GM Corvette 1963-1982 Repair Guide

Adjustments

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LINKAGE



1963 Muncie Three-Speed Transmissions

See Figures 1 through 7

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Fig. Fig. 1: Manual transmission linkage adjustment points-1963-64 Muncie 3-speed shown



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Fig. Fig. 2: Linkage adjustment point locations-1965-68 3-speed manual transmission shown



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Fig. Fig. 3: Adjusting the linkage on a 1969 3-speed manual transmission



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Fig. Fig. 4: Fabricate an adjustment gauge out of wood



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Fig. Fig. 5: View of the 1963 Borg-Warner T-10 transmission linkage



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Fig. Fig. 6: Linkage identification-1964-77 4-speed manual transmission shown



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Fig. Fig. 7: Shift linkage adjustment specifications for 1978-81 vehicles. Note that the locating gauge is shown on the left

  1. Position both transmission side-cover selector fork levers and the shift lever in Neutral.
  2.  
  3. Attach the rod to the lever, then adjust the clevis on its opposite end until the clevis pin will freely enter the side cover lever.
  4.  
  5. Insert the pin and secure it with a cotter pin.
  6.  
  7. Position the shift lever so that it activates the first and reverse lever, but still remains in Neutral.
  8.  
  9. Attach the first/reverse shift rod to the shift lever, adjust the clevis as done with the other shift rod, and secure it to the selector lever.
  10.  
  11. Tighten the locknuts on both shift rod clevis fittings, and check the shift pattern for correct operation.
  12.  

1964-68 Three-Speed Transmissions

  1. Set the side cover selector levers in Neutral and position the shift lever in Neutral and lock it in place with a 5 / 16 in. (early models) or 41 / 64 in. (late models) locating pin.
  2.  
  3. Attach the first and reverse rod as with earlier transmissions and secure it.
  4.  
  5. Attach the second/third shift rod and attach it in the same manner.
  6.  
  7. Secure the locknuts on the clevis of each rod, then withdraw the locating pin and check the shift pattern.
  8.  

1969 Three-Speed Transmissions with Backdrive

  1. Place the ignition switch in the OFF position and the side cover selector levers in Neutral.
  2.  
  3. Position the shift lever in Neutral and secure it with a 41 / 64 in. locating gauge, between the shift lever notch and the linkage bracket.
  4.  
  5. Adjust the clevis of each rod so that they freely enter the attachment locations on their respective ends. Secure the locknuts, remove the gauge, and shift the transmission into Reverse.
  6.  
  7. Loosen the bracket assembly on the dash and allow any tension in the backdrive cable to position the bracket.
  8.  
  9. Secure the bracket and switch the key from OFF to LOCK. Binding of the key will necessitate readjustment of the interlock mechanism.
  10.  
  11. Check the shift pattern.
  12.  

1963 Borg-Warner, T-10 Four-Speed Transmissions

The illustrated wooden gauge, if made, will greatly aid in shift linkage adjustment.

  1. Put the shift lever in Neutral, install the block gauge, and remove the clevis pin from the clevis of each shift rod.
  2.  
  3. Adjust the threaded clevis until the clevis pin freely enters the holes in the clevis and the selector levers.
  4.  
  5. Secure the pins and lock the clevis securing nuts.
  6.  

Remove the gauge block and check the shift pattern. Minor adjustment of the rods may be necessary to remove all traces of shifting roughness.

1963-68 Muncie Four-Speed Transmissions

  1. Position the individual selector levers and the shift lever in Neutral.
  2.  
  3. Construct a block gauge 1 / 8 in. thick by 41 / 64 in. wide and install it in the shift lever bracket assembly.
  4.  
  5. Attach the first/second shift rod to the lever. Hold the lever against the gauge block and adjust the threaded swivel on the shift rod until the clevis pin freely enters the clevis hold and hole in selector lever. Secure the locking nuts.
  6.  
  7. Repeat the procedure and attach the reverse rod to the selector lever, and the bracket lever. Repeat again to adjust the third/fourth rod.
  8.  
  9. Remove the block gauge, check the pattern for correct shifting, and adjust, if necessary, to correct minor shifting, and adjust, if necessary, to correct minor shifting difficulties.
  10.  
  11. An alternate clevis pin hole is placed on each selector lever below the regular pattern hole. This lower placement of the shift rods will tighten the pattern and permit shorter shift lever movement for a faster shift. Bear in mind, however, that this adjustment will increase the shifting effort.
  12.  

1969-77 Transmissions

  1. Place the ignition switch in LOCK.
  2.  
  3. Loosen the locknuts at the swivels on the shift rods and reverse control rod.
  4.  
  5. Set the transmission shift levers in neutral positions.
  6.  
  7. Shift the lever into neutral. Insert a locating gauge, 1 / 8 thick X 41 / 64 wide X 3 in. long, into the control lever bracket assembly.
  8.  
  9. Hold each lever against the gauge and adjust in turn. Tighten the shift rod locknuts and remove the gauge.
  10.  
  11. Loosen the interlock bracket assembly bolts at the bottom of the steering column. Make sure that the bracket is not stuck to the dash and then tighten the bracket again.
  12.  
  13. Move the ignition key through OFF and LOCK positions. If there is any binding, readjust the interlock linkage.
  14.  

1978-81 Transmissions

  1. Place the shift lever in the Neutral position.
  2.  
  3. Raise the vehicle and support it safely with jackstands.
  4.  
  5. Disconnect the shift rods from the transmission levers.
  6.  
  7. Perform this step for each of the transmission levers individually: Rotate the transmission lever counterclockwise (forward detent position) then turn it back until the first detent is felt (Neutral position). This is done to verify that each transmission lever is in its Neutral position.
  8.  
  9. Fabricate a locating gauge according to the accompanying illustration. Insert the locating gauge into the notch of the shifter housing and through the shift levers to properly align the levers. It may be necessary to move the shift lever(s) to install the locating gauge completely.
  10.  
  11. Loosen the locknuts of the 3-4 shift rod swivel (front of transmission side cover) and turn the swivel as necessary to allow the swivel to easily enter the hole of the 3-4 transmission lever. Apply a slight rearward pressure to the transmission lever and tighten the swivel locknuts. Attach the shift rod to the transmission lever with the retaining clip (and washer, if used).
  12.  
  13. Repeat step 6 for the 1-2 and reverse shift rods.
  14.  
  15. Remove the locating gauge and lower the vehicle.
  16.  

After the adjustments have been made, the centerlines of the shifter levers must be aligned to prevent rubbing.

 
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