Brake Master Cylinder Guide: Replacement Cost, FAQ, and More

Maintaining your brake system is critical to your safety on the road. You should ideally have your brake parts checked once every six months to make sure that everything is working. However, despite regular maintenance, some parts can still fail over time. The brake master cylinder is one of them. This component converts the force you apply on the brake pedal into hydraulic pressure. If your brake master cylinder fails, your vehicle’s braking will be compromised.

What is a Brake Master Cylinder?

The brake master cylinder is a component that distributes pressure to the braking mechanism at each of a vehicle’s wheels. The brake master cylinder primarily consists of two piston assemblies controlled by a pair of circuit return springs. These pistons are known as the primary and secondary pistons, each with their own respective chambers. The primary chamber receives brake fluid through the primary port, while the secondary port feeds the secondary chamber.

In a vehicle equipped with disc brakes, the brake master cylinder transfers the pressure you apply to the brake pedal to get the brake calipers to squeeze the brake rotor.

What Are Two Types of Brake Master Cylinders?

Brake master cylinders come in a variety of shapes, sizes, and mechanisms, but they all serve the same purpose. They distribute pressure to the brake calipers. The following are two of the most common types of brake master cylinders.

Single-Cylinder

This is the most basic type of brake master cylinder. The inside of a single brake master cylinder is identical to a medical syringe. The brake pedal is directly connected to the piston inside the cylinder. When the brake pedal is pushed, the piston moves and compresses the fluid. When you release the pedal, the return spring expands and pushes the piston to its original position. There’s only one piston and chamber in a single-cylinder brake master cylinder.

Tandem Cylinder

Unlike a single-cylinder master cylinder, a tandem brake master cylinder has two pistons in one assembly. The primary piston is the only one that has a direct connection to the brake pedal. The benefit of a tandem master cylinder is that one hydraulic circuit should still slow you down if you have an issue with the other circuit.

What Are Signs of a Bad Brake Master Cylinder?

A bad brake master cylinder will exhibit one or more symptoms. You might notice some of the following symptoms if your brake master cylinder fails.

Spongy or Mushy Brake Pedal

A spongy or mushy brake pedal can be a sign of a bad master cylinder. If you rapidly press the brake pedal and it rises and gets harder then usually it’s the master cylinder failing. When the brake master cylinder’s sealing or pressure distribution is failing, the brake pedal tends to behave abnormally. There could be a fluid leak involved, which makes your pedal spongy, airy, or difficult to press.

Stuck Brake Pedal

A spongy brake pedal is bad enough, but a stuck brake pedal is even worse. If your brake pedal takes a while to get back into its original position, you’ll have a harder time controlling your vehicle. In some cases, the pedal can get stuck due to the return springs or clogged compensation port in the brake master cylinder.

Longer Braking Distance

This is another telltale sign of a failing brake master cylinder. Longer braking distances can be the result of low brake fluid levels, which may be caused by a leak in the assembly. Worn seals can lead to a lack of brake fluid and don’t hold brake pressure as good as a fresh seal. This symptom is usually accompanied by mushy or spongy pedals.

Contaminated Brake Fluid

Contaminants such as dirt and dust can enter the brake master cylinder through broken seals, affecting brake performance. You can tell if your brake fluid is new or contaminated just by the color. New brake fluid has a clear, amber tone. Contaminated brake fluid has a darker brown or black color.

FAQs

Some Notes on Brake Master Cylinders

If your vehicle is a newer model, its brake system is most likely divided into two circuits. Both of these circuits are likely to be serviced by a brake master cylinder.

Where to Get a New Brake Master Cylinder for Your Vehicle

If you notice any of the symptoms above, it’s best to take your vehicle to an auto repair shop. Licensed mechanics can check your vehicle for the underlying cause. If the issues are due to a bad brake master cylinder, don’t think twice about replacing it to nip potential problems in the bud and prevent costly repairs.

For top-notch cylinders that work like your stock part, shop online at CarParts.com. We have a wide array of brake master cylinders sourced from top aftermarket manufacturers. They passed stringent quality control tests, ensuring they’re built to last.

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All our products are on hand and ready to ship from our strategically located warehouses across the country. That means you can get your new brake master cylinder in as fast as two business days after ordering.

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