GM Full-Size Trucks 1980-1987 Repair Guide

Manual Transmission

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REMOVAL & INSTALLATION2-Wheel Drive



See Figures 1, 2 and 3

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Fig. Fig. 1: Transmission to bellhousing mounting, manual transmissions



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Fig. Fig. 2: Transfer case mounting, 205 series



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Fig. Fig. 3: Transfer case mounting, 208 series

3-SPEED AND 4-SPEED
  1. Jack up your vehicle and support it with jackstands.
  2.  
  3. Drain the transmission.
  4.  
  5. Disconnect the speedometer cable, and back-up lamp wire at transmission.
  6.  
  7. Disconnect the shift control lever or shift control from the transmission. On 4-speeds transmissions, remove the gearshift lever by pressing down firmly on the slotted collar plate with a pair of channel lock pliers and rotating counterclockwise. Plug the opening to keep out dirt.
  8.  
  9. Remove the driveshaft after marking the position of the shaft to the flange.
  10.  
  11. Position a transmission jack or its equivalent under the transmission to support it.
  12.  
  13. Remove the crossmember. Visually inspect to see if other equipment, brackets or lines, must be removed to permit removal of transmission.
  14.  

Mark position of crossmember when removing to prevent incorrect installation. The tapered surface should face the rear.

  1. Remove the flywheel housing underpan.
  2.  
  3. Remove the top two transmission to housing bolts and insert two guide pins.
  4.  

The use of guide pins will help support the transmission and also prevent damage to the clutch disc. Guide pins can be made by taking two bolts, the same as those just removed only longer, and cutting off the heads. Cut a slot in the head so the bolt can be turned with a screwdriver. Be sure to support the clutch release bearing and support assembly during removal of the transmission. This will prevent the release bearing from falling out of the flywheel housing.

  1. Remove two remaining bolts and slide transmission straight back from engine. Use care to keep the transmission drive gear straight in line with clutch disc hub.
  2.  
  3. Remove the transmission from beneath your vehicle.
  4.  

To install:
  1. Install the transmission into the vehicle, using care when guiding assembly over the guide pins. Install a few mounting bolts to hold transmission in position. If you have a problem installing the transmission into position, place the transmission in gear and rotate transmission flange or output yoke to aid entry of main drive gear into disc's splines. Make sure the clutch release bearing is in position.
  2.  


WARNING
Do not force the transmission into the clutch disc hub. Do not let the transmission hang unsupported in the splined portion of the clutch disc.

  1. Install the remaining mounting bolts. Remember to remove the guide pins and install the appropriate mounting bolts. Once all the mounting bolts are installed, torque the bolts to 75 ft. lbs.
  2.  
  3. Install the remaining components by reversing the removal procedures listed above.
  4.  

4-Wheel Drive

3-SPEED
  1. Jack up the vehicle and support it on jackstands. Remove the skid plate, if so equipped.
  2.  
  3. Drain the transmission and transfer case. Remove the speedometer cable and the TCS switch, if so equipped, from the side of the transmission.
  4.  
  5. Disconnect the driveshafts and secure them out of the way.
  6.  
  7. Remove the shifter lever by removing the pivot bolt to the adapter assembly. You can then push the shifter up out of the way.
  8.  
  9. Remove the bolts attaching the strut to the right side of the transfer case and the rear of the engine, and remove the strut.
  10.  
  11. While supporting the transfer case, remove the attaching bolts to the adapter.
  12.  
  13. Remove the transfer case securing bolts from the frame and lower and remove the transfer case. (The case is attached to the right side of the frame).
  14.  
  15. Disconnect the shift rods from the transmission.
  16.  
  17. While holding the rear of the engine with a jack, remove the adapter mounting bolts.
  18.  
  19. Remove the upper transmission bolts and insert two guide pins to keep the assembly aligned. See the two wheel drive procedure for details on making these.
  20.  
  21. Remove the flywheel pan and the lower transmission bolts.
  22.  
  23. Pull the transmission and the adapter straight back on the guide pins until the input shaft is free of the clutch disc.
  24.  
  25. The transmission and the adapter are removed as an assembly. The adapter can be separated once the assembly is out.
  26.  
  27. Installation is the reverse of the removal procedure. When installing transmission, it may be necessary to place the transmission in gear and turn the output shaft to help align the clutch splines. Install and tighten the transmission mounting bolts to 75 ft. lbs. See Transfer Case installation for adapter bolt torques.
  28.  

4-SPEED
  1. Remove the shifter boots and retainers.
  2.  
  3. Remove the transmission shift lever. See the two wheel drive procedure for details on removing the lever.
  4.  

It may be necessary to remove the center floor outlet from the heater to complete the next step. Remove the center console, if so equipped.

  1. Remove the transmission cover after releasing the attaching screws. It will be necessary to rotate the cover 90 degrees to clear the transfer case shift lever.
  2.  
  3. Disconnect the transfer case shift lever link assembly and the lever from the adapter. Remove the skid plate, if any.
  4.  
  5. Remove the back-up light, the TCS switch, and the speedometer cable from the transmission.
  6.  
  7. Raise and support the truck with jackstands. Support the engine. Drain the transmission and the transfer case. Detach both driveshafts and secure them out of the way.
  8.  
  9. Remove the transmission-to-frame bolts. To do this, it will be necessary to open the locking tabs. Remove the transfer case-to-frame bracket bolts.
  10.  
  11. While supporting the transmission and transfer case, remove the crossmember bolts and the crossmember. It will be necessary to rotate the crossmember to remove it from the frame.
  12.  
  13. Remove the lower clutch housing cover.
  14.  

On V8 engines it is necessary to remove the exhaust crossover pipe.

  1. Remove the transmission-to-clutch housing bolts. Remove the upper bolts first and install guide pins. See the two wheel drive procedure for details.
  2.  
  3. Slide the transmission back until the input shaft clears the clutch assembly and then lower the unit.
  4.  
  5. The transfer case and transmission is installed as an assembly. Put the transmission in gear and turn the output shaft to align the clutch splines. Install the transmission mounting bolts and torque them to 75 ft. lbs.
  6.  

 
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