GM Service Manual Online
For 1990-2009 cars only

Front Case Half


    Object Number: 772111  Size: SH
  1. Clean the front case half in cleaning solvent and air dry.
  2. Notice:  Do not nick, scratch or damage the sealing surface. The sealing surface is a machined surface. Damage to the machined surface can cause leakage.

  3. Remove the sealer from the case sealing surfaces.
  4. Inspect the front output shaft front bearing (4) for:
  5. • Roughness
    • Brinelling
    • Pitting
  6. Replace the front output shaft front bearing if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  7. Inspect the case for spun bearings.
  8. Replace the case if a bearing has spun.
  9. Inspect the case for being broken or cracked.
  10. Replace the case if it is broken or cracked.
  11. Inspect the sealing surfaces (1) for damage.
  12. Repair small scratches or nicks with a soft stone.
  13. Inspect the front case to transmission case mounting surface for damage.
  14. Inspect the case threaded bolt holes (3) for damage.
  15. Repair any damaged threads.
  16. Inspect the transmission to transfer case studs (2) for damage.
  17. Replace any damaged studs.

Rear Case Half


    Object Number: 765979  Size: SH
  1. Clean the rear case half in cleaning solvent and air dry.
  2. Notice:  Do not nick, scratch or damage the sealing surface. The sealing surface is a machined surface. Damage to the machined surface can cause leakage.

  3. Remove the sealer from the case sealing surfaces.
  4. Inspect the front output shaft rear bearing (5) for the following:
  5. • Roughness
    • Brinelling
    • Pitting
  6. Replace the front output shaft rear bearing if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  7. Inspect the rear output shaft bearing (6) for the following:
  8. • Roughness
    • Brinelling
    • Pitting
  9. Replace the rear output shaft bearing if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  10. Inspect the case for spun bearings.
  11. Replace the case if a bearing has spun.
  12. Inspect the control actuator lever shaft bearing and seal (3) for the following:
  13. • Leakage
    • Roughness
    • Brinelling
    • Pitting
  14. Replace the control actuator lever shaft seal and bearing if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  15. Inspect the case for being broken or cracked.
  16. Replace the case if it is broken or cracked.
  17. Inspect the sealing surfaces (1) for damage.
  18. Repair small scratches or nicks with a soft stone.
  19. Inspect the case threaded bolt holes for damage.
  20. Repair any damaged threads.
  21. Inspect the dowel pins (4) for being loose or missing.
  22. Repair or replace any damaged dowel pins.
  23. Inspect the oil pump bushing bore (7) for scoring or damage.
  24. Replace the case if the oil pump bushing bore is damaged.
  25. Inspect the clutch lever studs (2) for wear.
  26. Replace the case if the clutch lever studs are worn.

  27. Object Number: 765981  Size: SH
  28. Remove the oil pump suction pipe and the oil pump suction hose from the oil pump screen.
  29. Clean the pipe, hose, and screen in cleaning solvent and air dry.
  30. If the screen is embedded with debris, replace the screen.
  31. Inspect the hose for cracking or tears.
  32. Replace the hose if faulty.

Rear Extension


    Object Number: 765982  Size: SH
  1. Clean the rear extension in cleaning solvent and air dry.
  2. Notice:  Do not nick, scratch or damage the sealing surface. The sealing surface is a machined surface. Damage to the machined surface can cause leakage.

  3. Remove the sealer from the extension sealing surfaces (2).
  4. Inspect the extension for being broken or cracked.
  5. Replace the extension if it is broken or cracked.
  6. Inspect the sealing surfaces for damage.
  7. Repair small scratches or nicks with a soft stone.
  8. Inspect the dowel pins (3) for being loose or missing.
  9. Repair or replace a damaged dowel pin.
  10. Inspect the rear extension bushing (1) for scoring and excessive wear.
  11. Replace the rear extension bushing if damaged or worn. Refer to Transfer Case Disassemble and Transfer Case Assemble .

Rear Output Shaft


    Object Number: 765984  Size: SH
  1. Clean the rear output shaft in cleaning solvent.
  2. Clean the rear output shaft oil galleries (1) and air dry.
  3. Important: Do not attempt to smooth any roughness in the bearing journals or seal surfaces.

  4. Inspect the input gear thrust bearing surface (2) and the clutch housing bearing surface (3) for the following:
  5. • Scoring
    • Pitting
    • Brinelling
    • Excessive wear
  6. Inspect the rear output shaft splines (4) for damage or excessive wear. Witness marks at the location of the gears is normal.
  7. Replace the rear output shaft if any of the above conditions are found.

Clutch Components


    Object Number: 765985  Size: SH
  1. Do not clean the inner clutch discs (1) and outer clutch discs (2) in cleaning solvent.
  2. Inspect the clutch discs for the following:
  3. • Worn friction material
    • Grooved or scored friction material
    • Warped
    • Burnt
  4. Replace the clutch discs if any of the above conditions are found.

  5. Object Number: 765987  Size: SH
  6. Clean the clutch inner plate (1) and the clutch pressure plate bearing (2) in cleaning solvent and air dry.
  7. Inspect the pressure plate bearing for roughness and smooth movement.
  8. Replace the pressure plate bearing if damaged or worn.
  9. Inspect the clutch inner plate inner bushing for wear or damage.
  10. Inspect the clutch inner plate for wear.
  11. Replace the clutch inner plate if any of the above conditions are found.

  12. Object Number: 765988  Size: SH
  13. Clean the clutch housing, with the bearing, in cleaning solvent.
  14. Air dry and ensure all solvent is removed from the bearing.
  15. Inspect the bearing for wear or damage.
  16. Inspect the clutch housing disc teeth for excessive wear. Excessive wear can be identified by the steps in the teeth, which prevents the clutch disc from moving freely.
  17. Replace the clutch housing if the bearing is faulty or if the clutch disc teeth are worn. The bearing is not serviced separately.

  18. Object Number: 765989  Size: SH
  19. Clean the clutch hub in cleaning solvent and air dry.
  20. Inspect the inner splines of the clutch hub for wear or damage.
  21. Inspect the clutch inner hub on the rear output shaft for excessive wear on the splines.
  22. Inspect the clutch hub teeth for excessive wear. Excessive wear can be identified by the steps in the teeth, which prevents the clutch disc from moving freely.
  23. Replace the clutch hub if any of the above conditions are found.

  24. Object Number: 766004  Size: SH
  25. Clean the clutch lever in cleaning solvent and air dry.
  26. Inspect the clutch lever roller (1) for the following:
  27. • Wear
    • Rotates easily
  28. Inspect the clutch lever for worn wear pads (2).
  29. Inspect the clutch lever for wear at the pivot pin sockets (3).
  30. Replace the clutch lever if the above conditions are found.

  31. Object Number: 766008  Size: SH
  32. Clean the control actuator lever shaft in cleaning solvent and air dry.
  33. Inspect the roller (1) on the control actuator lever shaft for the following:
  34. • Wear
    • Rotates easily
  35. Inspect the bearing (2) and the seal surface on the control actuator lever shaft for the following:
  36. • Pitted
    • Wear
    • Corrosion
  37. Replace the control actuator lever shaft if any of the above conditions are found.

Drive Chain and Sprockets


    Object Number: 765991  Size: SH
  1. Clean the drive chain (1), drive sprocket (3), and driven sprocket (2) in cleaning solvent and air dry.
  2. Inspect the drive chain (1) for the following:
  3. • Loose link pins
    • Binding or stiff links
    • Debris embedded in the links
    • Worn teeth surfaces
  4. Replace the chain if any of the above conditions are found.
  5. Inspect the driven sprocket (2) and the drive sprocket (3) for the following:
  6. • Chipped teeth
    • Excessive worn gear surfaces, slight wear marks are normal
    • Debris embedded in the root of the teeth
  7. Replace the sprocket if any of the above conditions are found. The chain and sprockets may be replaced separately.

Front Output Shaft


    Object Number: 765992  Size: SH
  1. Clean the front output shaft in cleaning solvent and air dry.
  2. Inspect the teeth on the speed sensor reluctor wheel (3) for damage.
  3. Replace the speed sensor reluctor wheel if damaged.
  4. Inspect the front output shaft seal surface (2) for wear or damage.
  5. Inspect the front output shaft splines (1) for damage.
  6. Replace the front output shaft if damaged.

Input Gear


    Object Number: 772115  Size: SH
  1. Clean the input gear, with thrust bearing, in cleaning solvent.
  2. Air dry, and ensure all solvent is removed from the thrust bearing.
  3. Inspect the thrust bearing (1) for the following:
  4. • Pitted
    • Wear
    • Corrosion
  5. Replace the input gear thrust bearing if any of the above conditions are found. Refer to Transfer Case Disassemble and Transfer Case Assemble .
  6. Inspect the internal splines (2) for:
  7. • Wear
    • Spalding
  8. Replace the input gear if any of the above conditions are found.