A brake caliper has three main components, these being the caliper body, the caliper pistons and the brake pads, as shown in the diagram below:
The main function of the caliper is to hold the brake pistons in place when the brakes are not being applied and to direct the brake fluid onto the back of the brake pistons when the brakes are being applied. As a result of the massive forces that applied through the braking system during a race, the caliper has to exceedingly stiff. Stiff calipers also give greater pedal “feel” as more the pressure exerted by the drive goes to pushing the brake pads onto the brake disk and not causing the brake caliper to flex.
Brake calipers are often made of high strength lightweight aluminium.
In order to ensure even pad brake wear, modern racing calipers are designed with differential piston sizing that minimize pad taper by equalising piston pressure to the pad backing plate.
As brake disc sizes increase the number of pistons that push the brake pads onto the brake disc increase. This gives a more uniform pressure application, more even brake pad wear and greater stopping efficiency. This is often referred to a “? Pot” calipers, where a 6 pot caliper has 6 pistons. Of course, the more pots, the bigger the caliper
Caliper pistons can be manufactured from a range of materials depending on the available budget. The thermal expansion of the piston material has to be known when designing the caliper body and the seal.
Titanium is the ideal piston material as it does a really good job of insulating the fluid in the caliper from conductive heat transfer from the pads. Virtually all-serious racing cars use Titanium caliper pistons with an anti-galling surface treatment, which changes the colour from a natural almost dull silver to gold.
Brakes pads will be covered in another update.