Three thinking
BSA Group’s, autocratic boss Edward Turner Many tomes quote Triumph’s, and later concept ‘potty.’ A bit rich from a Hele three-cylinder stating the Bert Hopwood/Doug engine for Ariel over three decades earlier… chap who designed a complex four-cylinder
No halfway house
Classic motorcycle enthusiasts fall into one of two camps – they either love or loath Triumph Tridents and BSA Rocket 3s. No middle ground here.
On the minus side, they’re heavy, thirsty, had pushrods at a time rivals from Japan moved their camshafts up top, suffered from many design hiccups during conception, reliability was achieved by detuning the engine, manufacture of their crankshafts was, well, ‘interesting’ and refitting the airbox is a nightmare, or at least it is on our Triumph T150V. However, it’s not all bad news.
Compared with rivals of the late 1960s to mid-1970s, they’re fast, accelerate even better, handle well, most stopped well except the comical (oops, conical…) hub models and under power their exhaust note is compelling. Some question their reliability and claim they’ve a weak bottom end. There may be a tiny element of truth here, but, often, such ills are down to maintenance issues and if your ride a Trident/Rocket 3, rule one reads: ‘Always rev the engine, never slog it.’
Personal experience
Since the Trident/Rocket 3 launch, until June 30, 2008, I had never considered a 1960s/70s triple, although many spotty, lustful youths in period found the models posing on Tridents for publicity shots to their liking, especially if they wore short skirts. For over 50 years, my passion has been veteran and vintage motorcycles, often stating ‘no real motorcycles have been made since 1928,’ after all one can use every last drop of juice from flat petrol tanks when running low. And my 1927 Sunbeam TT90 breezes along at 60-65mph, passes lorries on motorways, handles and stops okay, starts easily and returns 5080mpg depending on rider mood, so why on earth would I want a newer motorcycle?
Single mindedness can be regarded as an illness… So I’m told! And to prove I don’t suffer, over the years I’ve enjoyed having more modern machines: New Imperial Model 30 – ‘grey porridge’ to many but a delight – plus a bevy of two-strokes, including a DKW RT200VS for over 20 years and a tiny maroon James Cadet, plus a very tatty (which saves cleaning) BSA DB34 in production racing trim. Over the years, I’ve had just three parallel twins – a plunger framed BSA A10 I collected from Norwich and sold before I got home, a totally reliable oil-in-frame BSA A65 Thunderbolt which took me around Europe and more recently a ‘bought crashed’ 1966 BSA A50, which son Peter is now fixing.
Being honest, I’m single-minded (i.e. prefer single cylinder engines) as I can see no point in having all those extra engine parts thrashing about in a motorcycle’s motor when my singles work well with many less, and the less parts on the move, the less chance of it failing. Well, that’s my theory. So how on earth did I become a Trident enthusiast, because whichever way you look at the Triumph triple, it’s all wrong – even its tank badge doesn’t read BSA…
Picture the scene
On that long summer day 13 years ago, in the days before I forsook cars for far more useful vans, son Peter and I headed south from Cambridgeshire in a Vauxhall Astra estate car (also a gas guzzler thanks to its transplanted pokey engine) lugging a three bike trailer to the
Bonhams Professor Fritz Ehn sale at the RAF Museum, Hendon, London.
The plan was to bid for a stylish c1950 Steyr Waffenrad lady’s cycle (lot 70) for my daughter Lucy, then Peter would try for the 1971 50cc Kreidler Florett (lot 199) – as he has enough ‘real’ lusty motorcycles one could ask why… and finally hunt down a big single or parallel twin needing work for his business’s sales fleet. Lucy, then working in a North London fashion design studio, followed the sale online and excitedly rang within seconds of the hammer coming down to confirm I’d really won the Steyr cycle for £60 (there’d have been questions in the Common’s if I hadn’t…). The best part of two hours later, and after a leisurely ‘heart attack on a plate’ fry up at the nearby greasy spoon, Peter was the proud new owner of an orange and rust coloured, seized-engined Kreidler Florett, knocked down at £250. Days later it had been wiped over with an oily rag, the motor rocked free, and it was running, albeit noisily. Soon shod with new tyres it was registered and into use – and still is looking just as disgusting and sounding no better.
All the potential ‘sales fleet’ machines either needed too much money spending to be worthwhile, or Peter was outbid.
A 1974 Trident T150V brought this section of the sale to a close, before Malcolm Barber of Bonhams moved onto the cream of the Ehn collection on offer. We hadn’t looked this triple over as we reckoned it would make at least the top end of its £2-3000 estimate, but bidding opened without enthusiasm at £1900, hesitated – persuading me to knee Peter, sitting next to me, into action. Up went his paddle at £2000 and as the hammer was about to descend, the opposition – after phoning a friend – came back with £2100, leaving Peter to venture the winning £2200.
What came next
The trip home was as tedious as one would expect with leaving London at 4.30pm on a Monday afternoon. But at least the sight of us, joined by Lucy who’d cut out from shoe designing early to view her purchase, gave a couple of TCM readers a laugh, with one spluttering only ‘you’ could buy that motley lot. The following morning Peter had the German registered Trident running after slumbering for many years in Ehn Museum. It soon spluttered and stopped with electronic ignition failure.
It gained new ignition, wiring loom, rear tyre and a few odds, before applying for a UK registration with DVLA. And other than servicing and a few consumables like light bulbs, that has been that for more than a decade of irregular use. Often, we’re asked why we’ve this gas guzzling lump in the workshop. The answer is because every time we ride it, we return smiling and although it gets little summer use other than motorway work, which it gobbles up, it’s perfect for dark evenings as its lights are excellent and indicators are a real bonus.
Throughout its stay with us, its top end has rattled and clanked, not excessively, but just enough to remind me there are far too many moving parts involved, but it’s probably allowed to rattle as its scant history implies that including the mileage we’ve added, it is now approaching 140,000 miles.
It always starts within three kicks (unless you’ve done something stupid like not turn on the ignition key; flipping new-fangled ideas…) idles reasonably evenly and, so long as its engine is spinning at above 2500rpm, it’s super smooth. And of course petrol never becomes stale in its tank, as it drinks it so enthusiastically – when checked, we average 35-40mpg and have reduced this to 28mpg with some enthusiastic effort. To put this in perspective, if the Trident is loaded into Kermit (my green Renault Traffic) the consumption improves to 45mpg when cruising the van at 65-70mph. Long may the smile factor of the triple outweigh such mundane thoughts!
Birth of the triple
Folklore, interview and history confirm engineers Bert Hopwood and Doug Hele had discussed three and four cylinder engines while both were still with Norton in Birmingham. Norton draughtsman Brian Jones had even sketched out preliminary designs for a transverse four-cylinder engine but all were unhappy, as it would lead to a wide motorcycle with the riders needing to sit with legs splayed, making it more difficult to grip the tank with one’s knees unless the tank was made wider too, and would increase wind resistance.
Traditionally, British motorcycles had for the most part been narrow, even the parallel twins. This led the two ‘Hs’ to continue to discuss a three-cylinder concept, even after Bert left Norton and returned to Triumph, proving real engineers rise above rival company politics. Their common need was to satisfy the then demand for ever more power, especially from America, the primary
major outlet for big British motorcycles. To their joint minds, the Triumph and Norton parallel twins had reached their limit. More power could – and later was – developed from both engines by raising compressions, more radical cams and in the case of Norton more ccs, but this was at the expense of engine smoothness and if over development occurred, then reliability suffered.
As AMC planned to move Norton production to Plumstead, London, Doug Hele had no desire to leave the Midlands and was in the early stages of planning a career move away from the British motorcycle industry, either into the automotive world or engineering lecturing to trainees. Then, in autumn 1962, Bert Hopwood offered his friend and former colleague the post of chief development engineer at Meriden.
Initially, Hele’s day job comprised of working on developing the unit construction 650cc twin, making more powerful versions for the performance Bonneville range, and designing project two-stroke engines. But the triple remained firmly in the minds of both Hele and Hopwood, although both had concerns as to how smooth the engine would be.
Back in 1962/3, they didn’t have the hindsight knowledge we’ve learned more recently from especially German and Japanese car makers, who have proved the smoothness of odd numbers of cylinders (three and five notably). However, Italian motorcycle racing engine makers had successfully built inline and transverse three-cylinder engines, two-stroke car engine makers exampled by Saab and DKW/Auto-Union built tough cars with smallish (often 750cc) three-cylinder twostroke engines and, albeit in diesel form, threes were used successfully by makers of smallish tractors when installed in the likes of selected Massey-Ferguson 35s and the Fordson Dexta.
Initially, the three cylinder concept was largely an end of working day/afterhours project, which MD Edward Turner wanted none of. His thought was that two cylinders were ideal and in his heart of hearts, he felt the Triumph 500cc parallel twin best in terms of satisfactory power output and smooth running through its rev range. In effect: “I designed the perfect parallel twin engine in 1937.” True, it later became unit construction and had its bore and stroke revised but, for the rest, thought Turner, leave it alone. However, he was also wise enough to see the need for more power to satisfy especially American demands, so had backed the 650cc development, but a three cylinder of 750cc was a step too far. Though it’s interesting to note that while he didn’t back it, he didn’t ban it from Meriden either.
Initially, drawings were for an air-cooled three cylinder engine with design heavily based on that of Edward Turner’s 500cc (498.76cc) Speed Twin engine, launched to the public in 1937 and with updates continued in production until 1959, the last year for the final pre-unit Tiger 100s only. Thus their triple design had Turner’s initial bore/stroke dimensions of 63x80mm, to minimise engine width rather than appease ET, camshafts tucked up high in the crankcases and just behind the barrels with the rear serving inlet valves and the front exhaust valves.
As with Turner’s design, this permitted short pushrods to operate the valves on the theory they were better suited to high revving engines than long pushrods. An interesting thought which many including Vincent stuck to, but it is worth remembering BSA Gold Stars and associated B-series singles with long pushrods rev to over 6000rpm safely, a fact proved by our two Goldies – Peter’s DBD engine was assembled by us in 2001 and has been used/pasted every summer since, without needing any more than a decoke.
Further design included a 120 degree crankshaft, which, as history proves, ensured a high degree of smooth running and after clutch position redesign the Triumph Bonneville four-speed gearbox was grafted onto the back of the wider three-cylinder engine.
Senior Meriden designer Brian Jones (ex-Norton) headed the team drawing the design ready for the Experimental Shop, leading to the first Project 1 (P1) series engine with sand cast crankcases and an iron barrel block in 1964. Although crude in its assembly finish, by early 1965 the engine delivered almost 60bhp (59.5bhp is often quoted), a promising start compared with the existing latest specification Triumph Bonneville, but a mass of problems surfaced once road testing and extended duration bench testing got underway, including barrel and cylinder head distortion due
“Edward Turner felt he’d designed the perfect parallel twin engine in 1937.”
to overheating and crankshaft bearing failures with the rate rising as power output was improved.
After early road testing, the iron barrel block gave way to an aluminium alloy casting with liners and some heated discussions with suppliers, who attributed product failure to the Triumph Experimental Shop not cleaning the sand from the castings adequately. No, boys, your shells weren’t up to the job, as proved when the material used for high performance car engines was employed, the shells lasted.
Short term, the P1 triple engines were put into the Doug Hele-designed single downtube unit Bonneville frames for road testing and as a keen rider and ‘coal face’ engineer, Doug used a P1 for his commuting and own road testing. More problems surfaced and were overcome, including further overheating – albeit not so marked – with the new aluminium alloy barrel block needing revised liners, development of improved exhaust systems, quietening the drive system and more… Including doubts about the production line suitability of the then currently fitted chopped Amal Mononbloc carburettors to the outside cylinders. The Concentric was yet to be launched.
Testing can be a worrying time, but it also has its amusing asides. En route to work, Hele’s prototype Trident caught fire – a lashed up electrical connection may have been the cause – and he often later recounted how the prototype was saved by the local postman. Between him and Hele, they used a discarded steel roofing sheet to channel water from an animal drinking source onto the burning machine!
Testers, including Doug, found under enthusiastic acceleration the weighty Tridents shredded the then available tyres fitted to their rear wheels and Experimental Shop member Harry Woolridge reckoned after a long motorway blast (no 70mph limit in the 1965!) the engine was so hot, he was amazed it didn’t melt. His input here led to the fitment of oil coolers to production models.
In 1966, Meriden started building revised P2s with bore and stroke dimensions of 67x70mm to give the triple’s famed 741cc; it’s claimed due to Hopwood’s faith in modular design he favoured using the dimensions of the Group’s existing BSA C15.
Other developments included larger valves accommodated thanks to the larger bore diameter and the discarding of the three pinion primary drive in favour of a Renolds triplex chain to quieten transmission.
Despite frame development, the P2s looked very like three-cylinder Bonnevilles – without doubt an attractive appearance from a long line of well styled machines crafted by ET, Jack Wickes and his staff. But since Hopwood and Hele had conceived their triple as a Triumph and test prototypes had been grafted into modified Bonneville frames, it had become a BSA group, rather than Triumph, project, and would be marketed under both brands, which had differing established styles.
On the grounds of economics, brand loyalty of the respective in-house designers from both marques and other politics, they contracted the acknowledged David Ogle founded Ogle Design, Letchworth (Reliant Scimitar, Bond Bug, radios casings, Raleigh Chopper, models, marble runs and much more) to style the new triple for both companies.
Next month: styling, into production and landmarks.