GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Gasoline Vehicle Transmission Adjustments

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BANDS



Powerglide and Torque Drive
LOW BAND

The low band must be adjusted at the first required fluid change or whenever there is slippage.

  1. Position the shift lever in NEUTRAL.
  2.  
  3. Remove the protective cap from the adjusting screw on the left side of the transmission.
  4.  
  5. Loosen the locknut 1 / 4 turn and hold it with a wrench during the entire adjusting procedure.
  6.  
  7. Tighten the adjusting nut to 70 inch lbs. (8 Nm), using a 7 / 32 in. Allen wrench drive.
  8.  
  9. Back off the adjusting nut exactly three turns for a band used less than 6,000 miles. Back off exactly four turns for a band used 6,000 miles or more.
  10.  
  11. Torque the locknut to 15 ft. lbs. (20 Nm) and replace the cap.
  12.  

Turbo Hydra-Matic 250
INTERMEDIATE BAND

The intermediate band must be adjusted with every required fluid change or whenever there is slippage.

  1. Position the shift lever in NEUTRAL.
  2.  
  3. Loosen the locknut on the right side of the transmission and tighten the adjusting screw to 30 inch lbs. (3.4 Nm)
  4.  
  5. Back the screw out three turns and then tighten the locknut to 15 ft. lbs. (20 Nm).
  6.  

Except Powerglide, Torque Drive and Turbo Hydra-Matic 250

There are no band adjustments possible or required for the Turbo Hydra-Matic 200, 200-4R, 350 or 400 transmissions.

TRANSMISSION SHIFT LINKAGE



Powerglide Column Shift

See Figures 1 and 2

  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 transmission detent.
  4.  
  5. Release the selector lever. The lever should be prevented from engaging 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 selector lever should not be kept from engaging REVERSE unless the lever is lifted. If the linkage is adjusted correctly, the selector lever should be prevented from moving beyond both the NEUTRAL detent and the DRIVE detent unless the lever is lifted to pass over the mechanical stop in the steering column.
  10.  

If adjustment is necessary, perform the following steps:

  1. Adjust the linkage by loosening the adjustment clamp at the cross-shaft. Place the transmission lever in DRIVE by rotating the lever counterclockwise to the LOW detent, and then clockwise one detent to DRIVE.
  2.  
  3. Place the selector lever in DRIVE and remove any free-play by holding the cross-shaft up and pulling the shift rod downward.
  4.  
  5. Tighten the clamp and check the adjustment.
  6.  

On 1969-73 cars, carry out the following additional steps:

  1. Place the shift lever in PARK and the ignition switch in LOCK . Loosen the reverse rod clamp nut. Remove any lash in the column and tighten the clamp nut.
  2.  
  3. When the selector lever is in PARK, the ignition key should move freely into LOCK . The ignition LOCK position should be obtainable only when the transmission is in PARK.
  4.  



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Fig. Fig. 1: Column shift linkage adjustment-early Powerglide



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Fig. Fig. 2: Column shift linkage adjustment-1970 and later Powerglide

Powerglide Floor Shift
1964-67 VEHICLES

See Figure 3

  1. Loosen the adjustment nuts at the swivel. Place the transmission lever in the DRIVE position by moving it counterclockwise to the LOW detent, and then clockwise one detent position to DRIVE.
  2.  
  3. Place the floorshift lever in DRIVE. Hold the floorshift unit lower operating lever for ward against the shift lever detent.
  4.  
  5. Place a 7 / 64 in. spacer between the rear nut and the swivel. Tighten the rear nut against the spacer.
  6.  
  7. Remove the spacer and tighten the front nut against the swivel, locking the swivel between the nuts.
  8.  



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Fig. Fig. 3: Floor shift linkage adjustment-1964-67 Powerglide

1968-73 VEHICLES

See Figures 4 and 5

1968 and later cars use a cable-type shift linkage.

  1. Place the shift lever in DRIVE.
  2.  
  3. Disconnect the cable from the transmission lever. Place the transmission lever in DRIVE by rotating the lever counterclockwise to the LOW detent, and then clockwise one detent to DRIVE.
  4.  
  5. Measure the distance from the rearward face of the attaching bracket to the center of the cable attaching pin. If this distance is not 5 1 / 2 in., loosen and move the cable end stud nut to obtain the correct measurement.
  6.  

1969 and later models require an additional backdrive adjustment.

  1. Place the shift lever in PARK and the ignition switch in the LOCK position.
  2.  
  3. Loosen and adjust the backdrive rod.
  4.  
  5. With the selector lever in PARK, the ignition key should move freely into the LOCK position. The ignition LOCK position should not be obtainable in any transmission position other than PARK.
  6.  



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Fig. Fig. 4: Floor shift linkage adjustment-1968-72 Powerglide



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Fig. Fig. 5: Floor shift linkage adjustment-1968-72 Powerglide

Turbo Hydra-Matic Column and Floor Shift Linkage Adjustment
VEHICLES THROUGH 1974

See Figure 6

Linkages used on Turbo Hydra-Matic transmissions are similar to those used on Powerglides. Adjustments are the same, except that the transmission lever is adjusted to DRIVE by moving the lever clockwise to the LOW detent, and then counterclockwise two detent positions to DRIVE.



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Fig. Fig. 6: Example of the column shift linkage components-Turbo Hydra-Matic transmissions

Column Shift (Except Turbo Hydra-Matic 200)

See Figure 6

  1. Loosen the swivel at the lower end of the rod that comes from the column.
  2.  
  3. On 1973 and later models, set the transmission lever in the NEUTRAL detent by turning the lever counterclockwise to the L1 detent, then clockwise three positions. On models through 1972, set the lever in the DRIVE detent by turning the lever counterclockwise to the L1 detent, then clockwise two positions.
  4.  
  5. Put the column lever in NEUTRAL for 1973 and later models, and in DRIVE for models through 1972. The important thing here is not where the indicator points but that the lever be in the correct position.
  6.  
  7. Tighten the swivel. Readjust the neutral start switch as necessary.
  8.  
  9. Check that the key cannot be removed and that the wheel is not locked with the key in RUN . Check that the key can be removed in LOCK with the lever in PARK, and that the steering wheel is locked.
  10.  

Turbo Hydra-Matic 200

See Figure 6

  1. Remove the screw and washer from the swivel assembly on the rod which activates the transmission shift lever.
  2.  
  3. Put the transmission shift lever in NEUTRAL by turning it counterclockwise to L1 detent and then clockwise three detent positions. Put the transmission selector lever in NEUTRAL as determined by the mechanical stop in the steering column assembly - do not use the indicator pointer.
  4.  
  5. Turn the swivel until it lines up directly with the hole in the shift lever, and install screw and washer. You should not have to force the transmission lever to move in either direction to install the screw.
  6.  
  7. Adjust the transmission indicator pointer and neutral start switch.
  8.  
  9. Check that the key cannot be removed from the RUN position if the transmission selector is in REVERSE and that the key can be removed with the selector in PARK. Make sure the lever will not move from PARK position with key out of ignition.
  10.  

1975-81 Cars with Cable Linkage

See Figure 7

  1. Loosen the swivel at the lower end of the rod that comes from the steering column.
  2.  
  3. Loosen the pin at the transmission end of the cable.
  4.  
  5. Set the floorshift lever in the DRIVE detent.
  6.  
  7. Set the transmission lever in the DRIVE detent by moving it counterclockwise to the L1 detent, then clockwise three detent positions.
  8.  
  9. Tighten the nut on the pin at the transmission end of the cable.
  10.  
  11. Push the floorshift lever in PARK and the ignition switch in LOCK .
  12.  
  13. Pull down lightly on the rod from the column and tighten its clamp nut.
  14.  



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Fig. Fig. 7: Floor shift linkage adjustment-1973 and later Turbo Hydra-Matic

1982 and Later Vehicles

See Figures 6 and 8

  1. Loosen the clamping screw at the shifting rod-to-equalizer lever.
  2.  
  3. Position the steering column shifting lever into the NEUTRAL position.
  4.  
  5. Set the transmission lever into the NEUTRAL position.
  6.  
  7. Finger tighten the equalizer lever clamping screw to the sifting rod.
  8.  

While performing this operation, DO NOT exert force in any direction.

  1. Tighten the equalizer clamping screw.
  2.  



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Fig. Fig. 8: Steering column shift linkage adjustment-1982 and later

THROTTLE VALVE LINKAGE



See Figure 9

1964-66 Powerglide w/V8 and 1964-73 6-Cylinder Engines
  1. Depress the accelerator pedal.
  2.  
  3. The bellcrank on 6-cylinder engines must be at the wide open throttle position.
  4.  
  5. The dash lever at the firewall must be 1 / 64 - 1 / 16 in. off its lever stop.
  6.  
  7. The transmission lever must be against the transmission internal stop.
  8.  
  9. Adjust the linkage to simultaneously obtain the conditions in Steps 1-4.
  10.  



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Fig. Fig. 9: Adjusting the throttle valve linkage

1967-73 Powerglide w/V8 Engines
  1. Remove the air cleaner assembly.
  2.  
  3. Disconnect the accelerator linkage at the carburetor.
  4.  
  5. Disconnect both return springs.
  6.  
  7. Pull the throttle valve upper rod forward until the transmission is through the detent.
  8.  
  9. Open the carburetor to the wide open throttle position. Adjust the swivel on the end of the upper throttle valve rod so that the carburetor reaches wide open throttle position at the same time that the ball stud contact the end of the slot in the upper throttle valve rod. A play of 1 / 32 in. is allowable.
  10.  

THROTTLE VALVE DETENT CABLE



Turbo Hydra-Matic 200, 250, 350
THROUGH 1972

See Figures 10, 11 and 12

These transmission utilize a downshift cable instead of a linkage rod between the carburetor and the transmission.

  1. Pry up on each side of the detent cable snap-lock with a small pry bar to release the lock. On cars equipped with a retaining screw, loosen the detent cable screw.
  2.  
  3. Squeeze the locking tabs and disconnect the snap-lock assembly from the throttle bracket.
  4.  
  5. Place the carburetor lever in the wide open throttle position. Make sure that the lever is against the wide open stop. On cars with Quadrajet carburetors, disengage the secondary lock-out before placing the lever in the wide open position.
  6.  

The detent cable must be pulled through the detent position.

  1. With the carburetor lever in the wide open position, push the snap-lock on the cable or else tighten the retaining screw.
  2.  

Do not lubricate the detent cable.



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Fig. Fig. 10: Downshift cable adjustment-Turbo Hydra-Matic 200



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Fig. Fig. 11: Detent cable adjustment-Turbo Hydra-Matic 350 (250 model similar)



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Fig. Fig. 12: Detent cable adjustment-Turbo Hydra-Matic 200, 250 and 350

1973 AND LATER

See Figure 13

On these models the T.V. cable controls line pressure, shift points, shift feel, part throttle downshifts and detent downshifts. The T.V. cable operates the throttle valve lever and bracket assembly in the control valve.

  1. Stop the engine.
  2.  
  3. Locate the TV cable adjuster near the carburetor.
  4.  
  5. Depress and hold down the metal tab of the TV cable adjuster.
  6.  
  7. Move the slider until it stops against the fitting.
  8.  
  9. Release the adjuster tab.
  10.  
  11. Turn the carburetor lever to the Full Throttle Stop position and release it.
  12.  

By turning the carburetor lever to the Full Throttle Stop, the TV cable will automatically adjust itself.



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Fig. Fig. 13: TV Detent cable adjustment-1973 and later vehicles

DETENT SWITCH ADJUSTMENT



See Figures 14, 15 and 16

Turbo Hydra-matic 400 transmissions are equipped with an electrical detent, or downshift switch operated by the throttle linkage.

1968 Vehicles
  1. Place the carburetor lever in the wide open position.
  2.  
  3. Position the automatic choke so that it is off.
  4.  
  5. Fully depress the switch plunger.
  6.  
  7. Adjust the switch mounting to obtain a distance of 0.05 in. (1.27mm) between the switch plunger and the throttle lever paddle.
  8.  



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Fig. Fig. 14: Adjusting the detent switch-1968-72 Turbo Hydra-Matic 400



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Fig. Fig. 15: Detent (downshift) switch wiring



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Fig. Fig. 16: Adjusting the detent switch-1969-78 THM 400

1969-78 Vehicles
  1. Pull the detent switch driver rearward until the hole in the switch body aligns with the hole in the driver. Insert a #42 wire gauge (approximately 0.094 in. diameter pin) through the aligned holes to hold the driver in position.
  2.  
  3. Loosen the mounting bolt.
  4.  
  5. Press the switch plunger as far forward as possible. This will preset the switch for adjustment, which will occur on the first application of wide open throttle.
  6.  
  7. Tighten the mounting bolt and remove the pin.
  8.  

 
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