The Brabham BT21 was an

open-wheel An open-wheel car is a car with the wheels outside the car's main body, and usually having only one seat. Open-wheel cars contrast with street cars, sports cars, stock cars, and touring cars, which have their wheels below the body or inside fend ...

formula racing Formula racing, also known as open-wheel racing in North America, is any of several forms of open-wheeled single-seater motorsport. A "formula", first devised by FIA for its post–World War II single-seater races, is a set of regulations for ...

car, designed, developed, and built by

Brabham Motor Racing Developments Ltd., commonly known as Brabham ( ), was a British race car, racing car manufacturer and Formula One racing team. It was founded in 1960 by the Australian driver Jack Brabham and the British-Australian designer Ron Ta ...

in large numbers in 1966 and delivered to private individuals; 110 vehicles were manufactured. Most were manufactured as

Formula 3 Formula Three (F3) is a third-tier class of open-wheel formula racing. The various championships held in Europe, Australia, South America and Asia form an important step for many prospective Formula One drivers. History Formula Three (adop ...

cars, with some built for US Formula B and given the designation 21B. The wagons for the Formule Libre ran under the identifier 21C. The first BT21s came to international racetracks in 1966. The chassis was flatter than the BT18, the suspension was revised and the body was completely rebuilt. In 1966 and 1967, a

naturally aspirated A naturally aspirated engine, also known as a normally aspirated engine, and abbreviated to N/A or NA, is an internal combustion engine in which air intake depends solely on atmospheric pressure and does not have forced induction through a turboc ...

Cosworth MAE

four-cylinder engine The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized. Piston engines are often categorized by their cylinder layout, valves and camshafts. Wankel engines are often categoriz ...

with and in 1968 a Holbay unit were used as engines. This drove the rear wheels through a

Hewland Hewland is a British engineering company, founded in 1957 by Mike Hewland, which specialises in racing-car gearboxes. Hewland currently employ 130 people at their Maidenhead facility and have diversified into a variety of markets being particul ...

Mk.4 five-speed manual transmission. The chassis was constructed out of a tubular space frame, with a lightweight

fibreglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass c ...

body. This meant the car was very light and nimble, weighing in at only . Private drivers like

Peter Westbury Peter Westbury (26 May 1938 – 7 December 2015) was a British racing driver from England. He participated in two World Championship Formula One Grands Prix, scoring no championship points. In 1969, he raced a Formula 2 Brabham-Cosworth, driving ...

with his Felday Engineering Ltd. had much success with the BT21 in 1967. In 1968 the BT21 became a serious opponent with the new Tecno and the victories in Formula 3 became fewer. The BT21B, therefore, underwent some changes. The car got wider wheels and a sturdier tubular space frame derived from the BT23, a Formula 2 car. This eliminated the shortcomings. In 1969 the BT21 was slowly being replaced by the BT28.

References

{{Brabham 1960s cars Cars introduced in 1966 Brabham racing cars Formula Three cars