Norton Dominator
| Manufacturer | Norton Motorcycle Company |
|---|---|
| Also called | 'Dommie' |
| Production | 1949–1960s |
| 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 height | 31 in (787 mm) |
| Weight | 395 lb (179 kg) (dry) |
| Fuel capacity | 3.5 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. Available for sale from mid 1949, this design set the pattern for Norton twins for the next 30 years.
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. 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.
The Featherbed frame was designed for Norton by the McCandless brothers and made by the Reynolds company because the Norton works did not have the necessary welding capacity for its manufacture. 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. The 88 suffered from oil leaks from the primary chain case but it was the outdated and inefficient Norton works that resulted in quality control problems for the 200 Model 88's produced each week.
The 597cc featherbed framed Model 99 Dominator was introduced in 1956, as a larger capacity version alongside the 500 cc Model 88 version. 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
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.
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