A masterpiece in Amaranth Red
Eighty years ago, one of the most significant motorcycles ever created emerged from the Triumph Engineering works. Although an intrinsically simple design, it forced the hand of virtually every other major manufacturer to follow suit.
When questioned as to why he had chosen to design a 500cc vertical twin instead of an equivalent displacement single, Triumph Managing Director and Designer Edward Turner replied, “A twin gives better torque – twice as good in fact, if, as in this case, the firing intervals are equal. It has a capacity for running at higher revolutions without unduly stressing major components, and on account of its even torque it pulls better at low speeds. It starts easier and requires no exhaust (valve) lifter. It is easier to silence, has better acceleration, better fuel consumption for the same power, increased reliability and durability, and is better cooled. In fact it is a much more agreeable engine to handle.” So there you have it – any further questions?
Triumph was in very bad shape, at least financially, when Jack Sangster bought the company in 1936 for a reputed £50,000. Sangster was a shrewd businessman and a talented designer in his own right. His father Charles, also a designer of note, had gained control of the motorcycle division of Components Limited and he took control of the Ariel works around 1905. By the early 1920s, Ariel was lagging behind current motorcycle trends, and when Jack joined the company he immediately lured the immensely talented designer Valentine Page from J.A.P. But in 1932 the Depression claimed Ariel, and Jack Sangster purchased the assets, although the restructuring meant that Page left to join Triumph. But Sangster already had a replacement in young Edward Turner, who had sketched the design of the now-legendary Ariel Square Four some years earlier. Turner had hawked his design around the traps of the Birmingham motorcycle industry but had found no takers until Sangster took him into the Ariel fold. With Sangster’s purchase of Triumph, Turner packed his drafting board and moved from Selly Oak, Birmingham, to the Triumph works at Coventry. Triumph had actually designed and built a sidevalve vertical twin engine back in 1914, which featured a 180-degree forged crankshaft, and an integrally-cast iron head and barrel with the valves operated from a central camshaft driven by skew gears from the centre of the crank. It was a promising design but the war effort meant that it was never produced as a complete motorcycle. In 1933, Val Page, now at Triumph, penned a 650cc twin, the Model 6/1 which had bore and stroke dimensions of 70mm x 84mm, double-helical geared primary drive (the crankshaft turning backwards) and semi-unit construction with the four-speed hand-change gearbox bolted to the engine. This power plant was dropped into an existing chassis with a Gloria sidecar attached in time for the International Six Days Trial which was held in Wales. The 650 outfit performed extremely well, winning rider (and Triumph designer) Harry Perrey a Silver medal, and later covered 500 miles
in 498 minutes at the Brooklands circuit under the supervision of the Auto Cycle Union, winning for Triumph the coveted Maudes Trophy. But Triumph needed more than a silver trophy to shore up its operations, and although the 6/1 did proceed to production, it was very expensive at £75.00 and, at 187kg, rather overweight, being really only suitable for use with a sidecar. It is believed only around 500 were manufactured in the two-years of production. By the time Turner arrived at Triumph the 6/1 was gone, and under Page’s supervision he began to experiment with what amounted to half his Square Four design. What eventually emerged was a very neat overhead valve parallel twin with dimensions of 63mm x 80mm (the same dimensions as Triumph’s 250 single), an iron barrel with a one-piece iron head. The built-up crankshaft, patented by Triumph, was made from manganese-molybdenum steel alloy running in 2.75” OD ball bearings, with each crank half flanged at its inner end and bolted to a central flywheel. The con-rods, forged in RR56 aluminium alloy, ran directly onto the crank journals with white metal-lined steel caps. Compression ratio was 7.2:1. Camshafts were located front and rear of the crankcase mouths, with the shafts running in bronze bushes, gear-driven to the pushrod followers. The rear-mounted magneto was gear-driven from the inlet camshaft, with a peg driving the twin-plunger oil pump that produced a constant 6o psi. Officially, the engine produced 26hp at 6,000 rpm, with a top speed of 90mph. The new twin was so compact that it fitted straight into the single-down tube frame used on the Tiger 90 493cc single, with a girder front fork and rigid rear end. Front wheel was 20-inch and rear 19-inch, both with chromium plated rims. The four-speed foot-change gearbox was also identical to the Tiger 90. Turner’s statement that the new twin produced the same balance as a single of the same capacity proved to be a little wide of the mark, due to the flexing of the crankshaft and the loss of rigidity due to the wider spacing of the main bearings. Nevertheless, vibration was not seen as an issue, and fuel consumption, or rather, lack of it, as a bonus. Turner added, “For a given power output it is possible to use a far smaller choke, which implies better vaporization and atomization. Whereas a single of 27hp would require a 1 1/8” diameter choke, the twin would need a diameter of only 15/16”. The vertical twin with cranks at 60-degrees (in line) was chosen as the best all-round layout as it has the best carburation possibilities of any type of twin owing to its even firing impulses and short induction pipes.”
The sparkling new Triumph 5T Speed Twin, resplendent in Amaranth Red for all cycle parts with a chrome and red petrol tank, was shown to journalists in July, 1937, to universal acclaim. Behind the scenes however, Turner was quietly at loggerheads with Sangster over the latter’s proposal to float Ariel and Triumph on the stock exchange, with Turner as Managing Director of both companies. Apparently, Turner’s opinion of his worth differed from Sangster’s, but the discussions were kept private as they both strove to ensure production of the eleven-strong 1938 Triumph range remained on track.
The August 1938 Motorcycle Show was held for the first time at Earl’s Court in London in and the Speed Twin was unquestionably the belle of the ball. The first road tests began appearing in October 1937, and while The Motor Cycle magazine achieved an impressive top speed of 93.75 mph, another journalist, riding with a strong tail wind, was clocked at an amazing 107 mph. Soon the new model was being pressed into service for record attempts everywhere; as far afield as South Australia where Les Fredericks set a new 12 Hour record at Coorong, near Goolwa, cramming 805 miles into the half day. At £75, the retail price was only £5 more than the Tiger 90 single, and such was the clamour for the new twin that Turner advocated dropping the single from the range. To extend the appeal of the twin and to hasten the demise of the single, Turner quickly began work on a second model, named the Tiger 100, which appeared in the same silver and chrome décor as the Tiger 90. The new twin used forged alloy pistons of higher 7.8:1 compression ratio, polished inlet ports with a one-inch carburettor, a slightly modified crankshaft and silencers with tapered ends that could be removed to expose open megaphones. To cope with the extra power, the sixstud fixing for the barrel gave way to an eight-stud arrangement that was carried over to the 5T. Post-war, Turner’s design appeared in the form of the Grand Prix, based on the tuned T100 model that had won the 1946 Manx Grand Prix, and in 1949 as the Thunderbird – a 650cc version with bore and stroke of 71 x 82. Testament to the strength of the original design is that the basic engine, in 350cc, 500cc and 650cc sizes remained in production from 1937 to the introduction of the unit-construction models in 1963. Ivor Davies, who worked in the Triumph Advertising and Marketing department for 16 years, said in his famous book, It’s a Triumph, “It (the Speed Twin), started a vertical twin bandwagon onto which almost every other manufacturer in UK and abroad has since jumped, and it enabled Turner to build Triumph Engineering into a company which, at the height of its fame, probably made more profit per pound invested than any company before or since. It also made Turner a rich man…a dominant character whose presence could not be ignored.”
A Down Under delight
The featured motorcycle here belongs to Jon Munn from Classic Style Australia in Seaford Victoria, and is another example of the meticulous restoration work carried out by resident restorer Geoff Knott. “A few years back I was approached by a Qantas pilot from Byron Bay who had a bike that his father had originally owned and he wanted to know if I was interested in buying it”, says Jon. “He sent some photos and I could see it was basically as described so we agreed on a price. It had been ‘restored’ by a friend of his some time before, and although the job wasn’t too bad it was not really what I considered acceptable for a motorcycle of this significance – this is one of the very first Speed Twins produced in 1938 with the six-stud barrels. So Geoff and I looked at it for a few weeks and then decided to do a ground-up restoration. We work strictly from the factory parts book, so it was completely dismantled and every nut and bolt was inspected. Geoff is fastidious in this way – he will not fit a nut if it has the slightest evidence of spanner rash.” The Speed Twin was mostly all there, but there were still parts to be sourced, such as the primary chain case which was damaged. Jon says that a good source of early Triumph parts is Ace Classics in London (www.aceclassics.co.uk) who were able to supply a good chain case as well as several other parts. Classic Style itself has a vast store of New Old Stock parts and much of what was needed came off their shelves, and in other cases Geoff was able to
reclaim items. The fuel tank for instance, had to be stripped of its chrome plating and Geoff spent many hours working with his set of dollies and special metal working tools to remove every tiny imperfection before the tank was ready for plating again – a specialist job done by A.A. Vinney Electroplating in Dandenong. Almost inevitably, the instruments contained within the tank top panel required major attention. The incorrect ammeter was replaced with the correct one from their NOS, while Geoff restored the oil pressure gauge and the map light. The speedometer was also incorrect but one was located which was in restorable condition. Various other processes were farmed out to experts, mostly in and around Melbourne. “Phil de Gruchy from Lightfoot Engineering did the wheels,” says Jon. “He always does a brilliant job and did the wheels on our Vincent (featured in OBA 71) as well. We fortunately had some new original parts still in wrappers which were painted in the Amaranth Red, so we were able to get the colour exactly right. The painting was done by Prestige Auto Paint who are only minutes away from us in Seaford, they also did our Vincent. Greg Wood at Woody’s Engine Services at Highett did the hydro blasting. Geoff did pretty much everything else. Once he had had the bike apart he produced a list of what was required, and once we’d gone through our own stock he gave me a shorter list of stuff I needed to chase up. Phil Pilgrim at Union Jack Motorcycles is another very good source of Triumph parts, and we got a brand new carb from Burlen Fuel Systems in England.” And so around three months after being dismantled, the Speed Twin was back together again, and looking absolutely splendid. Exhibited at Motorclassica 2017 in Melbourne, it drew rave reviews – a machine of enormous significance and one that literally changed the face of motorcycling.
Ammeter, oil pressure gauge and light switch are contained in a Bakelite panel in the fuel tank. The topmost item in the panel is an inspection light with a wander lead.
Lycett saddle was standard fitment for many makes and models. The elegant primary chain case, with the flared bump for the engine shock absorber.
The very early Speed Twins had painted headlight shells, but this soon changed to chrome plating to match the rim. Initial road tests showed that the Speed Twin would actually wind the speedometer off the clock.
ABOVE Lord Montgomery examining a 1949 Triumph Speed Twin. His Lordship had just officially opened the Earls Court Show and looking on are Triumph Chairman Jack Sangster and Managing Director Edward Turner. (Photo from Russell McIvor)
LEFT Announcement of the new Tiger 100 in November 1938.
ABOVE The triangular plate would become synonymous with the Triumph marque and continues to current production.