GM Full-Size Trucks 1988-1998 Repair Information

Driven Disc and Pressure Plate

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REMOVAL & INSTALLATION



See Figures 1 through 9


CAUTION
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.



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Fig. Fig. 1: Exploded view of typical clutch assembly components

Before removing the bellhousing, the engine must be supported. This can be done by placing a hydraulic jack, with a board on top, under the oil pan.

  1. Remove the slave cylinder.
  2.  
  3. Remove the transmission.
  4.  
  5. If equipped, remove the inspection cover from the clutch.
  6.  
  7. On all NVG 4500 models, remove the bellhousing.
  8.  
  9. Remove the throwout spring and fork.
  10.  
  11. Remove the ballstud from the bellhousing.
  12.  
  13. Install a pilot tool (an old input shaft makes a good pilot tool) to hold the clutch while you are removing it.
  14.  

Before removing the clutch from the flywheel, mark the flywheel, clutch cover and one pressure plate lug, so that these parts may be assembled in their same relative positions. They were balanced as an assembly.

  1. Loosen the clutch attaching bolts one turn at a time to prevent distortion of the clutch cover until the tension is released.
  2.  

  1. Remove the clutch pilot tool and the clutch from the vehicle.
  2.  
  3. Check the pressure plate and flywheel for signs of wear, scoring, overheating, etc. If the clutch plate, flywheel, or pressure plate is oil-soaked, inspect the engine rear main seal and the transmission input shaft seal, and correct leakage as required. Replace any damaged parts.
  4.  



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Fig. Fig. 2: Remove the clutch and pressure plate bolts



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Fig. Fig. 3: Remove the clutch and pressure plate assembly...



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Fig. Fig. 4: ... then separate the clutch and pressure plate



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Fig. Fig. 5: Be sure that the flywheel surface is clean, before installing the clutch

To install:
  1. On vehicles equipped with a gasoline engine, lubricate the pilot bearing with a few drops of machine oil. On vehicles equipped with diesel engines, the bearing is sealed and does not require lubrication.
  2.  
  3. Install a new pilot bearing. A brass drift or equivalent may be used to drive the bearing into place on vehicles equipped with a gasoline engine. On vehicles equipped with diesel engines, use a suitable pilot bearing driver.
  4.  
  5. Install the pressure plate in the cover assembly, aligning the notch in the pressure plate with the notch in the cover flange. Install pressure plate retracting springs, lockwashers and drive strap-to-pressure plate bolts. Tighten to 11 ft. lbs. (15 Nm). The clutch is now ready to be installed.
  6.  

The manufacturer recommends that new pressure plate bolts and washers be used.

  1. Turn the flywheel until the X mark is at the bottom.
  2.  
  3. Install the clutch disc, pressure plate and cover, using an old input shaft as an aligning tool.
  4.  
  5. Turn the clutch until the X mark or painted white letter on the clutch cover aligns with the X mark on the flywheel.
  6.  
  7. Install the attaching bolts and tighten them a little at a time in a crossing pattern until the spring pressure is taken up. On 1988-94 models, tighten the bolts to 22 ft. lbs. (30 Nm) on 4.3L, 5.0L and 5.7L engines; 32 ft. lbs. (43 Nm) on 6.2L and 6.5L engines; and 24 ft. lbs. (33 Nm) on 7.4L engines. On 1995-98 gasoline models tighten the bolts to 30 ft. lbs. (41 Nm). On 1995-98 diesel models, tighten the bolts to 25 ft. lbs. (34 Nm).
  8.  
  9. Remove the alignment tool.
  10.  
  11. Coat the rounded end of the ballstud with high temperature wheel bearing grease.
  12.  
  13. Install the ballstud in the bellhousing. Pack the ballstud from the lubrication fitting. Coat the rounded end of the ballstud with grease.
  14.  
  15. Pack the inside recess and the outside groove of the release bearing with high temperature wheel bearing grease and install the release bearing and fork.
  16.  
  17. Install the release bearing seat and spring.
  18.  
  19. Install the clutch housing. Tighten the bolts to:

    1988-90 R/V Series: 40 ft. lbs. (54 Nm)
     
    1988-90 C/K Series: 55 ft. lbs. (75 Nm)
     
    1991 Models: 31 ft. lbs. (43 Nm)
     
    1992-94 Models: 29 ft. lbs. (39 Nm)
     
    1995-98 Models: 23 ft. lbs. (31 Nm)
     

  20.  
  21. Install the transmission.
  22.  
  23. Install the inspection cover.
  24.  
  25. Install the slave cylinder. Tighten the bolt to 13 ft. lbs. (18 Nm).
  26.  
  27. Bleed the hydraulic system.
  28.  



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Fig. Fig. 6: Install a clutch alignment arbor, to align the clutch assembly during installation



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Fig. Fig. 7: Apply a thread locking agent to clutch assembly bolts



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Fig. Fig. 8: Be sure to use a torque wrench to tighten the bolts



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Fig. Fig. 9: Grease the clutch release fork ball

 
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