1938 Norton Sidecar
1938 Norton 600 Big Four with Motorized Sidecar Wheel
Crude but effective
In 1938, the Belgian Army organized great military maneuvers between various European countries at Spa. The British Army delegates returned home deeply impressed by the off road capabilities of the powered-wheel Belgian sidecar outfits.
Lucky Chance
So the British War Office invited the relevant marques to design similar powered-wheel sidecars for official trials. By sheer chance, Norton already had an off-road outfit of this type, developed by famed trials rider Dennis Mansell, son of Norton boss, Bill Mansell.
Barred from Sports
This outfit, powered by an overhead-cam 500cc engine, proved so superior to conventional sidecar combinations that the governing authorities of trials riding barred driven-wheel outfits from the sport. When the War Office request arrived, Norton put the experience gained by Mansell to good use. In late 1938, an initial series of ten sidecar outfits was produced for the Army. For this installation, the ohc sports single had been replaced by a 633cc side-valve lugger designed by “Pa” Norton himself before WWI. It was known as the “Big Four” from its taxable power rating. The rear wheel spindle was carried in roller-bearings on the frame and turned with the wheel. In normal usage, only the wheel of the bike was driven, but in difficult terrain, a dog-clutch was engaged, which transmitted the power to the sidecar wheel. It was crude but effective.
SPECIFICATIONS
Engine: 633cc (82×120mm) air-cooled single cylinder four-stroke
Power Rating: 15 hp @ 4400 rpm Valves: side
Fuel System: 1 inch Arnal carburetor
Transmission: 4-speed, chain final drive, sidecar wheel driven by shaft from rear wheel hub
Suspension: Webb center-sprung girder forks (front); rigid (rear)
Brakes: drum (front & rear); sidecar wheel unbraked
Wheels: interchangeable 18 inch (front, rear & sidecar)
Weight: 584 lb
Maximum Speed: 55 mph
Norton was the only British factory to build a powered-wheel sidecar – of the 100, 000 bikes delivered to the Army during WWII, 7000 were “Big Four” sidecar outfits.
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