Nissan 240SX/Altima 1993-1998 Repair Guide

Wheel Cylinder

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REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4



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Fig. Fig. 1: The wheel cylinder (arrow) is located at the top of the brake backing plate, and provides force to press the brake shoes against the drum



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Fig. Fig. 2: Note that the bleeder screw is missing in this photo. It was removed to prevent damaging it while loosening the brake line fitting



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Fig. Fig. 3: The wheel cylinder bolts are accessed from the rear of the backing plate



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Fig. Fig. 4: The wheel cylinder fits into a special cutout on the backing plate

  1. Raise and safely support the vehicle.
  2.  
  3. Remove the wheel(s).
  4.  
  5. Remove the brake drum.
  6.  
  7. Remove the brake shoe assembly.
  8.  
  9. Disconnect and cap the flare nut and the brake line from the wheel cylinder.
  10.  
  11. Remove the wheel cylinder-to-backing plate bolts.
  12.  
  13. Remove the wheel cylinder.
  14.  

If the wheel cylinder is difficult to remove, tap it with a soft hammer to release it from the backing plate.

To install:
  1. Install the wheel cylinder assembly to the backing plate and tighten the bolts to 4-72 inch lbs. (6-9 Nm).
  2.  
  3. Connect the brake line.
  4.  
  5. Install the brake shoe assembly.
  6.  
  7. Install the brake drum.
  8.  
  9. Install the wheel(s).
  10.  
  11. Bleed the brake system.
  12.  
  13. Adjust the rear brakes as necessary.
  14.  

OVERHAUL



See Figures 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14

Wheel cylinder overhaul kits may be available, but often at little or no savings over a new or reconditioned wheel cylinder. It often makes sense with these components to substitute a new or reconditioned part instead of attempting an overhaul.

If no replacement is available, or you would prefer to overhaul your wheel cylinders, the following procedure may be used. When rebuilding and installing wheel cylinders, avoid getting any contaminants into the system. Always use clean, new, high quality brake fluid. If dirty or improper fluid has been used, it will be necessary to drain the entire system, flush the system with the proper brake fluid, replace all rubber components, then refill and bleed the system.

  1. Remove the wheel cylinder from the vehicle and place on a clean workbench.
  2.  
  3. Remove and discard the old rubber boots, then withdraw the pistons. Piston cylinders are equipped with seals and a spring assembly, all located behind the pistons in the cylinder bore.
  4.  



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Fig. Fig. 5: Remove the outer boots from the wheel cylinder

  1. Remove the remaining inner components, seals and spring assembly. Compressed air may be useful in removing these components. If no compressed air is available, be VERY careful not to score the wheel cylinder bore when removing parts from it. Discard all components for which replacements were supplied in the rebuild kit.
  2.  



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Fig. Fig. 6: Compressed air can be used to remove the pistons and seals



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Fig. Fig. 7: Remove the pistons, cup seals and spring from the cylinder

  1. Wash the cylinder and metal parts in denatured alcohol or clean brake fluid.
  2.  



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Fig. Fig. 8: Use brake fluid and a soft brush to clean the pistons ...



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Fig. Fig. 9: ... and the bore of the wheel cylinder


WARNING
Never use a mineral-based solvent such as gasoline, kerosene or paint thinner for cleaning purposes. These solvents will swell rubber components and quickly deteriorate them.

  1. Allow the parts to air dry or use compressed air. Do not use rags for cleaning, since lint will remain in the cylinder bore.
  2.  
  3. Inspect the pistons and replace if they show scratches.
  4.  



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Fig. Fig. 10: Once cleaned and inspected, the wheel cylinder is ready for assembly

  1. Lubricate the cylinder bore and seals using clean brake fluid.
  2.  
  3. Position the spring assembly.
  4.  
  5. Install the inner seals, then the pistons.
  6.  



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Fig. Fig. 11: Lubricate the cup seals with brake fluid



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Fig. Fig. 12: Install the spring, then the cup seals in the bore



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Fig. Fig. 13: Lightly lubricate the pistons, then install them

  1. Insert the new boots into the counterbores by hand. Do not lubricate the boots.
  2.  



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Fig. Fig. 14: The boots can now be installed over the wheel cylinder ends

  1. Install the wheel cylinder.
  2.  

 
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