Jeep Wrangler/YJ 1987-1995 Repair Guide

Wheel Cylinders

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

OVERHAUL



See Figures 1 through 10



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Fig. Fig. 1: Remove the outer boots from the wheel cylinder



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Fig. Fig. 2: Compressed air can be used to remove the pistons and seals



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Fig. Fig. 3: Remove the pistons, cup seals and spring from the cylinder



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Fig. Fig. 4: Use brake fluid and a soft brush to clean the pistons ...



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Fig. Fig. 5: ... and the bore of the wheel cylinder



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Fig. Fig. 6: Once cleaned and inspected, the wheel cylinder is ready for assembly



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Fig. Fig. 7: Lubricate the cup seals with brake fluid



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Fig. Fig. 8: Install the spring, then the cup seals in the bore



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Fig. Fig. 9: Lightly lubricate the pistons, then install them



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Fig. Fig. 10: The boots can now be installed over the wheel cylinder ends

Wheel cylinder rebuilding kits are available for reconditioning wheel cylinders. The kits usually contain new cup springs, cylinder cups and in some, new boots. The most important factor to keep in mind when rebuilding wheel cylinders is cleanliness. Keep all dirt away from the wheel cylinders when you are reassembling them.

  1. To remove the wheel cylinder, jack up the vehicle and remove the drum.
  2.  
  3. Disconnect the brake line at the fitting on the brake backing plate.
  4.  
  5. Remove the brake assemblies.
  6.  
  7. Remove the screws or nuts that hold the wheel cylinder to the backing plate and remove the wheel cylinder from the vehicle.
  8.  
  9. Remove the rubber dust covers on the ends of the cylinder. Remove the pistons and piston cups and the spring. Remove the bleeder screw and make sure it is not plugged.
  10.  
  11. Discard all of the parts that the rebuilding kit will replace.
  12.  
  13. Examine the inside of the cylinder. If it is severely rusted, pitted or scratched, then the cylinder must be replaced as the piston cups won't be able to seal against the walls of the cylinder.
  14.  
  15. Using emery cloth or crocus cloth, polish the inside of the cylinder. Do not polish in a lengthwise direction. Polish by rotating the wheel cylinder around the polishing cloth supported on your fingers. The purpose of this is to put a new surface on the inside of the cylinder. Keep the inside of the cylinder coated with brake fluid while polishing.
  16.  

Honing the wheel cylinders is not recommended due to the possibility of removing too much material from the bore, making it too large to seal.

  1. Wash out the cylinder with clean brake fluid after polishing.
  2.  
  3. When reassembling the cylinder dip all of the parts in clean brake fluid. Reassemble in the reverse order of removal. Torque the wheel cylinder-to-backing plate fasteners to 90 inch lbs. (10 Nm). Torque the brake line-to-wheel cylinder connection to 160 inch lbs. (18 Nm).
  4.  

 
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