Brake Maintenance

Causes of Brake Squeal and What to Do About Them


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For both new and old vehicles alike, brake squeal can be both a disturbing and annoying occurrence that can have owners panicking to find a remedy. Not just a cause of discomfort, brake squeal can be a sign of potential safety issues.

Shims, Clips and Pad Clearance

Most brake pads come with a set of shims that help to prevent the brake pads from rattling and vibrating, and help to keep the brake pads located in the caliper. While stainless steel shims can be quite resistant to moisture and corrosion, plain steel shims can decay over time and cause an increase in squeal during use. Often times, anti rattle clips if installed, may work themselves loose, and often times may not have even been reinstalled during the previous brake replacement. Installation without supplied shims, clips and lubricant can cause squealing even in brand new brake pads, and the easiest way to remedy such problems is to reinstall using all of the factory supplied materials. If no shims are available, consider applying a high temperature brake noise compound to the back of the brake pad.

Disc and Pad Condition

Hard spots or uneven areas in your disc brakes caused by wear can cause brake squeal, as can improperly broken-in brake pads. Discolored hard spots or cracks in the rotor itself can be cause for replacement, while glazed pads can sometimes be salvaged if caught early enough. If both the pads and discs show extensive signs of glazing, resurfacing of the discs and replacement of the pads may be required. Pad composition can also be a major contributor in brake noise. Semi-metallic brake pads with a high amount of metal content will squeal regardless of shims or rotor condition, so quieting your brakes in these cases will require switching to a pad with a lower percentage of metal content, or to a full organic pad. Increases in brake dust with organic pads may be worth the quieter braking.

If you have recently had your brake rotors refinished and have been plagued by brake squeal, your brake finish may be to blame. Refinishing done on a lathe with dull bits, or on a unit that is set to turn at too high a speed can result in an overly rough finish, and vastly increased chances for noise.

Worn Brake Pads

Sometimes the cause for brake squeal is simply the indicator tab on your brake pads. As brake pads wear down, an indicator tab becomes revealed, causing a squealing sound when the brake pedal is depressed. The simple fix for this cause of brake squeal is simply replacing your worn brake pads.

New vehicles come with brakes that are generally designed to operate as quietly as possible, so when brake noises appear, it can be a surprising and disturbing development for owners. While many causes can stem from the simple wear of brake components, they should always be inspected to insure that there are no potentially dangerous brake problems such as friction material de-lamination or cracked brake rotors present. If none of these problems are present, refinishing your rotors, and making sure all shims and lubricants are used can quiet down that annoying squal and restore braking confidence.

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