Lotus 25

Lotus 25

Jim Clark's Championship-winning Lotus 25, in the Donington Grand Prix Collection.
Category	Formula One
Constructor	Team Lotus
Designer(s)	Colin Chapman
Predecessor	Lotus 21 / Lotus 24
Successor	Lotus 33
Technical specifications
Chassis	Aluminium monocoque
Suspension (front)	Double wishbone, with inboard coilover spring/damper units.
Suspension (rear)	Lower wishbone, top link and radius rod suspension, with outboard coilover spring/damper units.
Engine	Coventry Climax FWMV, 1496cc, 90° V8 Naturally aspirated, mid-mounted BRM P56, 1498 cc, 90° V8 Naturally aspirated, mid-mounted
Transmission	ZF 5DS10 5-speed manual
Tyres	Dunlop
Competition history
Notable entrants	Team Lotus Reg Parnell Racing Brabham Racing Organisation
Notable drivers	Jim Clark Trevor Taylor Mike Spence Chris Amon Mike Hailwood Richard Attwood
Debut	1962 Dutch Grand Prix
Races Wins Podiums Poles F.Laps 49 14 18 14 18
Constructors' Championships	2 (1963, 1965)
Drivers' Championships	2 (1963, 1965)
n.b. Unless otherwise stated, all data refer to Formula One World Championship Grands Prix only.

The Lotus 25 was a racing car designed by Colin Chapman for the 1962 Formula One season.^[1] It was a revolutionary design, the first fully stressed monocoque chassis to appear in F1. In the hands of Jim Clark it took 14 World Championship Grand Prix wins and propelled him to his 1963 World Championship title. Its last World Championship win was at the 1965 French Grand Prix.

Concept

Jim Clark at the 1964 Dutch Grand Prix.

Gerhard Mitter at the 1965 German Grand Prix.

Richard Attwood in Reg Parnell Racing privately entered Lotus 25 at the 1965 German Grand Prix.

An early brainchild of Chapman's fertile mind, the original sketches for the car were made on napkins while Chapman discussed his idea while dining out with Frank Costin (designer of Vanwall, Lotus Mk.8, 9, 10, 11 and Lotus 16 bodies, later of Marcos fame).

The monocoque made the car more rigid and structurally stronger than typical F1 cars of the period. The 25 was three times stiffer than the interim 24, while the chassis weighed only half as much.^[2] The car also was extremely low and narrow, with a frontal area of 8.0 ft², 0.74m² as compared to the normal 9.5 ft², 0.88 m²^[3] It was also envisaged to have a column gear lever, to keep the cockpit width to a minimum, although this was only experimental and discarded. To assist the low profile and low frontal area, the driver reclined sharply behind the wheel (an idea seen in the 18, and pioneered over a decade previously by Gustav Baumm at NSU^[3][4]), leading to the nickname 'The Bathtub', while front coil/damper units were moved inboard (as in the 1948 Maserati).^[5] The 25 was powered by the Mk.II 1496cc through to the Mk.5 1499cc versions of the Coventry Climax FWMV V8 in crossplane and flatplane formats. Later, Reg Parnell Racing in 1964 fitted BRM P56s of similar specification to their second-hand 25s. Such was the 25's effect on motor racing, even today's modern F1 cars follow its basic principles. Some privateers who had been buying Lotus chassis were disgruntled by the fact Chapman refused to provide them 25s. These teams, including Rob Walker Racing, were given Lotus 24s, while the works team had exclusive use of the 25 for Jim Clark and Trevor Taylor. When it first appeared at the Dutch Grand Prix, the futuristic 25 was inspected by John Cooper, who asked Chapman where he had put the frame tubes in the car.

Seven cars were built in total, numbered R1 to R7. Four cars - R1, R2, R3 and R5 - were written off (three of them by Trevor Taylor) in accidents between 1962 and 1966. The most successful was R4, which Clark drove to all seven of his World Championship wins in 1963. This car was later crashed by Richard Attwood, rebuilt around a Lotus 33 tub and unofficially known as R13.

Racing history

The car gave Clark his first World Championship Grand Prix victory, at Spa in 1962. He took another win in Britain and again in the USA, which put him in contention for the title, but while leading the final race in South Africa a much publicised engine seizure cost him the title to Graham Hill.

Clark gained his revenge the following year, taking his first World Championship in the 25, by winning 7 races, Belgium, France, Holland, Britain, Italy, South Africa, and Mexico. Lotus also won its first constructors' championship. Following the United States GP, a 25 was taken to the Indianapolis Motor Speedway for evaluation, where they also trialled Lucas electronic ignition for Ford.^[6] The results were encouraging enough for Colin Chapman to mount his ultimately successful challenge on the Indianapolis 500.

The 25 was again used during the 1964 season, winning a further three races in Clark's hands. At the final race in Mexico, just as in 1962, the Climax engine developed an oil leak and with literally a lap to run Clark coasted to a halt in sight of world championship victory, this time conceding to John Surtees. Despite the introduction of the Lotus 33 in 1964, the 25 was still used until well into the 1965 season, Clark taking the car's final win at the 1965 French Grand Prix.

In 1964, Reg Parnell Racing began racing the 25, using the BRM P56 V8 engine, with limited success. Piers Courage retired the 25 from its final World Championship race at the 1967 South African Grand Prix.

World Championship results

(key) (results in bold indicate pole position; results in italics indicate fastest lap)

¹ Points were awarded on a 9-6-4-3-2-1 basis to the first six finishers at each round, but only the best placed car for each make was eligible to score points. In 1962 and 1966 only the best five results from the season were retained, and only the best six results for 1963, 1964 and 1965. In 1967 the best five results from the first six rounds and the best four results from the last five rounds were retained.

² Jack Brabham raced the spare works Lotus after engine failure forced him to retire his own car.

³ Plans for Arundell to race the spare car were abandoned.

⁴ Clark swapped cars with Spence's Lotus 33 during the race following mechanical problems.

⁵ Revson tried out Hailwood's car in practice while the latter was away qualifying for the TT.

⁶ Total points scored by all Lotus-Climax cars, including 45 points scored by drivers of Lotus 33 variants.

⁷ Total points scored by all Lotus-BRM cars, including 9 points scored by drivers of Lotus 43 variants.

Legacy

In June 2008 Lotus launched a special edition of the Elise supercharged model, the Type 25 Jim Clark, in the Lotus racing colours of green with a yellow stripe. This had track standard sports suspension and traction control. A total of 25 of these cars were produced for the RHD market.

References

1. ↑ Automobile Year, No. 10, 1962-1963, Pages 198-199.
2. ↑ Setright, L.J.K. "Lotus: The Golden Mean", in Northey, Tom, ed. The World of Automobiles (London: Orbis, 1974), Volume 11, p.1230.
3. 1 2 Setright, p.1230.
4. ↑ Wikipedia, Lotus 18.
5. ↑ "Chapman was not concerned to be original, merely to be thorough." Setright, p.1230.
6. ↑ Super Street Cars, 9/81, p.34.

Team Lotus Founder Colin Chapman Noted personnel Frank Dernie Gérard Ducarouge Maurice Philippe Peter Warr Peter Wright Len Terry World Champions Mario Andretti Jim Clark Emerson Fittipaldi Graham Hill Jochen Rindt Other notable drivers Elio de Angelis Martin Donnelly Mika Häkkinen Johnny Herbert Jacky Ickx Nigel Mansell Satoru Nakajima Gunnar Nilsson Ronnie Peterson Nelson Piquet Carlos Reutemann Ayrton Senna John Surtees Derek Warwick Alex Zanardi Drivers' titles 1963 1965 1968 1970 1972 1978 Constructors' titles 1963 1965 1968 1970 1972 1973 1978 Formula One cars 16 18 21 24 25 33 43 49 56B 63 72 76 77 78 79 80 81 86 87 88 91 92 93T 94T 95T 97T 98T 99T 100T 101 102 107 109 112 Formula Two cars 12 16 18 32 35 41 44 48 59 69 Formula Three cars 22 31 35 41 55 59 69 Formula Junior cars 18 20 22 27 Formula Ford cars 51 59 61 69 Formula 5000 cars 68 70 Tasman Series cars 32 39 67 Indianapolis 500 cars 29 34 38 42 56 64 96T Sports racing cars 15 17 19 23 30 40 47 53