Why car brakes make a noise – and how to fix it

A. TYPES OF NOISE   -   B. VISUAL CLUES   -   C. AVOIDING NOISE PROBLEMS

Are you wondering, how do you fix squeaky brakes? Drivers often visit garages and workshops to ask about mysterious brake noise and there are many causes. Different types of noise indicate different types of problem. While the noise is often blamed on the brake itself, it can originate from vibrations or wear in the front-end assembly. Read on to find out about brake noise and information that will help you to make a brake noise diagnosis. 

The different types of brake noise

1.  Low frequency (deep noises or judders)

LIKELY CAUSES:

• Damaged discs
• Poor disc manufacture creating excessive disc thickness variation
• Incorrect disc installation leading to excessive runout
• Damaged, inconsistently worn or badly corroded discs
• Excessive pad wear leading to deposits on the disc

SOLUTION:

• Remove the brake disc and clean all surfaces of the brake assembly
• Replace the brake disc

2. Medium frequency (squealing)

LIKELY CAUSES:

• Poorly fitted brake pad
• Incorrect allocation of anti-noise fixings such as shims
• Discs too thin
• Sticky movement on the caliper piston
• Non-planarity of the working surface of the disc

SOLUTION:

• Clean and lubricate the components of the caliper
• Make sure disc planarity stays within a tolerance of 0.1mm (once fitted)
• Clean the surface of the hub
• Replace the brake disc and check that brake pads, shims and accessories are fitted correctly
• Consider damping the noise with shims or brake pads that have anti-noise features

3. High frequency (squeaking)

LIKELY CAUSES:

• The usual reason for a high-pitched squeaky noise is vibration within the friction material during application of the brakes

SOLUTION:

• Replace the brake pad set
• Check that the brake accessories (including the caliper clips) are correct and well fitted

Visual clues to brake noise problems

You can get a good idea of the probable causes of noise by looking at the appearance of the surfaces of brake parts. Jack up the vehicle, remove the pads and have a close look at all the surfaces to see symptoms and identify remedies. You may spot:

A) Tapered pads

If you can see tapered pads, this will be caused by the caliper. Either the caliper slides are sticking, the caliper has become distorted or there may be excessive caliper clearance.

Remedy: Replace the pad set and service the caliper.

B) Damaged back plate

Backing plates can get weak and damaged over time. This can be general wear and tear, or incorrect or forceful fitting. A worn back plate can cause noise and even brake failure.

Remedy:Replace the full brake pad set. 

C) Uneven wear

If there’s uneven wear on the surface of the brake pad then it means there’s irregular wear on the brake disc. You’ll be able to see a wear lip on the brake disc.

Remedy: Replace the brake discs and pads.

D) Uneven wear within the axle

You may be able to see that one or more brake pads within the axle set are excessively worn. This means that the caliper piston or guide pins are sticking.

Remedy: Service the caliper slides and pistons and replace the pads. Check the discs.

E) Damage from the piston

Sometimes, anti-noise features (like the rubber coat or shim) get damaged by the piston. This is because the piston doesn’t fully retract or through heavy brake use and overheating.

Remedy: Replace the brake pads set and service the caliper.

How do you stop brakes from squeaking?

To avoid any brake noise problems from developing, make sure the brake pads and calipers are assembled properly. Here are our tips for correct assembly:

Do a road test to make sure the braking system is in full working order. When the car is returned to the driver, advise them about bedding-in to avoid brake judder in the future and ensure optimum efficiency. 

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