Updated: 19th July 2007

Scale 1/20 Kit Manufacturer Tamiya Grade-up Parts Studio 27 Acu-Stion Thunder Valley Miniatures Year 1961 Driver Jim Clark (Great Britain) Event 1963 Mexican GP

1/20 Tamiya Lotus 25 'Coventry Climax'

1961 saw the engine capacity for Formula 1 reduced to 1.5 liters. Fuel regulations were also changed and now required engines to run on 101.5 octane fuel instead of the 130 octane Avgas. In the first season these regulations found all of the British teams down on power compared to Ferrari with the expected results. However in 1962 Lotus would answer with the Lotus 25. Mid-engined cars were standard and the Lotus 25 was not the first racing car with a monocoque chassis but its artistic simplicity and immense success in the hands of Jim Clark revolutionized Grand Prix racing car design.


Colin Chapman experimented with a backbone chassis on the Lotus Elan sports car and decided to apply the same techniques to a single-seater racing car. Using box-sections he built a tub wide enough for a driver and within would go rubber bags to hold fuel. The driver would now sit in an almost reclining position that took some getting used to for Clark, in fact it took a brave man indeed to drive one of these cars at full speed. The main benefits of this design were increased torsional rigidity and less weight and with a smaller frontal area. The resulting stiffness allowed Lotus to use more supple suspension which offered great advantages in slower, tighter turns. Colin Chapman was known as an instinctive seat of the pants designer. In fact when the first prototype was being built he took the opportunity of sitting in the car. To his surprise he found that he could fit quite comfortably and announced forthright that: "This cockpit's too wide ... take another inch and a half out out of it!" Dick Scammell, one of the mechanics that built the first car would later remark that: "None of us really knew what we were doing, but it all took shape very nicely and it certainly looked right."

Power was again provided by Coventry-Climax, the fire pump manufacturer at £3000 per motor but this time Ferrari's advantage would be bridged. The car was fast straight out of the box and when it finished it won. In 1963, Engineer Len Terry returned to Lotus and worked to improve the cars reliability. His work bore fruit the next year, 1963 when Jimmy Clark won a then record seven races and the World Championship.

Jim Clark by Eoin Young	Jim Clark by Eric Dymock	Lotus 25 & 33 by John Tipler	Lotus 25 Climax FWMV by Ian Bamsey
Formula 1 in Camera 1960-69 by Paul Parker

Details added:

• Replaced plastic parts/decals with photo-etch / white metal as follows;
  Driver Pedals
  Gear Selector Gate
  Brake disks replaced
  Rear Suspension - Springs replaced using RB Motion Units
  Exhaust Pipes
  Roll Over bar
  Steering Wheel
  Trumpets
  Transmission & Suspension bolts replaced
• Added photo-etch / White Metal & decals as follows;
  Front Radiator Grill
  Dial Surrounds
  Fasteners and rivet heads added onto body work
  Radiator cap
  Tyre Valves
• Scratch built add ons;
  Throttle Linkage
  Driver Pedal Housings
  Fluid Reservoirs
  Plug Leads / Sockets
  Throttle Cable & Brake Cable
  Various hoses & leads from rear of dashboard
  Dashboard Clock backs and retainers
  
  This was an extremely enjoyable build which was vastly improved by Thunder Valley F1 detail kit for the model, there were enough parts left over for me to complete a 1962 variant of the car which I will do at a later date.

Completed pics