GM Service Manual Online
For 1990-2009 cars
Makes 🢒 Chevrolet 🢒 2004 🢒 C-Series Medium Duty Truck C6/7/8 - Mexico 🢒 Transmission/Transaxle 🢒 Manual Transmission - Medium Duty 🢒 Transmission Replacement

Removal Procedure

    Object Number: 199865 Size: MH
  1. Remove vehicle components only if necessary, in order to provide adequate clearance for transmission removal.
  2. The vehicle will be equipped with one of the following:
    3. • Apron-type flywheel housing (2)
    • SAE number 2 type flywheel housing (6)
       - The apron-type flywheel housing (2) has a sheet metal pan which covers the lower portion of the clutch and flywheel. The flywheel housing is attached separately from the transmission body.
       - The SAE number 2 type flywheel housing (6) surrounds the entire clutch flywheel. The flywheel housing is not separate from the transmission body.
  3. Transmission replacement procedures differ slightly between the two types of housings.

    4. Object Number: 204729 Size: SH
  4. Block the front and rear wheels.
  5. Ensure that the transmission is in neutral.

    6. Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  6. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  7. Drain the transmission fluid. Refer to Transmission Oil Changing .
  8. Remove the control lever and/or boot. Refer to Control Lever and/or Boot Replacement .
  9. Remove the transmission air shift harness. Refer to Transmission Air Shift Harness Replacement .

    10. Object Number: 792167 Size: SH
  10. If equipped with regular production options (RPOs) MWW/MWX, remove the clutch return spring from the bracket and fork.

    11. Object Number: 792169 Size: SH
  11. If equipped with the 6.6L or 7.2L engine, and RPOs MUT/MS9/MT3/MK0/ML0, remove the clutch return spring from the bracket and lever.

    12. Object Number: 792170 Size: SH
  12. If equipped with the 6.6L or 7.2L engine, and RPOs M69/MK8/MK9 and MWW, remove the clutch return spring from the bracket and cable swivel.

    13. Object Number: 792042 Size: SH
  13. If equipped with the 7.2L engine and RPOs MS9/MT3, remove the clutch cable retainer (1).
  14. Remove the adjustment rod swivel (5) from the lever.

    15. Object Number: 793696 Size: SH
  15. Remove the clutch cable bracket nuts and washers.
  16. Remove and reposition the clutch cable bracket and cable.

    17. Object Number: 792043 Size: SH
  17. If equipped with the 6.6L or 7.2L engines and RPOs MUT/MS9/MT3, remove the clutch cable retainer (1).
  18. Remove the adjustment rod swivel (5) from the lever.
  19. Remove the clutch cable bracket nuts and washers.
  20. Remove and reposition the clutch cable bracket and cable.

    21. Object Number: 792044 Size: SH
  21. If equipped with the 6.6L engine and RPOs MTD/MK8/MK9 and MWW, remove the clutch cable retainer (1).
  22. Remove the adjustment rod swivel (5) from the lever.

    23. Object Number: 793700 Size: SH
  23. Remove the clutch cable bracket bolts.
  24. Remove and reposition the clutch cable bracket and cable.

    25. Object Number: 792046 Size: SH
  25. If equipped with the 6.6L or 7.2L engines and RPOs MK0/ML0/MM7/MNC and MPU, remove the clutch cable retainer (3).
  26. Remove the adjustment rod swivel (1) from the lever.

    27. Object Number: 793699 Size: SH
  27. Remove the clutch cable bracket bolts and washers.
  28. Remove and reposition the clutch cable bracket and cable.

    29. Object Number: 792233 Size: SH
  29. If equipped with the 8.1L engine and RPOs MM7/MNC/MPU/MSC/MSG and MPJ, remove the cable nuts (2) and retainer (1).

    30. Object Number: 793697 Size: SH
  30. Remove the clutch cable bracket bolts and washers.
  31. Remove and reposition the clutch cable bracket and cable.

    32. Object Number: 790997 Size: SH
  32. Disconnect the engine harness electrical connector from the transmission connector (1) (typical).
  33. If equipped with the 8.1L engine, remove the muffler. Refer to Muffler Replacement in Engine Exhaust.

    34. Object Number: 796538 Size: SH
  34. If equipped with the 6.6L or 7.2L engine, loosen the band clamp (2) joining the exhaust manifold front (3), and rear (1) pipes.

    35. Object Number: 796485 Size: SH
  35. If equipped with the 6.6L or 7.2L engine without PRO K40, perform the following:
    36. • Loosen the exhaust manifold front pipe clamp nut.
    • Remove the U-bolt nuts and U-bolt.
    • Remove the exhaust manifold front pipe.

    Object Number: 796486 Size: SH
  36. If equipped with the 6.6L or 7.2L engine with RPO K40, perform the following:
    37. • Loosen the exhaust manifold front pipe clamp nut.
    • Remove the U-bolt nuts and U-bolt.
    • Remove the exhaust manifold front pipe.
  37. Remove the propeller shaft. Refer to One-Piece Propeller Shaft Replacement , Two-Piece Propeller Shaft Replacement , or Three-Piece Propeller Shaft Replacement in Propeller Shaft.
  38. If equipped, remove the power take-off (PTO) and controls. Install a protective cover over the PTO opening.

    39. Object Number: 199880 Size: SH

    Important: When removing or installing the transmission, use a transmission dolly jack in order to support the weight of the transmission. Fasten safety chains over the top and to both sides of the dolly.

  39. Position the dolly jack under the transmission. Adjust the dolly jack in order to support the weight of the transmission.

    40. Object Number: 792320 Size: SH
  40. If equipped with the apron-type flywheel housing, remove the flywheel housing cover bolts and cover.

    41. Object Number: 792316 Size: SH
  41. If equipped with a apron-type flywheel housing, remove the clutch fork return spring bracket, caution tag, and housing cover extension bolts.

    42. Object Number: 792322 Size: SH
  42. If equipped with the apron-type flywheel housing, remove the flywheel housing bolts.

    43. Object Number: 791471 Size: SH
  43. If equipped with the 6.6L or 7.2L engine with RPOs, MK8/MK9, remove the transmission support bolts and washers.

    44. Object Number: 791472 Size: SH
  44. If equipped with RPOs, MS9/MT3, remove the transmission support nuts, washers, and spacers.

    45. Object Number: 796487 Size: SH
  45. If equipped with the SAE number 2 flywheel housing, remove the transmission bolts and exhaust manifold front pipe bracket.

    46. Object Number: 796608 Size: SH
  46. If equipped with the SAE number 2 flywheel housing, remove the transmission bolts.

    47. Notice: When removing the transmission, do not allow the weight of the transmission to hang on the clutch disc hub. The clutch disc will become distorted and seriously affect the operation of the clutch.

  47. Move the transmission straight back from the engine, keep the mainshaft in alignment with the clutch disc hub.
  48. When the transmission is free from the engine, lower and remove the transmission.

Installation Procedure

    Object Number: 199880 Size: SH
  1. Shift the transmission into high gear.
  2. With the transmission mounted to a suitable dolly, move the transmission into position under the vehicle.
  3. Rotate the output shaft to align the main drive gear shaft with the clutch disc hub.
  4. Move the transmission forward, guiding the main drive gear shaft into the clutch disc hub.
  5. Install the transmission.
    6. • Avoid springing the clutch when installing the transmission.
    • Do not allow the transmission to drop or hang unsupported in the splined hub of the clutch disc.

    Object Number: 796608 Size: SH
  6. If equipped with the SAE number 2 flywheel housing, install the transmission bolts.

    7. Object Number: 796487 Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  7. If equipped with the SAE number 2 flywheel housing, install the exhaust manifold front pipe bracket and transmission bolts.

    8. Tighten
    Tighten the transmission bolts to 50 N·m (37 lb ft).


    Object Number: 791472 Size: SH
  8. If equipped with RPOs, MS9/MT3, install the transmission spacers, washers, and support nuts.

    9. Tighten
    Tighten the nuts to 163 N·m (120 lb ft).


    Object Number: 791471 Size: SH
  9. If equipped with the 6.6L or 7.2L engine with RPOs, MK8/MK9, install the transmission support bolts and washers.

    10. Tighten
    Tighten the bolts to 195 N·m (144 lb ft).


    Object Number: 792322 Size: SH
  10. If equipped with the apron-type flywheel housing, install the flywheel housing bolts.

    11. Tighten
    Tighten the bolts to 67 N·m (49 lb ft).


    Object Number: 792316 Size: SH
  11. If equipped with a apron-type flywheel housing, install the clutch fork return spring bracket, caution tag, and housing cover extension bolts.

    12. Tighten
    Tighten the bolts to 43 N·m (32 lb ft).


    Object Number: 792320 Size: SH
  12. If equipped with the apron-type flywheel housing, install the flywheel housing cover and bolts.

    13. Tighten
    Tighten the bolts to 12 N·m (106 lb in).

  13. If equipped, remove the protective cover over the PTO opening. Install the PTO and controls.
  14. Install the propeller shaft. Refer to One-Piece Propeller Shaft Replacement , Two-Piece Propeller Shaft Replacement , or Three-Piece Propeller Shaft Replacement in Propeller Shaft.

    15. Object Number: 796486 Size: SH
  15. If equipped with the 6.6L or 7.2L engine with RPO K40, perform the following:
    16. • Install the exhaust manifold front pipe.
    • Install the U-bolt and nuts.

    Tighten
    Tighten the nuts to 24 N·m (18 lb ft).

    • Tighten the exhaust manifold front pipe clamp nut.

    Tighten
    Tighten the nut to 10 N·m (89 lb in).


    Object Number: 796485 Size: SH
  16. If equipped with the 6.6L or 7.2L engine without PRO K40, perform the following:
    17. • Install the exhaust manifold front pipe.
    • Install the U-bolt and nuts.

    Tighten
    Tighten the nuts to 24 N·m (18 lb ft).

    • Install the exhaust manifold front pipe clamp nut.

    Tighten
    Tighten the nut to 10 N·m (89 lb in).


    Object Number: 796538 Size: SH
  17. If equipped with the 6.6L or 7.2L engine, tighten the band clamp (2) joining the exhaust manifold front (3), and rear (1) pipes.
  18. If equipped with the 8.1L engine, install the muffler. Refer to Muffler Replacement in Engine Exhaust.

    19. Object Number: 790997 Size: SH
  19. Connect the engine harness electrical connector to the transmission connector (1) typical.

    20. Object Number: 793697 Size: SH
  20. Install and position the clutch cable bracket and cable.
  21. Install the clutch cable bracket bolts and washers.

    22. Tighten
    Tighten the bolts to 93 N·m (69 lb ft).


    Object Number: 792233 Size: SH
  22. If equipped with the 8.1L engine and RPOs MM7/MNC/MPU/MSC/MSG and MPJ, install the cable nuts (2) and retainer (1).

    23. Object Number: 793699 Size: SH
  23. Install and position the clutch cable bracket and cable.
  24. Install the clutch cable bracket bolts and washers.

    25. Tighten
    Tighten the bolts to 93 N·m (69 lb ft).


    Object Number: 792046 Size: SH
  25. If equipped with the 6.6L or 7.2L engines and RPOs MK0/ML0/MM7/MNC and MPU, install the clutch cable retainer (3).
  26. Install the adjustment rod swivel (1) from the lever.

    27. Object Number: 793700 Size: SH
  27. Install and position the clutch cable bracket and cable.
  28. Install the clutch cable bracket bolts.

    29. Tighten
    Tighten the bolts to 36 N·m (27 lb ft).


    Object Number: 792044 Size: SH
  29. If equipped with the 6.6L engine and RPOs MTD/MK8/MK9 and MWW, install the adjustment rod swivel (5) to the lever.
  30. Install the clutch cable retainer (1).

    31. Object Number: 792043 Size: SH
  31. If equipped with the 6.6L or 7.2L engines and RPOs MUT/MS9/MT3, install and position the clutch cable bracket and cable.
  32. Install the clutch cable bracket nuts and washers.

    33. Tighten
    Tighten the nuts to 36 N·m (27 lb ft).

  33. Install the adjustment rod swivel (5) to the lever.
  34. Install the clutch cable retainer (1).

    35. Object Number: 793696 Size: SH
  35. Install and position the clutch cable bracket and cable.
  36. Install the clutch cable bracket nuts and washers.

    37. Tighten
    Tighten the nuts to 23 N·m (17 lb ft).


    Object Number: 792042 Size: SH
  37. If equipped with the 7.2L engine and RPOs MS9/MT3, install the adjustment rod swivel (5) to the lever.
  38. Install the clutch cable retainer (1).

    39. Object Number: 792170 Size: SH
  39. If equipped with the 6.6L or 7.2L engine, and RPOs M69/MK8/MK9 and MWW, install the clutch return spring to the bracket and cable swivel.

    40. Object Number: 792169 Size: SH
  40. If equipped with the 6.6L or 7.2L engine, and RPOs MUT/MS9/MT3/MK0/ML0, install the clutch return spring to the bracket and lever.

    41. Object Number: 792167 Size: SH
  41. If equipped with RPOs MWW/MWX, install the clutch return spring to the bracket and fork.
  42. Install the transmission air shift harness. Refer to Transmission Air Shift Harness Replacement .
  43. Install the control lever and/or boot. Refer to Control Lever and/or Boot Replacement .
  44. Fill the transmission fluid. Refer to Transmission Oil Changing .

    45. Object Number: 204729 Size: SH
  45. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  46. Adjust the clutch cable. Refer to Clutch Control Cable Adjustment in Clutch.