Calipers are an essential part of your brake system. Here’s how they work.
The brake caliper is one of the most important parts of your car or truck’s braking system. In a disc brake system, it is the only part that you control. It’s the component that does the work when you press down on the brake pedal. But what exactly is a brake caliper, and how does it work?
A BIT OF HISTORY
Brakes might be the most crucial part of a modern car. After all, there’s no point in driving if you have no way to stop. But brakes were around long before the invention of the car: trains had brakes, bicycles had brakes—even horse-drawn wagons could have brakes fitted.
Early cars had drum brakes. These systems feature a curved pad called a brake shoe that presses outward against the inside of a metal drum. Heavy trucks and some other vehicles still use drums, but as of the 1970s, nearly every car, SUV, and pickup has switched to a disc brake system. At least in the front—some vehicles, including the latest electric cars, use drum brakes on the rear wheels.
These days, many motorcycles, ATVs, side-by-sides, and bicycles also use disc brakes.
THE PARTS OF A DISC BRAKE SYSTEM
A disc brake system is wonderfully simple. It consists of a pedal with a plunger to move the brake fluid, a brake disc (hence the name), pads to grip the disc, and a brake caliper.
BRAKE CALIPER
Brake calipers got their name because they look like the vernier calipers you use for measuring objects. Like their namesake, most brake calipers have one fixed part that stays in place and one that moves. That design is called a sliding or floating caliper, and it is one of two that are commonly used in car braking systems.
BRAKE CALIPER COMPONENTS
Brake calipers have two main parts and a few smaller parts. It’s the smaller parts that need maintenance and occasional replacement as part of a rebuild, while the main parts can last almost forever.
FLOATING CALIPERS
The two main parts of a floating brake caliper are the bracket and the caliper itself. The bracket is bolted to the wheel hub or steering knuckle of your car. This part shouldn’t move unless you’re removing it.
The caliper is attached to the bracket in a way that lets it move in one direction. This movement is what clamps the brake pads against the brake rotor.
Inside the caliper is a moving part called the piston. The piston is a lot like the piston in your engine, but this one is pushed out by brake fluid. The brake caliper piston pushes the brake pad against the disc on one side. Because the caliper can slide, the movement also pulls the outside pad against the brake disc.
That’s what turns your vehicle’s forward momentum into heat and slows you down.
The bolt, or bolts, that hold the caliper to the bracket are also crucial. These bolts let the caliper slide against the bracket. That in-and-out movement allows you to apply and release the brakes.
BRAKE CALIPER SLIDING GUIDE PINS
Brake caliper sliders, also called brake pins, are the part of your brake system that requires the most maintenance. They’re also the part that’s most likely to fail and that can leave you stranded with seized brake calipers.
Caliper sliders are cleverly designed and have two main parts. The first is the guide pin. This goes inside your brake caliper bracket with the right amount of high-temp brake caliper lubricant.
The guide pin slides in and out of the caliper bracket. This is how the caliper itself slides in and out when you push and release the brake pedal.
The second is a simple bolt. It threads into the inside of the guide pin and keeps the caliper attached to the bracket.
You can picture these components as a metal sandwich: the guide pin and bolt are the bread, while the mounting tab of the caliper is the filling.
Those are the main parts, but there are also smaller parts that have an essential role, such as boots and seals. In addition to the boots that fit over the guide pins to keep brake dust and road grime from entering the sliders and blocking their movement, there are boots that stop the same dust and grime from getting into the bore where the caliper piston sits. Seals ensure that the high-pressure brake fluid moves the pistons instead of pushing past them and leaking out.
There is also the brake bleeder, which is a small bolt with an even smaller hole. It sits at the high point of the caliper and can be opened to let out air and old fluid. Bleeding your brakes is an important part of brake maintenance.
If you need any of the above-mentioned parts for a brake replacement or brake service, talk to the experts at your local SHENSHUAI Auto Parts store. They can get you exactly what you need for your car.
FIXED BRAKE CALIPERS
Fixed calipers are often found on high-performance cars. They have performance advantages but work in basically the same way as floating calipers. The difference is that instead of having a piston on just the inboard side, there are pistons on both the inside and the outside. The entire caliper is fixed in place (that’s where the name comes from). The pistons clamp and release and are the only moving parts in the system.
MULTI-PISTON CALIPERS
Today’s vehicles are faster, heavier, and more capable than ever. A modern pickup, for example, can tow as much as an older big rig. As a result, brake caliper design has had to evolve.
A single piston can only handle brake pads of a certain size. If the pad is too big, the piston will exert uneven pressure, which can bend or even break the pad. That’s what led automakers to start making calipers with two pistons, to distribute the force. This represented a big brake upgrade. Today, you can buy brake calipers with 10 or more pistons to clamp down on incredibly large brake pads.
CALIPER ACCESSORIES
What about those red and blue brake calipers you see on some cars? If they’re from the factory, the colour is usually applied with a durable finish, like a powder coat. But you can also paint your own brake calipers red, blue, green, or whatever colour you want using brake caliper paint.
All you have to do is remove each part, clean it thoroughly, paint it, and then reassemble. Want the look without the labour? Caliper covers attach to your calipers and make them look like race car parts—minus the need for a race car budget or loads of work.
