There are several reasons that a two-piece floating disc assembly is of benefit. First, by using an aluminum bell or (hat) for the hub section of the disc saves a great deal of weight. Since this is both rotating and unsprung, it benefits the acceleration, braking, and handling of the vehicle. Secondly, it is better able to handle the large temperature changes that a brake disc experiences. In a two-piece floating disc assembly, the iron disc heats up uniformly, and the controlled float which is present allows for the differential expansion of the very hot brake disc, and the relatively cool aluminum bell (hat). This allows the disc to be used under severe conditions without having a detrimental effect.