GM Full-Size Trucks 1988-1998 Repair Information

Transmission

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REMOVAL & INSTALLATION



See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Use guide pins when removing and installing the transmission



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the transmission mounting-85mm 5-speed shown, others similar

  1. Place the transmission in third or fourth gear.
  2.  
  3. Jack up your vehicle and support it with jackstands.
  4.  
  5. Drain the transmission.
  6.  
  7. Unplug the speedometer cable or Vehicle Speed Sensor (VSS) connector, back-up lamp wire and any other wires that would interfere with transmission removal.
  8.  
  9. Remove the gearshift lever. Plug the opening to keep out dirt.
  10.  
  11. Remove driveshaft after making the position of the shaft to the flange.
  12.  
  13. On 4WD models, remove the transfer case.
  14.  
  15. If necessary, remove the parking brake and controls.
  16.  
  17. Remove the exhaust pipes.
  18.  
  19. If equipped, remove the clutch slave cylinder and position it aside.
  20.  
  21. Position a transmission jack or its equivalent under the transmission to support it.
  22.  
  23. Remove the crossmember. Visually inspect to see if other equipment, brackets or lines must be removed to permit removal of transmission.
  24.  

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. On NVG 4500 models, unbolt the transmission-to-bell housing bolts.
  4.  
  5. On all except the NVG 4500 models, remove the top two transmission-to-housing bolts and insert two guide pins.
  6.  

The use of guide pins will not only support the transmission but will 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 that will receive 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. On all except the NVG 4500 models, remove the 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:

Installation is the reverse of removal but please note the following important steps.

  1. Make sure the transmission is in third or fourth gear. On NVG transmissions, place the transmission in Neutral.
  2.  
  3. Coat the input shaft splines with high temperature grease.
  4.  
  5. On all except the NVG 4500 models, install the guide pins in the top 2 bolt holes.
  6.  
  7. On NVG 4500 models, install the transmission-to-housing bolts.
  8.  


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. On all except the NVG 4500 models, tighten the transmission-to-engine bolts to 35 ft. lbs. (47 Nm). On NVG 4500 models tighten transmission-to-housing bolts to 74 ft. lbs. (100 Nm).
  2.  

 
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