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 vehicle is being driven WITHOUT the brakes applied. It may or may not be present under braking 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 Figure 2
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.
After the pads are removed, measure the thickness of the LINING portion (NOT the backing) of the pads. It must be at least 0.04 in. (1mm) for all 1983-86 vehicles and 0.08 in. (2mm) for all vehicles built after 1987. This is a Mitsubishi factory minimum; please note that local inspection standards enforced by your state must be given precedence if they require a greater thickness.
REMOVAL & INSTALLATION
See Figures 3, 4 and 5
Whenever brake pads are replaced, replace them in complete sets; that is, replace the pads on both front wheels even if only one side is worn.
There are several combinations of shims, spacers and clips in use on Mitsubishi vehicles. When disassembling, work on one side at a time and pay attention to placement of these components. If you become confused during reassembly, refer to the other side for correct placement. To remove the brake pads:
- Raise the vehicle and support it safely on stands.
- Remove the front wheels.
- Unscrew and remove the lockpin without disturbing the grease coating. Place the pin in a clean spot where grease will not pick up dust. Lift up the caliper body by using the guide pin bolt as a fulcrum. Fasten the caliper in the raised position with wire.
- Remove the shims, brake pads and spring clips in order. Depending on the number of such components, either diagram their placement or lay them aside in order.
- Clean the surface of the piston with a clean, damp rag. Make sure there is room in the master cylinder reservoir for more fluid (fluid will be forced back into the reservoir in the next step). If necessary, remove some fluid with a clean squeeze ball syringe.
- Use a large C-clamp or similar tool to depress the caliper pistons back into the calipers. The pistons will need to be almost flush with the case to fit over the new, thicker pads.
- Install the brake pads with the shims, clips and fittings in the correct order. Vehicles with upper and lower spring clips for each pad should have these clips replaced with the pads.
Keep the brake surface of each pad free of grease, oil and fluids during the installation. A greasy fingerprint or similar light contact may be removed with a commercial brake cleaning spray.
- Remove the wire, lower the caliper into position, and screw in the lower lockpin. Make certain the rubber boot is correctly placed on the lockpin and is not pinched or deformed.
- Replace the wheels and lower the vehicle.
- Pump the brake pedal several times with the engine off. The first two or three pedal strokes may be longer than usual as the pistons return from their compressed position and drive the pads inward. After a reasonable feel has been achieved, check the master cylinder reservoir and top up the fluid as needed. Start the engine and pump the brake pedal again, checking for the proper feel and engagement point.
- Since the brake hoses and hydraulic system was not opened during the repair, it is usually not necessary to bleed the brake system after pad replacement. Use good judgement in determining pedal feel; bleeding may be necessary for other reasons.
Braking should be moderate for the first 10 miles (16 km) 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.