Norton International - Development

Development

The name International was first used by Norton both for its newly designed race bikes and also for the TT replica sports roadster in 1932. Overseen by Joe Craig, Arthur Carroll had designed an overhead-camshaft engine for the works racers and although it retained the 79 mm × 100 mm (3.1 in × 3.9 in) bore and stroke of the Norton CS1 the Model 30 International was all new. The racing heritage led to quickly detachable wheels and hairpin type valve springs that could be changed rapidly when racing. In 1933, the forks and gearbox were redesigned and in 1935, the Sturmey-Archer gearbox was replaced, as Sturmey-Archer had stopped making gearboxes, so Norton bought the rights to the design and commissioned Burman to produce them. These gearboxes proved so good they remained unchanged for the next 30 years, although the external appearance was altered several times, and the gearchange mechanism fully enclosed and thus lubricated.

In 1936, the engine was upgraded with an alloy head and barrel with a bronze liner, available as an option. In 1938 suspension was upgraded to plunger type, also available as an option. Production of the Model 30 and 40 ended on the outbreak of World War II. After the war, production of the International Model 30 (500 cc) and Model 40 (350 cc) restarted with an iron head and barrel, as fitted to the pre-war CS1 and CJ Nortons. The suspension was upgraded to Norton Roadholder telescopic forks instead of girders and Clubmans versions were also produced without silencers and lights for racing use. Close ratios gearboxes were supplied as standard from 1947, and the alloy engine made a comeback in 1953 with a new version of the Featherbed frame. Volume production of the International ended in 1955, although small numbers were built to special order for two or three years after.