GM Firebird 1967-1981 Repair Guide

Linkage

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INSPECTION



A clutch may have all the symptoms of going bad when the real trouble lies in the linkage. To avoid the unnecessary replacement of a clutch, make the following linkage checks:

  1. Start the engine and depress the clutch pedal until it is about 1 / 2 in. from the floor mat and move the shift lever between First and Reverse (First and Second on a four-speed) several times. If this can be done smoothly without any grinding, the clutch is releasing fully. If the shifting is not smooth, the clutch is not releasing fully and adjustment is necessary.
  2.  
  3. Check the condition of the clutch pedal bushings for signs of sticking or excessive wear.
  4.  
  5. Check the throwout bearing fork for proper installation on the ball stud. The fork could possibly be pulled off the ball if not properly lubricated.
  6.  
  7. Check the cross-shaft levers for distortion or damage.
  8.  
  9. Check the car for loose or damaged motor mounts. Bad motor mounts can cause the engine to shift under acceleration and bind the clutch linkage at the cross-shaft. There must be some clearance between the cross-shaft and motor mount.
  10.  
  11. Check the throwout bearing clearance between the clutch spring fingers and the front bearing retainer on the transmission. If there is no clearance, the fork may be improperly installed on the ball stud or the clutch disc may be worn out.
  12.  

ADJUSTMENT



Only one adjustment is necessary to compensate for all normal clutch wear. Depress the clutch pedal and slowly release it. If adjusted correctly, the throwout bearing should begin to disengage the clutch diaphragm spring levers when the top of the pedal pad is 1-1 1 / 8 in. from the floor mat. The car should begin to move forward. If clutch engagement begins at a point noticeably greater than 1 1 / 8 in. from the floor mat or less than 1 in. from the floor mat, this free-play measurement must be adjusted as follows:

1967-69 Models See Figures 1 and 2

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Fig. Fig. 1: Exploded view of the clutch linkage used on 1967-68 models



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Fig. Fig. 2: Exploded view of the clutch linkage components used on 1969 models

  1. Disconnect the pedal return spring at the fork.
  2.  
  3. Hold the clutch pedal against the rubber stop and loosen the locknut.
  4.  
  5. Turn the adjusting rod out and against clutch fork until the throwout bearing lightly contacts the pressure plate fingers.
  6.  
  7. Turn the rod into the swivel 3 times and tighten the locknut.
  8.  
  9. Install the clutch spring and check pedal free-play (1-1 1 / 8 in.).
  10.  

1970-81 Models See Figures 3 and 4

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Fig. Fig. 3: Exploded view of the clutch linkage used by 1970-71 models



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Fig. Fig. 4: Exploded view of the clutch linkage used on 1972-81 models

The clutch on these models can be adjusted as outlined previously or by this alternate procedure:

  1. Disconnect the return spring at the clutch fork.
  2.  
  3. Hold the pedal against the rubber bumper on the dash brace.
  4.  
  5. Push the clutch fork so that the throwout bearing lightly contacts the pressure plate fingers.
  6.  
  7. Loosen the locknut and adjust the length of the rod so that the swivel or rod can slip freely into the gauge hole in the lever. Increase the length of the rod until all free-play is removed.
  8.  
  9. Remove the rod or swivel from the gauge hole and insert it in the lower hole on the lever. Install the retainer and tighten the locknut to 10 ft. lbs.
  10.  
  11. Install the return spring and check the free-play measurement from the floor mat to top of the pedal pad. It should measure 1-1 1 / 2 in.
  12.  

 
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