bearings.
Oil slinger: Inspect first/reverse oil slinger for cracks.
Synchronizer components: Inspect for worn, chipped or cracked teeth and burned or flaking off friction material. Synchronizer are serviced as an assembly.
Input Shaft: Inspect shaft (1), bearing (2) surfaces for wear or flat-spotted. Inspect fifth gear (3) for worn, chipped or cracked teeth. Inspect splines (4) for wear and chips.
Shift forks and Rails: Inspect shift forks (1) and shoes for wear and distortion. Check fit of fork shoes in synchronizer sleeve to ensure parts fit and work smoothly. Inspect shift rails (2), for wear and distortion. 5-6 shift fork shoes (3) are serviced separately. Inspect 5-6 shift fork pivot pin O-rings.
Front Housing: Inspect sealing and mating surfaces are free of burrs and nicks. Inspect alignment dowels are tight and in good condition. Inspect shift rail guide (1) for wear and verify bearing oil baffle (2) is not bent or damaged.
Rear Housing: Inspect sealing and mating surfaces are free of burrs and nicks. Inspect shift rail guide (1) for wear and verify bearing oil baffle (2) is not bent or damaged.
Input Retainer: Inspect release bearing slide surface (2) and sealing surface.