Technical Articles

By braking operation, contact vibration caused between pad and disc touch (vibration = natural frequency = sound) will be amplified by disc body to amplified as larger sound (disc itself functioned as speaker and enlarge the sound) Brake squeal can be explained in the illustration as follows.

When brake applied, pad pushed by piston, contact with disc. There is no problem when strong and uniformed pressure applied,
however in reality it will not happen and vibration occur (judder).
Such judder amplified by disc and in the worst case it transferred to caliper and suspension, further widely to vehicle body, also become variety of noise.

Such Judder will

1. Absorbed by pad material softness (attenuation characteristics)
2. Absorbed by disc softness (attenuation characteristics)
3. Absorbed by the shim between pad back plate and piston.

Should absorption not effective → become larger and unpleasant noise (claim)

Brake noise generated initially by pad and disc contact, therefore may suspect pad and disc only. It is too simple-minded. Although pad and disc cause the noise, it is highly important to find the real cause creating such situation. The followings are the illustration by examples and explanations.