Parts of a Brake Caliper Explained

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Brakes calipers, used in disc brakes, play a very important role and should be monitored timely. If the brake caliper fails, your car may spin on slippery tracks due to low friction for the front brakes to function effectively. A brake caliper comprises a number of small pistons and other important components.

What are the parts of a brake caliper? Brake calipers comprise slipper pins, dust boots, piston seals, mounting clips, brake pads, locking bolts, and shims. The brake caliper assembly has components all made of metal; they are all prone to excessive wear, over time; hence, you should always have them checked.

Brake Caliper Overview

parts of brake caliper
Image credit: Pixabay

A brake caliper is an assembly of about, roughly eight different components that are important to make disc brakes function as supposed. You’d only find calipers in disc brakes, and disc brakes are typically used in modern vehicles’ front wheels. So, to find a brake caliper, check your vehicle’s front wheel hub.

The caliper houses the brake pads and pistons, along with other smaller components like pins and shims. Calipers have one major function, which is to increase friction with the brake rotors, thereby causing the wheels to stop moving, bringing the vehicle to a stop. Brake calipers run with hydraulic brake fluids generated from the master cylinder.

Actually, the caliper itself is a “clamp” on the wheel’s rotor, which when engaged, tightens itself on the rotor to stop wheel rotation. The caliper is engaged the moment you match the brake pedal inside the driver’s cabin. A damaged brake caliper may cause trigger a lot of unusual signs and might subsequently cause the entire brake system to fail if not fixed as soon as possible.

Part of a Brake Caliper Explained

1. Caliper Pin (Slipper Pin)

The caliper pin is the reason why the brake caliper unit moves back and forth. These pins are also called “slipper pins,” due to the way they function. Brake caliper pins are greased into position, and protected by dust boot and slide. The caliper pin grease is usually silicon-based, waterproof, and highly resistant to water.

2. Pistons

Calipers come with a varying number of pistons depending on the brake assembly design and vehicle type. Some calipers have just one piston, while some have as many as four, or even more. The pistons play an important role in making the brake calipers perform efficiently.

Caliper pistons push the brake pads to press on the rotors and stop the wheels from moving. These pistons are built strong and should last over 80,000 miles, but for quite many reasons, they may start to fail before you reach that mileage.

3. Slide Pins

Slide pins, also called caliper guide pins, are two metallic pins that stop the caliper from sliding backward more than it should. Each brake caliper unit has two slide pins. Apparently, the pistons in the caliper force it to move back and forth when you press or release the brake pedal; the slide pins help to control these back-and-forth movements to ensure the caliper doesn’t move more than it should. Broken slide pins will definitely affect the caliper’s performance.

4. Dust Boots

Without the dust boots, dirt and moisture will easily get into the caliper assembly, and that could cause the caliper not to function efficiently. Caliper dust boots are usually made of rubber; so they are flexible to fit on. If the dust boots are broken, you should replace them earlier before much dirt and moisture gets into the caliper cylinder bore.

5. Piston Seals

There are two major functions performed by the pistons seals; first, the seal rolls back (retraces) the caliper piston to its initial position (inside the bore) after it (the piston) has moved forward earlier to push the brake pads against the rotors. The second function of the caliper piston seal is to protect the piston bore from dirt and dust.

6. Brake Shims

The brake shims are small tiny metallic adhesive pads that hold the brake pads and calipers together. It is like a bracket that binds the brake pads to the calipers to keep both units firm and steady; this helps to minimize noise when braking is applied, whether at top or low speeds.

7. Mounting Bracket

Calipers don’t “magnet” onto the rotors; they are mounted, and that is achieved using a mounting bracket. A caliper mounting bracket is used to hold the caliper to the steering knuckle and brake rotor or disc. This bracket is solid and build to last long; however, hard impacts may cause it to break and require replacement.

Frequently Asked Questions

What are the Types of Brake Calipers?

There are two major types of brake calipers: fixed and floating. The fixed caliper is the type that has more pistons placed on opposite sides of the brake rotor(s) and remains static always, while a floating caliper slides in and out of the rotor – guided by the slide pins. Fixed calipers typically offer better overall performance.

What are the Signs of a Failing Brake Caliper?

A failing brake caliper may cause the check engine icon to illuminate on the car’s dashboard. Also, the bad caliper may cause the vehicle to pull one side whenever you match down the brake pedal. Other common signs include hydraulic fluid leaks, reduced braking efficiency, and squealing noise whenever you press down the brake pedals.

What is Caliper Assembly?

The brake caliper assembly refers to the collection of quite many different components that help the brake caliper to carry out its designed function(s) effectively. Every vehicle with a disc brake system has a set of calipers installed on the rotors.


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