Oddball Facts & Figures

Automotive brakes have benefited from over 100 years of development, transforming them from the crude and near-useless devices of yesteryear to today's reliable and efficient, electronic anti lock braking systems. Here's a few facts and figures collected on the long and fascinating path...

Volvo introduced asbestos-free clutch and brake linings to its cars as long ago as 1986. Another feature the same company brought to a wider Australian market: "twin triangular" dual circuit brakes. They came with the Volvo 140 in April 1967.

Disc Brakes Australia (DBA), this country's only after market manufacturer of disc rotors, supplies products for 96 per cent of the disc-brake equipped cars, light commercials and recreational vehicles on the road. To put that in perspective, it still manufactures rotors for such obscure disc brake-equipped vehicles as the Leyland P76, Triumph TR3A convertible, Rambler Javelin, Lada Sable, Humber Snipe and various early model Rolls-Royces.

The first disc brake appeared in 1902, though it could hardly be described as practical. Widespread interest in automotive disc brakes didn't come about until the 1950s when Jaguar used them to devastating effect at Le Mans. In the 1953 "24-Hour", Jaguar C-Types - fitted with discs developed by Dunlop - finished first, second and fourth.

Early braking systems were usually hazardous. When Richard Lean of Lithgow, NSW, built a motor car in 1901, the local police chief insisted on being taken for a drive to ensure the car was safe. A contemporary report from The Lithgow Mercury stated that when Lean was ordered to hit the brakes "there was a jittering screech of iron on ground and then the strangled bellow of the sergeant as he sailed cleanly over the top of the motor and sprawled on his stomach in the dust".

Australia's Felix Caldwell was a pioneer of four-wheel drive and all-wheel steering, and fitted four-wheel brakes to a road vehicle as early as 1910. Although four-wheel brakes were also used on a few racing cars before World War One, they didn't become near-universal until the 1920s.

The hydraulic brake system - which uses fluids to distribute to the wheels the force applied to the brake pedal - has been around since the 1920s and became common in the 1930s. Today all cars use hydraulics for their normal braking, though most parking brakes are still cable operated.

To counter Jaguar's disc brakes at Le Mans, Mercedes came up with a novel solution. Its W196S racing sports car (produced for the 1955 season) still had "drums" but incorporated a large metal wing behind the driver designed to rise during braking. Although this "wind-catcher" did help slow the Mercedes, it caused other problems and the idea never really caught on.

During a test undertaken by Williams-Renault, a Formula one racing car took just 18 metres to brake from 100km/h to a standstill. During the same test, an exotic mid-engine sports car recorded a distance of 40 metres and an everyday hatchback recorded 46 metres. The race car's main advantages include its wide and sticky "slick" tyres, its huge carbon-fibre disc rotors and its massive calipers and pads.

The Renault 8 of 1962 had disc brakes on all four wheels, a world first for a popularly priced car. The first mass-produced Australian car to have "discs all round" was the 1973 Ford LTD/Landau.

Anti lock brakes (also called anti skid brakes and ABS) are nothing new: they were tried on trains in 1908 and at least one sophisticated anti lock system was patented for cars before World War Two. Not until the 1950s, however, did serious automotive development take place. ABS was not widely fitted to road cars until the late 1980s.

Why not Formula One-style carbon-fibre brakes for road cars? Firstly, because a set of four Formula One disc rotors are worth more than the entire cost of most road cars. Secondly, because they aren't even slightly practical. To quote veteran racer Martin Brundle: "carbon-fibre brakes simply don't work until you've got a minimum of 400 degrees Centigrade, and preferably 600".

The 1996 Lotus Elise roadster became the first road car to use aluminium disc rotors. These rotors (which uses silicon carbide reinforcement) weigh about half as much as cast-iron equivalents and boast better thermal conductivity. The major down side is the high cost. In Australia, a joint research project between Disc Brakes Australia and Cyco Systems Group is investigating using a cheaper and more durable aluminium-ceramic composite rotor for normal road cars.

According to recent General Motors statistics, an airbag deploys every 175 "vehicle years", while a panic stop utilising antilock brakes occurs once each vehicle year.

To put racing car capabilities in context, a high-performance road car will record a braking force of about 1G during extreme braking, but in Formula One the deceleration forces can be in the order of 3.5G. That's enough to bring a driver close to blacking out, to distort his eyeballs (and consequently blur his vision), and to increase his effective body weight to 270kg.