THUNDERBIRDS ARE GO
When Triumphs are involved, you can’t have too much of a good thing. Here’s the proof
Well, they will be when Keith Pottinger has finished with them. He was restoring three at once when we visited the workshop of this committed Triumph restorer
If restoring three 1950s Triumph Thunderbirds at the same time sounds like a lot to take on, think again. Not long before our visit to his workshop, Keith Pottinger had four on the go at once – one he’d finished earlier had recently been sold to a dealership in Cheshire. The other three are still work in progress while we’re there, though – and there are many other Triumphs, most of which look likely candidates for restoration.
Keith is a hardcore Triumph enthusiast who is keeping himself more than busy during his semi-retirement by restoring the old British twins. “I’ve done the four Thunderbirds over a sixth month period,” he explains. “It’s the first time I’ve worked on four bikes at the same time, but I had all the bits to hand so it made sense. Doing the same job four times, it’s like a production line – a bit like the Triumph factory but without the wooden trestles!”
On his desk in the corner of the workshop are various manuals along with his old photo album, next to an original 1968 Triumph Instruction Manual he’s kept from new. The photo album is full of Triumphs and Rickmans.
“As a kid, I built a racing Bantam, then a trials Bantam. I had Triumph Cubs and a 350 Jawa. I wanted a Bonnie when I was an apprentice engineer, but they were £395 new so I built a TRIBSA instead. It cost me £35.
“All us apprentices used to build our own bikes. I bought an iron-head Triumph, hacksawed up a frame and built my TRIBSA in 1968. I used to clean it on Saturday, then go to race meetings on Sunday with all my mates. Then I’d spend all week fixing what had gone wrong, ready for the following weekend’s trip. We went to a lot of the bike road-race meetings. I finally sold everything off when I moved house back in 1979 – cars as well as bikes.”
Like many bikers of that era, Keith never quite shrugged off the bug. He restored Austin 7s for a while, but eventually got back
into two wheels and now runs a sweet, red and silver 1961 TR6. “My TR6 is original and I had a 1961 Bonnie in sky blue and silver, although that wasn’t quite original. They got me back into bikes ten years ago,” he explains. “I built the Bonnie in my shed, but have since sold it, so I’ve been trying to get the TR6 rideable for when the sun comes out. It’s much nicer to ride than the Bonnie, which vibrated so much it made my fingers go numb.”
Keith is a ballistic engineer – he uses special equipment to test guns and measure the performance of ammunition. He ran the test ranges at Enfield for 12 years until 1988, but is now a consulting engineer for a ballistics firm selling equipment for companies to test munitions and body armour.
“We ship to 30 countries,” he says. “I only do three days a week now, though. I was 70 just before Christmas – I’m winding down so I can focus more on building bikes!
“Ten years ago, when I set about restoring the Bonnie, I quickly realised there were plenty of bits available, so I ended up doing another, and another... and so on. Then I started to pick up other Triumph projects and realised I could sell the restored bikes. There’s not much profit in it, though – it takes three months to build a bike and it’s an expensive business buying all the new spares you need. I need to charge for my labour, but as I’m retired there’s no need to chase money.”
So why so many Thunderbirds, Keith? “I prefer the pre-unit Triumphs, especially the rigids. I like single carbs and iron heads. Those older models don’t seem to vibrate as much as the later Triumphs do. It seems like the more performance they added, the more the bikes vibrated.”
The Triumph 6T Thunderbird was launched in 1949, looking no different to the established 500cc Speed Twin, but with engine capacity increased by 150cc to give the improved power-to-weight ratio demanded by the American market. The motor featured a 71mm bore and 82mm stroke to give a capacity of 649cc, hopping up horsepower by 7bhp to 34bhp at 6300rpm and giving a wider spread of torque. The compression ratio was 7:1, although the American market bikes could run 8.5:1 compression thanks to the better-quality petrol on that side of the Atlantic.
As a publicity stunt to sell the new 650, Triumph took three machines off the production line, then had a team of riders ride them to Montlhéry, south of Paris and cover 500 miles around the banked speed oval at over 90mph before riding them back to Meriden. The bikes still featured a rigid frame and sprung-hub rear wheel, and had limited modifications: Dunlop racing rubber, KLG racing spark plugs, 25-tooth front sprockets (24 was standard) and footpegs relocated to improve rider comfort.
When it came to the production road bikes, the Americans were initially disappointed by the Thunderbird’s performance, although that was overcome with a larger-bore carburettor, introduced during the model’s first year on sale. More withering criticism came from the choice of the what Cycle magazine called the bike’s ‘slate blue’ livery (called Thunder Blue in the States, but Polychromatic Blue in the UK) that was used on the frame and cycle parts as well as the fuel tank.
The colour was later changed to a lighter metallic blue, but US dealers kept demanding black enamel frames which were easier to touch up, which led to Triumph offering an all-black 6T for the American market in 1953, prompting the 6T’s ‘Blackbird’ moniker. US dealers soon expressed their preference for the black version of the Triumph, leading the company to issue a dealer bulletin almost begging them to take some of the unwanted metallic blue bikes that were left unsold.
In 1955 Triumph introduced the 6T (SA) swingarm version to the American range and offered it in black or blue, while the 6T (AC) rigid stayed in the catalogue for one more year.
Keith built all four of his T-birds as Us-spec ‘Blackbirds’, explaining: “I like the look of the American-spec bikes with the
‘IT’S LIKE A PRODUCTION LINE – A BIT LIKE THE TRIUMPH FACTORY!’
black livery and the gold tank badges. There’s a pillion pad option and rear pegs, but I don’t fit them because it spoils the ‘bobber’ look which sells so well.”
One of Keith’s builds is a 1954 model, complete with an SU carb which was first offered on the 6T in 1952. Two of them are 1951 models, while the one he’d recently finished and sold was a 1950 model. The bikes came to him in dire need of restoration: “I got two of them from a contact in Derbyshire who brings containers full of bikes in from the States. Another was kept in a barn. When I went to pick it up, I spotted another Thunderbird frame hanging up. The bike in the barn was a chopper with a weird exhaust system that I still have – and springer forks, which I sold. The bike had matching frame and engine numbers, so I decided to take it back to original. The frame had been cut about with all the ‘unnecessary’ lugs removed, so I had to get the brake pedal hinge casting supplied by Ace Classics and welded back in place by Abba Motorcycle Engineering in South Woodham Ferrers.”
Keith relies heavily on Ace Classics in south-east London for his pre-unit Triumph parts. “Not only do they have a huge range of stock, most of Cliff’s parts bolt straight on,” says Keith, adding ruefully: “a lot of the pattern stuff you get nowadays doesn’t. Cliff’s stuff is more expensive, but you know it all fits because he takes stuff off old bikes, gets them copied exactly, then bolts the replica part on to make sure it fits. Cliff does all the wiring looms for all the models, so we fit them as standard practice.
“I also use Mark Francis Triumph Spares, FD Autos who have a lot of old stock, and ebay is a great source for secondhand parts, as is the Kempton autojumble. Things like wheel hubs, brake plates and fork bottoms, you can only get them secondhand now. It’s the same story for crankcases, heads and rocker boxes.
“I get my speedos refurbished by Russell Smalley in Nottingham (chronometrics.co.uk). He’s an ex-smiths’ instruments engineer who is now running his own instrument workshop. Central Wheels rebuilt all the wheels on the four Thunderbirds and painted the black centres and gold lines, too – the eight wheels cost £3500. Normally, the guy next door does all my black paint, while Ace Classics do any colour work.”
Working on pre-unit Triumphs is not all plain sailing, as Keith attests: “Setting up the clutches on pre-units is a pain. You build them and leave the cover off. Then run them up and down the road. Then seal up the cover. The timing is with auto advance on the magneto versions, so you have to take the cover off to alter that. All pre-units are the same.
“And while Edward Turner designed the sprung hub because he didn’t want a plunger rear end, it’s an absolute disaster of design! When you’ve stripped the thing down to restore it, it’s so difficult to get all the springs back in place when you try to reassemble it.”
Keith then adds the overriding caveat: “Other than that they are all pretty basic to work on. I do my own engine work, though I get my cranks rebuilt by Thurston Engineering in Ongar (thurstonengineering.co.uk). I’ve tried re-sleeving old carbs, but you are better off buying new. I still use magnetos – they’re all rebuilt and are still six-volt. I use gel batteries and it’s a solid-state regulator inside the old regulator box.
“I can build an engine in an afternoon, but then I’ve been doing them a while. I’m lucky to have a good friend in Tony Reynolds who does the gearbox rebuilds. He’s 83, but is a great help in the workshop. Somebody asked me to do an Ariel, but I had to turn the chap down because I know nothing about them. I think it’s
‘APART FROM THE SPRUNG HUB, PRE-UNIT TRIUMPHS ARE ALL PRETTY BASIC TO WORK ON’
best to stick to one make – you get to know all their foibles!”
Those “foibles” include the 1954 bikes having differentlyshaped silencers to the earlier 6Ts, as well as the shape of the nacelle and fork covers changing slightly for each model. Bolts should be integral with washers, but there were no washers on anything on these 6T Triumphs. “I tend to use washers to save the paint. Cliff does sell bolt kits, though.”
Keith still likes to get out on his Triumphs and makes sure his builds are in good working order by road-testing each one. “I find all these Thunderbirds ride differently. They all vibrate in a slightly different way, too. It depends on gearing – but even then, two identically-geared bikes perform in different ways.”
Once he has completed the three remaining Thunderbirds, Keith is looking forward to other projects like the Rickman Metisse he discovered that had been stored in a barn for 30 years. It’s got the full CRMC certificate from 1986 and we’re covering the restoration as part of our Barn Find of the Year competition.
Keith’s also promised us first dibs on another exciting project – a motorcycle which, at first, appeared to be yet another 6T Thunderbird, but checking the frame number revealed it to be a genuine 1957 Triumph T100RR dirt-track racing frame.
According to Lindsey Brooke’s excellent book Triumph Motorcycles in America, Triumph offered a T100R in 1955 and then a T100RR from 1957 until 1958. And it’s obvious Keith can’t wait to get started on this project. “It’s currently got a 650 engine, but I’m going take that out and fit a 6T iron head... then it’ll need a new frame. But I’ve got a 5T 500cc twin engine which I can fit a twin-carb head to and put in to the dirt track frame. The 5T forks are same as the 6T’s, so I’m OK with these but I need a different tank and wheels. The ’57 models had cylindrical oil tanks...
“It’s turned out to be an even better buy than I first thought. We’ll see how well that comes up, but I’ve already started buying a few bits for it. I’ve got a couple of Bonnies to do, too.”
Sounds like the production line in Keith’s workshop will be rolling for a good while yet...
‘KEITH MAKES SURE HIS BUILDS ARE IN GOOD WORKING ORDER BY ROAD-TESTING EACH ONE’