The Bondini Special
Craig Bondini’s ‘Special-mente da Bondini’ was a highlight of the recent Festival of Italian motorcycles in Carlton, Melbourne.
This machine built, largely from scratch, by Melbourne racer Craig Bondini has, at its core, the head and crankcase of a 1956 Moto Guzzi 250cc ‘Airone’, housed in a Bondini fabricated chassis. The frame is based on drawings Bondini obtained from Arthur Wheeler, a Guzzi Engineer and works/privateer rider. Bondini had met Wheeler at the (Phillip) Island Classic in the mid 1990s. The frame design represents cutting edge technology of the early 1960s and was the culmination of Moto Guzzi’s highly successful race program and that of their most famous privateer.
Arthur Wheeler and Moto Guzzi
Arthur Wheeler was born in 1916 in Epsom, Surrey. He left school at 15 and started racing around 1935. In 1937 he opened a motorcycle shop and being an innovative and practical engineer, was chosen to work with Barnes Wallis on the bouncing bomb project during the war. From 1949, he raced Velocettes, Triumphs, Nortons and B.S.A.s with success in international events, and from 1952 he campaigned a 250cc Moto Guzzi ‘Gambalunghino’ (“little long legs”). This machine had started life as a 1948 ‘Albatross’ which Wheeler acquired at the end of 1951. He had it reconditioned at the Moto Guzzi factory ready for the 1952 season and raced it through to the 1955 season with great success. The ‘Gambalunghino’, shown here, is not quite as
Wheeler campaigned it. The rear sub frame, swing arm and large aluminium plates to the rear and below the engine are from a later era. The engine, front end and remaining frame are as used by Wheeler in the years 1952 – 1955. The front frame section of his ‘Gambalunghino’ would not have been highly resistant to twisting. The tubes connecting to the steering head are quite thin and are in a single plane. Only below the petrol tank do the down tubes separate to connect to both sides of the motor. On this machine, (albeit with original rear end), he gained 4th place at the Isle of Man in 1953 and 1955 and a 4th place in the 1954 World Championship. In 1954 he won the Italian 250cc GP at Monza. In recognition of these and other results, he received a factory 350cc machine for the 1956 and 1957 seasons. The works machines by this time (1956) had a large diameter backbone that doubled as an oil tank. The backbone tube had smaller diameter tubes running from near the steering head that picked up connection lugs for the engine at both sides near the crankcase cylinder mouth. These tubes extended horizontally to the rear of the gearbox and from here a double triangulated frame picked up the top shock mounts, the rear end of the backbone and the swing arm pivot. This design would have given the machines much greater torsional rigidity and influenced the design of Wheeler’s special frames.
Dominance of the Guzzi Singles
Moto Guzzi had dominated the Junior (350cc) class of World Championship Grand Prix, winning the title for five consecutive years, 1953 to 1957. The 250cc, 350cc and 500cc single cylinder Moto Guzzi racers had a direct pedigree stemming from the 1920 prototype G.P. (Guzzi and Parodi) and the 1921 – 1924 ‘Normale’ 500cc production models. This 56year pedigree continued through many production models, including the ‘Airones’, 1939 – 1957, to the ‘Falcones’ of 1950 – 1967 and the ‘Nuovo Falcones’ of 1970 – 1976. The features that these machines shared was a horizontal, single cylinder engine with external flywheel, gear primary drive, unit construction for engine and gearbox and vertically stacked gearbox shafts. That Carlo Guzzi hit the nail on the head with this design is demonstrated by the machines’ racing success and longevity. If further proof were needed, then the adoption by Norton of all these features for their model F Manx of 1955 provides it. It should be noted that this engine configuration is the best option for mass centralization about the roll axis, and together with their light weight endowed the Guzzis with extreme agility. This configuration exposes the head to cooling air with less masking from the frame tubes. The external flywheel allows the use of a smaller crank and crankcase, which are inherently less susceptible to flex. The racing program, driven by engineer Giulio Carcano, refined these machines and relentlessly pared excess weight. The 1957 ‘Bialbero’ 350cc racer was a featherweight at 216 pounds, (98 kg) with a magnesium “dust bin” fairing fitted.
Wheeler’s Moto Guzzi Hiatus
Moto Guzzi withdrew from full support of a team in 1957 and Wheeler campaigned a 125cc and 250cc Mondial for the 1958 season. His friend and long time Guzzi privateer colleague of 40 years, John Kidson, explained Wheeler’s 1958 season: ‘He had a lot of frustration with a 250 Mondial in 1958 which was a very quick bike and he led many races against the aces of the time but nearly always blew the engine. It suffered from many big end failures and he sold the bike to Stan Hailwood, who took it with Arthur to the factory and placed a wad on the race shop counter, whereupon they fixed it and Mike proceeded to win almost everything on this bike in 1959/60, Mondial discovered the reason for the engine failure was that the rev counter was reading 1000 rpm low, so Arthur had been over revving drastically.’ Wheeler could only claim a 5th at the Dutch TT, for 16th overall in the 250cc title of 1958. The 125cc Mondial gave Wheeler a 9th in the Isle of Man and 6th in Ireland for 13th in the 1958 championship.
Arthur Wheeler’s special Moto Guzzi
Wheeler commissioned the Reynolds Tube company to build a frame to be campaigned by himself in the Grand Prix seasons commencing in 1959. He housed 250 and 350 Guzzi engines in these frames and continued racing through to the 1962 season, in which he placed 1st at the last round in Argentina,
giving him 3rd in the lightweight (250cc) World championship. Another notable highlight of Wheeler’s career on the Reynolds-framed machine was his 4th place in the 1962 Isle of Man lightweight race. Only the fourcylinder factory Hondas of Minter, Redman and Phillis were ahead of him. Wheeler’s frame was built by the legendary Ken Sprayson of the Reynolds Tube company of 531 grade tube. There is some slight misinformation about the design of this frame in previous publications. John Kidson again takes up the story: ‘I have been talking to Ken Sprayson (who did many jobs for me at the TT & Manx) and the correct story on the frame is as follows: Arthur approached Reynolds to make a new frame in the late ‘fifties and they agreed to do it. They based the new frame loosely on the standard Guzzi frame of the time with improvements agreed between Ken, Alex Frick and Arthur. It was drawn by Alex Frick, and Ken actually built it so it was a joint design by Ken and Alex with input from Arthur.’ (Alex Frick was the Reynolds Motor Cycle department Design Draughtsman). The frame’s main similarity to the 1956 Guzzi 350 and 500 racers is in the use of a large diameter top tube to contain the oil. This tube slopes at a greater angle (18 degrees from horizontal) than that of the factory racers. The steering head is at 25 degrees to vertical. Instead of the numerous smaller diameter tubes to pick up the top of engine, rear suspension swing arm and shock mounts, the Wheeler frame has two triangular 10 gauge (3.25mm) cleats welded each side, at the rear end of the 3” backbone tube. There is an upper bolted connection to the backbone shared by the rear subframe upper struts and by the large 1/4” thick aluminium ‘L’ shape engine plates. A lower bolted connection is shared by the lower rear subframe struts and the aluminium engine plates. The swing arm is pivoted from the engine plates which have 3 bolts for the engine. The front engine bolt also connects to the frame front down tubes.
Bondini’s special: the chassis
Bondini’s copy of the frame drawing shows a 3 inch outside diameter tube of 16 gauge wall thickness as the top member. The front down tubes are 1-1/4” o.d. x 16 g, the rear subframe tubes are 7/8” o.d x 17 g. Unless you have unlimited funds, most people would be daunted by the reality of obtaining the small quantities of 531 or equivalent tube in three different sizes, for a one-off project. Bondini was undaunted; he knew a certain Chrysler Valiant model had a thin wall, 3” o.d. chrome-moly tail shaft. Of course any wreckers could supply this, at a fraction of the steel merchant’s price!
Bondini’s frame took shape from 2004. It is inspired by, rather than a replica of the Wheeler frame. Bondini would never copy anything if he thought an improvement could be made. The main differences between his frame and the Wheeler frame are the rectangular section (rear) swing arm, the extension to the oil ‚
tank, the design of the leading link forks and the rear sub-frame extension. The last variation is for the practical needs of attaching a mudguard and registration plate holder. Rectangular tube was used for the swing arm, possibly for increased rigidity or due to availability and ease of fabrication. The Wheeler swing arm uses round section. The Wheeler machine had triangular cleats at the bottom rear of its 3” backbone tube. Bondini boxed these cleats in and cut back the tube so the resulting triangular box formed a continuation of the tubular oil tank. The Wheeler machine has one fork yoke below the bottom steering bearing; it is similar to a bicycle in that there is no top triple clamp. The springs and damping units are inside the fork stanchion tubes. Both of these features were common Moto Guzzi practice of the early 1950s. Referring to the earlier forks Ken Sprayson recalls that ‘Arthur Wheeler found no problems with the Guzzi forks and therefore retained them.’ In about 1955 Moto Guzzi changed the design by using Girling spring/damper units mounted to the front of the fork stanchions and the bottoms were mounted to the leading links, very close to the axle.
Bondini opted for the latter Guzzi design, to take advantage of modern damping technology available in the off-the-shelf shock units that are readily available. His design also follows the Guzzi practice with a very strong 4 bolt axle clamp each side; the axle is 25mm diameter for great rigidity and the front brake backing plate is anchored to the stanchion. The brake link is parallel to the suspension leading link so there is no front end lift under braking. The front wheel hub of Bondini’s machine is from a Matchless G50, the brake backing plate is Norton Manx. These are items that were at hand, and were just the starting point for Bondini. The operating arm is designed so the cable alignment does not vary at the adjustment screw. The design also ensures that there is no ‘in action’ bending at the nipple. The operating arm for the back brake, is of similar design, the back hub and backing plate are from a Parilla.
The most interesting aspect of the front brake, and testimony to Bondini’s refusal to follow the pack, is hidden from view. Although appearing to be of conventional single leading shoe operation, this brake follows the principles of the duo-servo brake design. The principle of this is that the shoes are linked at the opposite side to the operating cam, and not anchored here to the backing plate. The first shoe, in the direction of wheel rotation, is termed the primary shoe, and is actuated by the brake cam. In pressing against the drum, it is rotated slightly due to the frictional forces and transmits the force of the cam and addi- tional frictional forces to the secondary shoe via the link pin. The secondary shoe is held at its other end by an anchor pin attached to the backing plate.
This design gives the brake larger self-energizing forces than that of a single leading shoe brake. Text books claim that the duo-servo brake will work equally well in forward or reverse. This is only the case where the actuation is at both the head of primary shoe and at the tail of secondary shoe and the shoes are of equal length. Where the secondary shoe is anchored, the bi-directional advantage is lost, not a great consideration in motorcycle use. Bondini may well have been inspired by an interesting Guzzi innovation on Arthur Wheeler’s machine; the front brake is not operated in conventional fashion. The cable enters the backing plate; no operating lever is visible. Like Bondini’s brake the interesting features are hidden. Inside it has a pair of levers that act like external circlip pliers. These levers are within the brake shoe inner radius and laterally central to the shoes. The lower end of the levers are pulled together by the cable inner and outer, at about half drum radius below the axle. They pivot at two points, at about half drum radius, above the axle, the top ends push apart the brake shoes. This design gives very good mechanical advantage and has less sliding action at the brake shoe ends than a rotating cam gives. Furthermore, the force imparted to the leading and trailing shoes by the cable inner and outer, is equalized automatically.
Bondini’s special: Refinements
Bondini’s machine has oil in the frame top tube as per the Wheeler Guzzi. To prevent oil draining from this tank into the crankcase there is a valve fitted in the oil feed pipe. Oil draining is a common problem for dry sump motors, the oil pump gear clearances allow slight leakage, not a problem for daily drivers, but a nuisance when the machine is only used for occasional outings. Bondini opted for a valve but by
carefully locating the valve, the clutch cannot be disengaged unless the valve is turned on. Bondini’s machine has a petrol tank and half fairing fabricated by Bernie Willet. The fairing incorporates a mudguard that echoes the style of the Moto Guzzi ‘Bird Beak’ fairings which were introduced on the 1953 racers as a result of wind tunnel testing. The mirrors are a machinist’s delight. The stems and mirror cases are milled from plate aluminium. The stalks have spherical connections, top and bottom. Carrier plates clamp these balls and allow adjustment friction to be varied. The upper side of the stems have a shallow groove that carries a blinker wire; the blinker is a series of LEDs in the shape of an arrow set into the front face of the mirror case – priceless!
Bondini’s special: the engine
The engine is Bondini’s handiwork through and through. The crank is made up of two drive side crank halves from a 1960s 250 Benelli. The bore is 80mm, increased from the original 70mm, to give 321.8cc, while the stroke is unchanged at 64mm. The crank pin and connecting rod are from an XT 500cc Yamaha and the ratio of connecting rod length to stroke is 2:1. The drive side outer case was cast from a Bondini pattern to incorporate a crank outrigger bearing to improve reliability. A 50% balance factor was tried first but vibration proved to be a problem. It was calculated that a 26% factor would give better results for an engine of horizontal configuration, and this proved to be correct in practice. Bondini machined straight cut primary gears to eliminate end thrust problems at the crank and clutch shaft. The primary gear ratio was reduced so that the gearbox runs at a slightly higher speed. This reduces gear tooth and gear box shaft bearing loadings. A 30mm Amal concentric carburettor is used. The valve springs are coil rather than the standard hair pin springs and the cam followers have oil feeds to them which was not an original feature. The 40mm inlet and 30.5mm exhaust valves are from a Ducati. The electrical system is powered by a Lucas generator, rewound for 12 volt 10 amp maximum output and is controlled by a Ducati regulator.
Bondini and the Wheeler connection
Craig Bondini was born in 1935 and grew up in Carnegie, at the time, an outer suburb of Melbourne. His Grandfather had migrated from Italy in the late 1800s and his mother was sister of sidecar racer Jack Craig. He took up racing in 1953 on a Plunger frame B.S.A. Gold Star and continued until 1959 when his first son Jay was born. Fifteen years and six children later he returned to riding and, after another ten years, in 1984, to racing. The machine this time was a 1977 Benelli 250cc; a single horizontal cylinder four stroke. When Bondini met Wheeler in the mid 1990s, Wheeler was already a fixture in the Australian and New Zealand classic racing scene. He had raced here since the late 1980s and at the Phillip Island Classic since 1991. Ken Lucas of Wangaratta had provided machinery for Wheeler to race at Phillip Island and other venues. In 2001 he also catered for John Kidson who accompanied Wheeler on a three month down under racing holiday. Wheeler kept a van and a 250 Ducati at the Brisbane house of Ken Percy for use in Australia. It was in 2001, at the age of 84 that Wheeler had his last rides in Australia. Competing at Eastern Creek on his 250 Ducati, Wheeler’s hand was struck by another competitor’s handlebar. The swelling necessitated cutting the glove away, but Wheeler was still keen enough to continue on with the racing. This accident was rumoured to have eventually been fatal but John Kidson has this account of events: ‘...Arthur was perfectly well and racing again after we returned to the UK and it is not believed that the cause of his death was caused by that or gravel rash. He usually went each day for a brisk walk along the seafront at Goring by Sea where he lived, and one day around the middle of May tripped on a raised flagstone, causing him to fall heavily and damage his shoulder. He became ill very quickly and was in intensive care in Worthing Hospital and was put on a life support system, but died on 9th June (2001). The cause was septicemia.’
Bondini’s special: Final touches
In about 2013 Bondini had the special to the stage of allowing club permit registration and was able to take it to classic race meetings and on short rides. Failing health slowed the project and the special had only gone about 200km when he sold it to his friend of 20 years, Keith Boyle in mid 2015. Sadly Craig’s health deteriorated further and he died in October 2015. Keith Boyle, a long time Guzzi Le Mans owner extols this machine’s excellent handling and ‘more than adequate’ power. He plans on smoothing a few rough edges, a coat of Moto Guzzi green for the fairing and renewed painting for the frame are a priority. He also wishes to improve the ignition. Currently it is what Bondini adapted from a Toyota Camry which has advance problems. Boyle is considering installing a Tri Spark system and some more instruments such as a tachometer and amp gauge in the near future. Bondini’s machine is a worthy tribute to the glory days of Moto Guzzi’s racing program, the engineers Carlo Guzzi and Guilio Carcano who drove it and to the efforts of Wheeler and his compatriots at the Reynolds company who against the odds, gave the four stroke single a final lease on life at the highest levels of competition.
I wish to acknowledge help from the Bondini family, Keith Boyle, Barry Jones, John Kidson, Teo Lamers, Ken Lucas and Ken Sprayson in the preparation of this article.