Formula 1 Innovations: the Carbon Brake Revolution

Source: The following is excerpted from a history of carbon-fiber brakes in Formula 1 race cars by Lawrence Butcher posted on the English site MotorSport.

Until the early 1980s, Formula 1 used cast iron brake discs and aluminum calipers not too dissimilar to those found on road cars. As Steve Bryan – trackside man in F1 from the 80s until 2017 for long-time brake supplier AP Racing – puts it, “I think the calipers used to be about £60 each. That wouldn’t even buy a pair of pads today. If you wanted to build a car back then that is how it was. You got an engine from Cosworth, a gearbox from Hewland, folded up some aluminum honeycomb, bought brakes and a clutch and you were nearly there.”

However, these simple brake systems were being taken to the limit thanks to rapid aero and tire development as an example, Bryan highlights Renault. “They were the first to switch to turbocharged engines and they had a particular problem with the brakes overheating, because you don’t get as much engine braking from a 1500cc V6 compared to a big old 3.0 liter V8,” he said. “The car was also a bit heavy at that stage with all of the radiators and intercoolers hanging off it.”

Carbon-carbon brakes would prove to be the answer to such problems, though not without their share of teething problems. Brabham started to use the material in 1976, but it would not reach maturity until the 80s. By way of background, carbon-carbon brakes originated in the aerospace industry, where they were first developed by BF Goodrich and one of their earliest uses was on the Concorde supersonic airliner, the brakes for which were developed under license by Dunlop.

Gordon Murray, who at the time was working for Brabham, recognized the benefits they could bring to vehicle braking: greatly reduced weight compared with cast-iron discs, and much higher temperature resistance.

The very first carbon-carbon brakes used in racing were not of the pure carbon-carbon construction as we know them now. Dunlop was concerned about the matching of the thermal characteristics of a carbon disc on an aluminum brake bell and so built a composite disc assembly. This consisted of an inner steel plate with 20 carbon pucks mounted on the surface, ten per side. Unfortunately, this approach did not work, as the differential in the thermal expansion rates of the carbon and the steel caused the discs to deform. Once deformed, they rubbed against the calipers, causing them to overheat and boil the brake fluid.

To view the entire MotorSport post, with additional images, click HERE.