Following the adoption of the 500cc formula for Formula Three in 1949, Cooper evolved the Mark III into the Mark IV. The car retained a ladder frame, with an aluminium body supported by hoops. Lockheed twin-shoe disc brakes became standard, coupled to two master cylinders, while Fiat 500 transverse leaf spring independent suspension was used at both front and rear.
The standard T11 was powered by a 498 cc one-cylinder Speedway JAP engine. Cars were supplied without engines, a practice that would later become routine in Formula One, with customers sourcing their own powerplants.
The long-wheelbase T12 variant was intended for Formula Two. The first 500cc Cooper modified with a 1000cc JAP twin was prepared by customer Spike Rhiando in 1948, and in 1949 a model powered by the 1,250 cc engine from an MG TD was built and won on its first outing. Cliff Davis was the most successful driver to campaign a TD-engined T12.
The T12s were best suited for hillclimbs and sprints rather than longer events, owing to durability limitations. In September 1950, French driver Raymond Sommer died in a crash at Cadours while driving a T12, a sobering moment for the marque.
The F2 Mark IV, based on the TD-engined variant, made its proper debut in 1952. This version was powered by a 127 hp Bristol inline six of 1,971 cc displacement. At just 1,000 lb (450 kg), the car was approximately 400 lb lighter than the Ferrari opposition, and its mid-mounted engine gave it a cornering advantage. However, it gave up around 50 hp to the Ferraris.
The F2 Mark IV debuted at Goodwood on Easter Monday, run by Eric Brandon and Alan Brown for Ecurie Richmond, and by Mike Hawthorn driving for Bob Chase. Hawthorn won the Formula Two event and one of two Formula Libre races, and came second in another Libre outing behind Gonzalez in a 4.5-litre Ferrari. The occasion marked the first mid-engined entrant in Formula Two, and only the second constructor to bring a mid-engined car to top-rank European racing, following Auto Union in the pre-war era.
Mark IVs competed successfully in F2 throughout 1952 and 1953, driven by Hawthorn, Peter Collins, and John Cooper himself, among others.
The Cooper T12, the long-chassis version of the Mark IV, made a single appearance in the Formula One World Championship. It was entered by the Horschell Racing Corporation for Harry Schell at the 1950 Monaco Grand Prix; Schell retired from the race. Across all competitive appearances, the T12 was used at 35 races, achieving two podium positions. Its only outright victory came when John Barber won the 500 Car Club Formula 2 Race.
Late in 1957, Arthur Owen modified a Mark IV with a streamlined glassfibre body and a 250cc Norton engine. Bill Knight subsequently used this car to set five speed records at Monza, demonstrating the longevity and adaptability of the basic design well after its competitive prime.
Used examples sold for around £425 in 1952, reflecting the car's continued demand among privateer racers even as newer designs emerged.
The Cooper Mark IV, and particularly the T12's F2 variant, represented a pivotal moment in single-seater racing history. By demonstrating that a lighter, mid-engined car with superior cornering could be competitive against more powerful front-engined machines, Cooper laid important conceptual groundwork for the mid-engine revolution that would fully transform Formula One by the end of the decade.
Gallery · 1 related image
