GIRODISC A1-307 Front Brake Rotor Kit for BMW Z4 M40i (G29) / TOYOTA GR Supra

These GiroDisc 2-piece rotors are a direct replacement for the front rotors on the Toyota GR Supra with the 3.0L motor, as well as BMW G-chassis cars with a 348mm front rotor, including (but not limited to):

• G2X M340i & M440i
• G2X with optional M Sport brakes
• G01 X3 M40i & G02 X4 M40i
• G29 Z4 M40i

Our 2-piece, fully floating assemblies help shed unsprung weight and rotating mass from the front axle of the vehicle. The rotor rings are machined from a proprietary casting made of high-carbon steel formulated to GiroDisc’s specifications. This superior metallurgy results in a rotor that holds up better, and the 72 curved vanes act as a centrifugal pump pulling air in through the hub to effectively cool the rotors under hard use. The 2-piece design means a reusable hat which can be attached to new rings (part number D1-307) when they need to be replaced.

All major components including the hats, rotor rings, and drive pins are manufactured in-house at our facility in Bellingham, WA from domestically sourced materials. The hat is made from 6061-T6 aluminum and coated in a black anodize finish. The drive pins are made from a high-strength steel alloy and cadmium-plated for corrosion resistance. All rotors are assembled with spring clips and Belleville washers for race-ready float while also being street-friendly with no noise from loose hardware.

The minimum thickness at which we recommend replacing these rings is 34mm. We also recommend replacing them if a crack leads to the edge of the ring.