Tech Support

Why use a two-piece "floating" disc assembly?

There are several reasons that a two-piece floating disc assembly is of benefit. First, by using an aluminum bell 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. During severe use, temperature variances become present in a one-piece disc and generally cause warping of the disc. This not only results in vibration of the vehicle, and pulsing of the brake pedal, but also pushes the pistons farther away from the disc. In a two-piece floating disc assembly, the iron disc heats up more 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. This allows the disc to be used under severe conditions without having a detrimental effect.