2-Piece Brake Rotors

Fixed vs Floating assemblies: What are the differences?

Fixed

Although not having the advantages of a fully floating assembly, 2-piece rotors that use a fixed rotor to hat assembly do offer one of the most significant advantages that 2-piece rotors offer; reduced weight. By making the center-section of the disc out of aluminum, a great deal of weight can be saved in a key location, as it is both unsprung and rotating. Another advantage to this construction is reduced heat-transfer to the vehicle’s hub and wheel bearings. While overheating wheel bearings in street-use isn’t normally a concern, it certainly can be when driving on the racetrack. Because of the more simple rotor to hat assembly design, fixed 2-piece rotors are often also cheaper as to their fully floating counterparts.

Floating

The greatest advantage lies in the float itself. The brake discs must cope with extreme temperature levels. In some cases, the disc temperatures can exceed 600℃. When a material is heated it expands, and due to the large temperature change experienced in brake discs, this effect can be significant. In the case of a non-floating disc, not all of the material heats up uniformly. The center-section of the disc remains relatively cool compared to the braking surfaces. This temperature difference causes thermal stresses to develop which lead to warping of the disc and cupping of the braking surface, as well as increased crack potential. With the full-floating system, the disc is free to grow relative to the bell, and can remain straight and true.