"But that also means this design doesn't have the clamping load to distribute the forces. The 4 bolt holes see much more force on this when compared to the rear. The aluminum alloy is too soft for the rotational moment as well as the clamping from the bolt heads, so I made steel inserts that enlarge the holes, reducing the stress in the aluminum. The inserts also are stepped, and protrude above the surface of the aluminum, so they take most of the clamping load as well."

"This rotor hat is an unusual design in that it doesn't get clamped between the wheel and the hub as most rotors do. This hat is only bolted to the back side of the hub. The offset is actually the underside of the outer ring, where the rotor bolts, compared to the visible side of the inner ring with 4 holes, where the hat mounts to the back side of the hub. The offset is actually only 2mm, so if it were a flat plate design the total thickness would have been 2mm, much too thin to carry the load..."

"the Lotus design was a flat plate, so I tried to improve the stiffness, while still keeping it easy to manufacture (with my skills and limited tools). So this dish helps, but adds another dimension in the shape of any distortion. The idea behind the floating rotor is that the rotor is allowed to seek the center of the caliper axially, and also grow radially, with thermal expansion, without distorting the aluminum hat."

"Makes sense. Did you try to match stiffness as well, or did the interfacing dimensions drive the whole design?"

"That isn't a typical load case. It was a comparative load to the design that Lotus used. The flange thickness for the Brembo floating rotor hardware must be withing a specified range for the system to function, so that drives the part thickness. Then the rotor and caliper offset dimension drives the rest. Any more offset and the rotor or caliper will hit the steering, and result in damage or a reduced turning circle. Any less offset and the caliper will interfere with the wheel spokes."