Early Carbon Fiber Bikes – Silverstone Armstrong Racers

In England, Race by Tim HuberLeave a Comment

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I loves me some carbon fiber. For roughly the last three decades, this precious material has been helping to shave off weight while simultaneously looking pretty trick in the process. The high tensile strength, low weight, temperature tolerance, and stiffness have made it a go to choice for many components of all types. Though it has technically been in use since the 1800’s, one of the earlier examples of a motorcycle that heavily used carbon fiber was this 1984 ex-works 350cc Armstrong racer. Like most performance in motorcycle development, carbon fiber was first utilized in racing before finding its way onto production machines, leading to dozens of “Carbon Edition” production models as well as a few elite machines with stock carbon bodywork.

Armstrong was a large British automotive conglomerate, though the motorcycle division was performing terribly (aside from military sales). Armstrong Automotive’s Chairman, Harry Hopper – who would go on to start the Hopper-Armstrong race team – was fortunately both optimistic and a passionate motorcycle enthusiast. He led the corporate charge to revive the failing moco, and just before the dawn of the 1980’s “Armstrong Clews Ltd ” (ACL) was formed out of the union of the successful Clews Competition Machines. Interestingly, Armstrong established their shop where Barton Motors – who I recently wrote about – was previously setup.

The plan was for the company to build road bikes but somehow along the way the decision was made to develop hardware in racing. A big part of this idea was to further the machine’s durability and potential to withstand prolonged abuse and use the race program as a valuable marketing opportunity to raise public awareness of the company, team, and their bikes. Barry Hart and Mike Eatough had been hired as co-lead engineers and were responsible for the general mechanical and structural development of the new quarter-liter Rotax motors.

In 1981, Mike Eatough-designed units became available to the public. They utilized a bronze-welded twin cradle chassis made of Reynolds 531 chromoly tubing, top shelf Marzorcchi telescopic forks, and trick rear suspension with a rising rate linkage – a design first conceived by Mike Mills who was a design engineer at BSA. The entire production run consisted of just 80 250cc CM35 units, only a quarter of which were bound for American shores under the Can-Am name.

That same year, Armstrong also built its first race machines in the form of 250cc bikes powered by Rotax twins. The quarter-liter racers were an instant hit, quickly proving themselves on the racetrack. Armstrong’s debut race bikes first made their mark at the ’81 TT in the Lightweight Class, piloted by the UK’s Steve Tonkin who had an average course speed of 98.59mph. The following year a Works support team would be put together by Ruth Randle who owned a handful of shops in Yorkshire. The team consisted of a trio of riders: Steve Tonkin, Clive Horton, and Australia’s Jeff Sayle, who would be racing aboard production-based Armstrong’s. That year Tonkin’s success at the “Vladimir Vodka” 250cc Title – a prestigious British race – would further put Armstrong on the map.

Another important happening in ’81 came in the form of Barry Hart tinkering with the idea of a tandem twin 350 with a disc valve engine in which both pistons rise and fall simultaneously. The project was labeled the CM36 and just a single pair of of them were built. These larger displacement tandem twins were burdened with a myriad of problems such as overheating and a faulty gearbox. Coincidentally around this very same time, the 350cc market was rapidly drying up and the plug was even pulled on the 350cc World Championship at the end of the ’82 season before other smaller leagues would follow suite over the next couple years.

The next year the Works team would sign a promising kid named Scot Niall Mackenzie as the team’s main rider, employing the youngster full time as a test rider and racer, helping with further development of the company’s racers. In 1983 Mackenzie and the rest of the team would be given Works machines with 250cc and 350cc engines wrapped in steel-alloy frames. Bikes known as the CMW35 & 36 (35=250, 36=350). The new chassis had different steering geometry as a result of it being fitted with a 16” front wheel. The frame also featured tubing that was narrower and lighter, and it had a box-section swing-arm. The next year’s frames would have something in common with Ducati and BMW’s newest ultra-elite homologated Superbike’s.

The switch to a carbon frame was a pretty big deal. The carbon fiber frame – which was made by Reynard – shaved 5lbs off of the frame and another 5lbs off the swing-arm. The new frame also eliminated its needing rocker-arms in the subframe or suspension, Interestingly both the subframe (the tail section and seat), and rear suspension each weighed 5lbs too. This is the origin of the CFR’s “5lb Special” moniker. The design team decided to go the distance and adorn the bike’s in full carbon bodywork with titanium fasteners throughout. More weight was shaved off from the machine’s wheels when Astralite was hired to produce special thin gauge spun rims that had an extra lip around the rim which would provide additional strength. Even more weight was trimmed when aluminum plasma coated discs were used with the previous bike’s trusty magnesium Brembo calipers.

Charlie Wood – an expert on all things suspenders from Armstrong Automotive’s suspension division – stepped in to design a new a single rear suspension unit that operated via extension instead of compression. This new system enabled the body to be held via a pair of machined brackets mounted on the underside of the engine. Said brackets also enabled the unit to be pivot while it was being pulled by the swing arm, resulting in rising rate suspension.

Barry Hart and Mike Eatough were hired to collaborate on producing the first carbon fiber bike to accommodate the 250cc and 350cc tandem twins prior to going on to have Hart design one for the 500cc triple. Unfortunately, Armstrong’s CF500 project was dead on arrival and making matters worse was the fact Hart jumped ship immediately following this, taking a different job in working with carbon development. All the weight was now on the shoulders of Mike Eatough, the man who was individually responsible for the company’s racing program. Though things must have felt a little dodgy at the time, the years that would follow would validate Eatough’s hard work.

In ’84, Mackenzie was able to achieve considerable success in the national 250cc and 350cc classes, winning the 350cc Promoters series and the iconic Superprestigo at Calafat, an event made up of many of the top 250GP riders on the planet. The Superprestigio continues until today and is one of the most fun, less-than-serious races to watch every year.) The “Silverstone Armstrong GP team” was born which was an effort spearheaded by the directors of the Silverstone-based British Racing Drivers Club (BRDC) who wanted to see British machines piloted by British pilots. Armstrong agreed to provide both bikes and support staff – including two full-time mechanics for each pilot – for the BRDC-backed, Silverstone-based team. The team also got addition support from the likes of Arai, Champion, Dunlop, EBC Brakes, Regina and Shell Oils. The BRDC’s Silverstone Armstrong GP team was optimistic for the ’85 season.

The race bikes in ’85 got the benefit of a handful of updates such as new powervalve cylinders which resulted in the Rotax engines now making 74hp at 12,500rpm. While the engine boasted solid performance, its reliability left a lot to be desired, destroying the team’s chances at good results on a number of occasions thanks to repeated engine seizures. The 250 fortunately possessed better reliability than its big-brother, allowing Mackenzie to win the British 250cc Championship, though he also managed to hold onto his his 350cc Promoter’s Title.

Mackenzie’s teammate – Donnie McLeod – was able to secure better results than the lesser-seasoned Mackenzie, scoring two sixth-place finishes at Germany and Holland as well as a seventh-place finish at Sweden, finishing the season overall in 14th. MacKenzie did even worse, though often qualified ahead of McLeod. McLeod has joined the team after a successful career racing in UK-based 250 competitions, winning the 1978 Scottish Championship title, the ’83 Startrack 250cc British Championship, and the ’84 250cc Gold Star British Championship.

The winter-development that followed the ’85 season would give birth to four new “MK2” carbon GP machines to be used in the upcoming ’86 season. In addition to new redesigned, wind-tunnel-developed bodywork, a new wider chassis was utilized to accommodate new larger exhausts. The composition of the carbon fiber being used has proven to be extremely reliable, with only minor repairs being needed over the years since the materials introduction (such as steering damper mounting and front fairing brackets). To squeeze more power out of the Rotax the higher-ups brought Austrian tuner, Michael Schaftleitner on board to head this endeavor. Schaftleitner was successful in producing a variant of the power-plant that ran smoothly and offered a wider power spread, he was ultimately unable to get past the engine’s big ends being prone to overheating.

Unfortunately Mackenzie would suffer a badly broken leg resulting from crashing his CF350cc machine at Cadwell Park in April of ’86, meaning the promising young pilot would be out for the first three rounds of the ’86 season. Mckenzie’s replacement – Ian Newton – didn’t have a particularly successful run aboard the carbon racer. Fortunately Macleod faired much better – at least when he didn’t go home with a DNF – routinely finishing in the top-ten. The two-time British 250 Champion would go on to score a second-place finish, shortly followed by a fourth-place finish, landing him in 10th overall that season.

The Silverstone Armstrong Team would go on to compete in future seasons without ever experiencing much success. MCN did one of its “What Ever Happened To?” articles on Donnie McLeod that’s worth a quick read. Nonetheless the machines that the team raced hold an important place in the history of motorcycle technology and development. They are also very rare, especially in the States. Two Armstrong tandem twin racer examples are currently for sale, one of which is a 250, and the other is the 40-times rarer 350 CM36.

The first example is an authentic 1984 ex-works Armstrong 350cc and it is just one of the two examples that were made in the 350cc displacement. Of the two 350 examples, this is the only one that has magnesium engine cases. This machine is one of the first carbon fiber motorcycles, featuring an MK1 frame, of which only five were ever produced. The current owner has been in possession of this example since November of ’89 and it was last ridden by Mackenzie at Cadwell Park in March of ’86. Since then, it has been restored to the condition it was in in Spring of ’86, though the Niall Mackenzie livery is original (albeit it was touched up and had its period-correct decals replaced).

The focus of the restoration of this machine was to retain as much of the original features as possible. The original adjustable offset yokes, fully adjustable Forcelli FI forks, original temperature gauge and rev counter, and the bike’s original fasteners were all used. The rear shock is a unique under slung Ohlins unit that uses internals & operating in “Pull” configuration, equipped with a titanium spring & fasteners. The extensive and meticulous refurbishment this racer underwent was done by Charlie Woods who also refurbished the front forks, had the wheels crack tested before fitting new bearings, all brake calipers and master cylinders have been reconditioned, (with all new brake lines), the original exhausts have been reclaimed & refitted, and the carbon chassis underwent a detailed examination, ensuring there are no signs of delamination.

The engine in the bike is a reclaimed works engine consisting of magnesium crankcases, clutch, and disc-valve covers. The engine internals have been rebuilt using new components wherever required, resulting in rebuilt cranks, new gears, and reconditioned cylinders. The Rotax power-plant also features a Works cylinder-head with interchangeable combustion chamber inserts. Though the seller mentions a good source for parts, the sale of this bike also includes a pair of Marvic 17″ wheels, various sprockets, carb jets, the original damaged fairing, an extra seat-unit, and one rear-suspension spring.

The sale also includes Rotax conversion parts which allow for a Rotax 256 engine to be fitted, along with a pair of Rotax 250 suspension hangers. This example was campaigned in the 1980s by both Niall Mackenzie and Donnie McLeod. It was rebuilt as a spare 250cc machine for both Mackenzie and McLeod to use for domestic British championships. As the seller points out: “This is a rare opportunity to own a works 350cc Carbon Fiber Armstrong.

The next example is a non-original Armstrong Ex Works 250, though it is powered by an early Rotax tandem twin. The seller built this bike in 2005, basing the design of the frame on a number 007 Ex Works (non-carbon) frame. It was raced in the ICGP, FRC and CRMC between 2005 and 2010, and according to the seller it was “totally reliable”. I assume the bodywork is a recreation, though it looks pretty solid. Every inch of this example looks to be in remarkably clean condition, the engine, wheels, frame, everything. These examples are obviously much less rare than the factory carbon Armstrong racers, however the prices reflect this.

This 250 Ex Works-based example does happen to be fitted with some awesome period-correct components. The bike has new Marzocchi forks fitted with CBR cartridges, new Gaz adjustable rear-shock, Lectron carbs, PVL digital Ignition, Brembo hardware throughout, all sitting on Dymag wheels wrapped in new Avons. The current owner stripped and rebuilt the engine, hoping to run it again this year, but his old-age is preventing this. Though these parts aren’t included in the sale of this 250, for an additional price the seller has a spare race-ready engine and a huge amount of spares available.

Examples of these racers do occasionally pop up, and Bonhams has sold a few in recent years. Armstrong Automotive’s Chairman Harry Hopper would start his own “Hopper-Armstrong” race-team towards the end of the ’80’s. A Formula 2 Sidecar racer was sold at a recent Bonhams auctions earlier this month for only $8K. A beautiful orange 1979 Ex-Steve Tonkin IOM-TT Formula 2 Four-Stroke 598cc Honda sold at a UK Bonhams auction in 2012 for just over $10K. Another company that was developing the Rotax type 256 twin tandem two-stroke was Waddon. Bonhams also sold a pristine black 1983 Waddon Rotax 250 racer example in 2010 for only $10K. Mackenzie himself also wrote an article for VisorDown about his experience on these machines that’s also a really cool read.

You can find this 1984 Ex Works 350cc Armstrong Carbon Fiber Racer here on Racebikemart in the UK with its seller currently running closed bids which will be accepted if they are submitted by September 30th.

You can find the rebuilt 1980 Ex Works Armstrong 250 Grand Prix Racer for sale here on Racebikemart in the UK with a price of $12,775 (or £9,500).

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