Kiinteitä yhdestä metallista sorvattuja jarrulevyjä ei olla käytetty etujarruina pitkään aikaan. Takajarruja on vielä nähtävillä.
Tässä pieni pätkä Brembon kavereiden kirjoittamana:
Q: Why use a two-piece "floating" disc assembly?
A: 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.
Eli kiteytettynä lämpölaajeneminen ja painon säästö ovat syitä kahden metallin käyttämiseen.
Jossain haastattelussa kyseltiin rr-mekaanikolta etujarrulevyjen kieroutumisesta. Hän sanoi, että ei ole uransa aikana ikinä törmännyt kieroihin jarrulevyihin. Itse olen myös hyvin skeptinen, että jarrulevyjä saa kieroksi pelkästään jarruttelemalla.
edit: Lisätäämpä tämäkin tähän samaan syssyyn.
Q: Some of the bushings in the two-piece disc assembly seem to be loose.
A: The two-piece disc assemblies utilize a floating disc. The mounting system of the disc is designed to allow a specific amount of float in both the radial and axial directions. The merits of this system have been discussed earlier. Brembo has engineered special springs that are used on every other fastener in order to slightly preload the assembly. This has been done to prevent excessive noise from the system during street use, while still maintaining the benefits of a floating disc. These springs can be seen when looking at the backside of the disc. The small screws on the backside of the disc are properly torqued during assembly and utilize thread lock compound to prevent loosening. They must not be tightened further.