Car Parts Discount
Brake Master Cylinder

Aftermarket & OEM Brake Master Cylinder

How does a brake master cylinder fail?

Losing brake pressure? Can you depress your brake pedal all the way to the floor? There could be several reasons why you may be experiencing intermittent, or even frequent, failures to stop or slow down due to a loss of pressure in the brake lines. It is possible you could have a brake hose with a bubble or a leak. It is possible your brake master cylinder cap is loose, or a grommet is worn out. Either way, it's likely that you are low on fluid and there is air in the lines. Take a look at the reservoir and check the level to confirm. This would cause low pressure and poor response which could potentially lead to a safety concern. Look for leaks, and the location will tell you if you need to replace a hose or your master cylinder. Brake hoses tend to leak near the wheels, where they attach to the caliper or wheel cylinder. However, a brake master cylinder leak will be right up front by the engine. Eventually, these parts will go bad since they are constantly being used, under stress most of the time, and operated in high heat conditions.

What does my brake master cylinder do?

New Brake Master CylindersHydraulic pressure has been used by engineers for thousands of years. It is an effective way to transfer manual pressure to a remote location through a fluid medium. Your car's brake master cylinder receives the pressure applied to it by the brake pedal, and uses a piston to compress hydraulic fluid in a cylinder. That fluid is supplied to the master cylinder by the attached reservoir. Once under pressure, it is sent to slave cylinders (either a caliper or wheel cylinder) via brake hose where the friction material (the brake pad or shoe) contacts the wheel's rotating surface (a rotor or drum) and slows your vehicle. Hydraulic pressure poses great advantages over cable linkage due to the efficiency of the system in which it works. And the brake master cylinder is where the pressure is created.

A good way to spend your Saturday.

Performing service on brake systems can be complicated at times. Since replacing or rebuilding your brake master cylinder requires you to bleed the system, all the fluid must be removed and replaced. This is best handled by two people, so if you do not have someone to help you it would be best left to professionals.
  • First, remove the cap to the brake master cylinder reservoir and use a turkey baster to get all the fluid out.
  • Next, disconnect the brake hoses on the side of the cylinder. You may want to put down a cloth or bucket to catch any leaking fluid.
  • Now you can remove your old brake master cylinder. At this time, you can fix it with a rebuild kit or replace it with a new one.
  • Before installing it back on your car, you have to bench bleed it. This involves connecting plastic tubes to the brake hose attachments and then directing them back up to the open reservoir. You will fill the reservoir with new fluid, and depress the piston until you see all the air bubbles pass through the plastic tubes and back into the reservoir.
  • Once you have done this a few times, quickly remove the hoses and plug the holes. Then cap the reservoir and reattach the brake master cylinder to the car.
  • It is now time to connect the brake hoses to the cylinder, and bleed each line at the caliper by opening the bleeder screws and depressing the brake pedal a normal travel length until the new fluid comes out of the caliper. Start with the position furthest from the master cylinder, and work your way closer.
  • Finally, top off the master cylinder reservoir with new fluid and cap it.

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A car or truck broken down with no brakes is no joke. Obviously, you need to get your vehicle back on the road ASAP. That's why we offer top quality replacement brake master cylinders and rebuild kits if you need to have it swapped out or fixed. Not only do we carry the best brands, but our prices are low and shipping is super fast. That means you will minimize your down time when you order your new brake master cylinder from Car Parts Discount.