Mechanics

Brake Caliper

Article describes how an automotive brake caliper works.

A brake caliper is designed to utilize brake fluid under pressure to transfer force the brake pads. In turn, the brake pads contact the rotating brake rotor to slow the car through friction. A brake caliper is typically mounted to the spindle or backing plate. There are two basic designs of brake caliper mounting, fixed and floating. A fixed position brake caliper is bolted to the spindle and is not allowed to move. This kind of brake caliper is constructed with caliper pistons on both sides of the caliper. The floating style of caliper which is more common is mounted to the spindle or backing plate using slide bolts. These slide bolts allow the caliper to slide as the brake pads wear. This design uses pistons on one side of the brake caliper.

Fixed Mount Brake Caliper
Fixed Mount Brake Caliper

Brake calipers can have from 1 to 6 pistons depending on manufacturer design. All brake calipers are fitted with a brake fluid bleeder. This bleeder is designed to allow air to escape from the system. If air is allowed in the system it can cause brake operation failure. A brake caliper piston is sealed to the brake caliper housing using a main piston seal. This seal allows the piston to move back and forth without allowing brake fluid to leak out. This seal is protected by a dust seal that keeps debris from contaminating the integrity of the seal. The brake system should always be flushed and bled regularly to prevent moisture from creating rust. This rust can cause the caliper piston seal to fail allowing brake fluid to leak. If a brake caliper is leaking a rebuilt or new caliper is needed.

Floating Brake Caliper
Floating Brake Caliper

A rebuild kit replaces the main seal and dust guard. A high pressure brake hose is connected from the car frame or body to the caliper. This hose is sealed against the brake caliper using copper sealing washers. When removing this hose it's recommended that a new copper sealing washer is installed. Anytime the brake system is opened a brake system bleed is necessary. Visit - Bleed brake system

Exploded Brake Caliper
Exploded Brake Caliper (Floating)

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-11-19)