GM Full Size Vans 1967-1986 Repair Guide

Manual Transmission Assembly

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REMOVAL & INSTALLATION



1967 Models
  1. Drain the lubricant from the transmission.
  2.  
  3. Remove the driveshaft.
  4.  
  5. Remove the screws holding the steering jacket grommet to the floor and slide the grommet up the jacket out of the way.
  6.  
  7. Remove the accelerator pedal and floor mat.
  8.  
  9. Remove the transmission cover and the floor pans (if equipped).
  10.  
  11. Disconnect the speedometer cable at the transmission rear bearing retainer.
  12.  
  13. Remove the top 2 screws attaching the transmission the bellhousing. Insert 2 guide pins in these holes. They will support the weight of the transmission and keep it level while it is being removed.
  14.  
  15. Remove the flywheel underpan and remove the lower screws attaching the transmission to the bellhousing.
  16.  
  17. Slide the transmission straight back on the guide pins until the mainshaft is free of the splines in the clutch disc.
  18.  
  19. Remove the transmission from the vehicle.
  20.  
  21. Installation is the reverse of removal. Fill the transmission with the specified amount and type of fluid. Road test the vehicle to be sure that the transmission and clutch operate properly.
  22.  

1968-70 Models
  1. Drain the lubricant from the transmission.
  2.  
  3. Disconnect the speedometer cable.
  4.  
  5. Remove the shift controls from the transmission.
  6.  
  7. On vehicles with the 4-speed transmission, remove the floor mat, transmission floor pan cover and place the transmission gearshift in Neutral. Remove the transmission gearshift lever and cover.
  8.  
  9. Place a clean cloth over the opening in the side of the 4-speed transmission.
  10.  
  11. Disconnect the backup light switch.
  12.  
  13. Disconnect the driveshaft and remove it.
  14.  
  15. Support the transmission with a suitable jack.
  16.  
  17. Place a protective shield between the radiator and fan.
  18.  
  19. Support the engine with a floor jack.
  20.  
  21. Remove the engine rear mount-to-transmission attaching bolts.
  22.  
  23. Carefully lower both the engine and transmission to clear the support bracket.
  24.  
  25. Visually, make sure that all necessary parts have been disconnected or removed.
  26.  
  27. Remove the flywheel housing underpan and the mounting bolts from the transmission.
  28.  
  29. Support the clutch release bearing to prevent its falling from the flywheel housing when the transmission is removed.
  30.  
  31. Move the transmission assembly straight out of the bellhousing. Be sure that it is supported firmly to be sure that the clutch is not damaged.
  32.  
  33. Installation is the reverse of removal. Apply a very light coating of high temperature grease to the mainshaft to be sure that the clutch and transmission mainshaft slide freely.
  34.  
  35. Tighten the flywheel housing-to-transmission mounting nuts to 40-50 ft. lbs. (54-67 Nm). Tighten the rear engine mount-to-bracket nuts to 55-75 ft. lbs. (74-101 Nm). Fill the transmission with lubricant. Road test the vehicle.
  36.  

1971-86 Models
  1. Raise and support the van.
  2.  
  3. Drain the transmission. The 1976-80 Tremec top cover transmission is drained by removing the lower case to extension housing bolt.
  4.  
  5. Disconnect the speedometer cable, back-up light and TCS switch.
  6.  
  7. Remove the shift controls from the transmission.
  8.  
  9. Disconnect the driveshaft and remove it from the vehicle.
  10.  
  11. Support the transmission with a floor jack.
  12.  
  13. Inspect the transmission to be sure that all necessary components have been removed or disconnected.
  14.  
  15. Mark the front of the crossmember to be sure that it is installed correctly.
  16.  
  17. Support the clutch release bearing to prevent it from falling out of the flywheel housing when the transmission is removed.
  18.  
  19. Remove the flywheel housing under pan and transmission mounting bolts.
  20.  
  21. Move the transmission slowly away from the engine, keeping the mainshaft in alignment with the clutch disc hub. Be sure that the transmission is supported.
  22.  
  23. Remove the transmission from under the vehicle.
  24.  
  25. Installation is the reverse of removal. Lightly coat the mainshaft with high temperature grease. Do not use much grease, since, under normal operation, the grease will be thrown onto the clutch, causing it to fail.
  26.  
  27. Tighten the transmission to flywheel housing bolts to 55 ft. lbs. (75 Nm) through 1972, and to 75 ft. lbs. (101 Nm) for 1973 and later. Fill the transmission with lubricant. Road test the vehicle.
  28.  

 
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