GM Astro/Safari 1985-1996 Repair Guide

Transmission

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REMOVAL & INSTALLATION



The following procedures require the use of the Torque Converter Holding tool No. J-21366 or equivalent.

The manufacturer recommends that you drain the transmission fluid before attempting to remove the transmission assembly from the vehicle. The major reason for this is that depending on the condition of the transmission's seals and how the transmission is manipulated during removal, there is a good chance that the fluid will spill causing quite a mess. Keep in mind that in almost all instances, the transmission dipstick tube must be removed from the housing before the transmission can be removed from the vehicle. This provides a great escape route for fluid unless it can be thoroughly and safely plugged for the duration of the procedure. The bottom line is that you will have to make up your own mind.

If you decide to drain the fluid from a transmission that you are also planning on returning to service, it may be a good idea to drive the vehicle and thoroughly warm the fluid before draining. This will assure you the best fluid change possible.

THM 700 R-4 (4L60) Transmission

See Figures 1, 2, 3, 4 and 5



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Fig. Fig. 1: Exploded view of the speedometer cable assembly-early model THM 700-R4 (4L60) only



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Fig. Fig. 2: Automatic transmission support brackets-2.5L engine



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Fig. Fig. 3: Automatic transmission support brackets-4.3L engine



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Fig. Fig. 4: Exploded view of the transmission mount assembly

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Remove the engine cover from the passenger compartment for access. For details, please refer to General Information & Maintenance of this guide.
  4.  
  5. Remove the air cleaner for access, then disconnect the Throttle Valve (TV) cable from the throttle lever.
  6.  
  7. Raise and support the front of the vehicle safely using jackstands.
  8.  
  9. Drain the transmission fluid by removing the pan.
  10.  
  11. Disconnect the shift linkage from the transmission assembly.
  12.  
  13. Matchmark and remove the driveshaft from the vehicle. On All Wheel Drive (AWD) vehicles, the front driveshaft should be removed as well.
  14.  
  15. Disconnect the support bracket at the catalytic converter along with any other components which must be removed for clearance.
  16.  
  17. Support the transmission or transmission and transfer case (as applicable) using a suitable floor jack.
  18.  
  19. Remove the transmission crossmember.
  20.  


WARNING
DO NOT stretch or otherwise damage any cables, wires or other components when lowering the transmission in the next step.

  1. Carefully lower the transmission in order to provide the necessary clearance to reach other components.
  2.  
  3. Remove the dipstick tube and seal from the transmission assembly, then cover or plug the opening to prevent dirt or contamination from entering the transmission and to minimize fluid leakage. Remember that even if you drained the transmission there is still a decent amount of the slimly fluid in the assembly and it will seep out of any opening you make during the procedure.
  4.  
  5. Disconnect the speedometer cable, on early-models or disengage speedometer harness (speed sensor) connector on late-models.
  6.  
  7. If used, disconnect the vacuum modulator line.
  8.  
  9. Disengage the electrical connectors and any electrical connector retaining clips from the transmission.
  10.  
  11. Disconnect the oil cooler lines. Immediately cap all openings in the transmission assembly and the lines to prevent excessive fluid loss or system contamination.
  12.  
  13. If equipped, remove the dampener and support.
  14.  



Click image to see an enlarged view

Fig. Fig. 5: Exploded view of the automatic transmission mounting-1985-93 vehicles shown (1994-96 similar)

  1. On AWD vehicles, check the transfer case for any wires, hoses, cables or other connections, then disengage them and position aside.
  2.  

Before removal, note the position of the transmission support braces as they must be reinstalled in their original positions.

  1. Remove the transmission support braces (at the torque converter cover).
  2.  
  3. Remove the torque converter cover, then matchmark the flexplate to the torque converter; re-aligning the marks during installation will maintain the original balance.
  4.  
  5. Remove the torque converter-to-flywheel bolts and slide the converter back into the transmission.
  6.  
  7. Place a block of wood and a jackstand under the rear of the engine and support it.
  8.  
  9. Remove the transmission-to-engine mounting bolts. Note the location of any clips or brackets for installation purposes, then position them aside.
  10.  
  11. With the transmission still supported by the first floor jack, carefully slide the transmission back off the locating pins. Once there is sufficient clearance, install a torque converter holding tool such as No. J-21366 or equivalent.
  12.  
  13. Carefully lower the transmission assembly from the vehicle.
  14.  

To install:
  1. Make sure the torque converter is properly seated in the transmission assembly and install the converter holding tool.
  2.  
  3. Support the transmission assembly (and transfer case on AWD vehicles) on a floor jack, then position it under the vehicle.
  4.  
  5. Carefully raise the transmission into position and remove the torque converter holding tool.
  6.  
  7. Slide the transmission straight onto the locating pins while aligning the flexplate and torque converter matchmarks which were made during removal.
  8.  

Once in position, the torque converter must be flush onto the flexplate and must be able to rotate freely by hand.

  1. Install the transmission assembly-to-engine retaining bolts along with any brackets or clips which were positioned aside during removal. Tighten the transmission retaining bolts to 55 ft. lbs. (75 Nm) for 2.5L engines or to 35 ft. lbs. (47 Nm) for 1985-90 4.3L engines or to 23 ft. lbs. (32 Nm) for 1991-92 4.3L engines.
  2.  
  3. Thread the torque converter-to-flexplate screws by hand until they are finger-tight to assure proper converter seating.
  4.  
  5. Tighten the torque converter bolts to 46 ft. lbs. (63 Nm) slowly and evenly.
  6.  
  7. Install the converter cover, carefully hooking the cover under the lip of the engine oil pan.
  8.  
  9. If equipped, install the support and dampener. Make sure the dampener is positioned 90° from the transmission's centerline.
  10.  
  11. Install the transmission support braces in the positions noted during removal.
  12.  
  13. Remove the caps or plugs, then connect the oil cooler lines to the transmission.
  14.  
  15. Connect the speedometer cable or engage the speedometer harness (speed sensor) connector, as applicable.
  16.  
  17. Engage the electrical wiring connectors to the transmission and secure any wiring clips which were removed.
  18.  
  19. Remove the cover or plug and install the dipstick tube using a new seal. Install the new seal first, then the tube.
  20.  
  21. Remove the support from the engine, then carefully raise the engine and transmission assembly fully into position.
  22.  

When raising the transmission into place, be sure NOT to pinch or damage any cables, wires or other components.

  1. Install the transmission crossmember and the transmission mount, along with any other components which were removed for clearance. Remove the floor jack.
  2.  
  3. Install the support bracket at the catalytic converter.
  4.  
  5. Align and install the driveshaft(s).
  6.  
  7. Connect the shift linkage.
  8.  
  9. Connect the TV cable to the throttle lever, then if removed for clearance, install the air cleaner.
  10.  
  11. Adjust the shift linkage and the TV cable, as necessary.
  12.  
  13. Remove the jackstands and carefully lower the vehicle.
  14.  
  15. If drained earlier, IMMEDIATELY refill the transmission using fresh fluid.
  16.  
  17. From inside the vehicle, install the engine cover.
  18.  
  19. Connect the negative battery cable.
  20.  

4L60-E Transmission

See Figures 5, 6 and 7



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of the automatic transmission mount-1993-95 vehicles and 1996 AWD vehicles



Click image to see an enlarged view

Fig. Fig. 7: Exploded view of the automatic transmission mount-1996 2WD vehicles

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Raise and support the front of the vehicle safely using jackstands.
  4.  
  5. Drain the transmission fluid by removing the pan.
  6.  
  7. Disconnect the shift linkage (1993-95 vehicles) or the shift cable (1996 vehicles) from the transmission assembly, as applicable.
  8.  
  9. Matchmark and remove the driveshaft from the vehicle. On All Wheel Drive (AWD) vehicles, the front driveshaft should be removed as well.
  10.  
  11. On 1996 vehicles, remove the transfer case and adapter from the transmission assembly. For details, please refer to the transfer case removal procedure found later in this section.
  12.  
  13. On 1993-95 vehicles, disconnect the support bracket at the catalytic converter along with any other components which must be removed for clearance.
  14.  
  15. Support the transmission or transmission and transfer case (as applicable) using a suitable floor jack.
  16.  
  17. On 1996 vehicles, remove the 2 front torsion bars. For details, please refer to Suspension & Steering of this guide.
  18.  
  19. On 1994-95 vehicles, unload the torsion bars. For details, please refer to Suspension & Steering of this guide.
  20.  
  21. On 1994-96 vehicles, remove the rear transmission mount.
  22.  
  23. On 1993-95 vehicles, remove the transmission crossmember.
  24.  


WARNING
DO NOT stretch or otherwise damage any cables, wires or other components when lowering the transmission in the next step.

  1. Carefully lower the transmission in order to provide the necessary clearance to reach other components.
  2.  
  3. Remove the dipstick tube and seal from the transmission assembly, then cover or plug the opening to prevent dirt or contamination from entering the transmission and to minimize fluid leakage. Remember that even if you drained the transmission there is still a decent amount of the slimly fluid in the assembly and it will seep out of any opening you make during the procedure.
  4.  
  5. Disengage speedometer harness (speed sensor) connector.
  6.  
  7. Disengage the electrical connectors and any electrical connector retaining clips from the transmission.
  8.  
  9. Disconnect the oil cooler lines. Immediately cap all openings in the transmission assembly and the lines to prevent excessive fluid loss or system contamination.
  10.  
  11. On 1993 AWD vehicles, check the transfer case for any wires, hoses, cables or other connections, then disengage them and position aside.
  12.  

On vehicles so equipped, before removal of the transmission support braces, note the brace positioning as they must be reinstalled in their original positions.

  1. On 1993-95 vehicles, remove the transmission support braces (at the torque converter cover).
  2.  
  3. On 1996 vehicles, remove the starter motor assembly from the engine.
  4.  
  5. Remove the torque converter cover, then matchmark the flexplate to the torque converter; re-aligning the marks during installation will maintain the original balance.
  6.  
  7. Remove the torque converter-to-flywheel bolts and slide the converter back into the transmission.
  8.  
  9. Place a block of wood and a jackstand under the rear of the engine and support it.
  10.  
  11. Remove the transmission-to-engine mounting bolts. Note the location of any clips or brackets for installation purposes, then position them aside.
  12.  
  13. With the transmission still supported by the first floor jack, carefully slide the transmission back off the locating pins., Once there is sufficient clearance, install a torque converter holding tool such as No. J-21366 or equivalent.
  14.  
  15. Carefully lower the transmission assembly from the vehicle.
  16.  

To install:
  1. Make sure the torque converter is properly seated in the transmission assembly and install the converter holding tool.
  2.  
  3. Support the transmission assembly (and the transfer case if it was removed with the transmission earlier AWD vehicles) on a floor jack, then position it under the vehicle.
  4.  
  5. Carefully raise the transmission into position and remove the torque converter holding tool.
  6.  
  7. Slide the transmission straight onto the locating pins while aligning the flexplate and torque converter matchmarks which were made during removal.
  8.  

Once in position, the torque converter must be flush onto the flexplate and must be able to rotate freely by hand.

  1. Install the transmission assembly-to-engine retaining bolts along with any brackets or clips which were positioned aside during removal. Tighten the transmission retaining bolts to 23 ft. lbs. (32 Nm).
  2.  
  3. Thread the torque converter-to-flexplate screws by hand until they are finger-tight to assure proper converter seating.
  4.  
  5. Tighten the torque converter bolts to 46 ft. lbs. (63 Nm) slowly and evenly.
  6.  
  7. Remove the jackstand which was positioned to support the engine.
  8.  
  9. Install the converter cover. On most models the cover must be carefully hooked under the lip of the engine oil pan during installation.
  10.  
  11. On 1996 models, install the starter motor assembly.
  12.  
  13. On 1993-95 models, install the transmission support braces in the positions noted during removal.
  14.  
  15. On 1993 AWD vehicles, position and engage any wires, cables or other connections to the transfer case.
  16.  
  17. Remove the caps or plugs, then connect the oil cooler lines to the transmission.
  18.  
  19. Engage the speedometer harness (speed sensor) connector.
  20.  
  21. Engage the electrical wiring connectors to the transmission and secure any wiring clips which were removed.
  22.  
  23. Remove the cover or plug and install the dipstick tube using a new seal. Install the new seal first, then the tube.
  24.  
  25. Carefully raise the engine and transmission assembly fully into position.
  26.  

When raising the transmission into place, be sure NOT to pinch or damage any cables, wires or other components.

  1. On 1993-95 vehicles:
    1. Install the transmission crossmember and the transmission mount, along with any other components which were removed for clearance.
    2.  
    3. Remove the floor jack.
    4.  
    5. On 1994-95 vehicles, load the torsion bars.
    6.  
    7. Install the support bracket at the catalytic converter.
    8.  

  2.  
  3. On 1996 vehicles:
    1. Install the transmission mount, then remove the floor jack.
    2.  
    3. On AWD vehicles, install the transfer case and adaptor.
    4.  

  4.  
  5. Align and install the driveshaft(s). On AWD vehicles, install the rear driveshaft first.
  6.  
  7. On 1996 vehicles, install the front torsion bars.
  8.  
  9. Connect the shift linkage or cable, as applicable and adjust, as necessary.
  10.  
  11. Remove the jackstands and carefully lower the vehicle.
  12.  
  13. If drained earlier, IMMEDIATELY refill the transmission using fresh fluid.
  14.  
  15. Connect the negative battery cable.
  16.  

 
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