GM Full-Size Trucks 1980-1987 Repair Guide

Adjustments

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BAND ADJUSTMENT



No band adjustments are necessary or possible on Turbo Hydra-Matic transmissions; they use clutches instead of bands.

SHIFT LINKAGE ADJUSTMENT



See Figures 1 and 2

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Fig. Fig. 1: Turbo Hydra-Matic shift linkage 1980-81



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Fig. Fig. 2: 1982-87 Turbo Hydra-Matic shift linkage

1980-81
  1. The shift tube and lever assembly must be free in the mast jacket.
  2.  
  3. Lift the selector lever toward the steering wheel and allow the selector lever to be positioned in Drive by the detent. Do not use the selector lever pointer as a reference.
  4.  
  5. Release the selector lever. The lever should not be able to go into Low unless the lever is lifted.
  6.  
  7. Lift the selector lever toward the steering wheel and allow the lever to be positioned in Neutral by the transmission detent.
  8.  
  9. Release the selector lever. The lever should not be able to engage Reverse unless the lever is lifted. A properly adjusted linkage will prevent the lever from moving beyond both the Neutral and Drive detents unless the lever is lifted.
  10.  
  11. If adjustment is required, remove the screw and spring washer from the swivel.
  12.  
  13. Set the transmission lever in Neutral by moving it counterclockwise to L and then three detents clockwise to Neutral.
  14.  
  15. Put the transmission selector lever in Neutral as determined by the mechanical stop in the steering column.
  16.  
  17. Do not use the pointer to determine these positions.
  18.  
  19. Assemble the swivel spring and washer to the lever and tighten to 20 ft. lbs.
  20.  
  21. Readjust the Neutral safety switch if necessary.
  22.  
  23. Check the operation. With the key in RUN, and the transmission in Reverse, be sure that the key cannot be removed and the steering wheel is not locked.
  24.  

With the key in LOCK and the shift lever in PARK, be sure that the key can be removed, the steering wheel is locked, and that the transmission remains in PARK when the steering column is locked.

Any inaccuracies in the above adjustments may result in premature transmission failure, due to operation of the transmission with the controls not in the full detent. Partial engagement of clutches and other internal parts will result in transmission failure after only a few miles.

1982-87
  1. Set the transmission lever A in the neutral position by moving it clockwise to the Park detent, then counterclockwise two detents to Neutral.
  2.  
  3. Set the column shift lever to the Neutral gate notch, by rotating it until the shift lever drops in the Neutral gate. Do not use the indicator pointer as a reference to position the shift lever, as this will not be accurate.
  4.  
  5. Attach rod C to the transmission shaft assembly as shown.
  6.  
  7. Slide the swivel and clamp onto rod C and align it with the column shift lever. Complete the attachment.
  8.  
  9. Hold the column lever against the Neutral stop on the Park position side. Tighten the nut.
  10.  

THROTTLE VALVE CABLE ADJUSTMENT



See Figure 3

  1. With the engine stopped, move the slider back through the fitting in the direction away from the throttle body until the slider stops against the fitting.
  2.  
  3. Release the readjust tab.
  4.  
  5. Open the throttle lever to the "full throttle stop" position to automatically adjust the cable. Release the lever.
  6.  



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Fig. Fig. 3: Turbo Hydra-Matic T.V. cable (self-adjusting)

DETENT CABLE ADJUSTMENT



With the snap-lock disengaged from the bracket, position the carburetor at the wide open throttle position. Push the snap-lock downward until the top is flush with the rest of the cable.

DETENT SWITCH ADJUSTMENT



See Figure 4

  1. Install the detent switch as shown.
  2.  
  3. After installing the switch, press the switch plunger as far forward as possible. This will preset the switch for adjustment. The switch will automatically adjust itself with the first wide open throttle application of the accelerator pedal.
  4.  



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Fig. Fig. 4: Detent switch

 
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