What is a brake rotor?

Brake rotors are braking devices that improve the braking performance of vehicles with wheels in contact with the ground.

They are an essential part of a vehicle's disc brake system. They work in conjunction with brake pads and calipers and are installed on the wheel hubs. The brake rotor is a solid disc attached to the wheel hub of a vehicle with a disc brake system. The hub is the central part of the wheel.

When the driver applies the brake pedal, the brake pads compress the discs in proportion to the pressure applied to the pedal. This squeezing creates friction, which helps stop the vehicle by converting kinetic energy into heat.

How does the rotor work?

The brake rotor is attached to the wheel hub so that it rotates with the wheel. Each rotor contains brake pads. When the brake pedal is depressed, a piston creates pressure in the brake fluid circulating in a cylinder and transfers that pressure to the brake caliper.

The pressure causes the caliper to push the pads against the rotor. The friction between these two elements reduces the rotational speed of the disc. When the rotor sticks to the wheel, the wheel is also braked.

However, due to the friction between the pads and the rotor, the rotor heats up considerably, easily reaching over 600°C. In this way, the rotor brake system converts the kinetic energy of the wheel motion into thermal energy.

Types of brake rotors

Brake rotors are components with different structural compositions. This is highly dependent on the type, power and use of the vehicle. For example, there are :

• Cast iron disks
• Steel disks
• Carbon disks
• Ceramic disks

It's becoming more and more common to find "bi-component" parts on the brake disc market: the material that makes up the surface of the disc is different from the material that makes up the backing. It is therefore possible to find cast iron/aluminum or carbon/ceramic rotors. But materials aren't the only parameters to consider when buying your discs: you also need to consider their design. Three types of rotors are available:

• Solid rotors: simple, rear-mounted rotors.
• Grooved rotors:These have grooves that serve the same purpose as the holes in perforated rotors.
• Vented rotors: Consists of two solid rotors stacked on top of each other with a space between them.
• Punched rotors: ventilated rotors that have been punched for better cooling.

How thick are the rotors?

The thickness of your rotors is also known as the rib. This is a good indicator of the condition of your brake parts. If the thickness of your rotors is less than the manufacturer's recommended thickness, it's time to replace your rotors because they are no longer as efficient as they should be. In this case, the disk is said to be "out of rib". In general, front rotors should not be less than 23 mm thick and rear rotors should not be more than 10 mm thick.

Brake rotors maintenance

Some manufacturers recommend replacing the rotor every two brake pad changes. Others suggest replacement every 20,000 miles. Always follow your vehicle manufacturer's recommendations.