When the brake pad against the caliper piston is not properly fit, the friction material has a problem, or gone, the brakes will squeal. The squealing is the result of high frequency vibration among the brake rotor, the caliper piston and the pad in either of the cases. Some vehicles come with the squeal problems directly from the manufacturer or factory. In these cases manufacturer simply change the brake pad to cure the problem. Because there are different harmonic frequencies for different pads.
- Steps to solve brake squeal: If your brakes are squealing follow these steps.
- Check for loose parts: Try to move slightly the calipers, brake pad and other components of the brake. They should not move only just with your hands, because loose parts can vibrate and it results in noise.
- Replacement of parts: Make sure that in the caliper assembly, the pad does not move. If you find any missing, damaged, and clips or shims are loose replace them.
- Apply dampening paste: Apply thin layer of the dampening paste between the caliper assembly and the pad. It creates a thin shock absorber to dampen the vibration and the sound. Give plenty of time two to three hours of time if you can, for paste to dry before assemble the brakes. When it is dry, it will become darker color and sticky. If you kept it under the direct sun or used a hair dryer to dry the paste more quicker, wait until the temperature is come down to room temperature.
- Check brake pads: Sometimes the brake pads will wear. Therefore, check for them if they are worn, replace them. Most of the disc brakes have a wear indicator. If the pad is worn up to a certain point, the indicator makes noise. Check the manual or material for suitable brake pads for your vehicle.
- Organic pad: It can be with or without asbestos. It may not wear resistance of metallic or semi-metallic, may lack of performance and it may quieter. It may not tolerate the heat as much as other pad materials so because more brake fade.
- Semi-metallic pad: It has organic material and metal particles. It is the best in both less noise and braking ability in the world. It may wear the rotors. It decreases the brake fade and increases the life of the pad. It can also tolerate the repeated hard stopping.
- Metallic pad: To provide most friction against rotor, different metals are used. At high speeds with minimum wear, it works great for repeated stopping. In the stock rotors, which are not designed for use with metal pads, rotor will wear faster when metallic pads are used.
- Lubricant materials: Carbon, Graphite, Brass and some other materials can help to reduce the noise, so look at the formula, which is for built into brake pads.
- Check brake rotor: Check the drum or rotor for grooving, scoring or other wear.
If the entire rotor is distorted or warped or wear is excessive, you need to replace the rotors. If the sound is like metallic grind and not squeal, you need to change the rotors.