This video covers a number of aspects related to the testing and operation of a brake 'booster' otherwise known as a brake servo.

Firstly, we test the one-way valve in the vacuum supply pipe. Then I show you how to complete a simple on-car test to see if the brake booster is working correctly.

The theory on how a a brake booster increases the braking force is covered and finally I show you how to take measurements to check that the brake booster to master cylinder push-rod length is within specification.

If not then I show you how to make the necessary adjustments needed.

As you will see in the video, the importance of this push-rod adjustment is often overlooked by individuals. Whether you are replacing the brake booster or the master cylinder, having the correct clearance between the end of the push rod and the primary piston in the master cylinder is critical. If incorrect can cause issues relating to binding brakes and difficulty to bleed up the system.

Any questions please add them to the comments section below...

Andy Mechanic!