One-Piece Brake Rotors

Are your original brake rotors worn, or do you need more from your brakes on country roads and at trackdays? One-piece brake rotors are typically cast as a single unit with the braking surface and hub together. You can choose between plain, slotted and drilled rotors from brands such as Brembo, EBC and Alcon.

What characterises a one-piece brake rotor?

A one-piece brake rotor has the braking surface and hub cast together, typically in cast iron. Many cars have this design from the factory, and the rotor is easy to replace. A two-piece brake rotor instead has a separate ring mounted on a bell. This can save weight and make it possible to replace only the brake rotor rings.

How to choose the right rotor

Start with the fitment, then choose the surface according to how you drive:

• Dimensions and mounting: Diameter, thickness and bolt pattern must match the hub and brake caliper, e.g. 326x30 mm and 5x114.3 on a Brembo rotor for Subaru.
• Surface: Slotted rotors, e.g. EBC USR, can keep the pad surface clean, while drilled rotors can channel heat and water away from the surface. Plain rotors typically give the most even wear.
• Mounting side: Some rotors are specific to the left or right side.
• Use: Rotors and pads must suit road use or trackdays, where overheating can cause braking performance to drop.

Fitting and maintenance

Always replace rotors in pairs on the same axle, clean the hub face thoroughly, and follow the manufacturer's bedding-in instructions together with new pads. Regularly check the thickness against the specified minimum. Whether a rotor may be used on the road depends on the product and the car, so check e.g. R90 approval for the specific part number. The category also includes rotors from Baer Brakes, Alcon and Performance Machine.

Frequently asked questions

Should I choose slotted or drilled one-piece brake rotors?

It depends on the use. Slotted rotors can keep the pad surface clean, while drilled rotors can channel heat and water away from the surface. Choose based on your driving, your pads and the manufacturer's recommendation for the specific rotor.

Can a soft brake pedal be caused by the brake rotors?

Rarely directly. A soft or long pedal is typically caused by air in the system or boiling brake fluid. Uneven rotors more often cause vibrations in the pedal and steering wheel. With overheating, braking performance can drop even though the pedal feels normal.

Are the brake rotors approved for road use?

It depends on the product and the car. Some rotors are intended for the road, others mainly for the track. Always check whether the specific part number has the required approval, e.g. R90, before fitting the rotors to a registered car.