Brake calipers are an important component of a car's braking system. They are responsible for applying force to the brake pads which in turn slows down or stops the car.
In a typical car, there are brake calipers on each wheel. They are typically located behind the wheel and are connected to the steering knuckle, with part of the caliper visible in front of the brake rotor. The calipers contain one or more pistons, which are pushed outwards when the brake pedal is pressed. These pistons apply force to the brake pads, which grip onto the brake rotor and slow down or stop the wheel.
Brake Caliper Materials
The brake calipers are typically made of aluminum or cast iron, which are materials that are both strong, with aluminium being quite lightweight and iron being relatively lightweight. They are also designed to withstand the high temperatures that are generated by the friction during braking.
Fixed calipers stay in place and have at least one piston per side that pushes the brake pads into the rotor when the brakes are applied. Because the force is applied in two directions from a fixed component, wear and tear can sometimes lead to uneven braking between the inner and outer brake pads, which may wear out the brake pad that recieves more pressure faster.
Fixed Caliper Pins
The pins in a fixed caliper keep the brake pads in place, preventing them from wearing at an odd angle. These pins are often lubricated but not always, and typically replaced during brake pad replacement.
Floating calipers are a specific type of brake caliper that have a caliper bracket fixed to the steering knuckle and the caliper itself "floats" by riding pins in and out of the caliper bracket. Because the force applied during braking is only on one side, it's much more forgiving when wear and tear comes into play. Floating calipers are often (but not always) easier to service than fixed calipers.
Floating Caliper Pins
The pins on floating calipers are thicker than those of fixed caliper pins because they have to withstand much more force and guide the entire caliper instead of just the pads. These are almost always lubricated, replaced often (but not always) during service, and sometimes have differences between the top and bottom that need to be remembered. Sometimes unusual wear patterns form in the pins, and may be a sign of other issues, defective/damaged pins, or sometimes even just normal wear and tear.
Caliper Bolt Torque
Brake calipers are often held on by just two bolts, so making sure they are tightened to the proper torque specification is vital for safety. One bolt coming out may allow the caliper to pivot in the wheel and loosen the other bolt, which could lead to the caliper falling completely off. Proper torque specs will differ from vehicle to vehicle.
Brake Caliper Paint
Brake caliper paint can add some style to brake calipers, as well as protect the metal from corrosion. Paint formulations specific to brake calipers will be able to withstand high temperatures, and ideally stand up to brake dust and wheel cleaner chemicals. Sometimes engine paint will be used interchangably, but lower quality engine paints may not last long on a brake caliper.