The master cylinder acts as the brake fluid reservoir on your vehicle. It’s necessary that this part be in good repair in order for the brake system to work properly – that means seals intact, pistons functioning optimally, and bore undamaged.

These cylinders take a lot of heavy-duty use, particularly in city driving conditions, and if the bore leaks it usually means the unit is worn out and needs replacing. You can sometimes deduce that the master cylinder is the problem if the brakes go to the floor, as opposed to spongy brakes which is typically caused by air in the brake lines.

Master cylinders are made in either aluminum or cast iron. While cast iron is generally more inexpensive, aluminum is lightweight and resists rust and corrosion better. However, it can be difficult to find new aluminum ones these days.

How to make sure you’re getting a good quality brake master cylinder:

  • Spec standards: Make sure the specs meet manufacturer’s standards.

  • OEM over aftermarket: Consider buying OEM over aftermarket. This part needs to fit precisely into the brake system and with OEM you know exactly what you’re getting.

  • Warranty: Check out the different warranties. If you opt for aftermarket, there can be a wide differential in the amount of years or miles offered in the warranty. Cardone is a brand with a good reputation, and they offer a three year warranty on certain cylinders.

  • Avoid rebuilds: This is not a part that you want to take chances with by going with remanufactured.

  • Opt for the kit: While you can buy just the cylinder alone, that can be a risky choice because if other parts are damaged – such as seals and other components in the unit – you’ll end up making a second trip for the rest. The kit includes bleeder kit and reservoir, so you’ll know you already have everything you need right up front.

YourMechanic supplies top-quality brake master cylinders to our certified mobile technicians. We can also install a brake master cylinder that you've purchased. Click here to get a quote and more information on brake master cylinder replacement.

This article originally appeared on YourMechanic.com as How to Buy a Good Quality Brake Master Cylinder and was authored by Valerie Johnston.


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