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Sunbeam Motorcycle Club : the first 75 years / Tony Churchill. - 2000. - 160p. : 18x24cms ; b&w photogr. Founded in 1924, the Sunbeam Motor Cycle Club is one of the oldest existing motorcycle clubs in the UK. Initially a one-make club it soon expanded to include all makes and became the leading organiser of motorcycle trials in the country - and still is. |
In 1943 the Sunbeam name was passed on to the B.S.A group.
B.S.A. was already thinking ahead for a new motorcycle for after the war. Together with a motorcycle magazine they set up a 'Forum' in November 1944 inviting readers to send in their ideas on the 'machine of the future'.
A completely new concept in motorcycle design resulted, entirely different from pre-war motorcycles.
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The first prototype was made in 1945. Much testing was carried out at the factory in Redditch. In 1946 it was introduced as the flagship model for the BSA range, England's answer to BMW in the late 40's and early 50's.
It was a large "gentleman's tourer". The 487cc engine was entirely of alloy, it had wedge-shaped combustion chambers, it was a tandem vertical twin cylinder overhead camshaft.
These touring machines had 25 bhp at 5800 rpm. They did a comfortable 75 mph.
It's engine is mounted longitudinally in a fully sprung frame. Drive is transmitted via a single plate, car type clutch and four speed gearbox, by shaft to an underslung worm drive at the rear wheel.
Supporting the envisaged role as a luxury tourer were 4.75 x 16 inch tyres and a cantilever sprung saddle which combined with the telescopic front forks and plunger rear suspension gave a comfortable ride.
Two production types were intended: the 'Tourer' which is the S7 as we know it and the little known 'Sports' which was tested but never put into production.
This sports model had a much higher compression ratio with a different OHC design. 'Motorcycle' got to roadtest this never-sold sports job in May 1946; it gave 94 mph. Why it was not put into production was never officially disclosed. Rumour has it that it produced too much BHP for the wellbeing of the components - notably the rear drive unit! - others say it didn't handle too well - which as these earlier versions had a rather more primitive undamped front fork system, and the rubber mountings for the sunbeam had't been completely sorted out - could well be very true!
They were the last Sunbeam models ever built; the S8 a more sporting version of the S7 but at 405lb a heavy machine.
Erling Poppe started to design and build his motorcycles in 1922. At one time he co-owned P&P. He sought always for better silencing, comfort and cleanliness. (His father was one of the partners in White & Poppe of Coventry, who built engines for motor vehicles in the pioneering days.)
He went on to design cars and heavy vehicles. Sunbeam brought him in from bus-building division of Bristol Tramways to design their new concept which was to be the shaftdriven S7s and S8s.
When Walter Hassan, chief engineer at Coventry Climax, was looking to up-date their fire-pump, he took a close look at motorcycle technology (which at the time was ahead of cars), and in particular at the Sunbeam S7.
Sunbeam S7 : roadtest. - Motorcycling 1946, February
Sunbeam S7: Model History. - Classic & Motorcycle Mechanics. - vol. 32 (1989), no. Aug/Sep
Sunbeam S7: Reader Restoration. - Classic & Motorcycle Mechanics. - vol. 54 (1992), no. Apr
Best of British / Peter Howdle. - 1979
Thirty eight classic motorcycles, including the Sunbeam S7. Includes accurate text and many mono pictures.
Classic British Motorcycles : The Final Years / Bob Currie. - 1984
Comprehensive profiles of twenty five diverse machines selected from the National Motorcycle Museum, including the Sunbeam S7.
The Sunbeam motorcycle / by Robert Cordon Champ. - Yeovil : Haynes, 1980 (North Cadbury : Foulis, 1980). - 2-205 p.; 2 leaves of plates. - (A Foulis motorcycling book)
ISBN: 0-85429-258-6
[Library Technical University Delft]
Stewart Engineering The Sunbeam Specialist
The Sunbeam Owners Fellowship : the club for Sunbeam S7 and S8 motorcycles since 1962
www.onthebeam.co.uk