These GiroDisc 2-piece rotors are a direct replacement for the E46 M3 345mm rotor found on Competition Package (ZCP) and CSL models. Weighing in at 17.5 lbs per rotor versus 19 lbs per factory rotor, these 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 48 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 D1-012) 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.
Our E46 M3 rotors have been designed with common aftermarket caliper setups in mind, in addition to the stock sliding calipers available on ZCP and CSL cars. These setups include the Brembo calipers from both the Porsche 996 and Megane RS swaps.
Diameter: 345mm
Thickness: 28mm
Weight: 17.5 lbs per rotor assembly
The minimum thickness at which we recommend replacing these rings is 26mm. We also recommend replacing them if a crack leads to the edge of the ring.