GM Cutlass RWD 1970-1987 Repair Guide

Wheel Cylinders

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The procedures given here are for both front and rear wheel cylinders.

REMOVAL & INSTALLATION



See Figures 1, 2 and 3

  1. Raise the vehicle and support it on jackstands. Remove the wheel and drum.
  2.  
  3. Remove the brake shoes.
  4.  
  5. On rear brakes, loosen the brake line on the rear of the cylinder but do not pull the line away from the cylinder or it may bend.
  6.  
  7. On front brakes, disconnect the metal brake line from the rubber brake hose where they join in the wheel well. Pull off the horseshoe clip that attaches the rubber brake hose to the underbody of the car. Loosen the hose at the cylinder, then turn the whole brake hose to remove it from the wheel cylinder.
  8.  
  9. Remove the bolts and lockwashers or retaining clip (1978 and later) that attach the wheel cylinder to the backing plate and remove the cylinder.
  10.  



Click image to see an enlarged view

Fig. Fig. 1: Use a flare nut wrench to remove the brake line fittings



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Fig. Fig. 2: Unfasten the wheel cylinder retaining bolts and remove the wheel cylinder from the backing plate



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Fig. Fig. 3: Internal components of a wheel cylinder

To install:
  1. Position the new wheel cylinder on the backing plate and install the cylinder attaching bolts and lockwashers or retainer clip.
  2.  
  3. Attach the metal brake line or rubber hose.
  4.  
  5. Install the brakes.
  6.  
  7. Install the drum and wheel.
  8.  

OVERHAUL



See Figures 4 and 5

Since the travel of the pistons in the wheel cylinder changes when new brake shoes are installed, it is possible for previously good wheel cylinders to start leaking after new brakes are installed. Therefore, to save yourself the expense of having to replace new brakes that become saturated with brake fluid and the aggravation of having to take everything apart again, it is strongly recommended that wheel cylinders be rebuilt every time new brake shoes are installed. This is especially true on high-mileage cars.

  1. Raise the vehicle and support it with jackstands.Remove the wheel and drum.
  2.  
  3. Remove the brakes.
  4.  
  5. Place an empty container under the brake backing plate to catch the brake fluid that will run out of the wheel cylinder.
  6.  
  7. Remove the boots from the end of the wheel cylinder.
  8.  
  9. Push one piston toward the center of the cylinder to force the opposite piston and cup out the other end of the cylinder. Reach in the open end of the cylinder and push the spring, cup, and piston out of the cylinder.
  10.  



Click image to see an enlarged view

Fig. Fig. 4: Remove the boots from the end of the wheel cylinder.



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Fig. Fig. 5: Push one piston toward the center of the cylinder to force the opposite piston and cup out the other end of the cylinder.

  1. Remove the bleeder screw from the rear of the cylinder, on the back of the backing plate.
  2.  
  3. Inspect the inside of the wheel cylinder. If it is scored in any way, the cylinder must be honed with a wheel cylinder hone or fine emery paper, and finished with crocus cloth if emery paper is used.
  4.  
  5. If the inside of the cylinder is excessively worn, the cylinder will have to be replaced, as only 0.003 in. (0.762mm) of material can be removed from the cylinder walls. When honing or cleaning the wheel cylinders, keep a small amount of brake fluid in the cylinder to serve as a lubricant.
  6.  
  7. Clean any foreign matter from the pistons. The sides of the pistons must be smooth for the wheel cylinders to operate properly.
  8.  
  9. Clean the cylinder bore with alcohol and lint-free rag. Pull the rag through the bore several times to remove all foreign matter and dry the cylinder.
  10.  
  11. Install the bleeder screw and the return spring in the cylinder.
  12.  
  13. Coat new cylinder cups with new brake fluid and install them in the cylinder. Make sure that they are square in the bore or they will leak.
  14.  
  15. Install the pistons in the cylinder after coating them with new brake fluid.
  16.  
  17. Coat the inside of the boots with new brake fluid and install them on the cylinder. Install the brakes.
  18.  

 
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