How Brake Calipers Work

Truck Brake Calipers
Big trucks need big brake calipers, too.
Big trucks need big brake calipers, too.
Richard Scherzinger/iStockphoto

There's no denying it: Trucks and SUVs are big -- excessively big, in some cases. With that increased size comes increased momentum. This means that trucks and SUVs need more stopping power than a car. So where can they get the stopping power they require? Truck brake calipers. The stopping power of a caliper is determined by its clamping force -- the amount of force it can apply to the surface of a rotor. This is primarily a function of the number of pistons and the surface area of the brake pad (where it actually contacts the rotor). Obviously, a caliper with a greater clamping force is capable of slowing or stopping a vehicle easier and faster than a caliper that has a lower clamping force.

­Many trucks come from the factory with basic floating calipers that provide sufficient clamping power for the vehicle as it's delivered to the dealer. However, when the truck is customized with larger tires and heavy accessories, and when a substantial load of cargo is brought on board, these factory-installed calipers might not be powerful enough to provide the braking power the truck needs. Fortunately, there's a substantial aftermarket for truck calipers. From the manufacturer, a truck might have calipers that provide in the neighborhood of 5,000 square millimeters (7.8 square inches) of surface area between the pistons and the rotor. An aftermarket caliper can more than double that surface area, providing the clamping force required by a fully customized vehicle.

More than most brake parts, truck brake calipers have to deal with a lot of heat. Heat is bad for brakes because it can lead to brake fade and reduced stopping distances. Good ventilation in the caliper is essential for continuous, consistent brake performance. In addition, a larger brake rotor (or brake disc) surface can also help spread the heat over a larger area.

Trucks and SUVs aren't the only vehicles that require special brake equipment; however, the calipers in these heavy-weight vehicles do have a difficult job to perform. Some might even say that truck brake calipers should be considered high-performance brake calipers. In the next section we'll look at some of the features that high-performance brake calipers can offer other vehicles.