JPN Monocoque Specs

That's the Southern 100 course of 4.25 miles not the Mountain course of 37.7 miles.



So a completely different proposition learning wise, the properly prepared rider will as well as doing the official race practise will scout out the course before using a hire car or a bike for a week of 2 weeks earlier in the year. Even though at race speeds and having both sides of the road available makes the course feel a lot different, they at least get to remember the main corners and the hazard locations eg manhole covers etc.

been there several times , still do not know half of the course.
it is not like a short circuit , 37 3/4 of .........

I remember the Vanneste Bros. going to the IOM when it still was a part of the World championship and they finish four in the Side Car race not to bad for a first time at the IOM
Yves

I think in that video 'Race of the power bikes', it mentions that Dave Croxford forgot where he was on the IOM circuit during a race. It's easy to have brain fade even on a short circuit. One of the reasons I prefer to limit my riding to Winton Raceway is that I never have to remember where I am at any time. I can go around there almost blind-fold. It's a big help to going fast if you can line the corners up without thinking. On the IOM, it must be horrendous. It might be very easy to find yourself in deep shit ?

If the lazy gits WALKED the Course , Theyd LEARN IT well Enough .

Our Course , City to Home , walking whilst hitching , Id studied every camber ,
braking point , and run off ( normally ditches , large trees , rivers & Lamposts )
The Later youd take care that ' loaded up ' the machine wasnt going to head into one
if you stuffed it up, Braking line usually took you aimed before it . Outside Bridge abutments etc .
Judicious & consided positioning and application of brakes & throttle was required, along with
a necesary degree of concentration & application . In Places .
Generally on the grvel county roads you could let loose a good deal more , apaRT FROM
ON THE MORE OPEN FASTER STUFF .
i always left a bit of lee for error . others didnt and occasionally visited the sceneary .
A degree of reserve was required,
AS AT the I.o.M. , .

50s era riders often ran 20 miles training for the race . A garden gate Norton would take
some holding in , or straight , at times .

Its not a ' short circuit ' , there were many long distance races in the preceeding era .
In N.Z. the Waiheke T.T. and Mangere T.T. were both Seven Mile Circuits .
Many Italian road races were city to city , & perhaps return .

Even on a short circuit, it is easy to get into a corner too hot. The videos of racing on the IOM are deceptive. Actually doing it must be very different. - 'Practice makes perfect' ? As I understand it, the first time Cameron Donald raced, it was on the IOM. I raced for years in the old days and I would think twice about racing there.

http://ridendrive.it/2017/01/07/la-john ... monocoque/
dont know if this has been posted before

Very nice article, Don. I don't recall seeing it before, so thanks for posting it.

Ken

These are the rest of the magazine article pages. I'm in the process of converting all my old photobucket posts to VIP attachments, and posted these separately to meet the 5 attachment per post limit.

Page 6



Page 7



Page 8



Page 9 previously posted

Page 10



Ken

Don
I used Google Translate so that I could read the French article you posted - nice read
I'll try to post the translation here for others

...nope - won't allow me to load Word or pdf file. If anyone wants an English translation please PM me
Cheers
Rob

madass140 said:

http://ridendrive.it/2017/01/07/la-john-player-norton-f750-del-1973-la-monocoque/
dont know if this has been posted before

Click to expand...

I'm taking Gortnipper's suggestion and posting the translated text here (see pics in link) - the translation is a bit weird here and there...
Cheers
Rob

The 1978 John Player Norton F750: The Monocoque

Published on January 7, 2017

The engineer and pilot who created this bike is called Peter Williams, one of the best British riders in the 1960s and 1970s, as well as a strenuous supporter of British motorcycle pride, giving up the tempting offers of Foreign Homes to defend colors of the glorious Norton, who at that time had succeeded in having a massive sponsorship from John Player, an archetype for having supported Lotus for many years in Formula One.

A challenge that, against the Japanese Honda giants, Kawasaki and Suzuki and their latest generation pluricilators, appeared as the legendary biblical clash between David and Goliath. Coupled with the two-stroke long-running two-stroke engine, capable of just over 60 hp on the wheel, Williams was just about to focus on weight, aerodynamics and the driving of his bike, drawing on technical solutions that would then reveal genial intuitions. When, a few years ago, I met Peter Williams in a pub in Norwich, I remember talking to me with special interest in this bike: "The" Monocoque "was without doubt the best bike I took on track, the one on which I poured all the my pilot experience and my ideas as a designer. And he paid me, allowing me to win the Tourist Trophy in the 1977 F750 class, a great satisfaction for me and Norton. "
The use of the monocoque structure applied to a racing bike was not an absolute novelty in those years. We remember the Grand Prix 250 bones that in 1969/70 came to light with Santiago Herrero, the great Spanish talent driver - and courage - who in 1969 contended until the end of the world title at Kel Carruthers and Benelli four cylinders. And then there was also the Kawasaki 500 H1R set up by Eric Offenstadt. But those monocoque were basically based on a torsionally high-strength boxed structure similar to those of Formula 1 cars, which in turn were derived from riveted aluminum sheet metal constructions.

Williams had the ingenious intuition to create a pair of parallel boxed structures between which the engine was placed: "I was inspired by an old Arter-Matchless in which we had mounted two sheet metal tanks on the hips to lower the center of gravity and the driving position. A solution we had adopted on the Norton F750 in 1971. I thought they could be excellent structural elements. " The draft was submitted to Frank Perris, Team Manager and John McLaren, the technician who could shape this idea. Both were immediately excited and ready to start. Made of thin electrowelded stainless steel sheet, the two boxes departed from the steering sleeve and dropped to the height of the swingarm pin. In this way the stiffness had even increased and, keeping the gas inside, kept the center of gravity low. Today, commonly referred to aluminum perimeter structures, such as the famous Yamaha Deltabox. The Norton chassis, forty years ago, had a very similar structure. And this is what makes Williams particularly proud of his work: to get ahead of time, with an intuition that is probably run by a large motorcycle house will advance new horizons in the chassis both for racing and standard racing. But at that time, the Houses invested in cubic centimeters, the number of cylinders and horses, or the one that most lured the appetite and imagination of the customers. A low, lightweight, manoeuvrable, but with a few horses was certainly not in their wishes. Today, fortunately, we are a bit contorted, but in the '70s it was so ... The bicycle was completed by a fork with magnesium alloy sheaths on which the Lockeed clamps were made and stems derived from those of the contemporary AJS Stormer by motocross. The front brake discs, cast iron, had a diameter of 10 "(254 mm). The rear brake was also a single disc with a diameter of 8 "(204 mm). The 5-spoke 18 "spokes (2 1/4" front channel, 3 "rear) were cast in magnesium alloy.

The short sporting career
After a brilliant start at Daytona, the 'Monocoque' have three statements in the races scheduled for the Anglo-American Match Race, which was held in spring in England. This was a very important event since he compared the English and American schools in a series of gare-sprints on some short English circuits. But Peter Williams's masterpiece was the victory in the TT class F750 at an average of 105.47 miles (nearly 170 km / h) ahead of Mick Grant with the same bike. The seal to his masterpiece.
The Norton Monocoque lasted, unfortunately, only one season. In 1974, it was replaced by a more conventional version, with the trunk frame (the so-called Space Frame), which turned out to be a little lower, so that, despite the slightest weight and even slightly higher engine power, neither Williams nor the courageous Dave Croxford managed to improve the time taken to score with the previous one. A bike that no longer reflected the construction philosophy of the Monocoque and on which Williams never found himself comfortable. A tough break that broke off at Oulton Park, with a fall that closed the British pilot career. It was the last of the classic Norton races.
The Replica
The author of this wonderful "replica" is Norbert Prokschi, a German gentleman with unquestionable technical skills that with a little unconscious has launched into this enterprise: "I absolutely wanted to have one of these bikes, and since I knew I would not be able to buy the original, I decided that I would build it with my hands ... ". Prokschi used constructive techniques similar to the originals, also because the Norton racing department wishing to challenge Japanese giants in the 1970s was just over a craft workshop ...

Hi everybody, that was a good idea from Rob. I have taken his translation from Italian and corrected the weird mistakes so it reads nicely now and is correct. Like "Ossa" translated as "Bones" when it should be left Ossa and so on.

Great article and wonderful pictures of that replica. I am definitely going to look Norbert up.

Have a great weekend,

Martin.

The engineer and rider who created this bike is called Peter Williams, one of the best British racers of the 1960s and 1970s and a proud supporter of the British motorcycle industry. Williams refused tempting offers from foreign manufacturers to fly the flag of the famous Norton, who at the time had secured lucrative sponsorship from John Player, renowned for having supported Lotus Formula One for many years.

It was a David and Goliath challenge against the Japanese giants Honda, Kawasaki and Suzuki with their latest generation multicylinder engines. Constrained by the obsolete long-stroke twin-cylinder engine capable of just over 60 hp at the rear wheel, Williams had to work on the weight, aerodynamics and handling of his bike, using his ingenious insights and technical solutions.

When, a few years ago, I met Peter Williams in a pub in Norwich, I remember he spoke with particular affection about this bike: "The" Monocoque "was without doubt the best bike I ever took on track, the one into which I poured all my experience as a rider and my ideas as a designer. And it paid me back, allowing me to win the Tourist Trophy in the 1977 F750 class, a great satisfaction for me and Norton. "

The use of the monocoque structure applied to a racing bike was not an absolute novelty in those years. Remember the Ossa 250 GP bike that shone in 1969/70 with Santiago Herrero, the hugely talented and courageous Spanish rider who contested the 1969 world title until the end with Kel Carruthers and the Benelli four. And there was also the Kawasaki 500 H1R built by Eric Offenstadt. But those monocoques were essentially a torsionally stiff box structure similar to those of Formula 1 cars, which in turn were derived from aircraft practice.

Williams had the ingenious idea of creating a pair of parallel box structures between which the motor was placed: "I was inspired by an old Arter-Matchless on which we had mounted two sheet metal tanks on the sides to lower the center of gravity and the riding position. A solution we had adopted on the Norton F750 in 1971. I thought they could be excellent structural elements. " The draft was submitted to Frank Perris, Team Manager and John McLaren, the chief designer who could realize this idea. Both were immediately excited and ready to start. Built in thin welded stainless steel sheet, the two boxes started at the steering head and descended to the swingarm pivot. In this way, the stiffness was even increased and, by using them as fuel tanks, the center of gravity was kept low.

Today, aluminium perimeter structures, such as the famous Yamaha Deltabox are common. The Norton chassis, forty years ago, had a very similar structure.
And this is what makes Williams particularly proud of his work: to be ahead of his time, with an idea that, had it come from a large motorcycle manufacturer, would have revolutionised chassis design for racing and for street motorcycles.
But in those days, the manufacturers were investing in cubic centimeters, cylinders and horsepower, or that which most satisfied the dreams and tastes of their customers. They certainly didn’t want a low, lightweight, manoeuvrable machine, lacking in horsepower. Today, fortunately, we have gone a bit the other way, but in the '70s that's how it was ...

The bike was completed by forks with magnesium alloy sliders, on which the Lockheed calipers were mounted and stanchions derived from the contemporary AJS Stormer motocrosser. The cast iron front brake discs were 10 "(254 mm) diameter. The rear brake was also a single disc with a diameter of 8 "(204 mm). The 18” 5-spoke wheels (2 1/4" front, 3 "rear) were cast in magnesium alloy.

The brief sporting career

After a less than brilliant start at Daytona, the 'Monocoque' took three wins in the Anglo-American Match Races held in the spring in England. This was a very important event where the English and American teams competed in a series of races on different English short circuits. But Peter Williams' greatest triumph was his victory in the F750 TT at an average of 105.47 mph (nearly 170 km / h) ahead of Mick Grant on a similar bike, which set the seal on his masterpiece.

The Norton Monocoque lasted, unfortunately, only one season. In 1974, it was replaced by a more conventional machine with a trellis frame (the so-called Space Frame). This turned out to be slightly inferior, so that, despite the lower weight and even slightly higher engine power, neither Williams nor the courageous Dave Croxford could improve on the lap times of its predecessor. A bike that no longer reflected the construction philosophy of the Monocoque and on which Williams never felt at ease. A difficult pairing that broke up at Oulton Park, where a crash ended the Britons racing career. It was the last of the classic Norton racers.

The Replica

The author of this wonderful "replica" is Norbert Prokschi, a German gentleman of unquestionable technical skills, who didn’t really realize what he was getting into: "I absolutely wanted to have one of these bikes, and since I knew I would not be able to buy the original, I decided that I would build it with my own hands ... ". Prokschi used construction techniques similar to the originals, also because in the Norton race shop wanting to challenge the Japanese giants in the 1970s they did, after all, do everything by hand…

Hi Everybody,

nice photos of PW and M Grant and TJ, 1st 2nd 3rd in that '73 F1 TT. Also Hans Butenuth 13th on the R90S

Martin.

I have an article about Peter Williams and the JPN in a magazine. The most important fact in it is that the JPN gave away 25 BHP to the Japanese two-strokes and still won. To me that says a lot about the JPN engine's torque characteristic and the handling of the bike. Unfortunately the JPN has forward axle front forks, so the rake and trail is not easily transferable. - Might be question for Peter himself ?

acotrel said:

I have an article about Peter Williams and the JPN in a magazine. The most important fact in it is that the JPN gave away 25 BHP to the Japanese two-strokes and still won. To me that says a lot about the JPN engine's torque characteristic and the handling of the bike. Unfortunately the JPN has forward axle front forks, so the rake and trail is not easily transferable. - Might be question for Peter himself ?

Click to expand...

Not so, as Ludwig has already implied. The rake is 27 degrees and the trail is 98 mm. Those don't change just because it has the offset axle. It has flatter yokes to compensate. The handling effects of the rake and trail numbers is the same as if it had standard forks. The only real benefit to using that arrangement is that it gives a lower moment of inertia around the steering axis. The offset axle design also allows the slider to be longer for more overlap with the stanchion, but I don't know if Norton took advantage of that feature.

Ken

Hi All,

Here is a link to a french-speaking site where you'll find more pictures of the Monocoque plus pre- and post Monocoque versions of Peter Willams' race Nortons:

http://www.pit-lane.biz/t858-oldies-joh ... =monocoque

I guess most of those pictures have already been published in magazines or on the web, but I found that interesting.

PS: searching this site for "Challenge" or "Cosworth" keyword will retrieve a post on the story of the Challenge Norton.

Laurent

Thanks for the numbers on the JPN steering geometry, Ken. With a normal bike, you can get an idea what the steering is like, by looking at the rake and the fork yokes and the wheel size. With the JPN, that is where it's major advantage must have come from. When you give away 25 BHP to the opposition and still win, you must be doing something right - other than sticking your neck right out . I read somewhere, that in about 1970 Peter Williams spent time at a race circuit with three different sets of fork yokes and tried each of them, while timing his laps. The steering geometry he came up with saved seconds per lap on a short circuit and minutes on the IOM. If you get it right, you can get on the gas much earlier coming out of corners.

Earlier this year I was at a local classic motorcycle show at Wistanstow in Shropshire where Peter Williams was appearing as a guest speaker. Peter uses a mobility scooter now and as I was leaving on my Fastback he lurched out in front of me on his scooter. I managed to avoid him but thought how ironic if he had been run over by a Norton Commando :cry:

Revenge of the Swamp People ?