GM Astro/Safari 1985-1996 Repair Guide

Slave (Secondary) Cylinder

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The slave cylinder is located on the left side of the bellhousing and controls the clutch release fork operation.

REMOVAL & INSTALLATION



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Clutch hydraulic actuating system and component mounting

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the front of the vehicle on jackstands.
  4.  
  5. Disconnect the hydraulic line from clutch master cylinder. Remove the hydraulic line-to-chassis screw and the clip from the chassis.
  6.  

Be sure to plug the line opening to keep dirt and moisture out of the system.

  1. Remove the slave cylinder-to-bellhousing nuts.
  2.  
  3. Remove the pushrod and the slave cylinder from the vehicle, then overhaul it (if necessary).
  4.  

To install:
  1. Lubricate the leading end of the slave cylinder with Girling® Rubber Lube or equivalent.
  2.  
  3. Install the pushrod and the slave cylinder into the vehicle.
  4.  
  5. Install the slave cylinder-to-bellhousing nuts.
  6.  
  7. Connect the hydraulic line to the clutch master cylinder.
  8.  
  9. Fill the master cylinder with new brake fluid conforming to DOT 3 specifications. Bleed the hydraulic system. If the front of the vehicle is still raised, keep in mind that the clutch master cylinder cannot be properly filled. Check the fluid level often, then recheck and top off once the vehicle is lowered.
  10.  
  11. Tighten the slave cylinder-to-bellhousing nuts to 10-15 ft. lbs. (14-20 Nm).
  12.  
  13. Lower the front of the vehicle, then top off the clutch master cylinder reservoir.
  14.  
  15. Connect the negative battery cable.
  16.  

OVERHAUL



See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the clutch slave cylinder assembly

  1. Remove the clutch slave cylinder from the vehicle.
  2.  
  3. Remove the shield, the pushrod and dust cover from the slave cylinder, then inspect the cover for damage or deterioration.
  4.  
  5. Remove the snapring from the end of the cylinder bore.
  6.  
  7. Using a block of wood, tap the slave cylinder on it to eject the plunger, then remove the seal and the spring.
  8.  
  9. Using clean brake fluid, clean all of the parts.
  10.  
  11. Inspect the cylinder bore and the plunger for ridges, pitting and/or scratches, the dust cover for wear and cracking; replace the parts if any of the conditions exist.
  12.  

To assemble:
  1. Use new seals and lubricate all of the parts in clean brake fluid. Install the spring, the plunger seal and the plunger into the cylinder bore, then install a new snapring.
  2.  
  3. Lubricate the inside of the dust cover with Girling® Rubber Grease or equivalent, then install it into the slave cylinder.
  4.  

Be careful not to use any lubricant that will deteriorate the rubber dust covers or seals.

  1. Install the clutch slave cylinder to the vehicle.
  2.  

BLEEDING THE HYDRAULIC CLUTCH



Bleeding air from the hydraulic clutch system is necessary whenever any part of the system has been disconnected or the fluid level (in the reservoir) has been allowed to fall so low, that air has been drawn into the master cylinder.

  1. Fill master cylinder reservoir with clean, fresh brake fluid conforming to DOT 3 specifications.
  2.  


WARNING
Never, under any circumstances, use fluid which has been bled from a system to fill the reservoir as it may be aerated, have too much moisture content and possibly be contaminated.

  1. Raise and support the front of the vehicle on jackstands.
  2.  
  3. Remove the slave cylinder attaching bolts.
  4.  
  5. Hold the slave cylinder at approximately 45° with the bleeder at its highest point. Fully depress the clutch pedal and open the bleeder screw.
  6.  
  7. Close the bleeder screw and release the clutch pedal.
  8.  
  9. Repeat the procedure until all of the air is evacuated from the system. Check and refill the master cylinder reservoir as required to prevent air from being drawn through the master cylinder.
  10.  

Never release a depressed clutch pedal with the bleeder screw open or air will be drawn into the system.

 
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