GM Full Size Vans 1967-1986 Repair Guide

Driven Disc and Pressure Plate



The clutch driven disc may contain asbestos, which has been determined to be a cancer causing agent. Never clean clutch surfaces with compressed air! Avoid inhaling any dust from any clutch surface! When cleaning clutch surfaces, use a commercially available brake cleaning fluid.

There are two types of clutch pressure plates used, diaphragm and coil spring. In general, the larger heavy duty clutches are usually of the coil spring pressure plate type. Removal and installation details are similar for both types.

See Figures 1 through 11

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Fig. Fig. 1: Exploded view of a common diaphragm clutch

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Fig. Fig. 2: Lubrication points on the clutch throwout bearing

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Fig. Fig. 3: Remove the pressure plate bolts in an X pattern

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Fig. Fig. 4: Carefullt remove the clutch and pressure plate

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Fig. Fig. 5: View of the flywheel once the clutch assembly is removed

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Fig. Fig. 6: Be sure that the flywheel surface is clean, before installing the clutch

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Fig. Fig. 7: Check across the flywheel surface; it should be flat

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Fig. Fig. 8: Checking the pressure plate for warpage

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Fig. Fig. 9: Install a clutch alignment arbor, to align the clutch assembly during installation

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Fig. Fig. 10: Install a locking agent to the clutch assembly bolts

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Fig. Fig. 11: Be sure to use a torque wrench to tighten all bolts

Diaphragm Spring Pressure Plate
  1. Remove the transmission as previously outlined.
  3. Disconnect the fork pushrod and remove the flywheel housing. Remove the clutch throwout bearing from the fork.
  5. Remove the clutch fork by pressing it away from the ball mounting with a screwdriver until the fork snaps loose from the ball or remove the ball stud from the clutch housing.
  7. Install a pilot tool (an old mainshaft makes a good pilot tool) to hold the clutch while you are removing it.

Before removing the clutch from the flywheel, matchmark the flywheel, the clutch cover and one of the pressure plate lugs. These parts must be reassembled in their original positions as they are a balanced assembly.

  1. Loosen the clutch attaching bolts one turn at a time to prevent distortion of the clutch cover until the tension is released.
  3. Remove the clutch pilot tool and the clutch from the vehicle.

Inspect the flywheel and pressure plate for discoloration, scoring or wear marks. The flywheel can be refaced if necessary, otherwise replace the parts. Also inspect the clutch fork and throwout bearing for looseness or wear. Replace if either is evident.

To install:
  1. Install the pressure plate in the cover assembly, aligning the notch in the pressure plate with the notch in the cover flange.
  3. Install the pressure plate retracting spring, lockwashers, and the drive strap to the pressure plate bolts. Tighten to 11 ft. lbs. (14 Nm).
  5. Turn the flywheel until the X mark is at the bottom.
  7. Install the clutch disc, pressure plate and cover, using an old mainshaft as an aligning tool.
  9. Turn the clutch until the X mark on the clutch cover aligns with the X mark on the flywheel.
  11. Install the attaching bolts and tighten them a little at a time in a crisscross pattern until the spring pressure is taken up.
  13. Remove the aligning tool.
  15. Pack the clutch ball fork seat with a small amount of high temperature grease. Too much grease will cause slippage. Install a new retainer in the groove of the clutch fork, if necessary. Install the retainer with the high side up and the open end on the horizontal.
  17. If the clutch fork ball was removed, reinstall it in the clutch housing and snap the clutch fork onto the ball.
  19. Lubricate the inside of the throwout bearing collar and the throwout fork groove with a small amount of graphite grease.
  21. Install the throwout bearing.
  23. Install the flywheel housing and transmission.
  25. Further installation is the reverse of removal. Adjust the clutch linkage.

Coil Spring Pressure Plate

Basically, the same procedures apply to diaphragm clutch removal as to the coil spring clutch removal.

When loosening the clutch holding bolts, loosen them only a turn or two at a time in order to avoid bending the rim of the cover. It will be helpful to place wood or metal spacers, about 3 / 8 in. (9.5mm) thick, between the clutch levers and the cover to hold the levers down as the holding bolts are being removed or when the clutch is being removed from the engine.