Brakes Part 5: Cooling
Most of the enormous amounts of heat generated during deceleration must be dissipated into the free air stream. Most high performance (and/or heavy) cars today use some variation of the “ventilated” brake disc in which air entering the center or “eye” of the rotor is forced through the interior of the rotor by the pumping action of the rotating assembly.
The most efficient practical way yet devised to accomplish this is through the use of the “curved vane” ventilated brake rotor originally designed for the LeMans winning Ford GT 40s in 1966. In this design the interior vanes are curved to form an efficient pump impeller.
They also stabilize the rotor from distortion and serve as very effective barriers to stop the propagation of cracks due to thermal stress. In laboratory testing it has been shown that race discs with vane rotors have increased air flow through the rotor by over 50% over some OEM rotors. This results in a cost effective but very stable direct replacement rotor that runs typically 15% cooler than stock. Of course the brake discs have to installed in the correct orientation….
Additional cooling can be provided through the provision of brake cooling ducts. These are used to take air from a high pressure point at the front (or rear) of the car and direct it to the centre of the brake disc. This is only really needed on the high end GT3 cars that have significantly greater heat levels to dissipate.