Brake Servo repair & replacement made easy

What does a brake servo / booster do?

The brake servo, or to give it its correct name, a brake power booster, is used to augment the effort applied to the brake pedal by the driver to increase the force of the brake pads and shoes against the brake discs and/or brake drums.

How does a brake servo work and what are the components?

When the brake pedal is pushed, this movement activates a spring, which in turn opens an air valve allowing air at atmospheric pressure to enter into the chamber. There are two chambers, one at atmospheric pressure and one that has a vacuum. So when the pedal is applied, the diaphragm between two two moves towards the vacuum chamber and exerts an additional force to push against the brake master cylinder piston

Inside the brake servo there are various valves, springs, seals and diaphragms. There are no serviceable components in a brake servo as it is a sealed unit and as such is replaced as a whole. Tampering with the unit can have a detrimental outcome of its ability to work correctly.

How do you know there is something wrong with the brake servo?

In most cases there could be more than one symptom. If you feel that your brakes are not performing as they should, please book an inspection with immediate effect and do not drive the vehicle.

• You may find that you are requiring to press the brake pedal harder in order to slow the vehicle
• You may hear air escaping from the unit when the brake pedal is depressed.

When should you consider a brake servo replacement?

Quite simply as soon as you are aware there is an issue with it! Not only will it result in an MOT failure, it is dangerous to you, your passengers and other road users to have any fault with the brake system.

How common is a brake servo replacement?

These days it is rare that a brake servo will fail. As it is a sealed unit, water ingress and dirt will not enter it and cause any undue wear. However, it has been known for the sealed structure to fail due to corrosion on older vehicles.

How can I extend the life of my brake servo?

The only thing you can do is ensure that the area where the brake booster is mounted is clear of debris and therefore water is not collecting in the area.

What happens during a brake servo replacement?

• The mechanic will inspect the brake system.
• If necessary, the brake booster will be replaced.
• The mechanic will check the brake fluid level.
• If necessary, the mechanic will bleed the brake fluid system.
• The vehicle will inspect the brake system again and if deemed safe, test drive the car.

How much does a brake servo replacement cost?

The cost of a brake booster replacement depends on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having your brake booster replaced by ClickMechanic, by selecting your car at the top of this page