Sunbeam Model 9
THE SPEED OF LIGHT
Of all the British motorcycle manufacturers during the 1920s, Sunbeam reigned supreme as the purveyor of quality, single-cylinder motorcycles. Built by craftsmen dedicated to attention to detail, Sunbeams exhibited the finest workmanship and finish of all singles built in England. When the Model 9 Sunbeam was released in 1924, motorcycles of its class were still priced in guineas (one pound, one shilling), not pounds, reflecting their role as a gentleman’s conveyance.
AHEAD OF ITS TIME
Although Sunbeam’s reputation was built on the success of its side-valve singles, in 1924 it introduced two new overhead-valve models: the 350cc Model 8 and 500cc Model 9.
While the Model 8 always remained in the shadow of its big brother, the Model 9 soon earned a reputation as a very fast and reliable sportstourer. With dimensions of 90 x 98mm, the Model 9 engine layout was state of the art for 1924.
The two overhead valves were operated by pushrods and rockers and inclined in a hemispherical cylinder head at a steep angle. Each valve had three external coil springs and the rockers were supplied with greasers and equipped with return springs.
The cylinder head included dual exhaust ports and the lubrication was dry sump with a mechanical double gear pump. The conrod ran on roller bearings and the crank in three ball bearings and, unlike most British singles of the time, the primary drive chain was totally enclosed in an oil-bath, cast alloy case. A two-lever Amac carburettor supplied the fuel and the spark was from an E.I.C. magneto. A hand change on the right operated the three-speed, crossover-drive gearbox.
Sunbeam designed an entirely new frame for the Model 8 and 9, providing a 1372mm wheelbase and a detachable, sloping top rail to facilitate access to the cylinder head.
Until 1929, the tank was the classic flat-tank style, this changing in 1929 to the saddle tank (as on this example). The wheels were 26in items, with front and rear internal expanding brakes. The rigid rear end was standard for the period, as was the sprung girder fork with hand-adjustable friction dampers. An advanced feature was electric lighting but the only instrument incorporated in the headlight shell was an oil pressure gauge.
In 1926 the Model 9 evolved into the more sporting Model 90, forming the basis of the Isle of Man TT-winners of 1928 and 1929. But, already, things were on the decline for Sunbeam.
The large conglomerate ICI was formed in 1927, of which Sunbeam was only a small part, and Sunbeam’s future as a motorcycle manufacturer was always in doubt.
Around 1930 the tag-line “A subsidiary company of Imperial Chemical Industries” began appearing on Sunbeam advertising. With ICI, in came the accountants and much of the tradition was lost. ICI initiated a time and motions study, rationalising many old-fashioned, uneconomical processes such as the large amount of hand soldering of components (including fuel tanks).
During the 1930s, more parts were outsourced and the quality deteriorated. Also, due to the Great Depression, Sunbeam was forced to reduce its prices. The Model 9 cost 105 guineas in 1924 when it was released but, 12 years later, the list price was £66.
The 1936 model looked virtually identical to the 1929 version shown here but now included a four-speed gearbox and an illuminated clock in the headlight shell.
By 1937, ICI felt it could use the ‘Sunbeamland’ factory more profitably so it sold the motorcycle business.
The pre-war Sunbeam is a remnant of an earlier age, one where craftsmanship was prioritised over production and profit. During the 1920s only around 35 motorcycles were constructed each week, each hand-built on a bench, and production techniques didn’t change over time.
Right through until the Wolverhampton works closed in 1937, Sunbeam spares still had to be hand-fitted, which could involve filing or re-drilling holes to a suitable size.
As exhibited by their racing success, Sunbeams were light, fast, good handling and reliable.
To quote a 1931 Motor Cycling road test, “The Sunbeam Model 9 is a thoroughly sound and a particularly attractive machine with an engine which gives an excellent turn of speed coupled with extraordinary docility and tractability. It is a splendid steering model which can be thoroughly recommended to riders – of no matter what class – who are looking for a machine which will accomplish arduous work pleasantly, easily and nigh on indefinitely.”
Many thanks to Allen and Lorraine Smith of the Australian Motorcycle Museum, Haigslea, Queensland, for the use of the 1929 Sunbeam Model 9 featured here.
THE VALUE PROPOSITION
• Original price (1929) £78, 10 shillings
• Current valuation for one in average condition: $7000
• Current valuation for one in mint condition: $12,000
Sunbeam Model 9
• John Marston Ltd built Sunbeam motorcycles at the ‘Sunbeamland’ works in Wolverhampton, England. Originally a saucepan manufacturer, Sunbeam built tricycles and bicycles from 1887, cars from 1899, and motorcycles from 1912.
• Marston’s first motorcycle was a 350cc single produced almost entirely in-house. Although not cheap, Sunbeams soon earned a reputation for quality and reliability and, during World War I, were used by the Russian and French armies.
• Sunbeam won its first Isle of Man TT victory in 1920, with Tommy De La Hay, and by 1921 the company offered three versions of its 3.5hp side-valve model. In 1922 Alec Bennet provided Sunbeam with the last win by a side-valve motorcycle in the Senior TT.
• A new model numbering system was introduced in 1924: Models 1 through 11. Although the majority had single-cylinder engines developing relatively low power, they were very successful in the TT. Sunbeam’s final TT victory was in 1929.
• In 1937, the Sunbeam name was sold to AMC but ‘Sunbeamland’ continued to produce automotive radiators. BSA acquired the name in 1943, moving production to Redditch, Worcestershire, UK. BSA Sunbeams bore no relation to the pre-war machines. The final Sunbeam motorcycle was built in 1956 but scooter production continued until 1964.
Want to know more?
There is a good history here: SunbeamSideValve.com
Another history is here: TheWorldOfMotorcycles.com/
Look at a photo gallery of Sunbeams here: Classic-Motorbikes.net/
This is a history of the Sunbeams built at Wolverhampton
More history is here: TheSunbeamMotorcycle.co.uk/1920s.htm