Sunbeam B24T
Rare ‘Beam
Sunbeams are motorcycles unlike the others, and that’s as true about the High-Camshaft B-series bikes built by the Collier brothers’ AMC/Associated Motor Cycles concern during the Wolverhampton-derived marque’s brief sojourn in Southeast London between 1937 and 1943. Three of these years formed the first half of WW2, so AMC deserves some credit for what it achieved in the short time available to it.
Like so many early British motorcycle marques, Sunbeam’s antecedents date back to its origins as a bicycle manufacturer. Twice Mayor of Wolverhampton, John Marston was a pillar of Victorian England’s civic society as owner of the largest japanning factory in the Black Country, a local speciality comprising a form of Oriental-inspired metal finishing then popular for all kinds of household utensils and other metalwork, before it was replaced by enamelling and, later, electroplating. Marston was a keen cyclist, so almost inevitably he began building his own bicycles using his firm’s japanning treatment to impart a finished lustre to them. Apparently his wife Ellen saw one of his early bikes leaning against a wall with its polished frame glinting in the sunshine, leading her to suggest he called his bicycle The Sunbeam.
The name stuck, so Marston’s factory was renamed Sunbeamland, and in 1877 he began making bicycles commercially. Though expensive, they were very successful, and a second component factory was duly opened nearby to make pedals and other parts for Sunbeam bicycles. From 1912 onwards it manufactured an ever-wider range of two-stroke motors under the Villiers name which powered the products of many other motorcycle companies. In 1956 Villiers Engineering produced its two millionth engine, and presented it to the Science Museum in London, and the following year purchased J.A. Prestwich Industries, makers of four-stroke J.A.P. engines. Marston disliked motorcycles, and originally diversified into cars, before becoming uneasy at the amount of capital needed, so he floated Sunbeam cars off as a separate company. At the age of 76 in 1912 his core business John Marston Ltd. produced its first Sunbeam motorcycle, a 350cc side-valve single made almost entirely in-house, followed by a range of 500cc singles and a few V-twins from 1914-1923. Like Sunbeam bicycles, these were built to a very high level of quality, invariably finished in black with 22-carat gold-leaf pinstriping. To prove his products’ worth under the most arduous conditions, Marston sanctioned an intensive campaign of racing, local rider Howard R. Davies (later to found his own HRD concern) deadheated for 2nd place in the 1914 Senior TT on a Sunbeam in the marque’s IoM debut. In 1920 Tommy de la Haye recorded Sunbeam’s debut Island victory – the first of six wins on the Mountain Course during that decade, in which works Sunbeams were raced successfully all over Europe.
Sadly, John Marston died in 1918, aged 82, just as the First World War ended (during which Sunbeam motorcycles were used by the victorious Russian and French Armies), and his business was ultimately acquired in 1919 by Nobel Industries, a British company founded by Swedish chemist Alfred Nobel, the inventor of dynamite, later to be the founder of the Nobel Prize award scheme. Nobel poured substantial investment into the company, including for new machinery and extended floor space at Sunbeamland which allowed annual production to grow to a peak of 2,500 bikes by 1930, all of them high quality machines. Such were the attributes of Sunbeam's roadster models that they were dubbed the ‘Gentleman's Motorcycle’, although the Model 90, Sunbeam's most sporting 1920s model, was a true racer-with-lights which repeatedly won Grand Prix races all over Europe, as well as the Isle of Man, including four Senior TT wins. Comparing that to the up to 35,000 bikes per year produced just across town by AJS gives a sense of Sunbeamland’s more focused operation. ‚
“Such were the attributes of Sunbeam's roadster models that they were dubbed the ‘Gentleman's Motorcycle’.”
In 1927 Nobel became ICI/Imperial Chemical Industries, an amalgam of 40 different companies in a wide variety of sectors, of which John Marston Ltd. was just one. For many decades ICI was one of Britain’s largest companies, playing a key role in the provision of new chemical products like Perspex, Terylene and various Nylon items developed under licence from America’s DuPont, which coincidentally then also owned Indian Motorcycles. ICI ran Sunbeam at a distance, where what mattered most was the bottom line, an even more critical issue as the Depression took hold. Though ICI management kept Sunbeam afloat, especially the bicycle side, this did mean investment dried up, the racing team was disbanded, machinery was not replaced.
While in 1934 Sunbeam bicycle production doubled in size, motorcycle sales were badly hit. As war grew ever closer and aircraft manufacture ramped up, the ICI radiator business essentially took over at Sunbeamland, leading ICI to seek a purchaser for its Sunbeam bicycle and motorcycle business. In September 1937 it was acquired by the Collier brothers’ Matchless concern, which had similarly purchased a bankrupt AJS in 1931 and moved it south to its Plumstead factory on the outskirts of
S.E. London. The same destiny befell Sunbeam, thus creating a new two-wheeled consortium originally named Amalgamated Motor Cycles, which for reasons unknown was changed to Associated Motor Cycles in 1938. The Sunbeam production machinery was so obsolete and worn out it wasn’t worth moving, so was scrapped, but what did move south was a massive quantity of parts comprising everything made in-house at Sunbeamland from engines and frames to wheels and brakes, all awaiting assembly into complete motorcycles, for which however there were no orders. The Sunbeam motorcycle operation had been completely run down by ICI.
From those parts the Colliers immediately began manufacture in Plumstead of the 1938 tenmodel range of Sunbeam motorcycles, while the bicycle division (which, together with the secrets of obtaining the very high quality of paint finish on all Sunbeams ever built, is thought to have been the main reason for the Matchless takeover) was completely revitalised, denoted by a fresh Sunbeam badge in rather florid script and a range of popular models sold through the large Sunbeam dealer network – another reason for the Colliers’ purchase. But in October 1938 AMC introduced a completely new four-model 1939 range of motorcycles ranging from the 246cc B23 to the 598cc B28 sidecar tug, all powered by a distinctive-looking High Camshaft family of OHV engines. According to the very detailed catalogue AMC published to promote the range, these were designed by Harry Collier himself, who was quoted in it thus: “It is the dream of all designers….to be given the opportunity of producing the best design that knowledge and experience can suggest, without limitations imposed by cost, by past design, or even by plant deficiencies. Such an opportunity has been given in the design of the new Sunbeams.”
It appears these engines had been on the stocks at AMC for some time, awaiting a range of models to be powered by them – hence the speed with which the Sunbeam range was completely refreshed within just 15 months of its acquisition by Matchless. While apparently robust and certainly very heavy, the heavily-finned new dry-sump motors were undeniably handsome, each with a large timing-side chaincase on the right that was embossed with a larger version of the bicycles’ new Sunbeam script. The cylinder and head finning could have their edges chromed as an optional extra, which must have looked pretty flash! Good lubrication was evidently a priority, with allinternal oilways meaning the only external oil line was that running to the oil pressure gauge in the ‚
“The cylinder and head finning could have their edges chromed.... which must have looked pretty flash!”
back of the headlight. There was a duplex oil pump driven by a skew gear off the timing side mainshaft, and a spring-loaded valve to provide an extra flow of oil to the cylinder walls when the engine was cold. The cylinder barrel was deeply sunk into the meaty crankcases, to which the cast iron cylinder head was directly attached via four long studs, with the high-set single camshaft driven by a long chain running directly off the crank via a Weller tensioner. This also drove the Lucas 6V Magdyno, positioned behind the cylinder. The short pushrods shared a single wide tube running up through the cylinder head finning to the integral rocker box, with enclosed hairpin valve springs using a Sunbeam patent, and the whole design conveying the appearance of an OHC motor, rather than a more humble OHV layout. The chain primary drive, fully enclosed in Sunbeam’s trademark cast aluminium housing, combined with a four-speed Burman gearbox. The single-loop tubular steel frame with bifurcated lower duplex cradle, was essentially a beefed-up version of the existing Sunbeam chassis held over from Wolverhampton days. This now carried a Matchless check spring girder fork up front, holding a front wheel fitted with a new design of AMC brake, an eightinch/203 mm single leading-shoe drum with wide
15⁄ 8in/ 41mm shoes within a so-called Chromidium – no, I don’t know what that is, either! – ribbed steel hub that was supposedly heaps more effective than anything Sunbeam had used before.
Each member of the new Sunbeam Series-B range was available in three versions, Standard, Sport and Competition. The latter had good looks to match their uprated engine with polished head and ports, with an upswept exhaust, aluminium mudguards, and a smaller two-gallon (nine-litre) fuel tank cut away on the right side. This was for access to the valve adjustment necessary on the long distance Trials they were essentially designed to participate in, as evidenced by the Dunlop ‘Drilastic’ competition saddle. But even in Competition mode these were not lightweight motorcycles, the 348cc B24T version with a long-stroke 69 x 93 mm engine delivering 17 bhp at 5,500 rpm from a lowly 6.2:1 compression ratio, weighing in at 410lb/186 kg dry. The two larger-capacity 500/600cc versions scaled the wrong side of 450lb/204kg in Standard guise, complete with reinforced frame to handle the weight of the heavy motor.
This did however mean that the new-for-1939 High-Camshaft Sunbeams were as robust as Collier evidently intended them to be, as expert
Road Trials rider Geoffrey GodberFord demonstrated on both 350cc and 500cc versions during the course of 1939. In the 1939 ISDT held in Austria and centred on Salzburg, GodberFord rode a 350cc B24T fitted with a larger standard three-gallon [13.6 litre] fuel tank. This later stood him in good stead, since by then Austria had been annexed by Nazi Germany, and with the chimes of war becoming ever louder, it’s some tribute to his concentration that he completed the Six Days’ course without losing a single mark. Geoffrey thus won a Gold Medal which he unfortunately never received, since after the war the FIM annulled the event, so no prizes were awarded for it! Immediately after completing the Speed Test, he hot-footed the B24T the length of Germany to Ostend, a 600mile/960km ride from Munich where General Hühnlein, the Third Reich’s Sportführer had thoughtfully sent a truck loaded with aptlynamed ‘jerrycans’ of fuel
for use by ISDT competitors in returning home (petrol stations had been closed throughout Germany). Thanks to this, with a spare can strapped to the bike, Geoff managed to cross the Belgian border one hour before it was sealed off until Hitler’s invasion on May 10, 1940, to catch a boat home. Thus ended the Sunbeam B24T’s all too short competition career, for while the Series-B range was also catalogued for 1940, early that year AMC’s Plumstead works was entirely given over to production of the British Army’s ubiquitous Matchless G3, and then in November 1943 AMC sold (or perhaps off-loaded) Sunbeam to the BSA Group.
Because it was essentially just a one-year wonder, only around 40 Sunbeam
B24T Competition models are believed to have been built. Indeed, there’s just a single bike on the UK Sunbeam Club’s register, bearing frame no. 767 and engine no. B24TE-619. What more natural than that this should belong to that repository of rarities, the Sammy Miller Museum on England’s South Coast, purchased together with a similar bike in 2018 as a Norfolk enthusiast’s failed restoration project. “We acquired what amounted to one and three-quarter motorcycles, which fortunately between them had everything we needed to produce one complete bike, even down to the tyre pump on the rear frame strut!” says Sammy. “Jim Devereux and I pieced it together in a couple of months, and YSL 116 is quite an attractive sporting single that has a fair snap to it.”
Invited to test the truth of that opinion via an afternoon ride along the New Forest country lanes surrounding the SMM, I discovered a slim but relatively substantial-seeming bike, with a convenient side-stand and easy-off springloaded rear-mounted main stand – just paddle forward, and it snaps back to be captured by the clip on the rear mudguard. There’s a low-set but adequately spacious riding position, with quite a taut feel to it all thanks to the rigid rear end and reduced springing built into the Dunlop Comp saddle. The engine itself seemed pretty quiet mechanically, which according to Harry Collier was one of his main aims in designing it. Evidence of the ‘Beam’s off-road bent is the choice of ratios for the Burman ‘box, with the bottom three gears quite low and close together, then a long gap to fourth/top – presumably for cruising between sections, which the Sunbeam will happily do at a relaxed 50-55 mph. Torquey, too: you can set off from rest on level ground in second gear without slipping the clutch unduly. Both brakes are really excellent by the standards of the era, so whatever Chromidium is, it works a treat! However, though the Sunbeam feels very well balanced at low speeds, there’s no denying that this is a very heavy bike for its capacity and era, presumably the reason why AMC paid such close attention to providing it with a good set of stoppers.
Still, the B24T Competition with its restrained but classy styling is the epitome of a pre-WW2 sporting single, and its creation went some way towards countering the claims made by some Marston-era apologists that AMC devalued the Sunbeam brand during its brief stay in the south of England. This motorcycle surely demonstrates that Sunbeam's strong quality values were entirely absorbed by AMC, and it’s just a shame that the outbreak of hostilities prevented it and its sister models from finding a wider audience, as the starting point of a revitalised Sunbeam range. I reckon that, from what I’ve discovered about him in researching this article, John Marston would have approved of what the Collier brothers and their henchmen did with Sunbeam while this pretty unique brand that he created was in their keeping.
Postscript
Did any of the AMC Sunbeams come to Australia? At least one did. In 1939, Len Blanksby purchased a 500cc B25 Sunbeam from the Sydney agents P&R Williams in Wentworth Avenue. 38 years later it was immortalised as one of artist Alan Puckett’s prized paintings in the book Classic Motorbikes. By this stage Len Blanksby had clocked up over 140,000 miles and the Sunbeam was still his sole means of transport, ridden every day. Is it still around?