The FORD GT40 is one of the most impressive and capable sports cars of all time. It was purpose-built to win the LeMans race, which it did four times between 1966 and 1969. The name "GT40" refers to the overall height of the car, at forty inches. Both original cars and kit models remain popular and competitive to this day. There are four generations of the GT40, and the design of the GT40 begat the 2005 Ford GT, powered by a forced-induction modular V10. Several years ago, the GT40 also inspired a concept car known as the GT90 which had a quad-turbo six liter V12 engine developing 720bhp @ 6600rpm. This car was too unwieldy and expensive to put into production, however.

PHYSICAL CHARACTERISTICS

The Ford GT40 features what would be an advanced design today, let alone in 1964. The chassis is a partial-monocoque design, with most structure built from tubular steel. The engine is mounted amidships, and there is a rear-facing five speed transaxle driving the rear wheels. The windshield is sloped similarly to the design of modern vehicles, for minimum wind resistance. The car ran the same size wheels front and back, but with meatier tires in the rear for added traction to assist acceleration. Smaller tires in the front reduce rolling friction and help keep the lines of the car smooth. The suspension is a double wishbone setup in the front, and multilink in the rear (with two upper links and a lower A-arm), which provides the best possible handling at the lowest cost in weight.

HISTORY

In the 1960s, Ford attempted to purchase Italian performance automaker Ferrari, which was the current dominant force at LeMans. After being shot down, Henry Ford II, head of the company, made the decision to take a stab at LeMans with a new Ford GT car. They made the decision to go with Eric Broadley and Lola Cars, then a small company which has since expanded into working with Ford cars at every level of racing. Lola had been working with Ford equipment for some time, and was a natural choice. In addition, they had just finished a mid-engine GT car powered by Ford's 289ci (4.2 liter) V8. In 1963, this car became the basis for testing and development of Ford's new LeMans competitor, with the assistance of John Wyer, who was responsible for Ford's GT40 racing program though 1964. Wyer, known for his relationship with Aston Martin, was later moved to production of the MkIII and MkIV cars, with the racing being run by John Shelby and Kar-Kraft, a Ford subsidiary in Detroit.

The first GT40 prototype was completed in April of 1964. Using an all-aluminum 289 with a dry sump and topped with a Weber carburetor, the car developed 350bhp at 7,000 RPM, and a peak of 275 lb-ft of torque at 5,600 RPM. It weighed in at just 1,835 pounds dry, or 2,450 pounds with fluids. For comparison, the curb weight of a 1999 Honda Civic SI coupe is 2,560 lbs. The MkII model (with the 427ci V8) weighed in at 2,000 lb even with oil and water, but no fuel.

The car was light at top speed, however, especially the tail end, and two prototypes were crashed. After being repaired, they were taken to MIRA for a solution to the light rear end. Bruce McLaren and Roy Salvadori were the test drivers, and they found that a spoiler across the width of the tail, contraindicated in wind tunnel tests, caused the rear to settle down and become stable. By mid 1965 the final prototype design was complete, and Ford built 50 of the cars to qualify them for the Production Sports Car category.

Unfortunately, the GT40 MkI did not turn out to be a LeMans race winner, but showed itself to be competitive. Ford developed the MkII, based on the 427ci (7 liter) V-8 engine, which had been successful for them elsewhere. This engine provided 485bhp at 6,200 RPM, and 475 ft-lb at 4,000 RPM, providing more power in a wider band. The bodywork was altered to fit the new engine, and scoops were added to cool the rear brakes. On its first time out, in 1966, the GT40 MkII won the Daytona 24 hour endurance race, finishing first, second, and third. The car went on to repeat the feat at LeMans' 24 hour race, causing quite a stir in the racing community.

Ford also designed an MkIII road model, primarily for America. It was based on the race-bred GT40 design, using the 289ci engine with a Holley carburetor (putting out 306bhp), an insulated body and cockpit, and a more functional interior, as well as moving the shift lever from the right hand side (as previous models of GT40 were laid out in the European style) to the center.

One final model, the MkIV or J-car, came from Ford. It was designed for styling, rather than being run through a wind tunnel, and the results were not good. It was completed by Kar-Kraft in Dearborn, Michigan, back in the US. After wind tunnel testing and subsequent changes to the body, and various chassis improvements, the car was taken to LeMans in 1967. Driven by Dan Gurney and A. J. Foyt, the GT40 MkIVs came in first and fourth, with Ferrari in the second and third place spots. This was the end of Ford's presence at LeMans.

John Wyer felt there was life in the GT40 yet, and received sponsorship from Gulf Oil, bringing us the now-familiar light sky blue and orange paint scheme. His car was enhanced with a wider rear to accomodate wider tires, a stronger engine (developing 400bhp in 1968 and 425bhp in 1969), and other improvements. The same car, serial P1075, won LeMans in both 1968 and 1969, the first car to ever win at LeMans twice. In 1969, the car was clocked at 217 MPH, astonishingly fast for the time. In an attempt to reduce speeds, GT racing adopted new rules governing engine size, and the GT40 retired a champion, having won at LeMans in 1966, 1967, 1968, and 1969.

MODELS

There are four models of "official" GT40, MkI through IV.

  1. GT40 MkI
      Engines:
    • 255ci Indy 4-cam
    • 289ci small block V8
    • 302ci small block V8
    • 351 Windsor V8 (in 1968 and 1969)
    The 289 was the most popular engine, and was tuned to develop between 380 and 400 horsepower for about 24 hours, the length of the LeMans race.

  2. GT40 MkII
      Engines:
    • NASCAR 427ci V8
    This is nothing more than a MkI with a different engine and transaxle. These cars won at Daytona, Sebring, and LeMans in 1966. The big engines carried 4 Weber 48 IDA double choke carburetors - Resulting in one choke and jet per cylinder. This is analogous, for the time, to having direct fuel injection.

  3. GT40 MkIII
      Engines:
    • 289ci small block V8
    Only 7 of these cars were built. This is the street-legal model of GT40. To make a MkI into a MkIII, the engine is detuned (9.0:1 instead of 10.0:1 compression) somewhat, the shocks are softened 25%, the steering wheel and so on are on the left side of the car, and the shift lever is moved to the center. Water lines and such are moved towards the doorsills to make room for the shift lever mechanicals.
    This car's engine developed 335 bhp and the vehicle had a top speed of 164 mph. Two racing fuel cells provided a total capacity of 31 gallons.

  4. GT40 MkIV
      Engines:
    • 427ci V8
    Also known as the "J-car". This is the last GT40 to come from Ford.

SPECIFICATIONS

The following specifications apply to the GT40 MkI. In most cases all numbers will be similar or identical on other models, especially dimensions. The engines, however, differ widely, as do the gearboxes. This information is copied verbatim (with some additional english -> metric translation) from a press release from Ford of Britain.

  • Dimensions
      Basic Dimensions
    • Wheelbase: 95 in. (2413mm)
    • Track, front and rear: 55in. (1397mm)
    • Length: 168 in. (4265mm)
    • Width: 70 in. (1778mm)
    • Height: 40.5 in. (1028.7mm)

      Miscellaneous Heights
    • Base of windscreen: 28.25 in. (717mm)
    • Top of windscreen: 39.2 in. (970.3mm)
    • Top of steering wheel: 31.35 in. (796.3mm)
    • Minimum ground clearance: 4 in. (101.6mm)

  • Weight (oil and water, no fuel)
    • Front: 920lb (414kg)
    • Rear: 1080lb (486kg)
    • Total: 2000lb (900kg)

  • Engine

      Power and Torque:
    • Maximum BHP: 380 @ 6,500RPM
    • Maximum Torque: 330 ft.lb. @ 5,500 RPM


  • Transmission
      ZF 5 DS-25 Transaxle
    • Ratios:
      • Final Drive: 4.22:1 or 3.33:1
      • First: 2.41:1
      • Second: 1.47:1
      • Third: 1.09:1
      • Fourth: 0.96:1
      • Fifth: 0.85:1
      • Reverse: 3.75:1

  • Clutch
      Borg & Beck 3-plate
    • Plate diameter: 7.25 in. (184.15mm)

  • Brakes
    • Front type: Girling CR
    • Front disc diameter: 11.5 in. (292.1mm)
    • Rear type: Girling BR
    • Rear disc diameter: 11.5 in. (292.1mm)

  • Steering
      Rack and Pinion
    • Ratio: 14.1
    • Turns, lock to lock: 2.8
    • Turning circle diameter: 37 ft. (11.27m)
    • Steering wheel diameter: 15 in. (381mm)
    • Steering wheel adjustment: 2 in. (50.8mm)

  • Wheels and Tires
      Borrani light alloy wire spoke wheels
    • Front wheel size: 6.5x15 in. (165.1x381mm)
    • Rear wheel size: 8x15 in. (203.2x381mm)

      Dunlop tires
    • Front size: 5.5x15 in. (139.7x381mm)
    • Front loaded radius: 12 in. (304.8mm)
    • Rear size: 7.25x15 in. (184.15x381mm)
    • Rear loaded radius: 14.75 in. (374.65mm)

      Goodyear tires
    • Front size: 5.5x15 in. (139.7x381mm)
    • Front loaded radius: 12.4 in. (314.96mm)
    • Rear size: 7x15 in. (177.8x381mm)
    • Rear loaded radius: 13.4 in. (340.36mm)

  • Fuel System
  • Cooling System
      Radiator
    • Type: Marston light alloy
    • Total area: 318.75 in^2 (2056cm^2)
    • Depth: 3 in. (76.2mm)

      Oil Cooler
    • Type: Serck light alloy
    • Total area: 53.2 in^2 (343cm^2)
    • Depth: 2 in. (50.8mm)

  • Exhaust System
      Tuned cross-over exhaust
    • Pipe diameter: 1.5 in. (38.1mm)

  • Electrical System
    • Voltage: 12VDC
    • Battery Capacity: 57 AH

Specifications for the MkIII (road car) are also provided, as differences from the car's normal specs.

  • Engine

      Power and Torque:
    • Maximum BHP: 335 @ 6,250RPM

  • Clutch
      Borg & Beck 2-plate
    • Plate diameter: 8.5 in. (215.9mm)


GT40 CONCEPT

The Ford GT-40 concept car, which became the Ford GT with only minor modifications, shares a great deal with its predecessors though it is three and a half inches taller, seven inches wider, and ninteen inches longer. The lines, however, are substantially similar to the original car. The car is once again powered by an American V-8, now the MOD 5.4 liter. This engine has four valves per cylinder, a forged crankshaft, forged connecting rods, and aluminum pistons. When coupled with its Eaton supercharger, the engine develops 500 hp and 500 foot pounds of torque, delivered to the rear wheels by a six-speed manual transaxle. The chassis has gone from a semi-monocoque steel setup to an all-aluminum space frame. Like the original, it features four wheel independent suspension. Rubber meets the road in the form of 18x8 inch tires in front, and 19x10 in the rear.

What makes this car special, and sets it apart from other concept cars, is the absence of unnecessary electronics, down to the point of having analog gauges. Offering it only with analog gauges might be a mistake, considering the fact that digital displays are becoming more and more common in racing use.


References:

  1. Prater, Matthew L. The Ford GT40 (http://www.me.mtu.edu/~prater/GT40/GT40.html)
  2. Ford GT-40 Concept. Ford Motor Company. (http://www.ford.com/en/ourVehicles/autoShows/detroit2002/vehicles/ford/fordGT40Concept/default.htm)
  3. Bartlett, Jeff. Ford GT40. Motor Trend Online. (http://www.motortrend.com/jan02/gt40/gt40_f.html)
  4. Guest, Richard. The Ford GT40 - The Early Years. (http://www.pncl.co.uk/~sundt/gt40st15.html)
  5. Chris' Car Site. (http://www.cars.simplenet.com/)
  6. Ford of Britain Public Affairs Staff. THE FORD GT40 - Background to the Le Mans Entries. Warley, Brentwood, Essex, 13th January, 1966. (Press release)

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