Norton Isolastic frame

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1969 750 cc Norton Commando 'Fastback' Norton Commando 750 Fastback 1969.jpg
1969 750 cc Norton Commando 'Fastback'
1973 850 cc Norton Commando with US-spec small fuel tank 1973 Norton 850.JPG
1973 850 cc Norton Commando with US-spec small fuel tank

The isolastic frame, designated by Norton as GlideRide, [2] used a system of engine-to-frame mountings incorporating rubber bushes to isolate the vibration of the vertical twin engine from the frame and rider. The isolastic frame was developed for use with the Commando inclined engine, whilst the Featherbed frame continued in production for the Mercury with a softer-specification 650 cc vertical-engine until 1970. [3] [4] [5]

Contents

History

Following the collapse of the old Norton parent-company AMC in 1966, a new business was structured to produce motorcycles using the name Norton Matchless Division, under a new parent company name of Norton Villiers Ltd. [2]

Part of the changes involved creating a new design frame produced as previously by Reynolds Tubes in Tyseley, Birmingham, England, where the traditional Featherbed frame had been produced since the 1950s, shipped for assembly at the Matchless works in Woolwich, London. [6]

In an attempt to reduce the worsening problem of engine vibration being transmitted through the frame, as the capacity of the engine increased to 750cc with the Norton Atlas, Norton Villiers decided to replace the Featherbed frame for their top model, and the Norton Commando was the result, although Norton-Matchless machines like the P11 continued to use conventional Matchless frames.

The innovative new design isolastic frame made it smoother through the use of rubber bushes to isolate the engine and swingarm from the frame, forks, and rider. As the rubber bushes deteriorated, however, the bike became prone to fishtailing[ clarification needed ] in high-speed turns. [7] Earlier models therefore required careful maintenance and adjustment of the clearance between frame and mounts using shims.

Several improvements were made in 1969. The frame benefitted from additional stiffening and strengthening, [8] which, together with an improved centre-stand, helped to improve ground-clearance which had been criticised. Slightly softer rubber mountings were introduced to reduce a vibration period at 1,500 to 1,900 rpm. A new model named Commando S was introduced with alternative styling having a different tank, mudguards and high-level exhausts. [9] [4]

The six-storey former Matchless factory at Woolwich closed on 25 July 1969, and production was transferred to a new, small, modern facility at Andover, Hampshire, [6] when the range was expanded to five Commando variants—Fastback, Roadster SS, Production racer and Hi-Rider, all having "Isolastic Construction—Norton's revolutionary answer to vibration".

By 1971, the company name had changed again to Norton Villiers Europe Ltd. [10] By 1973, a variant on the Roadster was introduced named Interstate, with larger 534-gallon (27 litre) fuel tank replacing the original US-specification 212 gallon (18 litre) capacity. [1] By 1974 the company name had changed yet again, to Norton Triumph Europe Limited. [11]

Prototype models

As part of an attempt to produce new models from existing parts, NVT produced a few prototype models using the Isolastic engine mounting system. None of the prototypes made it into production.

Norton P92

The P92 model comprised a BSA B50 engine in a BSA Fury/Triumph Bandit frame using Isolastic mountings from the Norton Commando. The US DOT had mandated that all motorcycles sold in the US should have a left hand gear change. The B50 had the gear lever on the right, so to comply with this requirement, the engine was tilted forward in the frame and a gear linkage run under the gearbox to provide a left hand gear change. [12]

900 Commando

A prototype '900 Commando' was also produced. [12] [ dead link ] It used a Triumph T180 triple engine (a T160 Trident engine increased in capacity to 870 cc) in Commando cycle parts. [13]

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Associated Motor Cycles

Associated Motor Cycles (AMC) was a British motorcycle manufacturer founded by the Collier brothers as a parent company for the Matchless and AJS motorcycle companies. It later absorbed Francis-Barnett, James, and Norton before incorporation into Norton-Villiers. Henry Herbert Collier founded Matchless as a cycle company in 1878. His sons Henry (Harry) and Charles (Charlie) joined him and the name was changed to H. Collier & Sons.

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Norton Atlas

The Norton Atlas was a Norton motorcycle made between 1962 and 1968, until it was replaced by the Norton Commando.

Featherbed frame Motorcycle frame

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Norton P11

The Norton P11 was a 745 cc (45.5 cu in) air-cooled OHV parallel twin motorcycle made by Norton-Villiers from 1967 to 1969. Designed as an extremely light high power-to-weight ratio desert racer, P11 was revised in 1968 to the P11A and marketed as the Norton Ranger, a road legal version of the P11 with a more comfortable seat to make it suitable for normal road use. The Norton P11 gained a reputation as a 'desert racer' in the late 1960s but by 1969 lighter two stroke desert racers began to dominate the sport and the Norton had begun Commando production and it was selling well. Norton ended production of the P11 series to concentrate on the Commando, which used a number of ideas developed on the P11 series.

Colin Jordan Seeley was a British motorcycle retailer who later became a motorcycle sidecar racer, motorcycle designer, constructor and retailer of accessories. In 1992 he was involved in running the Norton Rotary race team.

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References

  1. 1 2 Motorcycle Mechanics, June 1973, p.2 Full-page colour Norton factory advert. "Commando Roadster with 212 gallon (18 litre) steel petrol tank...also available Commando Interstate, with larger 534-gallon (27 litre) long distance steel petrol tank". Accessed 3 January 2016
  2. 1 2 Grand Prix, 1968 soft-back book, p.34, full-page B&W factory advert, a Motor Cycle News special publication. "Suddenly we've started a revolution on two wheels - It's called the COMMANDO 750. Inclined engine, better cooling. GlideRide frame—goodbye vibration" Accessed 1 January 2016
  3. Motorcycle Mechanics, May 1969, p.63 SHOWTIME. Show scene '69."Last of the traditional Nortons is the 647 cc Mercury. This machine has the Commando type cylinder head and single carburettor, producing 47 bhp. A rev counter and stainless steel mudguards are available as extras". Accessed 3 January 2016
  4. 1 2 Motorcycle Sport, April 1969, p.126, p.133, p.135 Accessed 1 January 2016
  5. Woollett 2004 [ verification needed ]
  6. 1 2 Motorcycle Sport, July 1971, pp.273-274, "When motorcycles were made in London". Accessed 2 January 2016
  7. Bacon 1989 [ verification needed ]
  8. Motorcycle Mechanics, May 1969, p.63 SHOWTIME. Show scene '69."The Norton Commando will appear with a slightly strengthened and consequently more rigid frame for 1969". Accessed 3 January 2016
  9. Motorcycle Mechanics, May 1969, p.63 SHOWTIME. Show scene '69."Seen for the first time at the Brighton show will be the Commando 'S' restyled to a more sporting specification, resulting in improved performance". Accessed 3 January 2016
  10. Motorcycle Sport, July 1971, p.257, "64 years ahead". (1907 first TT win to 1971) Full-page factory advert, Norton Villiers Europe Ltd, Andover, Hants. Accessed 2 January 2016
  11. Motorcycle Mechanics, December 1974, p.2 Full-page colour Norton Triumph factory advert. "Buy British. You've arrived.". Accessed 3 January 2016
  12. 1 2 Tanshanomi, Peter (6 January 2015). "Two Wheel Tuesday: Last Gasp Norton Isolastics". Hooniverse. Archived from the original on 15 September 2018. Retrieved 14 September 2018.
  13. Brooke, Lindsay (2002). Triumph : A Century of Passion and Power. MotorBooks International. p. 125. ISBN   9781610592277.

Further reading