Engineering a Better Brake Rotor
If you look at a brake rotor, you might think that it is pretty much a machined casting. That it is pretty much no big deal.
And if you did, you would be wrong.
Or so we learn from Mauricio Gonzalez, engineering direct, Advanced—Brakes, SANLUIS Rassini-Frenos (sanluisrassini.com). That company happens to be the largest fully integrated brake disc producer in the Americas; its operations range from R&D to casting to machining. So Gonzalez knows more than a little something about brake rotors. And as SANLUIS Rassini claims to be the one of the world’s largest suppliers of suspension components (e.g., leaf springs, coil springs, torsion bars), Gonzalez and his colleagues know more than an average amount about the issues and consequences of unsprung weight.
At the company’s facility in Plymouth, MI, where they perform a number of physical tests as well as run extensive digital analyses of brake rotors, Gonzalez points out that heat management is a critical aspect of rotor design, particularly for performance vehicles . . . like the 2014 Corvette Sting Ray. And the Corvette has been a vehicle where mass optimization is key, long before OEMs started zealously chasing mass reduction.
So SANLUIS Rassini developed a two-piece rotor design for the Corvette Z51 Performance Package, which combines a ductile iron hat with grey iron plates. This design provides a weight savings as great as 18%, and compared with an aluminum rotor that might otherwise be used for a performance application, the cost is approximately 30% less.
One of the features of the hat design is that there are I-beam extensions that extend out toward the periphery of the rotor. Gonzalez points out that this design, which creates a pocket in between the plates, is highly beneficial for thermal management, particularly as compared with using solid extensions (i.e., there is greater uniformity of cooling using the I-beam design, as well as improved airflow, which are beneficial under various braking conditions, whether this is medium braking or really getting on the pedal). The I-beam design, as it is based on strong ductile iron, allows the material to be cast in thinner sections, which not only contributes to the airflow, but which also helps reduce the weight of the rotor. In addition to which, the composite design of the rotor also allows the use of thinner braking plates.
Less mass and no compromise in performance. Clearly, clever engineering is going on at SANLUIS Rassini.—GSV
The composite rotor developed by SANLUIS Rassini for the 2014 Corvette Z51 Performance Package combines a ductile iron hat and gray cast iron plates. This design decreases weight while improving thermal management.