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AJS R7 1938

1938 A.J.S. R7. From the late twenties until the 1961 season, at least, the A.J.S. 350 c.c. racer has been a powerful force in the Junior class. It has undergone many changes, from a rigid-framed, spindly looking device capable of some 80 m.p.h. to an all-sprung compact design capable of approaching 120 m.p.h., but one design feature has remained constant throughout the period—the drive to the overhead camshaft has been by a chain. (An experimental engine in the mid-fifties had a shaft and bevels but was never raced.)

By 1938 the motor had light-alloy head and barrel with hairpin valve-springs and the magneto was behind the barrel instead of in front of the crankcase as on the early models. The rear pivoting-fork springing was unusual in that each "side" of the fork was a two-piece girder, rather like the bottom part of a girder fork, and this must have given far greater rigidity than a single-tube type.

Forged light-alloy back plates were used for both single-leading-shoe type brakes, and the front unit had a huge, near-full-width alloy hub and very long torque arm. In the 1938 T.T. a light-alloy rim was fitted to the front wheel on the "works" models, but the same machines used in the 1939 Island races had reverted to steel rims.

Whilst technically very interesting, the pre-war 350 c.c. A.J.S. did not cover itself in the glory achieved by its post-war descendants. This could well have been because the factory development staff was concentrating on the 500 c.c. four-cylinder models. Whatever the cause, the best Junior T.T. place gained in the thirties by the model was eighth in both 1935 and 1937.

BRIEF SPECIFICATION
Engine: single-cylinder 350 c.c. o.h.c; light-alloy head
and barrel, chain drive to camshaft. Ignition: Lucas magneto.
Transmission: chain via four-speed Burman gearbox. Frame: cradle type with single down-tube and swinging-■ fork rear suspension, controlled by "plunger-type" spring boxes.
Forks: girder pattern with single compression spring and twin rebound springs.

Photos: Phil Purdue & shannons.com