2008 Nissan Frontier - Brake Caliper Piston

Brake Caliper Piston Replacement

The brake caliper piston moves under hydraulic pressure to compress the brake pads. When the driver applies the brakes, hydraulic pressure is applied to the brake caliper, which then pushes the piston outward. This force is transferred to the brake pads, which clamp down on the rotor, creating friction to slow the vehicle down. After the brake pedal is released, the piston retracts slightly back into the caliper to prevent constant friction. The piston typically uses a caliper piston seal or rubber O-rings to prevent brake fluid leaks and may have dust boots to keep dirt and moisture from entering the caliper and damaging the piston or other components. Some brake calipers have multiple pistons, which allow for more even pressure distribution across the brake pads and rotor. Over time, corrosion can form on the sealing surface of the caliper or piston, causing leaks. It is also possible that the piston could seize in the caliper itself, which may keep it from retracting and lead to pulling when driving or braking. When you need to service or replace your brake calipers, rebuilding calipers is still an option with some older or limited-run vehicles and can help you restore braking performance if a completely remanufactured caliper is not available. When rebuilding a brake caliper, inspect your brake caliper piston to determine if a new piston might be required. This job will also require replacing the brake piston seal and other parts, which may be available in a brake caliper rebuild kit. When you are ready for your caliper rebuild, browse O'Reilly Auto Parts for the right caliper piston and seal. We also carry brake hoses, bleeder tools, brake pads, and rotors for a complete brake caliper repair, and can help you learn more about the symptoms of brake system failure in our How-To Hub.