Brakes squeal as the car accelerates

Squeaky brakes

Why do the brakes squeal and what can you do about it?

If the brakes start to squeal, it could be for a number of reasons. These range from brake dust in the system to incompatible brake pads and installation errors when changing the brakes. You can read about the cause and whether you should take it to the workshop immediately here.

You can also find the right workshop for a brake service of your choice on FairGarage and easily compare offers in your area online.

This page provides answers to the following questions:

Why do brakes squeal?

When braking, the rotating brake disc or drum is pressed against the respective stationary friction linings (brake linings or brake shoes). The car is braked by the friction generated. If these parts are not optimally coordinated with one another - i.e. the friction is uneven - vibrations can occur, which you will perceive as a squeaking noise.

A squeal of the brakes is not necessarily something to be alarming about, however. Sometimes it is even accepted - the more sporty a brake pad is, the more the brakes tend to squeal. In addition, brake systems with disc brakes are generally more prone to squeaking than drum brakes or others.

What are the causes of a brake squeal?

The most common causes are listed here:

  • Installation error when changing the brake
  • Brake dust and dirt on the brake pads
  • Longer vehicle downtime
  • Brake pads are not compatible with the braking system
  • Installed brake pads are of poor quality
  • Visible rust or rust spots on the brake discs
  • Brake system was completely overheated and is "glazed"

It is rather unlikely that the brake pads themselves have worn off. This sound would be significantly duller and more grinding than squeaking.

Brakes squeal after a brake change

If the car has just been to the workshop and the brakes squeal while driving, there could be an installation error. Because if only new pads are installed and not the brake discs replaced, the brake pads have to be sanded in order to nestle against the slightly worn discs. If that is forgotten, it squeaks. Leaving out zinc paste when installing the brake pads can also lead to squeaking. Since you cannot investigate this problem yourself, a workshop should be visited so that they can carry out a professional visual inspection and, if necessary, make improvements.

Brakes squeal from brake dust and dirt

The squeaking when braking can also be caused by brake dust and dirt on the brake pads. These settle on the brake pads if the car is not used for a long period of time or if the car is not washed in summer. Typically this occurs with vehicles that are only used in summer and that are stationary in the garage in winter.

Brakes squeal due to unsuitable parts

Every now and then, car owners try to save money in the wrong place by changing their brake pads. Instead of the usually somewhat more expensive original spare parts, rubbers from third-party suppliers are chosen. These are possibly not 100% compatible with the braking system of the car and that is not always noticeable during installation. It is only when driving that it becomes noticeable whether the parts fit together or not. If a screeching noise occurs when braking and does not go away even after a long period of driving, the parts probably do not fit together due to poor quality.

Brakes squeal from rust on the brake discs

If the brake discs are not used for a long time, they can rust. This can be recognized by visible spots on the brake. The attached rust again leads to uneven friction between the moving brake disc and the fixed brake lining. And this in turn results in the squeaking noise.

Brakes squeal after heavy braking

Sometimes screeching brakes occur after heavy braking. The high temperatures that result from enormous stress lead to overheating of the entire brake system. This can result in a glass-like, smooth layer on the brake lining, which significantly reduces the friction coefficient of the lining. This is why one speaks here of a “glazing” of the brake lining. Sometimes the overheating is so great that the brake disc can warp itself. After that, the brake pads no longer fit neatly on the disc. The only thing that helps here is to replace the damaged parts.

What can you do about screeching brakes?

In some cases, the squeak should resolve itself after a while. The reason for this is the self-cleaning function of the brakes when they are used regularly. With a perfectly functioning brake system, foreign particles such as dust, dirt or small rust are simply removed evenly again and the squeaking is thus eliminated. After the vehicle has been parked for a long time, it is therefore advisable to carefully retract the brakes.

The same applies to screeching brakes on new cars. A new car should be run in about a hundred kilometers before worrying about screeching brakes.

When should you go to a workshop with quenching brakes?

If the squeaking persists despite running in and using the brakes regularly, a workshop should be consulted. There is probably a problem with the braking system and that can quickly become a serious hazard. All possible causes can be analyzed in the workshop and the specialist in your area will be happy to advise you on the problem at hand and the repair options.