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Driving report John Player Norton (1973)

Strong performance, exceptional chassis

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Actually an anachronism on wheels, the 1973 John Player Norton with its groundbreaking monocoque chassis became a legend. She defeated stronger opponents and anticipated many design features of current GP racers.

The basic idea of ​​John Player Norton

No question about the John Player NOTorton (JPN) is much more than just a side note in the history of England’s most traditional racing brand. Not only because 40 years ago Norton was able to defy the more powerful Japanese two-stroke engines for a brief moment with this unusual machine. Instead, it also put a bike on its wheels whose sophisticated and avant-garde monocoque chassis overshadowed everything that the motorcycle world had seen up to then. The project also caused a stir because it was the first in motorcycle racing to be fully sponsored by a cigarette sponsor.

Even by today‘s standards, the Norton monocoque would be an outstanding design. Back then, clearly influenced by Britain’s Formula 1 domination in the early 1970s with manufacturers such as Lotus, Tyrell, Cooper, Brabham, BRM and Lola, it was actually an anachronism on two wheels. Because this archaic, air-cooled bumper twin, whose design dates back to the 1940s, was still working in the groundbreaking chassis. Only three copies of the monocoque JPN were built (plus a fourth prototype chassis), and these only for the 1973 season. However, the unexpected TT victory with Peter Williams at the Formula 750 race on the Isle of Man made them one Legend that is still considered the benchmark for modern racing motorcycles today.

The story of John Player Norton began in 1971 and is inextricably linked with Peter Williams. In addition to his job as a development engineer at Norton, he was also a successful Grand Prix driver. Norton boss Dennis Poore commissioned Williams to build a prototype with the 750 Commando engine. Poore was convinced that the venerable ohv-Langhuber could tear something in the new Formula 750 class, especially since the company relationship between BSA / Triumph had already won there. The Thruxton-based racing department of Norton-Villiers took over the development of the racing machine that was to be driven by the newly crowned 250cc world champion Phil Read alongside Williams. Former Suzuki works driver Frank Perris has also been won over as team manager.

The decisive help in the birth of the John Player Norton team, however, was provided by Dennis Poore, who, as a former racing car driver, managed to use his contacts in the racing scene and to make this project attractive to Imperial Tobacco. The tobacco manufacturer made cigarette sponsorship socially acceptable in racing in 1968 with the “Gold Leaf” brand on Lotus Formula 1 racing cars. And with the John Player brand, it should now also become a pioneer for motorcycles as a sponsor of the Norton racing team.

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Out of the ordinary – 19 series John Player Norton with monocoque chassis.

Dressed in the blue and white John Player livery at the time, the 750 cc machines from the 1972 season looked more compact than many 500 cc single-cylinder models. A result of countless wind tunnel tests by Peter Williams, who put a very low-profile, compact racing machine on its wheels with the one-piece tank seat cover. With it, Phil Read achieved a top of just over 155 miles (around 250 km / h) in training for the 200-mile race in Daytona. He finished fourth in the race.

A promising start to the 1972 season, which, however, turned out to be mixed due to recurring problems with power transmission. As a result, Williams had to retire in the Formula 750 TT race – in second place. Thanks to intensive further development, however, some victories were achieved in the second half of the season, especially in shorter races that put less strain on the transmission. So the first year of John Player-Norton turned out to be a halfway successful one.

Peter Williams knew exactly how the 1973 results could be improved. With a monocoque frame that combined the good approaches of the 1972 model – small frontal area, aerodynamic fairing – with a lower center of gravity for easy handling and a reduced moment of inertia thanks to the centralization of the masses.

All factors that are part of the basic principle of a GP racing machine today. Forty years ago, however, Williams and the JPN team were the first to take this route with a racing bike. “After the admittedly compromised 1972 bike, we had the chance to do everything right in 1973,” recalls Peter Williams. “We built a really small motorcycle with a chassis that gathered the rider around the engine, integrated tanks for oil and gasoline, and had excellent rigidity. And that although we had to adopt the Isolastic engine suspension known from the series motorcycles for tactical reasons. "

The monocoque chassis with airbox

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The massive frame segments encased the engine.

A special feature of the Norton were the two deeply drawn, closed frame profiles around the engine, which not only enabled a torsion-resistant connection between the steering head and the swing arm, but also served to guide the air. Behind the mailbox slot in the nose of the fairing, a horizontal metal plate divided the airflow. Tea lower one cooled the engine, the upper one led via the valve cover to the carburetors and the oil cooler under the seat, in order to finally escape through the rear slits of the seat hump.

The one-piece tank seat cover together with the chassis formed something like a primitive ram air box. Probably one reason why the rather underpowered machine – Williams puts the power on the rear wheel at around 67 hp at 7200 tours – reached such an astonishing top speed. Compared to the previous year’s model, Williams positioned the engine in the monocoque for better traction 25 millimeters further back, brake discs with a reduced diameter and special cast magnesium rims also reduced the unsprung mass.

With its incredibly compact structure, the monocoque JPN achieved a very favorable Cd value of 0.39. “The key to this was that we could calm the airflow over the pilot’s back, ”Williams said. “I succeeded in doing this with a relatively expansive fairing that completely covered both the handlebars and the shoulders of the long rider. The design of the seat and rear paneling were just as important. I was very proud of the Cw value – and, to be honest, I still am! "

Compared to the high effort involved in the countless wind tunnel tests, the modifications to the rubber-mounted engine were kept within limits. A higher compression, aluminum connecting rods on a one-piece crankshaft, modified valve timing, steel bumpers and 33 Amal carburettors were enough for 76 hp on the crankshaft. The decisive factor, however, were the improvements to the power transmission of the 1973 engine with an additional bearing in the primary drive. In addition, by changing the ratio, the speed of the gearbox was increased by 25 percent and a smaller clutch was installed, which made it possible to reduce the torque peaks on the tooth flanks of the gear wheels, which were additionally reinforced.

Other components and drive

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The massive frame segments encased the engine and required a sophisticated air duct for cooling.

Ultimately, the shock absorber of the primary drive moved to the crankshaft, which enabled a more compact and stiffer housing. These improvements brought a resounding success, transmission problems were a thing of the past.
After the first tests in Thruxton at the end of 1972, Williams suggested a few changes that were also incorporated into the three racing motorcycles. Their monocoque was now made of lighter and thinner stainless steel and weighed 16.8 kilograms. What at first seems like a lot is put into perspective when you consider that it contains the tanks for 24 liters of fuel and, in the rear frame part, 3.8 liters of oil for the dry sump engine. As a result, Williams managed to bunker just as much fuel as with the nine kilogram heavier previous year’s model, but significantly lower the center of gravity of the dry monocoque racer, which weighs 159 kilograms.

"This means that you need significantly less force to change direction, and it also reduces instability in fast, undulating corners, "says Williams." The bike was easy to throw back and forth, and the nodding was also kept within tight limits. With the monocoque JPN, I was able to take every faster curve from the apex in a controlled drift over both wheels. A really wonderful little machine. ”The best proof: The British run of the 750 series at Silverstone in August 1973, when Williams with his engine inferior JPN took the lead against all the Japanese factory two-stroke engines including the Suzuki from Sheene and Smart as well as the Kawasaki claimed by Yvon DuHamel by pulling through the ultra-fast corners like Abbey and Woodcote in masterful drifting over the front and rear wheels. Meter by meter he increased the lead, a victory never thought possible was within reach. But after Williams had even set Jaarno Saarinen’s lap record, he was stranded on the penultimate lap with an empty tank – the team had miscalculated! A bitter disappointment because the race is still considered to be the best of Williams on the John Player Norton.

The red and blue striped machines under their builder and his teammate Dave Croxford had already achieved the successes that the team and sponsor had hoped for. After a botched start in Daytona due to problems with the spray supply, Williams won three out of six races in the Easter Atlantic Match Races, collecting the most points with four fastest racing laps against the much more powerful two-stroke engines from Japan and the four-man factory team from Harley-Davidson. After another success in Cadwell Park and a ride at the Imola 200, it went to the Isle of Man, where Williams finally achieved the TT victory at JPN ahead of teammate Mick Grant, which he had long earned. With an average speed of 169.70 km / h, he kept Jack Findlay’s works Suzuki in check as well as the more powerful three-cylinder from Triumph / BSA in the 750 TT race, and also set a new record lap with 172.60 km / h, which made him the second fastest man on the TT course – and that with a tuned production bumper engine!

Still, the avant-garde machine was scrapped after just one successful season. A political decision by the team that still hurts Peter Williams today: “There was a lot of resentment in the game. It had annoyed some people that the monocoque JPN was viewed too much by the public as my very personal project, even if I thought up, helped develop and drove it on behalf of the team. "

Peter Wiliams – GP pilot and engineer

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Designer and successful racer: Peter Williams on his "baby", the John Player Norton.

Peter Williams was a real patriot. During his ten-year racing career, which he ended in 1974 after a terrible accident at Oulton Park, he rode almost exclusively British bikes. He was considered a gifted driver, but he achieved his greatest success on an MZ, where he achieved their last ever Grand Prix victory during his short liaison with the East German works team in 1971.

Peter is the son of legendary designer Jack Williams, who created the Matchless G50 during his time as chief engineer in AMC’s racing department. At the end of the 1960s, Peter had built an excellent reputation as a driver and engineer. After completing his engineering training, he joined Ford, where he was able to familiarize himself with the increasingly sophisticated racing car designs in the mid-1960s. On the racetracks, Peter and his inferior AJS and Matchless racers had no chance against Agostini and the three–cylinder MV. Technically, however, Williams was always a pioneer. As early as 1967 he was constructing cast rims from a magnesium alloy, on which he later fitted tubeless tires. He was also one of the first to use disc brakes and a full-face helmet.

He proved his driving skills with no less than six second places behind Agostini in the TT races on the Isle of Man and podium finishes on classic GP racetracks such as Assen, Monza, Hockenheim and Dundrod. Mike Hailwood wanted him as a teammate at Honda for the 1968 season, but then the Japanese surprisingly dropped out of GP racing. Williams turned down the offer to drive Read-Weslake’s new 500, and instead went to Norton’s factory racing team.

In close coordination with AMC boss Dennis Poore, Williams forged a new career as a successful big bike pilot with the new Commando Production Racer, and in 1971 also constructed a prototype with a 750 cc engine, with which he demonstrated the potential of racing as a sales argument for the Norton brand. This eventually led to the founding of the John Player Norton team and the construction of two distinctive racing machines. In 1972 it was initially the variant with a one-piece tank seat paneling, and the following year the unmistakable monocoque racer, both designed and driven by Williams, who finally achieved the success they deserved. When he won TT in 1973, his unique talent was revealed to the world. It was Williams’ avant-garde bike that enabled him to achieve his own ambitious goals – as a rider, but also as an engineer.

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