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Manx Norton
1961 NORTON "MANX". Although eleven years separated the 1961
model "Manx" Norton from the first "Featherbed" type made in 1950, the basic
design was almost unchanged except in detail.
Instead of being bolted on, the rear sub-frame was welded to the main frame, a
modification introduced in 1952, and the fancy tail fairing used jn 1950 lasted
only a year. But the basic frame pattern was unchanged. It is interesting to
note that in this period the entire range of Norton roadster models of over 350
c.c. had been redesigned to incorporate the all-welded racing-style frame, an
excellent example of racing improving the breed. The frame was probably cheaper
to make than the old lug-and-tube type.
In the intervening period the engine, which had been restyled
in 1950 to be slim enough to fit the frame, underwent several major changes, the
most noticeable being a much bigger bore, and consequently shorter stroke, which
enabled high revs to be maintained without undue stress.
The Norton factory was absorbed into the A.M.C. group in the
mid-fifties and a change of gearbox was made on the "Manx" to utilize the same
internals as the racers from Woolwich, so standardizing production and spares.
Only detail changes were announced to the design for the 1961 season. Main
external alteration was a new oil tank which pivoted and was held against a
rubber mat by twin rubber bands. As some trouble had been experienced with
megaphones fracturing, for 1961 this highly stressed component was held in a
"muff"-type clip. The G.P. Amal carburetter was replaced by the bigger-type
G.P.2, of iJJ in. bore.
SPECIFICATION
Engine: single-cylinder 500 c.c. d.o.h.c; drive to
camshafts by shaft and bevel gear. Ignition: magneto.
Transmission: chain via four-speed gearbox.
Frame: full duplex cradle with two tubes forming continuous loop on each side of
engine and gearbox and ends crossed to brace steering head; bolted-on sub-frame
providing top anchorage for swinging-fork rear suspension units.
Forks: "Roadholder" telescopies.
When it comes to vintage racing, few bikes are
more iconic than the Manx Norton.
The quintessential British-built road-racers of the 1950s, the bikes started
life as Norton Internationals, but were re-tuned from the factory for the
singular purpose of racing on the Isle of Man in the Manx TT, the most
prestigious race of its time.
The 495cc single-cylinder motor was designed for longevity—the Manx TT was,
after all, a 264-mile race. But the motorcycles were equally well-known for
their chassis, which were all-welded duplex frames with pivoting rear forks and
suspension. Designed by Rex McCandless in 1950, the frame provided the
high-speed stability so important to the TT.
So impressed was Norton's Harold Daniels that he described the chassis as
offering a "featherbed ride," and the Norton Featherbed frame was born. From the
start, the bikes built a reputation for speed and handling that was unmatched in
Europe, and Manxes were raced by legendary riders, including Geoff Duke and John
Surtees, through the 1950s.
Norton Manx Story
The Norton company has always applied the term "Manx" to the
racing motorcycles that it produces in limited quantity for the open market. The
name refers to the Isle of Man, where the Tourist Trophy is run. This annual
race attracts the finest British racers, who compete on racing motorcycles that
have been derived from production models are are available on the open market.
Norton built its first Manx (although it was called an International at the
time) in 1932. Derived from the Grand Prix, the motorcycle was the work of
Arthur Carrol and Joe Craig. The tuning and modification of the Internationals
was left to the customers, who proved to be up to the job.
Meanwhile the racing department of the company continued to
modernize the official models, which were transformed rapidly in those years to
meet the tough competition provided by the motorcycles and racers of Rudge,
Velocette, and Sunbeam in Britain, and Bianchi, Guzzi, and Moto-sacoche on the
Continent.
Between 1936 and 1938 the bore and stroke of the Grand Prix 500 were changed
twice and a double overhead camshaft distribution was installed for the first
time. Before racing was halted by World War II, the official Norton 500 boasted
a power of 50 h.p. No other single-cylinder engine of that class could generate
more horsepower, but its power was not enough to discourage the Italian and
German makers of multicylinder models. Norton managed to hold its own,
especially on mixed circuits, where its weight-power ratio helped racers.
The Norton company was fortunate to have such fine racers as
Jimmy Guthrie and Harold Daniell, two of the greatest champions of the time, and
new racers were continually appearing on the scene.
The first Norton motorcycles to reappear in racing in 1946
were old models that had been jealously guarded by their owners. Throughout
Europe most of the racers who won improvised races had old single-shaft Nortons,
and the official Norton team reappeared with prewar two-shaft motorcycles.
Indeed, with the prohibition of superchargers it almost looked as if the
single-cylinder might rule the roost, or at least have a temporary advantage
over the four-cylinder Gilera, the two-cylinder BMW, and the two-stroke DKW. In
reality, after losing the 1949 world championship to the two-cylinder AJS
Porcupine in the 500 class and to the single-cylinder Velocette in the 350
class, Norton had to struggle in the following years to defend the slight margin
that its racers had succeeded in winning for it.
From 1951 on, the chief factor in Norton wins was its
innovative Featherbed chassis, which was designed for Norton by the McCandless
brothers. With this chassis Norton could outrace any motorcycle of equal power,
especially on difficult tracks.
The Norton Grand Prix won the world championship in 1950 (500
class), 1951 (350 and 500), and 1952 (350). These were not easy wins, and much
credit was due to the fantastic skill of Geoffrey Duke, for whom the
single-cylinder was perfectly suited.
In 1949 the Norton International had become the Manx. That was the year the old
single-shaft distribution system was replaced by a two-shaft one. In 1952 the
Manx was given a squared-off engine.
In 1954, after Italian multicylinder motorcycles had outraced
the Norton (despite the valiant efforts of Ray Amm), the company decided that as
of 1955 only Manx models would be entered in races. Beginning in 1955 private
racers throughout the world also defended Norton's colors with honor.
Tuned by specialists, the final version of the Norton Manx 500 was considerably
more powerful than the Grand Prix model from which it had been derived. And for
some time to come it was a real threat to the most advanced motorcycles that
entered the Tourist Trophy.
Motorcycle: Norton Manx 500 Manufacturer: Norton Motors Ltd.,
Aston,
Birmingham Type: Racing Year: 1957
Engine: Norton single-cylinder, four-stroke, two-shaft overhead distribution,
bevel gear shaft. Displacement 498.3 cc. (86.1 mm. x 85.6 mm.)
Cooling: Air
Transmission: Four-speed separate Power: About 51 h.p. at 7,200 r.p.m. Maximum
speed: About 140 m.p.h. Chassis: Double cradle, continuous above
and below, tubular. Front and rear,
telescopic suspension Brakes: Front, double cam, side drum;
rear, side drum
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