A brake booster supports the driver's force on the brake pedal. The brake and braking system is one of the most important parts of your car, as it provides driving safety. Today, a brake booster belongs to every functioning brake in cars.
The brake booster was developed in the 1960s, but was initially used only in higher-value vehicles, such as the Mercedes 300 SL. At this time, the system was mainly referred to as brake helper. In the 1980s, the use of the brake booster in cars spread, but smaller vehicle classes such as the Fiat Panda, the VW Polo and VW Golf were still made without using the boosting system.
The brake booster is only fully functional when the system is hermetically sealed. This means that the system must be sealed so that no liquids or vapours can penetrate or escape. Therefore, brake booster failures are often triggered by holes and damage to the surrounding hoses, valves and manifolds.
If you drive to a garage with a bad brake booster, they will first check the cuffs, valves and hoses in the braking system to determine if the brake booster needs to be changed. Unfortunately, the pipes and hoses are very susceptible to wear as they can crack due to dirt and colder temperatures. In addition, they can be gnawed by animals, such as martens, causing a failure of the brake booster.
Even the brake booster itself may be defective. So the seals on the brake booster can wear out. In addition, the housing is susceptible to rust, so over time, air and residual water can get into the hoses.
If you think your brake booster is bad, you can easily check it yourself and detect a possible problem. If the engine of your car is turned off, press the brake pedal several times. Normally this should get more difficult every time. You have to use more and more force to pass through the brake pedal. You will do this until the resistance becomes too great and you cannot press the brake pedal anymore. This should be the case after about three to five times.
Then start the engine. With a functioning brake booster, the resistance in the brake pedal should normalize again. Should the brake pedal be hard and difficult to pedal even when the engine is running, then it is very likely that your brake booster is failing.
If you suspect your car has a bad brake booster, then you should visit a garage as soon as possible. Firstly, it is much more dangerous to drive with a failing brake booster, as the driver has to spend much more force to operate the brake pedal. This often extends the braking distance, which can be dangerous, especially when driving on rural roads and highways.
In addition, continuing to drive with a defective brake booster lead to further damage and thus becomes very expensive. For example, the master cylinder may be damaged. You should therefore create a request when you spot the first sign of a failing brake booster to prevent consequential damage to your car.
In the brake system of a car, the brake pedal pushes the master cylinder directly. The master cylinder in turn pushes the brake fluid into the conduit system to the brakes. This pressure is additionally supported by a diaphragm, which is located on the brake booster. Most cars have a brake booster that works because of a vacuum. This means that the brake booster uses the existing underinflation to increase the braking force.
The brake servo is divided into two chambers by a diaphragm. Both sides of the diaphragm are underinflated when the brakes are not in use. The underinflation is generated from the engine. The underinflation is also generated in diesel engines by a vacuum pump. If the brake pedal gets pushed, the chambers are getting sealed from each other. At the same time a valve ensures that the atmospheric pressure is flown in.
At this time, there is an atmospheric pressure on the driver's side of the diaphragm. On the main cylinder side - the other side of the brake booster - there is a negative pressure. This increases the pedal force of the brake and the brake pressure applied to the wheels.
When the brake pedal is released, then the two chambers of the brake booster are reconnected. In addition, the valve closes again, so that the atmospheric pressure escapes and there is an underinflation again in both chambers.
The cost of changing the brake booster varies greatly depending on the type of vehicle and the vehicle model. In addition, the cost depends on whether the master cylinder must also be replaced. Often the defect of the brake booster is triggered by a cracked and leaking conduit, so that only that conduit needs to be changed. However, if the entire brake booster needs to be replaced, then the repair becomes more complicated and extensive.
Before the brake booster can be replaced, the following items must be dismantled: the brake pedal, the brake lines, the master cylinder and the vacuum conduit. Then the new brake booster can be installed. In most cases, the garage also directly introduces a change of brake fluid at this point, as the system is already open and vented.
The material costs for a new brake booster vary greatly, but are normally between £62 and £266 depending on the manufacturer. Among the best known manufacturers for this spare part are Bosch, ATE and TRW. The amount of time needed is also very different as it depends on how many other parts have to be removed before changing. Normally the replacement of the brake booster takes between 30 minutes and four hours. Overall, a change of the brake booster costs between about £124 and £710.
| Make | Compare and save* | You save on average* | Ratings | |
|---|---|---|---|---|
| Audi | £122 | 23% |
4.7
(11)
9
1
1
0
0
Read the reviews
|
|
| BMW | £68 | 19% |
4.7
(24)
19
3
2
0
0
Read the reviews
|
|
| Citroën | £99 | 38% |
4.6
(5)
4
0
1
0
0
Read the reviews
|
|
| Ford | £101 | 22% |
4.5
(10)
6
3
1
0
0
Read the reviews
|
|
| Mercedes-Benz | £124 | 24% |
4.4
(10)
8
0
1
0
1
Read the reviews
|
|
| Nissan | £54 | 23% |
5.0
(6)
6
0
0
0
0
Read the reviews
|
|
| Renault | £50 | 19% |
5.0
(4)
4
0
0
0
0
Read the reviews
|
|
| SsangYong | £66 | 26% |
(0)
|
|
| Vauxhall | £120 | 23% |
5.0
(5)
5
0
0
0
0
Read the reviews
|
|
| Volkswagen | £125 | 22% |
4.5
(6)
4
1
1
0
0
Read the reviews
|
|
| Make | Save on average* | |||
|
Audi
4.7
(11)
9
1
1
0
0
Read the reviews
|
£122 / 23% | |||
|
BMW
4.7
(24)
19
3
2
0
0
Read the reviews
|
£68 / 19% | |||
|
Citroën
4.6
(5)
4
0
1
0
0
Read the reviews
|
£99 / 38% | |||
|
Ford
4.5
(10)
6
3
1
0
0
Read the reviews
|
£101 / 22% | |||
|
Mercedes-Benz
4.4
(10)
8
0
1
0
1
Read the reviews
|
£124 / 24% | |||
|
Nissan
5.0
(6)
6
0
0
0
0
Read the reviews
|
£54 / 23% | |||
|
Renault
5.0
(4)
4
0
0
0
0
Read the reviews
|
£50 / 19% | |||
|
SsangYong
(0)
|
£66 / 26% | |||
|
Vauxhall
5.0
(5)
5
0
0
0
0
Read the reviews
|
£120 / 23% | |||
|
Volkswagen
4.5
(6)
4
1
1
0
0
Read the reviews
|
£125 / 22% |
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