Caliper
A brake component that houses the brake pads and uses hydraulic pressure to clamp them against the rotor, creating friction to slow or stop the vehicle.
The brake caliper is a critical component of a disc brake system. It straddles the brake rotor (disc) and houses one or more pistons along with the brake pads. When you press the brake pedal, hydraulic fluid pressurizes the caliper pistons, which push the brake pads against the spinning rotor to create the friction needed to slow or stop the vehicle.
There are two main types of calipers: floating calipers (also called sliding calipers) and fixed calipers. Floating calipers have pistons on only one side and slide on pins to press both pads against the rotor. Fixed calipers have pistons on both sides and are bolted rigidly in place. Fixed calipers generally offer more even pad wear and superior braking feel, which is why they are common on performance and luxury vehicles.
Common caliper issues include sticking or seized pistons (often caused by corrosion or deteriorated seals), brake fluid leaks around the piston seal, and worn slide pins on floating calipers. A sticking caliper may cause the vehicle to pull to one side during braking, uneven pad wear, or a dragging sensation while driving. In severe cases, a seized caliper can generate excessive heat, damaging the rotor and pads.
During a brake service, mechanics inspect calipers for leaks, proper slide pin movement, piston retraction, and overall condition. Rebuilding or replacing a caliper typically involves bleeding the brake system to remove air from the hydraulic lines.