Brake Caliper: Definition, Working, Parts, Types, FAQ’s [PDF]

A brake caliper is an important part of a vehicle’s braking system. It helps in slowing down the wheels and bringing the vehicle to a stop. Let’s take a closer look at how it’s structured and functions.

What is a Brake Caliper?

The caliper is a component of the disc brake system. It is usually found in a car’s front brakes. It consist of brake pads and pistons. It creates friction with the brake rotors to slow down the wheels. Acting like a clamp on the rotor, brake fluid pressure on the pistons forces the pads against the rotor when you press the brake pedal, effectively slowing down the car.

Working of Brake Caliper

Working of Brake Caliper

A car’s braking system comprises essential components like

  • Brake Pedal
  • Master Cylinder
  • Brake Lines
  • Brake Calipers
  • Brake Pads
  • Brake rotors (also known as brake discs)

The brake caliper houses the brake pads. It’s job is to convert hydraulic pressure into mechanical force. When you press the brake pedal, hydraulic pressure reaches the caliper from the master cylinder. This prompts the pistons to move outward. These pistons force the brake pads to contact the brake rotor. Due to this friction is generated which slows down the wheels.

The clamping force exerted by the pistons on the brake pads determines braking power, modulated by the driver’s input. Releasing the brake pedal reduces hydraulic pressure, allowing pistons to retract. This retraction creates a gap between the brake pads and rotor, releasing the clamping force and enabling free wheel rotation.

Construction of Brake Caliper

Parts of Brake Caliper

The brake caliper is constructed from robust and high-quality materials. It is designed to endure the forces and heat generated during braking. Following are the main parts of brake caliper:

  1. Caliper Housing: The main body encloses the brake pads and rotor, housing other crucial components.
  2. Pistons: Cylindrical components inside the housing extend outward when hydraulic pressure is applied, pushing the brake pads against the rotor.
  3. Seals and Dust Boots: These components provide a reliable seal around the pistons, safeguarding them from dirt and contaminants. Proper seals are essential to prevent brake fluid leaks and maintain hydraulic pressure.
  4. Brake Pad Clips: These clips securely hold the brake pads within the caliper.
  5. Bleeder Screw: A small screw used for releasing air and excess brake fluid during brake bleeding procedures.

Modern brake calipers may also feature advanced elements like anti-rattle clips and electronic brake pad wear sensors, enhancing overall performance and safety.

What Are The Different Types of Brake Calipers?

Following are the three main types of brake caliper:

  • Floating
  • Fixed
  • Sliding
Fixed Caliper
Fixed Caliper
Floating Caliper
Floating Caliper

Floating calipers, common in modern vehicles, have one or two pistons on one side of the rotor. When brakes engage, the caliper slides inward, pressing the brake pads against the rotor. This simple and cost-effective design is widely used.

Fixed calipers feature pistons on both sides of the rotor, ensuring even pressure distribution and enhanced braking performance. Unlike floating calipers, fixed calipers stay stationary during braking, reducing flexing for consistent brake pad-to-rotor contact.

Sliding calipers, also called pin-slide calipers, have one or two pistons on one side of the rotor, akin to floating calipers. However, they use pins or sliders for slight back-and-forth movement during braking. This design equalizes pressure on both sides of the rotor and promotes even brake pad wear.

When should you Replace Brake Calipers?

In regular driving, brake system heat can damage caliper seals over time, especially if you don’t drive often, leading to rust, contamination, and potential brake fluid leaks.

Get your brakes checked ASAP if you encounter:

  • Continuous squeaking, squealing, or grinding.
  • Brake or ABS warning light.
  • Car jerking or pulling when braking.
  • Needing to pump brakes for proper function.
  • Unusually soft or hard brake pedal.
  • Brake fluid leaks around wheels or engine compartment.

When Does Brake Calipers Go Bad?

Brake pads and rotors typically wear out more frequently than calipers. Driving with worn-out pads or warped rotors, however, can lead to caliper damage. This is because these issues hinder the proper dissipation of friction heat, potentially harming the calipers.

When pads fail to insulate the caliper from excess heat, the piston can be damaged, or the heat may transfer to the brake fluid, causing degradation and potential brake failure.

A damaged or corroded piston may get stuck, affecting braking. If it sticks retracted, the wheel loses braking ability; if engaged, the wheel brakes continuously until freed.

How to Tell If a Caliper Has Failed?

A retracted piston can cause the car to pull towards the side with operating brakes and increase braking distance. Conversely, an engaged piston leads to the car pulling towards the engaged brake. Excess heat, quick brake pad wear, or leaking brake fluid may indicate caliper failure, prompting a warning light on the dashboard. Uneven pad wear suggests checking caliper function, while excessive brake dust on one wheel signals a seized caliper.

In rare cases, a snapped caliper bracket may cause a clunking sound during braking, warranting an immediate stop and avoidance of vehicle operation. Ignoring these symptoms can worsen damage, escalating repair costs and efforts. It’s crucial to address the issue promptly by examining it yourself or consulting a qualified technician.

How to Tell If a Caliper Has Failed?

Important Maintenance Points for Brake Calipers

As brake pads wear, it’s crucial to keep the caliper centered on the rotor for even pressure on both sides. Manufacturers use various designs to achieve this, and some are more effective at accommodating pad wear. During brake service, ensure to clean and grease the sliding mechanisms with high-temp brake grease to maintain full travel range. Without proper lubrication, calipers may lock in one position, leading to uneven pressure on the rotor.

Inspect the dust boots safeguarding the caliper piston and slide pins whenever possible. These covers prevent dirt and moisture from affecting the associated parts. Promptly address any damage or tears in the boots to prevent dirt and corrosion, which can cause parts to seize. While it’s possible to disassemble the caliper and replace boots for DIYers, labor charges in most auto shops make full caliper and bracket replacement a more common and practical solution.

Video of Working of Brake Caliper


The brake caliper plays a crucial role in a vehicle’s braking system, translating hydraulic pressure into mechanical force to bring the vehicle to a halt. It operates by facilitating the controlled movement of pistons, which apply pressure to the brake pads, creating friction and slowing down the wheels. Built with robust materials and diverse components, brake calipers come in various types like floating, fixed, and sliding calipers, each tailored to specific vehicle types and performance needs. The careful design and engineering of brake calipers are essential for ensuring safe and effective braking performance.

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