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Tuesday, May 24, 2011

Brake pads removal and installation for 1997 Buick Lesabre?

CAUTION
Older brake pads or 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 the brake surfaces, use a commercially available brake cleaning fluid.

Always replace all pads on both front wheels at the same time. Failure to do so will result in uneven braking action and premature wear.

REMOVAL & INSTALLATION



See Figures 1 through 10

  1. Disconnect the negative battery cable.
  2. Remove 2 / 3 of the brake fluid from the master cylinder reservoir using a clean syringe or equivalent. Install the reservoir cap.
  3. Raise and safely support the vehicle with jackstands.
  4. Mark the relationship of the wheel to the hub and bearing assembly.
  5. Remove the tire and wheel assembly.
  6. Remove the caliper, as outlined later, and suspend from the strut with a wire hook or suitable piece of wire. Do NOT disconnect the brake hose or allow the caliper to hang from the brake line!



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Fig. Fig. 1: Suspend the caliper from the strut with a suitable piece of wire. Do NOT allow the caliper to hang by the brake line

  1. Remove the outboard shoe and lining (pad) by using a prytool to disengage the buttons on the shoe from the holes in the caliper housing.



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Fig. Fig. 2: Use a prytool to release the outboard pad retaining buttons



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Fig. Fig. 3: Remove the outboard brake pad from the caliper

  1. Remove the inboard shoe and lining (pad) from the caliper.



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Fig. Fig. 4: Slide the inboard pad out, disengaging the retaining clip ears ...



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Fig. Fig. 5: ... and remove the inboard pad from the caliper

  1. Before installing new pads, clean the outside surface of the caliper boot with denatured alcohol, or equivalent.

To install:
  1. On 1987-90 vehicles, install new sleeves and bushings. Lubricate the sleeves with a light coating of silicone grease before installation. These parts must always be replaced when the pads are replaced. The parts are usually included in the pad replacement kits.
  2. Bottom the piston into the caliper bore, using a C-clamp, adjustable pliers, or a tool specifically designed for that purpose. Position the tool over the caliper and piston, tightening it slowly to press the piston into the bore. Be careful not to damage the piston or piston boot.



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Fig. Fig. 6: There is a special tool available to compress the caliper piston into its bore (inboard pad installed)

  1. After bottoming the piston, use a small plastic or wooden tool to lift the inner edge of the boot next to the piston, and press out any trapped air. Make sure the boot lies flat and that the convolutions are tucked back into place.



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Fig. Fig. 7: Carefully lift the edge of the piston boot to release any trapped air

  1. Install the inboard pad by snapping the pad retainer spring into the caliper piston. The shoe portion must lay flat against the piston. After installing the shoe and lining (pad), check that the boot is not touching the shoe. If it is, remove the pad and reseat or reposition the boot.



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Fig. Fig. 8: Install the inboard pad, making sure the retainer spring is fastened securely in the caliper piston

  1. Install the outboard pad with the wear sensor at the trailing edge of the pad during forward wheel rotation. The back of the shoe must lay flat against the caliper.



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Fig. Fig. 9: The outboard pad must be installed with the wear sensor at the trailing edge of the pad



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Fig. Fig. 10: Exploded view of the disc brake pads and caliper

  1. Install the caliper, as outlined later in this section.
  2. Install the wheel and tire assembly, then carefully lower the vehicle. Tighten the wheel lug nuts to 100 ft. lbs. (136 Nm).
  3. Fill the master cylinder with the proper amount of brake fluid from a fresh, sealed container. Install the reservoir cap.
  4. Apply about 175 lbs. (778 N) of force to the brake pedal, three times, to seat the pads.

INSPECTION



See Figures 11 and 12

The pad thickness should be inspected every time that the tires are removed for rotation. The outer pad has a wear sensor which will make a squealing noise when the pads wear to the point required replacement.



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Fig. Fig. 11: The outboard pad has a wear sensor that will make a screeching noise against the rotor when the pad is worn to a certain limit

When the pad thickness is worn to within 1 / 32 in. (0.76mm) of the shoe or rivet, at either end of the pad, replace the pads in axle sets. This is the factory recommended measurement; however, your state's automobile inspection laws may not agree with this.

When checking the disc brakes, check both ends of the outer pads by looking in at each end of the caliper. These are the points at which the highest rate of wear occurs. The inner pad can be checked for premature wear by looking down through the inspection hole in the top of the caliper. Some inboard pads have a thermal layer against the shoe, integrally molded with the lining. Do not confuse this extra layer with uneven inboard/outboard pad wear.



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Fig. Fig. 12: Disc brake pad inspection points

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