GiroDisc 345mm 2-Piece Slotted Rear Rotors 2018-2026 Toyota GR Supra, BMW X3, X4, Z4 M40i, M340i, M440i

GiroDisc slotted 2-piece rear rotors for the 2018-2026 BMW X3, X4, Z4 M40i, M340i, M440i, Toyota GR Supra. Each rotor pairs a slotted iron ring with a lightweight aluminum hat, so it runs cooler and weighs less than a one-piece disc. Each rotor weighs about 15.5 lb. GiroDisc builds its rotors for drivers who take their cars to the track, and they stay quiet and smooth enough for daily use.

How GiroDisc builds it

Each assembly is fully floating: a slotted iron ring rides on drive pins around a separate aluminum hat. The ring is machined from a proprietary high-carbon iron casting made to GiroDisc's own specification, which holds up better under hard use. Its 48 curved vanes act as a centrifugal pump, pulling air in through the hub to cool the rotor. GiroDisc makes the hats, rings and drive pins in-house in Bellingham, Washington, from domestically sourced material. The hat is 6061-T6 aluminum with a black anodized finish, and the high-strength alloy steel drive pins are cadmium plated against corrosion. Spring clips and Belleville washers give the ring race-ready float without rattling on the street.

Reusable hats

Because the hat is a separate part, you only replace the iron when it wears out. New GiroDisc rings (D2-307) bolt onto the hats you already have, which costs much less over time than buying complete rotors. Replace the rings at 22 mm minimum thickness, or sooner if a crack reaches the outer edge.

What's Included

Two assembled rear rotors, one for each side, with each iron ring already mounted to its aluminum hat. Brake pads are not included.

Specifications

Fitment notes

The product photo is GiroDisc's representative image of its 2-piece rotors.

Fitment