Squeaking noises when braking are not only annoying, they are also a cause of concern for many car drivers. However, it is not always the case that the car’s brakes are broken if they squeak loudly. In this guide, you will learn about the possible causes of squeaking brakes and when brake squeaking is really dangerous. You will also receive tips on how to eliminate squeaking brakes.

How brakes work and why they squeal

The brake system of modern cars is made up of numerous components. If a squeaking noise occurs, however, the cause is usually to be found in a very specific area.

When the driver steps on the brake pedal, he actuates the brake master cylinder. With its help, the braking force is transmitted hydraulically to the brake lines. After the brake is applied, pressure builds up in the brake lines, which actuates the brake cylinders.

These in turn press the brake pads of the disc brake against the discs. Inside drum brakes, the brake cylinders ensure that the brake pads are pressed against the rotating drum.

When the brake pads are pressed against the drum or disc, friction and heat are generated. The friction of the brake pad on the rotating component simultaneously initiates the desired deceleration of the car. This sometimes causes a high frequency vibration that is perceived as squealing.

Causes of brake squeal – why the brake squeals

When the brakes squeal, various causes can be responsible for the problem. In some cases, parts of the brake are worn or defective. Much more often however dirt or individual user behaviour are possible causes.

• Squealing of the brakes after a change of brake parts.
• Contamination of the brake components leads to noises.
• Rust on the brake discs is responsible for the squeaking.
• After overloading the brakes, they may squeal.
• Inferior components for brakes cause the noise.
• Wear makes the brakes squeal.

Brake squeaks after brake change

Occasionally, disc brakes or drum brakes squeal after the brake components have been changed. Squeaking brakes can also occur after a complete brake change. Often, the brake pads and brake disc or brake drum have not yet adapted to each other. New brake pads can also tend to squeak.

Squeaking brakes due to dirt

One of the most common causes of squealing brakes is contamination from brake dust and other dirt. Especially brake systems with discs get dirty quickly because the components are relatively unprotected. If dirt and brake dust adhere to the brake caliper and other parts, they can no longer work optimally. Instead, a vibration occurs in this area when braking, which is audible as squeaking.

Brakes squeak due to rust

If vehicles are used again after a long period of inactivity, rust may have formed on the brake discs. This rust on the discs is also a possible cause when the brakes squeal. This sometimes affects convertibles that have been parked over the winter and are rarely used. After a few gentle braking operations, the rust usually disappears from the brake disc, and with it the squealing.

Noises after overloading the brake

If brakes are overloaded, damage to the brake system can occur as a result. Sometimes this is also the cause of a squealing noise. After overloading the brakes, the brake disc may have warped, or a brake pad may be damaged. More frequently, however, so-called vitrification occurs on the brake pads. This changes the surface of the brake pads so that noises and a changed braking effect occur.

Inferior brakes installed

In individual cases, brakes are replaced with very cheap components after a defect. If brake pads and discs are not of high quality, their surface is sometimes not perfectly finished. Therefore, noises such as squeaking occur more frequently with inferior brakes. It is therefore advisable to only use original or OEM spare parts for brakes.

The brake is worn or defective

Defective or worn brake pads or brake discs can also cause squealing brakes. Often, worn brake pads produce a more metallic grinding noise. Some brake pads are equipped with an acoustic wear indicator that can also cause a noise like squealing. If you notice a decrease in braking efficiency when you step on the brake pedal, the car should be towed to a workshop.

Squeaking brakes – not always problematic

However, brake squeal in itself does not always indicate a problem with the brakes. It is possible for the brakes to squeal even though the brake system is working optimally. Disc brakes on sports cars in particular can tend to squeal easily, as special brake discs and brake pads are installed here for high braking performance.

Squeaking brakes – how to eliminate the problem

The brakes are one of the car’s safety-relevant systems. Only expert car mechanics should therefore carry out repairs to the brakes or a brake change themselves. All others are better off using the services of a professional workshop in the event of a problem with the brakes.

Brake squeals due to dirt – what to do:

If brakes with brake discs squeal, they should be partially disassembled for inspection and cleaning. Components such as the brake caliper can then be carefully cleaned. Sprays or pastes against squeaking brakes are commercially available, but they must always be used according to the manufacturer’s instructions. Adhering brake dust as abrasion from the brake pads should not be inhaled; a suitable breathing mask is helpful.

1. Remove the wheel: The wheel is removed in order to have access to the components of the brake system. To do this, the vehicle should be securely jacked up or lifted onto a lifting platform.
2. Remove the brake calliper: The brake caliper is then loosened and carefully removed. The procedure may differ depending on the make and model.
3. Check the brake disc: The now exposed brake disc can easily be visually checked for damage and wear. Likewise the other components of the brake system.
4. Remove the brake pads: The brake pads can now be removed from the caliper. The position of each brake pad should be noted. This way, the individual brake pads can be easily re-installed at the intended location later.
5. Clean the brake: The next step is to clean the components of the brakes. This can be done with a suitable wire brush. Here, all dirt is carefully removed from the brake calliper and the brake calliper holder. Brake cleaner can help with stubborn dirt, but should not get on parts made of plastic and rubber.
6. Reassemble the brake: Once all components have been cleaned, the brake system is reassembled. Each brake pad is checked again and inserted in the intended position. When reassembling the brakes, anti-squeak paste can be used to coat contact points and moving components of the brake. However, the paste is not applied to the friction surface of the brake pads or to the brake disc.
7. Mount the wheel: Once the brake system has been reassembled, the wheel can also be refitted. Before doing so, the brake is visually checked again. Then fit the wheel and tighten it to the specified torque.

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