See Figure 1
The front disc brake pads are equipped with a metal tab which will come into contact with the disc after the friction surface material has worn near its usable minimum. The wear indicators make a constant, distinct metallic sound that should be easily heard. (The sound has been described as similar to either fingernails on a blackboard or a field full of crickets.) The key to recognizing that it is the wear indicators and not some other brake noise is that the sound is heard when the car is being driven WITHOUT the brakes applied. It may or may not be present under braking is heard during normal driving.
It should also be noted that any disc brake system, by its design, cannot be made to work silently under all conditions. Each system includes various shims, plates, cushions and brackets to suppress brake noise but no system can completely silence all noises. Some brake noise-either high or low frequency-can be considered normal under some conditions. Such noises can be controlled and perhaps lessened, but cannot be totally eliminated.
See Figures 2 and 3
The front brake pads may be inspected without removal. With the front end elevated and supported, remove the wheel(s). Unlock the steering column lock and turn the wheel so that the brake caliper is out from under the fender.
View the pads - inner and outer - through the cut-out in the center of the caliper. Remember to look at the thickness of the pad friction material (the part that actually presses on the disc) rather than the thickness of the backing plate which does not change with wear.
Remember that you are looking at the profile of the pad, not the whole thing. Brake pads can wear on a taper which may not be visible through the window. It is also not possible to check the contact surface for cracking or scoring from this position. This quick check can be helpful only as a reference; detailed inspection requires pad removal.
REMOVAL & INSTALLATION
See Figures 4 through 15
- Raise and safely support the front of the vehicle on jackstands. Set the parking brake and block the rear wheels.
- Siphon a sufficient quantity of brake fluid from the master cylinder reservoir to prevent the brake fluid from overflowing from the master cylinder when removing or installing the brake pads. This is necessary as the piston must be forced into the cylinder bore to provide sufficient clearance to install the pads.
- Remove the wheel, then reinstall 2 lug nuts finger tight to hold the disc in place.
Disassemble brakes one wheel at a time. This will prevent parts confusion and also prevent the opposite caliper piston from popping out during pad installation.
- Remove the 2 caliper mounting bolts and then remove the caliper from the mounting bracket. Position the caliper out of the way and support it with wire so it doesn't hang by the brake line.
It may be necessary to rock the caliper back and forth a bit in order to reposition the piston so it will clear the brake pads.
- Remove the 2 brake pads, the 2 wear indicators, the 2 anti-squeal shims (1985-92) 4 anti-squeal shims (1993), the 4 support plates (anti-rattle springs) and the 2 anti squeal springs, if so equipped. Disassemble slowly and take note of how the parts fit together. This will save much time during reassembly.
- Inspect the brake disc (both sides) for scoring or gouging. Measure the disc for both thickness and run-out. Complete inspection procedures are given later in this section.
- Inspect the pads for remaining thickness and condition. Any sign of uneven wear, cracking, heat checking or spotting is cause for replacement. Compare the wear of the inner pad to the outer pad. While they will not wear at exactly the same rate, the remaining thickness should be about the same on both pads. If one is heavily worn and the other is not, suspect either a binding caliper piston or dirty slides in the caliper mount.
- Examine the 2 caliper retaining bolts and the slide bushings in which they run. Everything should be clean and dry. If cleaning is needed, use spray solvents and a clean cloth. Do not wire brush or sand the bolts-this will cause grooves in the metal which will trap more dirt. Check the condition of the rubber dust boots and replace them if damaged.
- Install the 4 pad support plates (anti-rattle springs) onto the mounting bracket.
- Install new pad wear indicators onto each pad, making sure the arrow on the tab points in the direction of disc rotation.
- Install new anti-squeal pads to the back of the pads.
- Install the pads into the mounting bracket and install the anti-squeal springs, if so equipped.
- Use a caliper compressor, a C-clamp or large pair of pliers to slowly press the caliper piston back into the caliper. If the piston is frozen, or if the caliper is leaking hydraulic fluid, the caliper must be overhauled or replaced.
- Install the caliper assembly to the mounting plate. Before installing the retaining bolts, apply a thin, even coating of anti-seize compound to the threads and slide surfaces. Don't use grease or spray lubricants; they will not hold up under the extreme temperatures generated by the brakes. Tighten the bolts to 18 ft. lbs (25 Nm) for 1985-92 and 25 ft. lbs. (34 Nm) for 1993.
- Remove the 2 lugs holding the disc in place and install the wheel.
- Lower the vehicle to the ground. Check the level of the brake fluid in the master cylinder reservoir; it should be at least to the middle of the reservoir.
- Depress the brake pedal several times and make sure that the movement feels normal. The first brake pedal application may result in a very long pedal due to the pistons being retracted. Always make several brake applications before starting the vehicle. Bleeding is not usually necessary after pad replacement.
- Recheck the fluid level and add to the MAX line if necessary.
Braking should be moderate for the first 5 miles or so until the new pads seat correctly. The new pads will bed best if put through several moderate heating and cooling cycles. Avoid hard braking until the brakes have experienced several long, slow stops with time to cool in between. Taking the time to properly bed the brakes will yield quieter operation, more efficient stopping and contribute to extended brake life.