There are many conditions at which your brakes may make noise.  These noises may vary depending on: the brake pad material, pad wear, improper installation of brake shims or clips, or if there is an issue with the brake rotors.  What people need to know is that some brake noises are normal, while others are indicative of a problem that needs to be fixed.  Below we discuss the different conditions of why brakes could be making noise and whether or not it should be of concern.

Brake Pad Material

Brake pads are made with a variety of different materials and some of them are more likely to make noise.  One example is metallic brake pads or brake pads made of a metallic formula.   The added metal can be the cause for noise and the noise can be described as a hissing sound.  Although it may not always be the case, noise is considered normal from a metallic brake pad and it is generally not an issue because brake performance compensates for it.  These days, manufacturers are great at coming up with compositions and ratios of brake pad material that are quiet and perform well. 

Worn-Out Brake Pads

In most cases, the issue of noise lies within worn brake pads or when your brake pads have not been broken-in properly.  If it is the former and your brake pads have worn down beyond its limit, there is a wear indicator made of metal that will be exposed.  This metal is meant to signal low wear by rubbing against the brake disc or brake rotor and creating a high-pitched squeal whenever the brakes are applied.  The obvious remedy here would be to replace the brake pads.  The same rule applies of the extreme glazing of brake pads.  If the brake pads are not replaced, the wear indicator may engrave or “score” the rotor, damaging it.

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Improper Use or Installation of Brake Shims and Clips

Brake shims and clips are primarily used to prevent the occurrence of rattling, vibrations and judders whenever brakes are used.  Although brake shims are usually made of stainless steel in order to resist corrosion and moisture – these may decay over a period of time and may lead to squealing and noise during braking.

Brake clips or anti-rattle clips may also be a cause of brake squeal when they are not installed properly, causing them to be loose.  This may either occur because no such clips or shims were installed, or if they were not reinstalled during a previous brake job.  Moreover, the non-installation of these tools may also lead to noises even if you have just recently installed new brake pads.

The best thing to do in this case is to reinstall the proper shims and clips accordingly and to apply the necessary lubricants to eliminate noise.  

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Problematic Brake Rotors

This is a more obvious cause of noise--If there are problems with your brake rotors, such as scoring metnioned earlier (which is visibly noticeable) noise will result.  This is also true If the friction surface is uneven or if your brake rotors or brake discs have hard spots or debris. 

In order to ensure that your brake rotors are in good shape, give them a thorough inspection.  If you see discoloured hard spots, cracks and other signs of damage – then you might want to consider having them resurfaced, if still possible, or have them replaced. 

In some instances, glazed pads or discs may be the culprit.  Brake pad glazing means the friction surface of the brake pad has become smooth due to excessive heat. (usually from improper bedding in).  Depending on the amount of severity of the glazing – this may be remedied by brake rotor resurfacing or brake pad replacement.  If you just had your brake rotors refinished, but the brake squeal and noise still persists, the problem may be with the finishing.  So you must adjust and remedy the finish accordingly in order to address this issue.

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In the end, brake noise could be relatively simple to fix.  There are obvious and less obvious causes of brake noise, but you now have some tools of information to help you investigate and fix the issue for yourself.