Dunlop and Jaguar: Pioneers of Disc Brake Technology in Road and Racing Cars

When Moss won at Reims, the disc brake was already almost half a century old, as patent applications for just such a device, dated in 1903 from the remarkable Dr Frederick Lanchester, show. But it was only after the war and in an entirely different application that they came into their own.

Dunlop’s first disc brakes were not designed for cars at all, but aircraft. With the dawning of the jet era and increased aerodynamic efficiency, aircraft were having to land at ever higher speeds, taxing extant drum brake technology beyond its practical limit. So bad was this problem that according to Dunlop, “brake design was becoming the factor limiting aircraft performance”. The beauty of the disc was that it was exposed to the high-speed airflow and would therefore suffer none of the overheating issues that plagued enclosed drum brakes. Moreover there would be only one application of the brakes per flight and no corners to negotiate, so the problems of knock-off and boiling fluid that would dog Jaguar never appeared. Dunlop aircraft discs first appeared in 1947 and by the 1950s were in widespread use throughout the industry.

Jaguar was not even the first to put a disc brake onto a road car, that accolade seemingly belonging to America’s little-remembered and apparently fairly ghastly 1949 Crosley Hotshot, among whose other less-vaunted claims to fame was to appear in Time magazine’s ‘50 Worst Cars of All Time’. The discs were so troublesome – failing to work if there was salt on the road in sub-zero temperatures – that they were soon abandoned in favour of conventional drums. Chrysler also had a go at discs, making them available on the Imperial from 1950 but these were fully enclosed and were also swiftly abandoned.