Norton Dominator

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Norton Dominator
Norton Dominator 650SS (1968) (8882446566).jpg
Dominator 650SS at Vale Royal Classic Car Show in 2013
Manufacturer Norton Motorcycle Company
Also called'Dommie'
Production19491960s
Engine 497 cc (Model 7 and 88) 596 cc (Model 99) OHV air cooled parallel twin
Transmission Primary by single-row chain; four-speed gearbox; final by chain
Brakes Drum
Wheelbase 55.5 in (1,410 mm)
Seat height31 in (787 mm)
Weight395 lb (179 kg) (dry)
Fuel capacity3.5 gallons (16 litres)

The Dominator is a twin cylinder motorcycle developed by Norton to compete against the Triumph Speed Twin. The original Dominator was designed in 1947 and 1948 by Bert Hopwood, who had been on the Speed Twin design team at Triumph. [1] Available for sale from mid 1949, this design set the pattern for Norton twins for the next 30 years. [2]

Contents

Model 7

The first Dominator, the Model 7, had a 497 cc parallel twin engine with iron cylinders and cylinder head and a Lucas K2F magneto. The crankshaft was of 360-degree layout with two main bearings. A single camshaft at the front of the engine was driven by gears and chain. The rocker box was integral with the head, so there were fewer gasket faces to leak and less valve noise. The engine was a long stroke design with 66.0 mm × 72.6 mm (2.60 in × 2.86 in) bore and stroke and mild tuning, resulting in more torque low down. For the first few years a plunger frame was used, but in 1953 the Model 7 was upgraded with a single downtube swinging arm frame, 19-inch front wheel and 'pear shaped' silencers, still known as a Model 7. [3] The Model 7 continued in production through to 1955 and was often used with a sidecar, which could not be fitted to the later Featherbed frame Dominators.

Model 77

The first Model 77 was a rigid-framed telescopic-forked Dominator version of 500 cc produced from 1950, and supplied to the Australian market only. This used the all-iron Dominator 500 cc twin engine, with an oil pressure gauge in the ES2 style but flat-bottomed petrol tank. About 240 were made, from 1950 to 1952.

The 596 cc Model 77 Dominator was introduced in late 1956. Essentially the cycle parts of the ES2 and a 600 cc Dominator 99 engine, it was in production at the same time as the Dominator 99 as a sidecar motorcycle but was dropped from production after 1957, when sidecar Featherbeds were introduced. [3]

Featherbed frames

Duplex cradle frames known as 'featherbed' were introduced in two types; the initial design was discontinued from 1960, becoming known as wideline when followed by an updated-version introduced during the 1960 model year (known as slimline) until eventual discontinuation circa 1970 on the low-specification 650 cc Norton Mercury.

Model 88

The Featherbed frame was first designed and raced by the McCandless brothers in Ireland with the design bought by The Norton Motorcycle company who had the frames made by the Reynolds company because the Norton works did not have the necessary welding capacity for its manufacture. [4] The Featherbed frame led to the Model 88 Dominator, also called the Dominator De Luxe, which used the same 497 cc engine and was developed in 1951. Originally developed for export it was sold on the home market from 1953. [5] The 88 suffered from oil leaks from the primary chain case but it was the outdated and inefficient Norton works that resulted in quality control problems for the 200 Model 88's produced each week. [6]

Model 99

1961 Norton Domiracer Model 99 Flickr - ronsaunders47 - NORTON DOMINATOR 99. 600 CC TWIN 1960s.jpg
1961 Norton Domiracer Model 99

The 597cc featherbed framed Model 99 Dominator was introduced in september 1955, as a larger capacity version alongside the 500 cc Model 88 version. [3] Due to the increased engine capacity, the 99 had a power output of 31 bhp, partly due also to a higher compression ratio possible with the alloy head introduced a year earlier. Full width alloy hubs with improved brakes had also been introduced a year earlier, preparatory for the capacity increase from 500 cc to 600 cc

Slimline Featherbed frames from 1960

From 1960 model year, the featherbed frame for all Dominators was altered so that the frame tubes in front of the seat were narrower, for improved rider comfort. The seats and tanks and indeed the whole styling of the Dominator was redesigned to suit. A large metal tank badge completed the look, along with some two-toned paint schemes. And some optional enclosed body styling on the "Deluxe" Models of the 88 and 99, along the lines of the 'bathtub' Triumph models.

1960 Manxman 650 and 1961 Dominator 650SS

A new 650 cc model was added to the lineup late in 1960. The frame was altered so that the top rails were closer together at the front of the seat area to create what became known as the 'slimline' featherbed. A 650 cc engine was installed to create the Norton Manxman. First built from 7 November 1960 to September 1961, these machines were a Limited Edition for the USA only, in custom-cruiser style - with high handlebars, all polychromatic blue paint and bright red seat with white piping round the edge. In September 1961 the 650SS was introduced. It had USA cafe bar style and twin carburettors. The SS stood for Sport Special and the 600 cc models were discontinued to concentrate on production of the 650SS, which quickly earned a reputation as the "best of the Dommies". [5]

1967 Norton Atlas Norton Atlas 1967.jpg
1967 Norton Atlas

Norton Atlas 745 cc

A development of the Dominator with enlarged engine was available from 1962.

Racing

Engineer Doug Hele had joined the Norton factory in 1956 under parent company AMC – instead of combining the two race shops, the AJS/Matchless facility was closed to Grand Prix development, and Hele was briefed to secretly develop an engine intended to ultimately compete at Daytona under AMA race regulations, requiring machines to be based on production roadster designs with a compression ratio no greater than 8.5:1, and using a kick starter mechanism. [7]

Dennis Greenfield and Fred Swift won the 500 cc class in the Thruxton 500 event for road-legal production machines in 1960.[ citation needed ]

Race-styled 1961 Norton Dominator Norton Domiracer 1961.jpg
Race-styled 1961 Norton Dominator

Norton briefly used race-tuned Dominators from circa 1960, but they were still outclassed by the Manx Norton which was used for general purpose racing. The highly developed 500 cc Dominator engine intended as a successor produced 55 bhp (41 kW) and revved to 8,000 rpm. The overall weight was 35 lb (16 kg) less than the Manx, [2] when mounted in a special lightweight-frame (dubbed lowboy), creating the factory "Domiracer". [7]

In the 1961 Isle of Man TT Tom Phillis took the bike to third place and lapped at over 100 mph (161 km/h), a first for a pushrod engine and a first for any twin. Norton abandoned the Domiracer project a year later when the Bracebridge Street race shop closed and the Domiracer and factory spares were sold to Paul Dunstall, who continued with development and began producing Norton performance parts, eventually selling complete Dunstall Norton bikes to customers including Steve McQueen. [3]

See also

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Doug Hele British motorcycle engineer

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Norton Atlas

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Featherbed frame Motorcycle frame

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Norton Dunstall Type of Norton motorcycle

The Dunstall Norton was a Norton motorcycle made by Paul Dunstall, a specialist tuner of the 1960s and early 1970s twins originally using some parts from Norton's Domiracer project when the Birmingham factory was closed in 1963. In 1966 Dunstall Motorcycles became a motorcycle manufacturer in its own right so that Dunstalls could compete in production races, and set a number of world records before sales of the Dunstall Nortons declined in the 1970s consistent with the demise of the British motor cycle industry and a corresponding rise in Japanese imports.

Norton Isolastic frame

The isolastic frame, designated by Norton as GlideRide, used a system of engine-to-frame mountings incorporating rubber bushes to isolate the vibration of the vertical twin engine from the frame and rider. The isolastic frame was developed for use with the Commando inclined engine, whilst the Featherbed frame continued in production for the Mercury with a softer-specification 650 cc vertical-engine until 1970.

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BSA A10 series

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Norton Model 7 Dominator

The Norton Model 7 Dominator was a 500 cc vertical twin motorcycle manufactured by the Norton Motorcycle Company from 1949 to 1955. It was the first of Norton's Dominator range of motorcycles. The engine was designed by Bert Hopwood and was a departure from Norton's previous practice of producing single-cylinder machines. The Model 7 was used in Japan as a police motorcycle.

The Norton Model 77 Dominator was a 600 cc vertical twin motorcycle manufactured by the Norton Motorcycle Company from 1956 to 1958. It was based on the Model 7 that it superseded, and was primarily intended for sidecar use. Norton modified the featherbed frame of the 88 and 99 models in 1957 to be suitable for sidecar use making the Model 77 superfluous and the model was dropped in 1958.

Norton Model 88 Dominator

The Norton Model 88 Dominator, also originally known as the Dominator De Luxe was a 500 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company from 1952 to 1966. It was the first of Norton's motorcycles to use the featherbed frame, which established Norton's reputation of producing fine handling machines. The 88 used the Bert Hopwood designed engine that was first fitted to the Model 7 and was initially for export only. It became available on the home market in 1953. Norton were a small manufacturer at the time and without the economies of scale the model was expensive compared to other manufacturer's equivalent machines. The 88 retailed for 20% more than the contemporary Triumph Speed Twin and was dearer than the 650 cc Triumph Thunderbird.

Norton Model 99 Dominator

The Norton Model 99 Dominator was a 600 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company at their Bracebridge St, Birmingham factory from 1956 to 1962. The 99 was based on the 500 cc Model 88 Dominator with an enlarged engine. The model was superseded by the 650SS.

The Norton Manxman was a 650 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company at their Bracebridge St, Birmingham factory for export. It was first shown at the November 1960 Earls Court Motorcycle Show and listed by the American importer, Berliner, in their catalogue from 1961 to 1963. Berliner had asked for the model to be named Manxman although the twin had never been raced at the Isle of Man.

Norton 650 Dominator British motorcycle produced from 1962 to 1967

The Norton 650 Dominator was a 650 cc vertical twin motorcycle manufactured by the British Norton Motorcycle Company from 1962 to 1967. Initially production was at Norton's Bracebridge St, Birmingham factory, but following the factory's closure in 1963, production was transferred to parent company AMC's works in Plumstead, London. Initially produced in single and twin carburettor versions, the single carb version were soon discontinued. The twin carb version, the 650SS, was described as the 'Best of the Dominators'.

Norton Mercury

The Norton Manxman was a 646 cc (39.4 cu in) air-cooled OHV parallel twin motorcycle made by Norton-Villiers from 1968 to 1970. It was the last Norton model to use the featherbed frame. Following the collapse of AMC and the subsequent formation of Norton Villiers, the company's focus had been on the new Norton Commando. There was a large inventory of parts from previous models that would not be used on the Commando, and to use up this stock the Mercury was conceived. The Mercury was introduced in October 1968 and around 750 machines were produced, most of the production going to the US. The model was also used by the Nigerian Police.

References

  1. Brown, Roland (1999). The History of British Bikes. Parragon. ISBN   978-0-7525-3153-3.
  2. 1 2 Reynolds, Jim (1990). Best of British Bikes . Patrick Stephens Ltd. ISBN   978-1-85260-033-4.
  3. 1 2 3 4 "Norton Dominator" (PDF). Retrieved 15 November 2008.[ permanent dead link ]
  4. "Norton Dominator, by Mick Walker" . Retrieved 16 November 2008.
  5. 1 2 Kemp, Andrew; De Cet (2004). Classic British Bikes. Mirco. Bookmart Ltd. ISBN   978-1-86147-136-9.
  6. Melling, Frank (27 September 2003). "Classic bikes: Norton Dominator". The Daily Telegraph. London. Retrieved 14 November 2008.
  7. 1 2 Story of the Domiracer, by Charlie Rous, Classic Racer (EMAP), Autumn 1988, pp.52-56 Accessed 23 December 2017