Shaft Drive Sunbeam Motorcycles



Why the BSA Badge? - A Brief History

The company which made eventually made 'The Sunbeam' is listed as being established in 1790, although it is possible to claim origins 50 years before this date. The original company made tinplate and later japanned or black-enamelled ware.

The Sunbeam name was registered by John Marston in 1888 (born 1836) after he decided to enter into the booming new bicycle industry. John Marston had solely owned the company since 1871 when his previous employer, under whom he had served his engineering and metal craft apprenticeship, died.

Sunbeam Motorcycles production began production in 1911/1912 and by 1914 Sunbeam Motorcycles who's image of high quality finish and superb engineering were being used for racing, almost winning the first TT they entered. Sunbeam enjoyed a very successful racing  campaign up until the start of the war in 1939.

John Marston was also responsible for building 'Seagull' outboard engines for marine use and also for starting the Villiers engineering company... here is a quote from 'The Classic Motorcycle' magazine:

"The Sunbeam Villiers Connection

In 1898 John Marston of Sunbeamland, maker of cycles, and later, motorcycles, established a new company next door to make cycle fittings and later, cycle freewheels.
As part of the premises faced Villiers Street in Wolverhampton, England (named after local MP Charles Pelham Villiers), John Marston named the new company Villiers Cycle Components, and it soon became a successful company in its own right.
Villiers had the financial clout and engineering expertise to develop and manufacture their own engines and by around 1910 were selling four stroke engines, however in 1913 at the Olympia show they displayed the first in their long line of two stroke engines, the MK1, a 269cc single cylinder motorcycle unit."

May 6th 1916 saw John Marston retire... he died in 1918 aged 82 and in 1918 the company became the property of Nobel Industries which in 1928 the property the chemical company ICI, who continued building motorcycles until 1937.

The brand name of Sunbeam Motorcycles then became the property of AMC who designed a completely new new range of Sunbeam motorcycles, keeping the quality and engineering standards for which Sunbeam were renowned. The War stopped Sunbeam production as AMC became a producer of military WD machines.

'John Marston Ltd' was wound up in 1943, to become 'Marston Excelsior' in amalgamation with 'Excelsior Motor Radiator Co. of Leeds' later becoming 'I.M.I Marston Ltd' and eventually 'Marston Palmer' who still exist to this day.

In 1943 the Sunbeam trademarks were acquired by the mighty BSA group who produced low quality 'war-grade' Sunbeams until the introduction of the new Sunbeam S7 in 1946 dubbed the 'Gentlemen's Tourer'.

S' Series Sunbeams were produced from 1946 until 1956 when all Sunbeam motorcycle production Stopped. BSA did however use the Sunbeam name on a couple of scooters in 1959... a sad end to an historic heritage.

During all this time the Sunbeam bicycles continued production and the Sunbeam Cycle rights were sold to Raleigh in 1956/7 who now also own the rights to BSA Cycles.

The S' Series Sunbeams were the only shaft drive Sunbeam motorcycles and were sold as the S7, the S7 de-luxe and the S8. Sunbeam's were not produced at BSA's mighty Small Heath factory but at BSA Redditch where they were also designed.



In the beginning

The S7 was designed by Erling Poppe with the first complete prototypes made in 1945. This followed examination of two captured German motorcycles, a DKW R125 which was almost exactly copied and became the BSA Bantam, and a BMW R75, however it was felt that this was too German looking and that due to bad feeling after the war that it would not sell. The motorcycle that was designed instead shared the shaft drive of the BMW and the heavy wheels and forks but instead of a flat twin apposed across the frame layout, a new in-line (with the frame) OHC, parallel twin was designed with a top speed in excess of 90 mph. These bikes did not have the rubber mounted engines of the production models and early production test reports stated that the vibration made the bikes unfit for purpose. However Sunbeam still sold these early versions and had to recall them all to retro fit the new engine mounts.

Believe it or not BSA originally planned three models based on this engine concept... The S7 'Tourer', The 'Sports' and a rigid 'Trials' version. The S7 'Tourer was said to be good for at least 75mph whereas the 'Sports' with high compression pistons and sports camshaft gave 94 mph. Unfortunately the 'Trials' and 'Sports' were never put into production probably due to either unsafe handling at speed or high wear rates of the rear drive units.  


Refinement

In 1949 the S7 was replaced by two new bikes, the S7 de-luxe and the S8. The two new models had modified frames, saddles and engines including greater oil capacity and redesigned cylinder liners and BSA 'A' series forks. The de-luxe was only available in Mist Green and the S8 in either Black or Polychromatic Gun Metal Grey, a pleasant silver colour. The S8 had a new stylish cast aluminium silencer and chrome plated wheels with narrow tyres replaced the 'Balloon' tyres used on all other models. The new S8 had increased performance with a top speed of 85mph.

Several prototype were built or designed for new S9 and even S10 models but due to falling (and never brilliant) sales figures BSA did not pursue the projects any further and the final S8 rolled off the production line in 1956. It is said that 'new' Sunbeams could still be found in showrooms well into the 1960's. 


Photographic Timeline

This is one of the first prototype 'Sports' models... notice the cylinder head and cam arrangement. This motorcycle was said to be good for in excess of 90 mph however in testing it was found to wear out engine and rear drive components at an alarming rate and was therefore never put into production. The rider of this machine is George Dance who had been one of Sunbeam's most successful racers in his youth.

This is the 'Rigid Rear' or 'Trials' S7... notice that the rear drive unit is completely different from the production S7. Again this bike was never produced.

This is Erling Poppe, the designer of the S7 sitting on a 'Trials' Model prototype.

This is the first prototype S7 with the production head arrangement and is actually the same bike that George Dance is ridding above but with the production modification fitted... notice it still had a different rear drive unit.

This is the Pre Production S7, nearly all modifications have been made and a few bikes were sold in this specification, however this motorcycle was never that popular.

And this is the Sunbeam S7 in final production trim with the new air-filter cover... A very handsome bike!

This is the 1949 S7 revamp... the Sunbeam S7 Deluxe, fitted with BSA forks which were very much needed, but spoilt by cheapening of the handlebar controls, which now have external cables and cheap switchgear.

Also for 1949 came the sportier Sunbeam S8 with thinner tyres, redesigned saddle springing, higher compression pistons, sporty aluminium exhaust silencer, redesigned forks and front and rear mudguards. The model was to stay like this to the end of it production run in 1956.

This is a prototype engine made by BSA and tested in an S8 frame, it was designed for another BSA vehicle, probably a car or three wheeler but was tested for suitability for a new Sunbeam (S9 maybe?). It failed and the prototype was scrapped only the engine remained, complete with S8 frame\engine mount attached to the front.


E-mail: sunbeams@classicglory.com

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