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Bonneville land speed record attempt - part three

By Mario

We’ve been covering the attempt by Fergus Maynes to set a new world land speed record for the 650 production pushrod class at Bonneville next year. In this third instalment, we cover more of the background to Ferg’s attempt and update the Triumph Bonneville’s rebuild.

When we recently popped round to see Ferg’s 1970 Triumph T120R Bonneville, the ‘bike was just a collection of components. The frame and other cycle parts had come back from the stove enameler’s, with some less showy items treated to a coat or two of rattle-can black. The forks were about to go away for a specialist rebuild (apparently specialist tools are needed, so it’s as cost effective and less work to get it done).

Close up of forks on their way for a rebuild

Front forks are off to a specialist for their rebuild

Once those were completed, the next milestone would be assembling the rolling chassis. The engine, meanwhile, was in two different places: the top half out for combustion chamber work and an entirely new valve train; the bottom half away with Bob the Balancer, along with some trick Carrillo rods to fit to a new billet crank.

A work bench with enameled parts

Stove enameled and painted parts for reassembly

A heavy secret

Weight might hinder acceleration but it’s almost entirely aerodynamic drag that reduces your top speed. At Bonneville another factor comes into play: the salt. Racers are always fighting for traction. Wheelspin, or slippage, means you can’t convert all your power into forward thrust, and it can cause frightening instability.

The answer is ballast. Weight towards the rear aids both traction and stability. The problem in a production class, like the one Ferg is set to race in, is the demand for originality, at least in appearance. So strapping on lead weights is a no-no.

You can, however, add weight where it’s not visible: what the eye doesn’t see, the scrutineer doesn’t fail. For a production ‘bike the accepted solution is to fill frame parts with lead shot, biased towards the rear. Carefully drilled access holes, and a clever arrangement in the main frame tube, will allow Ferg’s bike to carry the best part of 20kg of the stuff. But only that first run on the salt will reveal whether it’s enough and located in the right place.

Bike's frame and swing arm

Blasted and stove enameled frame and swing arm, soon to contain 20kg of lead shot

In the meantime, Ferg is working out just how much disguise the ballast addition will need to remain undetectable to the naked eye. Apparently, if you do get a record the authorities impound the ‘bike, take the head off then measure up the engine dimensions. And–in production class–refer tightly to the original workshop manual, which competitors must supply themselves. A small discrepancy from what’s shown in the book could mean disqualification.

Engine split

Although Ferg’s garage is full of carefully organised and labelled parts, noticeably absent on this early summer’s evening was anything to do with the unit-construction 650cc twin. That’s because the cases are away being machined for new ball-race bearings and a later model stator, before accommodating a brand new billet steel crank. The latter, due for finishing in a week, took three months to make. Identical to the original, it would be perfectly balanced and much stronger. No knife-edging was required because the Triumph is a dry-sump design. Clamping the crank will be American-made Carrillo rods, a familiar name in tuning old British ‘bikes. Apparently no longer obtainable, Ferg sourced his set with a ‘phone call, off a shelf in a mate’s shop in England. With everything, including pistons, pins etc. weighed and balanced by Bob Mead in Auckland, the bottom end will then be complete.

Labelled plastic sandwich bags filled with parts

All bagged up and labeled. That's gotta help

Up top, meanwhile, Dean Landon of Landon Motorsports has been weaving his magic over the engine’s breathing apparatus. In the last instalment, we mentioned the $1,000-worth of valve-train components that had just arrived from America. Sourced from Kibblewhite, the kit includes larger valves with narrower stems, narrower valve guides and specially-designed ‘beehive’-shape valve springs designed to reduce ‘float’ at high revs. Kibblewhite are a big name in valve-trains for motorcycle sports in the USA, especially drag racing. The big valves, pumping at high speed, should help with all-important flow in Bonneville’s thin air. But getting the most out of them requires serious work on combustion chamber design, different cams and even changes to the valve angles. And that’s what Dean Landon has been up to. “When he talks to me about what he’s doing, he descends into Mechanical-Engineering talk,” says Ferg. “Which means I don’t understand a thing. What I have learned is that basically, if you want your Triumph to go fast, you throw away the top end and start again.”

Once Dean has completed his work, including the installation of a full-race inlet cam and a half-race ‘Thruxton’ exhaust cam, the engine will be given over to Graham Cole for final, careful assembly. The objective is a top speed tested here in New Zealand of 130mph. When Ferg got hold of it, it managed 106mph, which is almost exactly the Bonneville record. But that’s on salt, at over 4,000ft. “The rule of thumb is you’re down about 20% on power at that altitude,” advises Ferg. “I talked to the tuner of the bike that set the record at 106mph, and he said it had about US$50,000 or work done on it. So we're breaking new ground here.”

Falling into salt addiction

Ferg first went to Bonneville in 2014 with Walter Rands-Trevor, the motorcycle insurance coordinator at Protecta Insurance and keen racer. His WRT Racing team first went there in 2012.

“He was going, I followed his progress, and he missed the record by half a mile per hour,” says Ferg. “Walter was competing in the modified production class on a tuned and prepped ZX-10R, where the record is 208mph with a full fairing. But if you take it off, you can compete in the naked class, where the record is 184. He got 183.5, and two black eyes from the buffeting.”

When Walter returned in 2014, Ferg asked if he could help, an offer that was a little late but which was gratefully accepted. “I thought if I got some holiday I’d head over independently. So the team was already over there, I arrived, only to find it was cancelled.” Ferg refers to the infamous 2014-2015 period when atrocious track conditions led to complete cancellations of Speed Week. “We ended up doing a ten day road trip around the south-west instead!” A challenge in 2015 was unaffordable, so the next opportunity was in 2016. While a handful of people accompanied Walter in 2014, nobody could make it in 2016. Ferg volunteered at the last minute go to the salt. “We spent 3-4 days setting up with the fairing on. The idea was to get it as fast as it could go then take the fairing off and go for it.” Walter ran a confidence-inspiring 197mph with the faring on.

It was at this point that Ferg’s time on the salt took an exciting turn, “With the bike running like clockwork, Walter said I could have a go. It meant I had to go through a course, getting licences for 110mph, 130, 170 and then a 200 licence. After an induction, you then have to go over a timed mile, at between 90 and 110mph”. That was for his 110 licence. “So I did 108, just using the speedo: easy. Another three licence runs enabled me to go for the 200 licence. Then, at 7pm, when everyone had cleared off for the day and with the churned up salt slippery as all hell, I was on. I had about 45 mins, enough for maybe three runs. The first was all a bit too much. The bike kept spinning up, and I kept shutting the throttle.” Ferg was given some hast and emphatic advice by the course stewards: deal with it, do not shut the throttle. “So, next run, I had my elbow over throttle, wound it on and never shut off. I got to 302km/h, with the fairing on. There’s no sense of speed as such, you just can’t fear what might happen and go for it.” Ferg managed three runs to get an official two-way timing of just over 300kmh. “That was a real sense of achievement for me, to break 300km/h and get my 200mph licence.”

For Walter, though, disappointment ruled. The next day, with the fairing off, he ran 183.5mph again while coping with a choking helmet strap and near ‘white outs’. Walter and his team have plans for how they’ll get that extra half-mile per hour and Ferg is looking forward to teaming up with WRT Racing on the salt in August 2018. “Really, Walter is the reason l’m doing this,” says Ferg. “It’s all because of him. He’s a top dude.”

Catch up on progress next time, when the rolling chassis should be together and beginning to look like a Bonneville again.

Bike parts on garage shelves

It's all here somewhere...