Jaguar successfully switched from drum brakes to disc brakes in 1952, winning the 24 Hours in 1953 with the C-Type, then again in 1955, 1956 and 1957 with the D-Type. The marque's rivals gradually adopted the technology, regardless of engine size.

While disc brakes were a clear improvement over drum brakes, they still had their limitations. The more the driver employed the brakes, the more they tended to heat up. Engineers set out to cool the discs during braking phases and straight line rest phases, resulting in ventilated discs that circulated fresh air between the two surfaces of the disc thanks to air intakes and boas (flexible pipes).

To remain effective, discs had to remain above a minimum temperature and not go beyond a maximum temp or the steel would deteriorate. The discs could not exceed 400 degrees, otherwise they would degrade quickly and fail to provide expected braking, both in terms of power and balance between the four wheels.

Also, disc weight was a factor as the braking assembly (discs, pads and calipers) were attached to the wheel hub carriers, greatly affecting grip.

By the end of the 1980s, research in motorsport and aeronautics made it possible to develop less limited materials for brake discs. Through extensive work with carbon layers and bonding resins, French company Carbone Industrie succeeded in developing carbon discs for competition cars and designing carbon pads to ensure the most efficient braking friction.

Lightness, performance and efficiency: the power of carbon

Carbon discs (and carbon pads) offered several advantages: a much lighter weight than steel discs which provided better grip and the ability to withstand temperatures that could exceed 1,000 degrees. Thanks to higher operating temperatures, the discs could endure more stress, resulting in shorter braking distances. That meant longer distances at full speed and better lap times.

However, carbon brakes did have some drawbacks. They took a long time to manufacture as the process required several days in an autoclave oven to ensure quality. Also, the first generations wore out rather quickly, so it was necessary to replace them during a 24-hour race.

In the late 1980s, Carbone Industrie convinced Nissan to use its carbon discs and pads at Le Mans, and proceeded to equip the R88 C prototypes. Improvements were also necessary in terms of the calipers and brake fluid so they could withstand much higher temperatures. Braking was indeed shortened, with drivers able to apply their brake pedal a third further than their braking marks with steel discs. As an added bonus, spectators always love the fiery red that lights up rims during hard braking, a particularly superb visual effect at night.

Very quickly, other manufacturers arrived on the scene to compete with Carbone Industrie, namely AP Racing as well as Brembo who gradually ended up establishing itself as the major player in carbon brakes.

Once carbon braking systems were adopted, even more effort was spent attempting to control the operating temperatures of the discs. The idea remained to ventilate the interior, but also to force air over the exterior. The discs were wrapped in carbon flanges positioned on both sides, fixed to the caliper or hub carrier, in which the air was pulsed from ventilation slots. The narrow space between the rotating disc and the fixed flange accelerated the air in circulation (heat sink system).

With operating temperatures even more controlled, assembly is rendered more complicated and weight is slightly increased, not to mention reducing the excitement of glowing red discs at Mulsanne, Arnage or the Dunlop Chicane. But the crowds can try to determine whether or not heat sink technology is being used, generally the case for Hypercars so far.

PHOTOS (Copyright - ACO Archives): LE MANS (SARTHE, FRANCE), CIRCUIT DES 24 HEURES, 24 HOURS OF LE MANS. From top to bottom: at the end of the 1980s, Nissan's #32 R88C prototype was one of the first cars to benefit from a partnership with French company Carbone Industrie for the development of carbon brakes; a close-up of Audi's carbon braking system during the free practice and qualifying in 2011; the sight of red-hot front carbon discs during heavy braking, here on an Alpine in 2017, is always appreciated by spectators and photographers.