Brake Master Cylinder Parts

Is it Time for a Brake Master Cylinder Replacement?

Stopping a motor vehicle is just as important as starting it, and many brake systems require brake boosters and master cylinders to operate. When you push the brake pedal to stop your vehicle, you need to know that your system is going to work correctly and quickly. If you notice that the brake pedal is hard to compress or sitting too high, or if your brake fluid level is low, it's time to visit your local NAPA to check the brake boosters and master cylinder.

What Does a Brake Booster Do?

Vehicle braking systems work on a scientific principle called Pascal's Law that says if you put pressure on an enclosed brake fluid, it will distribute evenly throughout. It's the same idea behind a syringe or toothpaste tube. The brake booster is bolted to the engine bay fire wall and is vacuumized with a hose from the engine. When you compress the brake pedal with your foot, the pedal is connected to a pushrod that travels forward into the vacuumized chamber of the booster. Inside, a diaphragm divides the chamber in half, and when atmospheric pressure enters the chamber as the pedal is depressed, the difference in vacuum and atmospheric pressure depresses the pushrod further. When the pedal is released, the pushrod returns to its original position and the vacuum is equalized. This system can add several hundred pounds of force to your stopping power, so you don't have to push so hard with your foot when trying to stop your vehicle.

What Does a Brake Master Cylinder Do?

On the opposite end of the brake booster is the brake master cylinder. The master cylinder contains two pistons that push hydraulic fluid from the reservoir on top into fluid lines that run to the brake proportioning valve, which in turn runs to the calipers on the brake rotors for each wheel. The hydraulic force then causes the calipers to squeeze over the brake rotor discs, which decelerates the wheel and allows your car to stop.

If tapping the brake pedal on your vehicle feels like a leg work-out, it is possible that the booster has failed or the fluid wasn't properly drained and has is now contaminated. If the brake pedal feels spongy or sinks, you could have a problem with your master cylinder. Learn more about what a brake master cylinder does, as well as how to test a brake master cylinder at home. If you're just not 100% sure what's causing the wheels on your vehicle to squeal, bring it to any of the convenient NAPA Auto Parts locations nearby and let's talk. We have all the master cylinder replacement parts and knowledge to get your braking system back in perfect working condition.