Brakes

The most violent thing an F1 car does is not accelerating. Braking from 320 km/h for a hairpin, the car sheds speed at up to 5g — five times harder than any road car can — and the driver's body slams forward against the belts as though the car has hit water. It happens in about 120 metres and two and a half seconds. This lesson is about where all that motion goes.

Where the energy goes

Kinetic energy scales with the square of speed:

For 800 kg at 320 km/h ($\approx 89\,\text{m/s}$) that is about 3.2 megajoules — a kettle boiled dry, disposed of in one braking zone. A slice is harvested by the hybrid system (the MGU-K lesson), but most of it becomes heat in four carbon discs, which flare to 1000 °C and glow like foundry pours in night races.

Carbon on carbon

Discs and pads are both carbon-carbon composite — not for weight alone (though each disc is under 1.5 kg, a third of a steel disc) but because the material's friction improves when scorching hot and survives temperatures that would melt iron. The price: below ~300 °C the brakes barely work, which is why out-laps and safety-car restarts are genuinely dangerous, and why the discs are drilled with over a thousand tiny cooling holes and fed by carefully sized ducts. Cooling is a setup decision like wing angle: too much airflow and the brakes never reach temperature; too little and they eat themselves before the flag.

Brake-by-wire

The front brakes are conventional hydraulics — pedal, fluid, calipers. The rear axle is stranger: braking there is shared between friction brakes and the MGU-K harvesting, whose contribution varies with battery state and engine mode. To keep the pedal honest, the rear circuit is brake-by-wire: a computer reads the driver's pedal, decides the split between friction and harvest each instant, and actuates the rear calipers itself. The driver feels one consistent pedal while the electronics juggle two braking systems underneath — and if the electronics fail, a hydraulic backup takes over directly.