Buyers Guide Sunbeam S8

When it comes to choosing new products, some companies swear by in-depth market research. Steve Jobs, the boss at Apple disagreed, saying: “Some people say, ‘give the customers what they want.’ But that’s not my approach.

Our job is to figure out what they’re going to want before they do. I think Henry Ford once said, ‘If I’d asked customers what they wanted, they would have told me, ‘a faster horse!’ People don’t know what they want until you show it to them.”

Article continues below...

Enjoy more Classic Bike Guide reading in the monthly magazine.
Click here to subscribe & save.

When BSA was looking for inspiration for the motorcycle of the future, the company did ask the public. People didn’t ask for a faster horse, but for a machine that differed from anything on the market – and when they were given it they didn’t buy it.

When the Sunbeam S7 was launched in 1946 the specification was years ahead of its time. It had coil and distributor ignition rather than a magneto. Without the ubiquitous Lucas Magdyno, a generator was used and mounted at the front end of the crank. There was a single plate car-type clutch and an overhead camshaft. The S7 had a shaft drive and telescopic forks, a single piece alloy casting for the wet sump car type crankcase and iron-lined barrels. After an embarrassing royal episode, the engine got rubber mountings. Within a few years the twin had an upgrade when Sunbeam launched the S8, which contained most of the sophistication of the S7 but was lighter, sportier and cheaper.

Sunbeam had established a reputation for building fine and high quality, if relatively unsophisticated, motorcycles between the wars. By 1926 John Marston Ltd (the company name behind Sunbeam) had become part of Nobel industries, which in turn became part of the 40 companies that made up ICI by 1928. A good TT that year had ICI pleased, with both Sunbeam and Amal – another ICI subsidiary – being victorious. Come 1937 the brand was then bought by AMC, largely because AMC wanted to get their hands on Sunbeam’s bicycle range. They introduced a range of high camshaft singles in 1938, the production of which was ended by the outbreak of war.

Article continues below...

In 1943 Sunbeam had changed hands again, being bought by BSA. The managers at Armoury Road brought in a designer to come up with a new model. That designer was Erling Poppe, an Austrian-born engineer, who studied engineering in Birmingham. Poppe actually had his own motorcycle factory, Packman & Poppe, in the 1920s.

By 1943 he was designing diesel engines for lorries and working on tram designs, when BSA poached him. Officially, Poppe was inspired by readers of the motorcycle press who had been asked by BSA in 1943 what the bike of the future should be like. In 1944 adverts appeared announcing that Sunbeam would be back as soon as the war ended, with a new and revolutionary design.

Poppe may have used a captured BMW R75 as his initial template for the new machine. He was also said to have taken the designs for the R75 which BSA had acquired as war reparations and had a good look at them, but rejected the flat twin layout, keeping the German machine’s basic principles. However, as Sunbeam were working on the design before the end of the war, this could have just been diplomatically expedient. BSA did not want the S series to look too ‘German’, so an in-line OHC, parallel twin was designed instead of a flat twin.

Article continues below...

When the first batch of production models were sent to South Africa for the Pretoria police department to provide a police escort for a royal visit, the S7 was found to vibrate unacceptably. After a recall, Sunbeam followed car design practice and fitted the bikes with rubber engine mounts at top and bottom and fitted a flexible length of exhaust tube to allow the plot to move about. This not only solved the vibration issue but made the twin one of the smoothest motorcycles you could buy. While some of the styling owed a little to BMW, there was also something transatlantic about the lines, with the Sunbeam having a touch of the Harley-Davidson and Indian machines that were a common sight in wartime Britain.

The inline engine was perfect for use with a shaft drive, but instead of using BMW-style bevel gears Sunbeam used the worm-gear machinery from BSA’s newly acquired car maker Lanchester Motors. This was not a success. While bevel gears would have been tough, the worm drive, which was underslung, tended to strip under power but was needed because of the height of the gearbox. A proposed sports version of the engine could break a worm drive in a few hundred miles. Sunbeam’s solution was to keep the S7 in a lower state of tune. By now Poppe’s sojourn at BSA had ended and the design shop got to work ironing out the defects.

BSA practice was to let its individual brands operate individually, so BSA, Triumph, Ariel and Sunbeam were all competing with each other. The bosses at BSA had decided to build the Sunbeam at a satellite factory in Redditch rather than at Armoury Road, and although the S7’s innovations had wowed the press, the twin was not a hit with the team at BSA.

Article continues below...

Designer Bert Hopwood was highly critical, saying: “Although its [Sunbeams] only product, the unusual shaft drive motorcycle was lauded by many cranks whose writings on the subject practically filled the gossip columns of the technical press; none of these admirers were anxious enough to own one of these wonders. Very few were sold, and the activity fluttered through a year or two to a lingering death.” Hopwood was often scathing about rival designers, and in reality, the S series managed a decade or more on the showroom floor, selling a combined 16,000 of both models, although given that BSA were turning out 1,000 bikes a week at the time, he may have had a point.

The technical press did indeed laud the S7 and S8, though as the years went on, Earls Court Show reports reveal that The Motor Cycle writers were despairing of the lack of progress, reporting each year that there was nothing new to see from Sunbeam, with the main attraction on Sunbeam’s stand a display cutaway that brought crowds to marvel at the technology.

Extracting more power from the engine being impossible, Sunbeam took a different approach to improving the performance when launching the S8, deciding to make it lighter. They used parts from the BSA range of twins, redesigned the seat springing and cut weight wherever they could, slicing 30lbs from the S7. They changed the S7’s 16in wheels and balloon tyres, which had added to the machine’s smoothness on the road, in favour of more conventional 18 and 19in items. And they carved £30 off the asking price.

Price wasn’t the real issue as the market for the S8 was supposed to be for a ‘gentleman’s motorcycle’, softly spoken, sophisticated, comfortable and more oil-tight than most, thanks to those one-piece castings, although where there was a join they leaked as much as any other bike of the period. The best attribute of the S8, due to those rubber mountings and the shaft drive, is smoothness, once the rider has reached 30mph. Not only is this a boon for the rider determined to cover distances, it has a beneficial effect on the rest of the machine too, as things don’t vibrate loose.

Read the full story in the December issue of Classic Bike Guide

Subscribe to Classic Bike Guide Magazine Enjoy more Classic Bike Guide reading in the monthly magazine. Click here to subscribe.