The brake master cylinder comes as one of the most vital components found in modern car braking systems. It functions as the main valve that pushes brake fluid through the brake lines so the brake calipers can squeeze the pads against the rotors. It works by pushing a metal rod through a cylinder to force fluid through the braking system to the wheels. One end of this rod is linked to the pedal and is actuated when the pedal is depressed. Often, a faulty brake master cylinder will give out one of these 4 symptoms that alert the driver of needed servicing.