They used to get very, very hot.
Porsche is a thoroughbred sports car brand and builds some of the best driver's cars the world has ever known. Like most other manufacturers with a similar heritage, Porsche's road cars were born out of the mistakes and lessons learned on the racetrack. Modern marvels such as the upcoming and exceptional Porsche GT3 RS and its effervescent 718 Cayman GT4 sibling are dynamic masterpieces because they have racing DNA in their blood (or fuel lines?), and Porsche's internally ventilated disc brake is the perfect example of how the German automaker's motorsport history has contributed to making its road cars great. Here's how it came about.
Every gearhead knows that if you can out-brake your opponent in the corners, you have a major overall advantage, but a car's braking system is only effective if it can remain cool under heavy use. Back in the 1960s, brake disks could reach temperatures of over 500 degrees Celsius (932 degrees Fahrenheit), at which point performance would be drastically diminished, and in some cases, such high temperatures would lead to complete brake failure. Porsche came up with a revolutionary solution to brake cooling in 1965 when it supplied mountain-racing legend Gerhard Mitter a Porsche 906-8 Bergspyder for the European Hill Climb Championship. This special race car tipped the scales at only 570 kilograms (1,256 pounds), and featured a naturally-aspirated 2.0-liter eight-cylinder engine producing a healthy 260 horsepower. But that wasn't the most innovative feature: it had double-walled brake discs with secret drilling in the front.
Porsche figured out that the radial channels that extend from the outside to the center of the disc are crucial to channeling air over the heated surface of the disk. This added cooling makes deceleration more stable, and in the case of Mitter, completely changed his angle of attack: instead of taking it easy on the brakes, Mitter could now use the improved braking as an offensive tool. He did so to great effect.
"What proves its worth in motorsport should also benefit series models - and the developers in Stuttgart operate with this motto in mind from the very start," says Porsche. "The technology of the internally vented brake disc is transferred more quickly than any before it, with buyers of the new Porsche 911 S also able to enjoy the innovative system just one year later in 1966. And now it's standard in every premium vehicle." We're thankful for your service, Stuttgart.