Next: German GP 20-22 July

Wednesday, March 11, 2009


When it comes to the business of slowing down, Formula One cars are surprisingly closely related to their road-going cousins. Indeed as ABS anti-skid systems have been banned from Formula One racing, most modern road cars can lay claim to having considerably cleverer retardation.

The principle of braking is simple: slowing an object by removing kinetic energy from it. Formula One cars have disc brakes (like most road-cars) with rotating discs (attached to the wheels) being squeezed between two brake pads by the action of a hydraulic calliper. This turns a car's momentum into large amounts of heat and light - note the way Formula One brake discs glow yellow hot.

In the same way that too much power applied through a wheel will cause it to spin, too much braking will cause it to lock as the brakes overpower the available levels of grip from the tyre. Formula One previously allowed anti-skid braking systems (which would reduce the brake pressure to allow the wheel to turn again and then continue to slow it at the maximum possible rate) but these were banned in the 1990s. Braking therefore remains one of the sternest tests of a Formula One driver's skill.

The technical regulations also require that each car has a twin-circuit hydraulic braking system with two separate reservoirs for the front and rear wheels. This ensures that, even in the event of one complete circuit failure, braking should still be available through the second circuit. The amount of braking power going to the front and rear circuits can be 'biased' by a control in the cockpit, allowing a driver to stabilise handling or take account of falling fuel load. Under normal operation about 60 percent of braking power goes to the front wheels which, because of load transfer under deceleration, take the brunt of the retardation duties. (Think of what would happen if you tried to slow down a skateboard with a tennis ball on it).

In one area Formula One brakes are empirically more advanced than road-car systems: materials. All the cars on the grid now use carbon fibre composite brake discs which save weight and are able to operate at higher temperatures than steel discs. A typical Formula One brake disc weighs about 1.5 kg (versus 3.0 kg for the similar sized steel discs used in the American CART series). These are gripped by special compound brake pads and are capable of running at vast temperatures - anything up to 750 degrees Celsius. Previously different sized discs would be used for qualifying and racing, but the 2003 changes to the rules means that all cars enter parc ferme after qualifying - and so therefore set their one-lap time on their race brakes.

Formula One brakes are remarkably efficient. In combination with the modern advanced tyre compounds they have dramatically reduced braking distances. It takes a Formula One car considerably less distance to stop from 160 km/h than a road car uses to stop from 100 km/h. So good are the brakes that the regulations deliberately discourage development through restrictions on materials or design, to prevent even shorter braking distances rendering overtaking all but impossible.

From 2009 teams have the option of harnessing the waste energy generated by the car’s braking process and reusing it via a Kinetic Energy Recovery System (KERS) to provide additional engine power, which can be made available to a driver in short bursts to help facilitate overtaking.