Lowboy Racer: 1960 Norton 350cc 40M
Photo by Kel Edge.
Engine: 348cc air-cooled DOHC single, 76mm x 76.7mm bore and stroke, 10.1:1 compression ratio, 42hp @ 7,800rpm
Top speed: NA
Carburetion: Single 31mm Amal GP with twin remote float chambers
Transmission: 4-speed AMC close-ratio, chain final drive
Electrics: Lucas magneto
Frame/wheelbase: Modified Norton Wideline Featherbed tubular steel duplex cradle frame/58.5in (1,485mm)
Suspension: Modified Norton Roadholder telescopic fork front, dual Girling shocks w/adjustable preload rear
Brakes: 8in (203mm) TLS Norton drum front, 7in (178mm) SLS Norton drum rear
Tires: 2.75/3.00 x 19in front, 3.50 x 18in rear
Weight (dry): 298lb (135kg)
Seat height: 28in (710mm)
Fuel capacity: 3.25gal (12.3ltr)
The Manx Norton has no rivals for the accolade of being the ultimate British racing single, whether in 350cc or 500cc guise. As a production race bike, only the later Yamaha TZ250/350 can match its global appeal and formidable record of success over such an extended period in the hands of its customers.
Way back when
In 1950 Norton introduced the “double-knocker” Manx engine (the nickname it received due to its new double overhead cam design). Combined with the Ulster-built Featherbed frame designed by the McCandless brothers, it enabled the Bracebridge Street factory to keep abreast of the emerging European multi-cylinder opposition for a few extra years, providing Geoff Duke with the means to take both 350cc and 500cc World Championships in 1951, and the 350cc title again in 1952.
The single-cylinder Manx Norton is a gallant example of the traditional British love of the underdog, for even after the factory team withdrew from racing at the end of 1954, Norton’s image was yet upheld by the hundreds of privateers who continued to race Manx Nortons successfully right up until the early 1970s.
But as far as World Championships went, Duke’s trio of titles was the end of the line for Norton. Yet the British factory continued developing new ways of keeping its aging singles competitive, particularly in terms of frontal area, against the wider, heavier fours. This resulted in the so-called “Silver Fish” Kneeler frame in 1953, and the following year’s low-slung F-Type (for “Flat”) engine with its horizontal cylinder, a concept borrowed from Moto Guzzi. Unfortunately, Norton race boss Joe Craig’s attempts to emulate Guzzi via the F-Type were stymied when the board of AMC, which had purchased Norton one year earlier, announced the company would withdraw from Grand Prix racing immediately. Moving forward, Norton would only race what it sold, so Norton’s race shop would only develop and manufacture the 350/500cc Manx customer racers. These became a mainstay of road racing throughout Europe and Australasia, and at all levels from club racing up to and including the Continental Circus, where Nortons stacked Grand Prix starting grids for two decades.
Order the January/February 2019 issue of Motorcycle Classics to read more about the Norton Lowboy racer. Contact Customer Service at (800) 880-7567 or contact us by email
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