Memorable Motorcycles Works Triumph Bonneville

May 12, 2008
Frank Melling
Frank Melling
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Our Memorable Motorcycles expert, Frank Melling also is the organizer of the British vintage motorcycle extravaganza known as Thundersprint. Melling began riding five decades ago and remains as much in love with motorcycles as when he drove his first bike into a cow shed wall aged ten. In the last 50 years, Melling has competed in every form of motorcycle sport and now declares himself to be too old to grow up and be sensible.

Our Memorable Motorcycles correspondent takes a ride on a Triumph oddity  one four special-build production Bonneville racers.
Our Memorable Motorcycles correspondent takes a ride on a Triumph oddity, one four special-build production Bonneville racers.

As a factory, Triumph was never keen on racing. The autocratic Edward Turner’s opinion always held sway and he felt that the way to make money was by producing excellent road bikes that ordinary customers wanted to buy at prices they could afford, rather than spending a fortune on Grand Prix racing.

The argument was soundly based because motorcycling in the 1960s was littered with factories that dominated Grand Prix but which were permanently on the point of extinction. Norton, FB Mondial, Velocette, Moto Guzzi, and AJS were just a few examples of marques that had made innovative, race winning motorcycles but were stagnating as manufacturers. By contrast, Triumph churned out simple, easy-to-build bikes that the customers loved – and without the need to spend fortunes on racing.

It was only when the Japanese came along with superb road bikes and charismatic race teams that GPs started to earn their keep in marketing terms – but that’s another story.

Triumph always had an interest in off-road sport and there were two exceptions to Triumph’s “no tarmac racing rule” too.

Interestingly, all competition activities, on and off-road, involved production based bikes.

The first was the Clubman’s TT which was intended for privately owned road machines and provided a wonderful showcase for super sports machinery like BSA’s Gold Stars. The second was the Southampton club’s Thruxton 500 mile endurance race, held in the south of England, that again provided an opportunity for, supposedly, standard production machines to show their prowess in terms of endurance and speed.

After the demise of the Clubman’s, ironically because it became a BSA benefit, the key event in Triumph’s British calendar was the Thruxton 500 miler. This race fitted the factory’s policy of not going GP racing but had the secondary benefit of keeping a race development program in existence that was relevant to the American market.

In the US, the big Meriden Twins did exceptionally well in oval dirt races, hare scrambles and classic on and off-road races like the Catalina GP. And given the choice of winning the Catalina GP, on the doorstep of his biggest market, or some obscure Grand Prix behind the Iron Curtain, there was no doubt which was the most commercially attractive to Turner – and who can blame him?

Bearing numbers between MAC 231E and MAC 234E  four Bonneville racers were built up by Triumph as production racers.
Bearing numbers between MAC 231E and MAC 234E, four Bonneville racers were built up by Triumph as production racers.

There was never a period when racing activities were not undertaken at Meriden but things took a turn for the better when Doug Hele joined the factory in 1961. Hele came from Norton and was the man responsible for Dommie Racer twins – the racing versions of Norton’s parallel Twin road bike. Hele was universally acknowledged as a good engineer; thoughtful, open minded and possessing vision. Doug was also an enthusiastic motorcyclist and believed strongly in the concept of the complete motorcycle – which was in contrast to Frank Barker, his predecessor at Triumph, who belonged to the school of thought that if the engine was sufficiently powerful, then the cycle parts didn’t have to be perfect.

In 1958, Mike Hailwood and Dan Shorey won the Thruxton race and in the following year, “Thruxton” Bonnevilles were available from the factory; well, they were available in theory at least. At this point, it needs to be said that the name “Thruxton” is often misused. Strictly speaking, the name “Thruxton” only applies to the 49 machines made for homologation purposes in 1964/65. However, it was Triumph practice to put a note in the build book “Thruxton” when the bike was only a 650 intended for racing.

These bikes were nominally available with a whole list of “optional extras” from the “High Performance List” but the reality of the matter was that only bikes supplied to key dealers came with the goodies installed by the factory – private owners had to retro fit them by whatever means they could. Parts available ranged from high compression pistons, to carburetors, cams and followers and with a good turner, it was possible to build a quick Triumph.

The Works Bonnevilles are powered by a big Twin  which  makes good racing power from 3 000 rpm to 6 500 rpm.
The Works Bonnevilles are powered by a big Twin, which “makes good racing power from 3,000 rpm to 6,500 rpm.”

There had been criticism that the factory were not keeping to the spirit of production racing – as if any ever did – so the factory decided to build a batch of true production racers to works specification. Not that they did of course – but this was the sales pitch. The key modification was to provide a positive oil feed to the exhaust cams, which were prone to seize under extreme conditions. This was done by fitting an external oil pipe to feed them directly. There were also wider front brake linings – increased to 1 5/8″ – 19-inch alloy wheels and chopped Monobloc carburetors with a central float bowl.

Interestingly, although the bikes had been built for homologation, the Triumph race shop immediately improved them by having the tool room machine standard crankcases internally so that the oil feed was kept inside the engine. Les Williams, who was a key figure in the race shop, remembers the bikes being built and confirms that they were nothing very special. “They were built on the production line, along with all the other standard bikes. Then they were taken to the storage bays where the Triumph Tina scooters were built and the factory paid service department and experimental shop fitters overtime to finish them off on Saturdays and Sundays.”

Strangely, Hele does not have too much affection for, or pride in, the MAC series. “I was always more proud of the bikes we put the most work into. The 1967 Daytona bikes (500cc Twins which won the Daytona race in1966 and 1967) were much greater achievements than the production bikes which were pretty standard.”

William smiles when he hears this comment: “It’s true – the production racers were Doug’s “day job”. When he went home at night he could dream of building Grands Prix racers – which was what he was really interested in.” 

The original aim was to build 50 Thruxton Bonnevilles, but apparently someone “mislaid” one of the special big-valve cylinder heads and so the fiftieth bike was broken for spares. This brings us to the start of the most famous of all the Bonnevilles, four bikes carrying the numbers MAC 231E to MAC 234E and arguably the finest production racers of their day.

In peak form  the special production Bonneville Twins produced 58 hp at 7 000 rpm.
In peak form, the special production Bonneville Twins produced 58 hp at 7,000 rpm.

Doug Hele expalins the design philosophy. “We always wanted to build bikes which were rider friendly. There’s no use building a bike which is rider unfriendly because not even the most talented rider will get the best out of it.”

Doug is also unstintingly generous in the contribution made by Triumph’s chief test rider, Percy Tait, and his colleagues in the experimental department.

“Percy was a wonderful test rider – wonderful. He could ride a bike right up to the limits of its performance, and beyond, and still not crash it. He could also do the same thing over and over again which was a wonderful skill for a test rider.”

“He had strong opinions too and needed to be convinced by argument and example that an idea worked. I encouraged this. All the team was encouraged to express their opinions and offer their ideas. It was a very happy team and we worked together well.”

Les Williams has the same memories. “Although Doug was a highly intelligent engineer, capable of solving a problem entirely on paper, he respected the men in the workshop and was always asking us for ideas and there was no criticism if they didn’t work.”

The MAC bikes all started off in the most humble way – all were production line failures. If a bike had a major problem on test it was dropped off at the experimental shop for transformation into a racer.

Les expalins: ” The first job was to disassemble the whole bike. If it was a problem like a porous crankcase, then this would be replaced or perhaps an oil pump had failed and we might have more work to do.

Our man Melling throws the Bonny around a corner  during its development Triumph utilized the riding skills of Malcolm Uphill for testing.
Our man Melling throws the Bonny around a corner, during its development Triumph utilized the riding skills of Malcolm Uphill for testing.

“The main modification to the works bikes were that they had toolroom heads and BSA Spitfire profile cams. To prevent excessive wear the cams were faced with Eutectic and the 3-inch radius “Big Foot” tappets were used.

“The pistons were normal Bonneville racing and gave an 11:1 compression ratio. We always used American S and W valve springs that we knew we could trust under racing conditions. Flywheel weight was increased to smooth out the roughness caused by the increased power.

“The best engines gave 58 hp at 7,000 rpm with a safe rev limit of 7,200 rpm.

“The rotors were skimmed to reduce drag and when the bikes were first built they had four-speed gearboxes because we weren’t 100% happy with the Quaife five speeders. Later on, all the bikes were fitted with the five-speed ‘box.

“The carburetors were quite special and built by Amal. They had extra long tapered needles and jet holders longer than standard too, which gave excellent mid-range power.

“We also introduced the balance pipe (between the two exhaust pipes) on this bike, again for mid-range power, and it was an immediate success. The silencers were another Hele success. They kept the bike quiet but still allowed good breathing.

Unlike many production racers of its day  the Works Bonneville features soft handling.
Unlike many production racers of its day, the Works Bonneville features soft handling.

“The chassis was very standard and is a credit to Hele’s design ability. The front forks were shortened by an inch and we ran AM3 red linings in the rear brake and AM4 green linings in the front with standard hubs.

“19-inch wheels, with alloy rims were essential and when we began, we ran Dunlop TT100s but Malcolm Uphill liked the Dunlop KR “triangular” racing tire which gave quicker steering but made the bike unstable at high speeds in a straight line. Uphill was prepared to trade corner speed for safety but other riders, like Rodney Gould didn’t get on with this set-up.”

Doug Hele takes up the story: “As much as possible had to be done in-house because we only had a tiny budget. I can’t remember how much it was, but our accounts’ department always signed off the bills even if we weren’t exactly in budget, so we always managed. Even so, some parts – like the alloy petrol tanks, seats and exhaust pipes were cheaper to buy in so we always did this.”

Doug also had a budget problem with riders too. “The truth was that we didn’t have sufficient money to buy the best riders and in any case, a production ride was not attractive – not like a GP ride. So we had to look for alternatives.

“In the case of Malcolm Uphill, who was the first rider to achieve a 100-mph lap of the TT circuit on a production machine, he was a much better rider than people think and than he was given credit for. I think that he would have been difficult to beat by anyone on a production bike.”

And so to MAC 231E our test bike. This was one of four built in the Triumph race shop over the winter of 1966/67 but was not one of the works bikes. All four of the bikes were taken to MIRA and the best ones kept for the works teams and the rest released to favored dealers who would use them seriously. MAC 231E went to production racing enthusiast Stan Hughes, of Hughes of Wallington, and after a long and checkered history ended up in the hands of Triumph enthusiast Tim Whitham.

The only aspect of the Works Bonneville that dismayed our tester was the 8-inch front brake.
The only aspect of the Works Bonneville that dismayed our tester was the 8-inch front brake.

Tim’s restoration philosophy is to leave the bike untouched cosmetically and to concentrate on the mechanical side of things. Certainly, the bike looks authentic and original but glancing down at the original TT100s, complete with sidewall-age cracks, I could not help wondering whether this approach was wholly appropriate for a racing bike. However, after just a few laps it was easy to see why this Bonny was the top of the production tree.

It is immediately striking that the Bonny does not feel like a production racer. Everything about the bike is comparable with a full-blown race machine of the time. Okay, it’s not up to the definitive over the counter racer of the day, the G.50-engined Seely, but it is right in there when compared with a standard Plumstead-made Matchless G.50. As for Manx Norton, I have never liked the ride they gave. For me it was always too stiff for comfort. When a Manx lets go, it does so with commitment and the first thing a second rate runner like me knows about the job is when the bike passes you on its side.

By comparison, the Bonny has soft, forgiving, docile handling which must have been a dream in long-distance races or true road circuits like the Isle of Man.

There is no escaping the fact that this is a big bike. At 5’11” and 182lbs, I am tall and heavy for a road racer and so the long stretch didn’t bother me but I could understand why small, lightweight pilots found the Bonny production racer something of a lump. Interestingly, Malcolm Uphill was tall compared with the norm, so perhaps this is one of the reasons he enjoyed the bike so much.

Not built for Grand Prix wins  the Triumph Works Bonneville turned laps in endurance races and the famed Isle of Man circuit.
Not built for Grand Prix wins, the Triumph Works Bonneville turned laps in endurance races and the famed Isle of Man circuit.

Ray Knight rode the bike to third place in the Brands Hatch 500-mile race and remembers the bike with fondness. “Some of the works BSA Spitfires were quicker than the Triumph but the Bonneville was a much better package. It really was a nice motorcycle and it was easy to ride hard.”

The engine is just as good as the handling. Despite its twin Amals, the big Twin pulls like a tractor and makes good racing power from 3,000 rpm to 6,500 rpm. If one does make a mistake, the merest dab of the clutch gets the motor spinning again.

The Quaife five-speed gearbox is wonderfully sweet. The down for up pattern, still favored by racers, is, was, and always will be the most natural shift pattern and the gears float in effortlessly. Out of respect for the age and condition of the bike, I always used the clutch but Triumph riders used to pop in ratios with just a dab of the gear lever and a momentary easing of the throttle. The clutch itself is feather light and must have reduced workload tremendously in endurance races.

The only part of the bike that was disappointing was the 8-inch tls front brake. This was chronically oval and had a thin, road cable to operate it. This brake was the best stopper ever produced by a British factory and it can be made into a respectable tool for racing. However, to do this it has got to be in perfect condition. Even if it was, Triumph’s preference for fitting the double sided tls Fontana front brake to its first string works bikes becomes understandable.

Without doubt, this is the one bike Triumph should have produced as a limited edition flagship model, as Ducati does now with its race replica Twins. Hand-built in small numbers, this Bonny would have soon accrued cult status and, unlike BSA’s DBD Goldstar and much hyped Velocette Thruxton, the Bonny would make a superb road bike.

The one batch of Thruxton Bonnevilles built by Triumph in 1965 now command astronomical prices – $20,000 being regularly achieved. Just imagine what one of these later, and far superior, Bonnys would make.

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