Norton Challenge P86

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Norton Challenge P86
ManufacturerNorton Motorcyles
Also calledNorton Cosworth
Parent companyNVT
ClassRacing motorcycle
EngineCosworth 748 cc (45.6 cu in) DOHC, four-valves per cylinder, water cooled parallel twin
Bore / stroke85.67 mm × 64.9 mm (3.373 in × 2.555 in)
Power95 bhp (71 kW) @ 9,750 rpm
Ignition typeLucas RITA CDI
Frame typeStressed engine member
SuspensionFront: telescopic forks
Rear: swinging arm with twin shocks
BrakesFront: Twin discs
Rear: Single disc
Footnotes / references
[1][2]

The Norton Challenge P86, also known as the Norton Cosworth, is a racing motorcycle designed in 1973 by Keith Duckworth of Cosworth Engineering for Norton Motorcyles. The 750 cc (46 cu in) DOHC vertical twin was essentially two cylinders from Cosworth's world championship winning V8 DFV Formula One engine. A road going version was intended to be a replacement for the Norton Commando. Four complete machines[3] and around 30 engines[4] were made before the project was cancelled due to the financial collapse of NVT.

Background[edit]

By 1973 the British motorcycle manufacturing industry was in trouble, no longer able to compete in world markets with mass produced, more technologically advanced models from the Japanese Big Four.[a] Many famous brands were no more. Following a collapse of the BSA group's shares on the stock market, BSA, along with its subsidiary Triumph, were merged with Norton Villiers to form Norton Villiers Triumph (NVT).[6][b] However, the merged company was underfunded.[9] Norton's vertical twin engine that powered the Commando had reached the limit of its development for both road and track by the early 1970s.[10] The engine design could be traced back to Bert Hopwood's 1947 497 cc (30.3 cu in) Norton Model 7 twin.[11] A new unit construction engine with a five speed gearbox was needed,[10] but Norton could not afford to develop one themselves.[12]

Two British Formula 1 engine manufacturers were approached: BRM, who had a 3 litre v12 from which a 750 cc triple could be built and Cosworth whose dominant V8 could be the basis for a 750 cc twin. Cosworth were chosen for the contract. This was initially to design the 'top end' of the engine but soon changed to Cosworth designing the whole engine/gearbox unit.[13] NVT chairman Dennis Poore felt this would not only save time but would add interest and credibility to the new bike.[14]

History[edit]

The Challenge finally made its debut at Brands Hatch in October 1975 ridden by Dave Croxford. In the Saturday heat Croxford was involved in a ten bike crash at the first corner. Croxford was injured in the crash and Alex George rode the bike in the Sunday race. The bike's cooling system had been damaged in the previous day's crash and the bike was retired.[15]

At the end of the 1975 season[16] Victor Palomo tested the Challenge at Silverstone on behalf of the Spanish Norton importer JA Rodes[2] with the intention of using the bike for F750. Unfortunately Norton's financial situation prevented the factory supporting the project. It also declined a request, sponsored by the RFME (Real Federación Motociclista Española), to supply the Venezuelan Venemotos team.[16]

In April 1976, Croxford and the Challenge were part of the British Transatlantic Trophy team. After performing poorly in the first round at Brands Hatch, the bike was withdrawn from the rest of the series. In June of that year the bike, again risen by Croxford, retired on the first lap of the Isle of Man Classic TT. Shortly after, NVT went into liquidation and the project was cancelled.[15]

Croxford was never able to achieve lap times on the Challenge that he had previously managed on the Commando engined John Player Nortons.[17]

P89[edit]

At the NVT liquidation sale, a machine with a water cooled, pre-unit DOHC engine in Commando running gear was put up for sale. The machine had primary and final drives on the right hand side, and used a reversed Norton gearbox. A plate marked P89 was attached to the bike. This bike may have been a test-bed for the Cosworth technology or possibly a prototype interim model between the Commando and Challenge to reduce initial tooling costs.[18] A second similar engine fitted with a single SU carburettor was also offered for sale.[19]

Sutherland machines[edit]

Two of the four bikes made went to the USA, the remaining two stayed in the UK until sold to a German entrepreneur along with numerous parts. The German then sold Scottish Norton enthusiast Ian Sutherland two engines and enough cycle parts to build a complete bike.[3] Southerland commissioned ex-Norton factory race mechanic Norman White to assemble a Challenge from the parts. The engine was built up by ex-Cosworth engineer Bob Osborne. The bike was given the chassis number 003 and was run-in on public country road near Sutherland's home. It was given two 20 minutes demonstration runs[15] at the August 1981 Donington Park 50th Anniversary meeting[17] by Scottish racer Jock Findlay and racing journalist Alan Cathcart.[15]

The second engine was built up into a Battle of the Twins racer using a Harris frame.[15] Rider Rob Sewell achieved a near 100 mph lap[17] at the 1985 Isle of Man Senior TT.[20]

A second Challenge was built for Sutherland by ex-JPN lead fabricator John McLaren out of spares purchased by Sutherland when the NVT race team was liquidated. Both the headstock and engine were stamped JAB004.[12]

Quantel Cosworth[edit]

In 1980 Cosworth was taken over by United Engineering Industries (UEI).[21] In July 1984, newly appointed Cosworth director, Bob Graves[c] was being shown around the Cosworth factory by Keith Duckworth and spotted some twin cylinder engines in a storeroom. Duckworth explained these were from the Norton project and added that "You're looking at the only engine we have ever built which has never won a race". Duckworth allowed Graves to have two of the engines on the proviso that Graves expected no support from Cosworth for them.[24]

Graves intended to build a Battle of the Twins[d] racer using the engine and asked F1 and Motorcycle GP world champion John Surtees to become involved in the project. Surtees became technical advisor, team manager and at times engine tuner.[29]

Surtees asked Exactweld to create the front and rear subframes for the bike.[29] Exactweld partners Guy Pearson and John Baldwin had previously worked for Surtees' F1 Team fabricating monocoques. They also had experience designing and building motorcycle chassis, their Exactweld 250 racer having taken the 1984 European 250cc Championship in the hands of rider Gary Noel.[30][e] Exactweld created a triangular front subframe out of 0.25 in (6.4 mm) duralumin with the steering head at the front and bolting onto all four sides of the cylinder head at the rear. At the rear they fitted a triangulated monoshock swinging arm that pivoted on the gearbox casing. A single, near-horizontal White Power shock absorber ran from the top of the swinging arm to the rear of the front subframe.[29]

Duckworth suggested that Ilmor Engineering[f] should carry out further development work on the engine, although Duckworth still offered advice on problems with the engine. Ilmor increased the capacity to 825 cc (50.3 cu in) by using 90 mm (3.5 in) pistons. They also modified the cylinder head, crankshaft, primary drive, clutch and gearbox. Forth and fifth gear were made closer together.[29]

The bike was developed in English club races in the later part of the 1985 season[33] and entered into the 1986 Daytona AMA BOTT race. Australian Gary Flood was brought in to act as team mechanic and fellow Australian Paul Lewis to ride the machine. The engine was fitted with 11.7:1 pistons, 40 mm (1.6 in) Amal Mk 2 Concentric carbs with remote floats and Motoplat ignition. It was producing 105 bhp (78 kW) at 10,500 rpm.[29] Lewis qualified 8th on the grid[33] and the race developed into a 3-way battle between Lewis and the works Ducatis of Marco Lucchinelli and Jimmy Adamo. Lucchinelli eventually won the race with Lewis finishing second.[29]

Returning to Daytona for 1987, Australian Rob Phillis rode the bike. Motec electronic fuel injection had been fitted. Phillis retired during the race due to technical issues.[29]

For 1988 the bike was fitted with an experimental mechanical fuel injection developed by Cosworth and produced 120 bhp (89 kW) at 10,500 rpm.[29] Graves asked Surtees to find a British rider and Roger Marshall was signed up.[34] At Daytona Marshall defeated Stefano Caracchi [es] on the works Ducati 851 after a hard fought battle. Marshall went on to win Battle of the Twins races at Spa and Assen later that year.[29] Having achieved his objective of winning with the bike and having spent £100,0000 of his own money on the project, Graves retired the bike at the end of the year.[35]

In 1995 it was reported that Triumph Motorcycles Ltd were considering producing a 750 Bonneville sports bike using a trellis frame and the Cosworth twin engine as developed for the Quantel.[36]

National Motorcycle Museum[edit]

Two Challenges were displayed at the British National Motorcycle Museum in Birmingham.[37] On 16 September 2003[38] the buildings were engulfed in fire and 600 motorcycles were destroyed or damaged. Museum owner Roy Richards commissioned former JPN development engineer Norman White, who ran a Norton engineering workshop at Thruxton, to restore the Challenge and also two John Player Nortons and a Commando production racer. White assembled a restoration team consisting of members of the original JPN race team: race shop foreman John McLaren, mechanic Peter Pyket, and draftsman Basil Knight. White's team got the four bikes ready and fully running for the planned re-opening of the museum in October 2004.[g] Richards was so pleased with the quality of work that the machines were placed in the museum's foyer. Richards subsequently commissioned White to build five further racing Nortons including a Challenge,[37] although this Challenge may have been for display purposes only and without engine internals.[17]

Technical details[edit]

Engine and transmission[edit]

Cycle parts[edit]

The Challenge used the engine as a fully-stressed frame member. A tubular sub-frame was mounted on the cambox to mount the [15] leading-axle front forks. The cast-aluminium, twin-shock swinging arm[17] pivoted on the gearbox casting.[15]

One of the two factory development bikes was fitted with experimental leading-link forks but these were never tested.[17]

Notes and references[edit]

Notes[edit]

  1. ^ Honda, Suzuki, Yamaha and Kawasaki[5]
  2. ^ BSA shareholders received £10m for the company, of this £4.8m came from the British Government and the remainder from Norton Villiers parent company Manganese Bronze Holdings.[7] BSA's non-motorcycle interests, most notably Carbodies, manufacturer of the London 'Black Cab' were taken over by Manganese Bronze[8]
  3. ^ Arthur 'Bob' Graves was a former Formula 3, air and motorcycle racer and co-founder of electronics company Quantel[22] which had recently joined UEI and was influential within the group.[23]
  4. ^ With multi-cylinder machines dominating the Superbike Championship, the AMA set up a series for twin-cylinder machines up to 1,000 cc (61 cu in), the Battle of the twins.[25] A demonstration event was run during the 1981 Daytona Week[26] with a full series starting the next year.[27] Similar series were later set up in other countries.[28]
  5. ^ 12 Yamaha TZ 250 engined Exactweld 250s were built using a perforated stainless steel spine frame. The bikes were over 10 kg (22 lb) lighter than the standard TZ250 racers and were the first 250 GP bikes that needed to carry ballast to meet the 90 kg (200 lb) minimum weight limit.[30]
  6. ^ Following discussions with Indycar team owner Roger Penske, engineers Paul Morgan and Mario Illien had left Cosworth's employ and formed Ilmor Engineering in January 1984 to develop a new Indycar engine. Penske, and from October 1984, Chevrolet provided financial backing for the project.[31] Morgan was one of the engineers involved in the development of the original Norton Cosworth engine.[32]
  7. ^ Although planned for October 2004, the museum reopening was delayed to 1 December.[39]

References[edit]

  1. ^ Cameron 2009, pp. 22, 26, 30–31.
  2. ^ a b Aynsley 2018.
  3. ^ a b Cathcart 1981.
  4. ^ Robson 2017, p. 217.
  5. ^ Cycle World 1984.
  6. ^ Falloon 2018, p. 73.
  7. ^ Glueck 1980, p. 437.
  8. ^ Comfort 2012, p. 1978.
  9. ^ Clayton 2020, p. 68.
  10. ^ a b Bacon 1995.
  11. ^ Bacon 1989, pp. 6–7.
  12. ^ a b Branch 2020.
  13. ^ Williams 2012.
  14. ^ Burr 2015, pp. 156–157.
  15. ^ a b c d e f g Bonhams 2015.
  16. ^ a b Domínguez 2014.
  17. ^ a b c d e f Bonhams 2021.
  18. ^ Bonhams 2021a.
  19. ^ Bonhams 2021b.
  20. ^ Isle of Man TT Race Results.
  21. ^ Robson 2017, p. 106.
  22. ^ Daily Telegraph 2012.
  23. ^ Burr 2015, p. 218.
  24. ^ Robson 2017, p. 78.
  25. ^ AHRMA.
  26. ^ Egan 1981.
  27. ^ West Coast British Racing.
  28. ^ Cathcart 2021.
  29. ^ a b c d e f g h i Clayton 2020, p. 70.
  30. ^ a b Cathcart 2017.
  31. ^ Wagstaff 2010, p. 134.
  32. ^ Ludvigsen 2001.
  33. ^ a b Harrison & van Barriger 1986.
  34. ^ Avossa 2019.
  35. ^ Clayton 2020, pp. 68, 70.
  36. ^ Cathcart 1995.
  37. ^ a b White.
  38. ^ Guardian 2003.
  39. ^ BBC 2004.

Bibliography[edit]

External links[edit]

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