Brake discs
The carbon brake discs used in Formula 1 may not be thicker than 28 millimetres and their diameter may not exceed 278 millimetres. When braking, the discs heat up to as much as 600 degrees Celsius within a single second.
Brakes
Formula 1 brakes are made of carbon. Under FIA regulations, each wheel is permitted only two brake shoes and a maximum of six pistons. Brake callipers must be made of an aluminium alloy. Cooling fluids, ABS and power-assisted braking are not allowed. Full braking will bring a Formula 1 car from 200 to 0 km/h within 55 metres, all within 1.9 seconds. Deceleration forces achieve up to 5 G – the driver has to endure five times his own weight.
These brakes are extremely expensive as they are made from hi-tech carbon materials (long chain carbon, as in carbon fibre) and they can take up to 5 months to produce a single brake disk. The first stage in making a disc is to heat white polyacrylo nitrile (PAN) fibres until they turn black. This makes them pre-oxidised, and are arranged in layers similar to felt. They are then cut into shape and carbonised to obtain very pure carbon fibres. Next, they undergo two densification heat cycles at around 1000 degrees Celsius. These stages last hundreds of hours, during which a hydrocarbon-rich gas in injected into the oven or furnace. This helps the layers of felt-like material to fuse together and form a solid material. The finished disc is then machined to size ready for installing onto the car.
The main company that makes brakes for F1 cars is Brembo. Carbon discs and pads are more abrasive than steel and dissipate heat better making them advantageous. Steel brakes as used in CART are heavier and have disadvantages in distortion and heat transfer. Metal brake discs weigh about 3 Kg, carbon systems typically 1.4 Kg. Metal brakes are advantageous in some aspects such as 'feel'. The driver can get more feedback from metal brakes than carbon brakes, with the carbon systems often being described like an on-off switch. The coefficient of friction between the pads and the discs can be as much as 0.6 when the brakes are up to temperature. You can often see the brake discs glowing during a race, this is due to the high temperatures in the disc, with the normal operating temperature between 400-800 degrees Celsius.