Caliper Parts

A disc brake caliper assembly comprises several key parts that work together to slow or stop a vehicle: the caliper body, piston, brake pads, and mounting bracket.

Main Caliper Components

The main structure and internal components of the caliper assembly are responsible for applying the necessary clamping force.

Caliper Housing/Body: The main assembly that houses the internal components, typically made of cast iron or aluminium, and is designed to withstand high heat and pressure.

Piston(s): A metal or phenolic component inside the caliper that is pushed outwards by hydraulic fluid pressure when the brake pedal is pressed.

Piston Seal: A rubber seal that sits in a groove in the caliper bore, preventing brake fluid leakage and helping to retract the piston slightly when the brakes are released.

Dust Boot (Piston Boot): A flexible rubber cover that protects the piston and cylinder bore from dirt, moisture, and road debris.

Bleeder Screw (or Nipple): A small valve that allows air to be removed (bled) from the hydraulic system to ensure a firm brake pedal feel and optimal performance.

Brake Hose Connection: The point where the brake line, carrying pressurised brake fluid from the master cylinder, connects to the caliper, often secured by a banjo bolt and washers.

Mounting and Hardware Components

These parts secure the caliper to the vehicle and allow for proper movement and alignment.

Mounting Bracket (Caliper Carrier/Support): A sturdy component bolted to the vehicle’s suspension or axle that holds the caliper assembly in place over the brake disc (rotor).

Guide Pins (Slide Pins): Pins that allow a floating caliper to move laterally (side-to-side) within the mounting bracket, ensuring even pressure is applied to both brake pads. They require high-temperature lubrication to function properly.
Guide Pin Boots (Pin Boots): Rubber boots that cover and protect the guide pins from contaminants.

Locking Bolts/Pins: Secure the guide pins or other components within the assembly.

Anti-Rattle Clips: Small metal clips or springs that hold the brake pads firmly in position within the caliper bracket, reducing noise and vibration.

Associated System Components

While not strictly part of the caliper assembly itself, these work directly with the caliper to stop the vehicle.

Brake Pads: Friction materials (often ceramic, metallic, or organic compounds) that are pressed against the brake disc to create friction and slow the wheel.

Brake Disc (Rotor): A flat, circular metal disc attached to the wheel hub that rotates with the wheel and is clamped by the brake pads.

Shims: Thin plates placed between the brake pad backing plate and the caliper to further reduce noise and dissipate heat.