1-Piece Brake Rotors

A one-piece brake disc (or rotor) is cast from iron in a single piece, with the friction faces and the centre hat that bolts to the hub made together. It is the standard design on road cars and the usual replacement for them.

The main choice is the face:

• Plain discs have an unbroken friction surface.
• Slotted discs have grooves across the face in straight, curved or bi-slotted patterns.
• Drilled and dimpled discs have holes or shallow dimples, and some combine slots with drilling or dimples.

Slots and holes are there to clear gas and pad material from between pad and disc. The usual trade-off is faster pad wear and a little more noise.

Vented discs have internal vanes between the two faces and are used on most front axles, while solid discs are common at the rear. Where the product data names a vane style, it describes that internal pattern. Some discs are listed as ECE R90 approved. Most are sold as an axle pair and some singly, so check the pack contents.

Fit new pads with new discs so that they bed in together, and follow the pad maker’s bedding-in procedure. Clean the hub face thoroughly before fitting, since rust or dirt behind the disc causes runout and vibration. While the wheel is off, check that the caliper slides move freely.