GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC C-Series Medium Duty Truck B7 🢒 Transmission/Transaxle 🢒 Manual Transmission - Medium Duty 🢒 Transmission Replacement

Removal Procedure

    Object Number: 199865 Size: MH

    Important: 

       • Remove components in order to provide clearance for transmission removal, if necessary.
       • The vehicles have either an apron clutch housing (2) or an SAE number 2 (6) type flywheel housing.
       • The apron-type clutch has a sheet metal pan which covers the entire lower portion of the clutch and flywheel. The clutch housing is not separate.
       • The SAE number 2 type flywheel housing also surrounds the flywheel. The SAE number 2 type flywheel housing uses a separate clutch housing. Transmission replacement procedures are different for each type of flywheel housing.

  1. Block the wheels of the vehicle.

    2. 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.

  2. Disconnect the negative battery cable.

    3. Object Number: 199880 Size: SH

    Important: Before you disconnect any air operated components or air lines, bleed all air pressure from the system.

    Check what type of front engine mount is used. If a single cushion center mount is used, support the engine with an overhead hoist during transmission or clutch replacement.

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

  3. Shift the transmission into neutral.
  4. Remove the air shift controls from the shift lever. Refer to Air Shift Control Valve Replacement .

    5. Object Number: 199831 Size: SH
  5. Remove the screws from the shift lever boot retainer.
  6. Remove the retainer from the shift boot.
  7. Remove the shift boot.

    8. Object Number: 199750 Size: SH
  8. For the 7.4 L remove the shift lever.
  9. Remove the clutch cable from the transmission. Refer to Clutch Assembly Adjustment .

    10. Object Number: 199737 Size: SH
  10. Remove the following components from the shift control lever:
    11. • The retainers
    • The bushings
    • The pin
  11. Remove the electric connectors, as necessary.
  12. Remove the air lines from the air shift control valve.
  13. Remove the oil from the transmission. Refer to Transmission Oil Changing .
  14. Remove the parking brake lever and controls, if used. Refer to Park Brake Cable Replacement .
  15. Remove the propeller shaft. Refer to the proper procedure:
    16. • The one piece propeller shaft:
       -  Propeller Shaft Replacement - One Piece - Flange Type
       -  Propeller Shaft Replacement - One-Piece - Yoke Type
    • The two piece propeller shaft:
       -  Propeller Shaft Replacement - Two Piece - Flange Type
       -  Propeller Shaft Replacement - Two Piece - Yoke Type
    • The three piece propeller shaft:
       -  Propeller Shaft Replacement - Three Piece - Flange Type
       -  Propeller Shaft Replacement - Three Piece - Yoke Type
  16. Remove the power take-off and controls, if used.
    17. • Place a protective cover over the opening.
    • Position a transmission dolly jack under the vehicle. Adjust the dolly jack in order to carry the weight of the transmission.
  17. Remove the power take-off and controls, if used.
    18. • Place a protective cover over the opening.
    • Position a transmission dolly jack under the vehicle. Adjust the dolly jack in order to carry the weight of the transmission.
  18. Remove the rear support, if used.

    19. 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.

  19. In order to remove the transmission from the engine (SAE number 2 flywheel housing), perform the following procedure :
    20. 19.1. If the engine rear mounting is attached to the transmission, support the engine weight with a hoist or jack.
    19.2. Adjust the transmission dolly in order to support the transmission's weight.
    19.3. Remove all bolts attaching the clutch housing to the engine flywheel housing.
    19.4. Move the transmission straight back from the engine. Keep the mainshaft in alignment with the clutch disc hub.
    19.5. When the transmission is free from the engine, lower and remove the transmission from beneath the vehicle.
  20. In order to remove the transmission from the engine (Apron-type flywheel housing), perform the following procedure:
    21. 20.1. Remove the cover from the bottom of the clutch housing (optional).
    20.2. Remove the lower transmission to flywheel housing bolts from the clutch housing.
    20.3. Remove the remaining upper attaching bolts.
    20.4. Move the transmission straight back from the engine. Keep the transmission mainshaft in alignment with the clutch disc hub.
    20.5. When the transmission is free from the engine, lower and remove the transmission from the vehicle.

Installation Procedure
  1. Shift the transmission into high gear.

    2. Object Number: 199880 Size: SH
  2. Mount the transmission on a suitable dolly and move the transmission into position under the vehicle.
  3. Rotate the output flange or yoke to align the main drive gear shaft with the clutch disc hub.

    4. 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.

  4. Move the transmission forward, guiding the main drive gear shaft into the clutch disc splines.
    5. • Avoid springing the clutch when you install the transmission.
    • Do not let the transmission drop or hang unsupported in the splined hub of the clutch disc.

    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.

  5. In order to install 2 type flywheel housing, install the bolts and washers that attach the transmission clutch housing to the transmission flywheel housing.

    6. Tighten
    Tighten all the attaching bolts to 44 N·m (32 lb ft).

  6. In order to install apron type flywheel housing, perform the following steps:
    7. 6.1. Install the upper bolts and washers that attach the transmission to the flywheel housing.
    6.2. Install the lower bolts and washers that attach the transmission to the flywheel housing.

    Tighten
    Tighten all the attaching bolts to 142 N·m (105 lb ft).

    6.3. Install the rear support, if used.
    6.4. Measure the space between the outer ends of the support beam and cushion assembly.
    6.5. Select spacers equal to this gap.
    6.6. If there is a difference in the gap between the left and right sides of the rear mounting, measure the total gap between the left and the right sides and divide by two.
    6.7. Remove the dolly.
  7. Install the power take-off and the controls, if used.
  8. Install the propeller shaft. Refer to the proper procedure:
    9. • The one piece propeller shaft:
       -  Propeller Shaft Replacement - One Piece - Flange Type
       -  Propeller Shaft Replacement - One-Piece - Yoke Type
    • The two piece propeller shaft:
       -  Propeller Shaft Replacement - Two Piece - Flange Type
       -  Propeller Shaft Replacement - Two Piece - Yoke Type
    • The three piece propeller shaft:
       -  Propeller Shaft Replacement - Three Piece - Flange Type
       -  Propeller Shaft Replacement - Three Piece - Yoke Type
  9. Remove the power take-off and controls, if used.
    10. • Place a protective cover over the opening.
    • Position a transmission dolly jack under the vehicle. Adjust the dolly jack in order to carry the weight of the transmission.
  10. Install the parking brake lever and the controls, if used. Refer to Park Brake Lever Assembly Replacement .
  11. Install the clutch cable. Refer to Clutch Assembly Adjustment .
  12. Install the electrical connectors, as necessary.
  13. Install the air lines to the transmission, as used.

    14. Object Number: 199750 Size: SH
  14. For the 7.4 L , install the shift lever.

    15. Object Number: 199737 Size: SH
  15. Install the following components to the control lever:
    16. • The pin
    • The bushings
    • The retainers
    • Apply a small amount of grease around the pin prior to installation.

    Object Number: 199831 Size: SH
  16. Install the retainer to the shift boot with screws.
  17. Install the air shift controls to the shift lever. Refer to Air Shift Control Valve Replacement .
  18. Fill the transmission with transmission oil. Refer to Transmission Oil Changing .
  19. Install the parking brake, if used. Refer to Park Brake Cable Replacement .
  20. Install the clutch cable. Refer to Clutch Assembly Adjustment .