Editing Ford GT40 (section)

== Original versions ==
=== Mk I ===
[[File:1969-06-01 Ford GT 40 von Kelleners-Jöst.jpg|thumb|A GT40 Mk I competing in the 1969 [[Nurburgring 1000]]&nbsp;km race]]
[[File:Gulf Racer (8716645127).jpg|thumb|Mk I in [[Gulf Oil]] colors]]
[[File:1968 Ford GT40 Mk I (14288662849).jpg|thumb|1968 GT40 Mk I]]

The Mk I was the original Ford GT40. Early prototypes were powered by 255 cu in (4.2 L) [[alloy]] [[V8 engine]]s<ref>{{cite web|url=http://www.racingsportscars.com/photo/Nurburgring-1964-05-31.html|title=Nürburgring 1000 Kilometres 1964|access-date=18 April 2010}}</ref> and production models were powered by [[Ford Windsor engine#289 HiPo (K-code)|{{cvt|289|CID|L|1}} engines]] as used in the [[Ford Mustang]]. Five prototype models were built with [[Roadster (automobile)|roadster]] bodywork, including the Ford X-1.<ref name=isr/> Two lightweight cars (of a planned five), AMGT40/1 and AMGT40/2, were built by Alan Mann Racing in 1966, with light alloy bodies and other weight-saving modifications.

The Mk I met with little success in its initial tune during the 1964 season. After the [[Bahamas Speed Week|Nassau]] in December, Ford handed over the project to Carroll Shelby's [[Shelby American]] team. The car won the 1965 [[24 Hours of Daytona#2000 km distance|Continental 2000 km of Daytona]] and the [[12 Hours of Sebring]], but otherwise the GT40 program was a disappointment overall, once again failing to finish at Le Mans. Much was later modified and run by [[J.W. Automotive]] (JW) in 1968 and 1969, winning Le Mans in both those years and [[Sebring International Raceway|Sebring]] in 1969. The Mk II and IV were both obsolete after the [[FIA]] had changed the rules to ban unlimited capacity engines, ruling out the 427 cu in (7 L) Ford V8. However, the Mk I, with its smaller engine, was legally able to race as a [[homologated]] sports car because of its production numbers.

In 1968, the GT40's main rival was the [[Porsche 908]], which was the first prototype built for the 3-liter Group 6. The result was a resounding success for the Mk I at the [[1968 24 Hours of Le Mans|24 Hours of Le Mans]], with [[Pedro Rodríguez (racing driver)|Pedro Rodríguez]] and [[Lucien Bianchi]] having a clear lead over the Porsches driving the 'almighty' #9 car with the '[[Gulf Oil]]' colors.<ref>{{cite web |url=https://primotipo.com/tag/ford-gt40-1076/ |title=Posts Tagged 'Ford GT40 '1076''|website=Primotipo.com|editor=GP Library|first=Rainer|last=Schlegelmilch|date=May 9, 2016|access-date=2018-09-08}}</ref> The season began slowly for JW, losing at Sebring and Daytona before taking their first win at the BOAC International 500 at Brands Hatch. Later victories included the Grand Prix de Spa, 21st Annual [[Watkins Glen International|Watkins Glen]] Sports Car Road Race and the 1000&nbsp;km di Monza.<ref>{{cite web|url=https://www.supercars.net/blog/1968-ford-gt40-mark-gulf-oil/|title=1968 Ford GT40 Mark I 'Gulf Oil'|website=supercars.net|language=en-US|access-date=2018-06-10|date=20 April 2016}}</ref> The engine installed on this car was a [[naturally aspirated]] [[Ford Windsor engine#302|Windsor]] {{convert|302|cuin|L|1|abbr=on}} [[V8 engine|V8]] with a [[compression ratio]] of 10.6:1; fuel fed by four 2-barrel 48 IDA [[Weber Carburetors|Weber]] carburettors, rated at {{convert|317|kW|hp PS|0|abbr=on}} at 6,000 rpm and a maximum [[Torque#Machine torque|torque]] of {{convert|395|lbft|Nm|0|abbr=on}} at 4,750 rpm.<ref>{{cite web|url=https://www.ultimatecarpage.com/spec/1599/Ford-GT40-Mk-I-Gulf.html|title=Ford GT40 Mk I Gulf specifications|website=ultimatecarpage.com|language=en-US|access-date=2018-06-10}}</ref>

A total of 31 Mk I cars were built at the Slough factory in "road" trim, which differed little from the race versions. Wire wheels, carpet, ruched fabric map pockets in the doors and a cigarette lighter made up most of the changes. Some cars deleted the ventilated seats, and at least one (chassis 1049) was built with the opening metal-framed windows from the Mk III.

; X-1 Roadster
The X-1 was a roadster built to contest the Fall 1965 North American Pro Series, a forerunner of [[Can-Am]], entered by the Bruce McLaren team and driven by Chris Amon. The car had an aluminium chassis built at Abbey Panels and was originally powered by a 289 cu in (4.7L) engine. The real purpose of this car was to test several improvements originating from Kar Kraft, Shelby, and McLaren. Several gearboxes were used: a [[Hewland]] LG500 and at least one automatic gearbox. It was later upgraded to Mk II specifications with a 427 cu in (7 L) engine and a standard four ratio Kar Kraft (subsidiary of Ford) gearbox, however, the car kept specific features such as its open roof and lightweight aluminium chassis. The car went on to win the [[1966 12 Hours of Sebring|12 Hours of Sebring]] in 1966. The X-1 was a one-off and, having been built in the United Kingdom and being liable for United States [[tariff]]s, was later ordered to be destroyed by United States customs officials.<ref>{{cite web|url=http://www.supercars.net/cars/2492.html|title=Ford GT40 X1|work=supercars.net|date=20 April 2016 }}</ref>
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=== Mk II ===
[[File:Ford GT40 (rear).jpg|thumb|left|GT40 Mk II rear]]
The Mk I design was altered separately by both Holman Moody and Shelby American to handle the much larger highly modified {{cvt|427|cuin|l|1}} "big block" [[Ford FE engine]] side oiler from the Ford's large family car called [[Ford Galaxie]], used in NASCAR at the time and modified for road course use. Referred to retroactively as the ''Ford Mk II'', the car had a new Kar Kraft-built four-speed gearbox (KKL-108 also called a Ford box) in place of the overpowered ZF five-speed (which had already belatedly replaced the over-stressed Colleti in the Mk I)<ref>{{Cite web|url=https://www.zf.com/mobile/en/stories_25280.html|title=Ford v Ferrari and the Era of the Ford GT 40 - ZF}}</ref> used in the Mk I.

In 1966, the three teams racing the Mk II ([[Chris Amon]] and [[Bruce McLaren]], [[Denny Hulme]] and [[Ken Miles]], and [[Dick Hutcherson]] and [[Ronnie Bucknum]]) dominated Le Mans,<ref>{{cite web| url = https://database.motorsportmagazine.com/database/races/1966-le-mans-24-hours| url-status = dead| archive-url = https://web.archive.org/web/20200126092240/https://database.motorsportmagazine.com/database/races/1966-le-mans-24-hours| archive-date = 26 January 2020| title = 1966 Le Mans 24 Hours {{!}} Motor Sport Magazine Database}}</ref> taking European audiences by surprise and beating Ferrari to finish 1-2-3 in the standings. The Ford GT40 went on to win the race for the next three years.

For 1967, the Mk IIs were upgraded to "B" spec, with re-designed bodywork and twin Holley carburettors (giving an additional {{Convert|11|kW|hp PS|abbr=}}). The new bodywork removed two top vents, which were for cooling rear brakes and added a spare wheel at the rear end. A batch of improperly heat-treated input shafts in the transaxles side-lined virtually every Ford in the race at the 24 Hours of Daytona, however, and Ferrari won 1–2–3. The Mk IIBs were also used for Sebring and Le Mans that year and won the Reims 12 Hours in France. For the Daytona, two Mk II models (chassis 1016 and 1047) had their bodies and engines re-badged as [[Mercury (automobile)|Mercury]] vehicles and engines<ref>{{cite web |last1=Peek |first1=Jeff |title=Costume change: Ford's little-known Mercury GT40s |url=https://www.hagerty.com/media/automotive-history/fords-little-known-mercury-gt40s/ |website=Hagerty Media |date=4 October 2018 |publisher=Hagerty |access-date=24 June 2024}}</ref> to promote that division of the Ford Motor Company.<ref>{{Cite book|last1=Li|first1=Naiyi|last2=Chen|first2=Xiaoming|last3=Hubbert|first3=Tim|last4=Berkmortel|first4=Richard|title=SAE Technical Paper Series |date=2005-04-11|chapter=2005 Ford GT Magnesium Instrument Panel Cross Car Beam|volume=1 |chapter-url=https://www.sae.org/publications/technical-papers/content/2005-01-0341/|language=en|location=Warrendale, PA|doi=10.4271/2005-01-0341 }}</ref>

In 2018, a Mk II that was 3rd overall at the 1966 Le Mans 24 Hours was sold by [[RM Sotheby's]] for $9,795,000 (£7,624,344) - the highest price paid at that time for a GT40 at auction.<ref>{{Cite web|url=https://www.theclassicvaluer.com/cars/ford/gt40|title=Price Guide: Ford GT40 [UPDATED 2025]|website=The Classic Valuer}}</ref>

=== Mk III ===
[[File:1968 Ford GT40 Mark 3 Red.jpg|thumb|Ford GT40 Mk III]]
The Mk III was a street-legal version of the GT40 Mk I, with its {{cvt|289|cuin|l}} engine detuned to {{convert|228|kW|hp PS|abbr=on}}.  A total of  seven were built,<ref name=isr /> four with right-hand drive, with four headlamps (raised to meet US lighting standards), an expanded rear (for luggage room), softer shock absorbers, a center-mounted shift lever, and an ashtray. {{clarify span|text=As the Mk III looked significantly different from the racing models due to the aforementioned lighting and lengthening for storage|reason=How?  Please explain, and, ideally, illustrate.|date=August 2024}} many customers interested in buying a GT40 for road use chose to buy a Mk I{{according to whom|date=August 2024}} that was available from Wyer Ltd.{{how|date=August 2024}}

=== Mk IV ===
[[File:1967 GT40 Mk IV at 2010 Canadian International AutoShow.JPG|thumb|left|1967 Ford GT40 Mk IV. This particular car, J-4, won the 1967 [[12 Hours of Sebring]].]]

In an effort to develop a car with better [[aerodynamics]] (potentially resulting in superior control and speed compared to competitors), the decision was made{{when|date=August 2024}} to re-conceptualize and redesign everything about the vehicle other than its 7-liter engine. This became the  Mk IV.<ref name="supercars.net">{{cite web|url=http://www.supercars.net/cars/694.html|title=1967 Ford GT40 Mark IV|access-date=2010-02-23|work=supercars.net}}</ref>

{{clarify span|text=In order to bring the car into alignment with Ford's "in house" ideology at the time,|reason=What is this word salad trying to say? *Specifically*.  And concisely.|date=August 2024}} more restrictive partnerships were implemented with English firms.  This resulted in the sale of Ford Advanced Vehicles to [[John Wyer]], ultimately leading to a new vehicle which would be slated for design by Ford's studios and produced by Ford's subsidiary Kar-Kraft under [[Ed Hull]]. Furthermore, there was also a partnership with the [[Brunswick Aircraft Corporation]] for expertise on the novel use of [[aluminium]] [[Honeycomb structure|honeycomb]] panels bonded together to form a lightweight, rigid "tub".

The nickname "J-car" came from its construction to meet the new Appendix J regulations<ref>{{cite web|url=http://www.ultimatecarpage.com/car/3406/Ford-Mk-IV.html|title=Ford Mk IV|access-date=22 February 2010}}</ref> introduced by the FIA in 1966;<ref>{{cite web|url=http://www.fia.com/resources/documents/2102817986__Hist_App_J_69_Art_252_a.pdf|title=Appendix J to the International Sporting Code|access-date=23 February 2010|archive-url=https://web.archive.org/web/20050302205843/http://www.fia.com/resources/documents/2102817986__Hist_App_J_69_Art_252_a.pdf|archive-date=2 March 2005|url-status=dead|df=dmy-all}}</ref> the redesign resulted in the abandonment of the original Mk I/Mk II chassis.

The first J-car was completed in March 1966 and set the fastest time at the Le Mans trials that year. The tub weighed only {{convert|86|lb|abbr=on}}, and the entire car weighed only {{convert|2660|lb|abbr=on|0}}, {{convert|300|lb|abbr=on|0}} less than the Mk II. In spite of this, it was decided to run the Mk IIs due to their proven reliability, and little or no development was done on the J-car for the rest of the season. Following Le Mans, the development program for the J-car was resumed, and a second car was built. During a test session at [[Riverside International Raceway]] in August 1966 with [[Ken Miles]] driving, the car suddenly went out of control at the end of its high-speed, {{convert|1|mi|km|adj=mid|-long|spell=in}} back straight. The honeycomb chassis shattered upon impact, and the car burst into flames, killing Miles.<ref name=stpcrk>{{cite news |url=https://news.google.com/newspapers?id=8l4xAAAAIBAJ&sjid=UHQDAAAAIBAJ&pg=3679%2C4254231 |work=St. Petersburg Times |location=(Florida) |agency=UPI |title=Crash kills ace driver Ken Miles |date=August 18, 1966 |page=1C}}</ref><ref name=dbmjapdir>{{cite news |url=https://news.google.com/newspapers?id=qZotAAAAIBAJ&sjid=vZ4FAAAAIBAJ&pg=3488%2C3514531 |work=Daytona Beach Morning Journal |location=(Florida) |agency=Associated Press |title=Miles dies in crash |date=August 18, 1966 |page=25}}</ref> It was determined that the unique, flat-topped "bread van" aerodynamics of the car, lacking any sort of spoiler, led to excess lift. Therefore, a conventional but significantly more aerodynamic body was designed.<ref name="supercars.net"/> A total of nine cars were constructed with J-car specification chassis, with six designated as Mk IVs and one as the G7A.<ref name=isr />

=== Racing ===
[[File:Winner at Le Mans (53535080453) (cropped).jpg|thumb|Ford GT40 Mk IV]]

The Mk IV was built around a reinforced J chassis powered by the same 7.0 L engine as the Mk II. Excluding the engine, gearbox, some suspension parts and the brakes from the Mk II, the Mk IV was totally different from other GT40s, using a specific, all-new chassis and bodywork. It was undoubtedly the most radical and American variant of all the GT40s over the years. As a direct result of the Miles accident, the team installed a NASCAR-style steel-tube roll cage in the Mk IV, which made it much safer, but the roll cage was so heavy that it negated most of the weight saving of the then-highly advanced, radically innovative honeycomb-panel construction. The Mk IV had a long, streamlined shape, which gave it exceptional top speed, crucial to do well at Le Mans (a circuit made up predominantly of straight roads connecting tight corners)—the race it was ultimately built for. A 2-speed automatic gearbox was tried, but during the extensive testing of the J-car chassis in 1966 and 1967, it was decided that the 4-speed from the Mk II would be retained.

In 1966 and early 1967, Ford's R&D department in Detroit developed a test rig to simulate circuit laps; the rig was programmed to accurately mimic the characteristics of the target circuit. The Mk IV design was revised based on weeks of simulated Le Mans laps. This was an early example of the now-common practice of using test rigs for Formula One and Le Mans vehicle protoyping.<ref>{{Cite web |title=Ford v Ferrari: The Untold Story that Saved Ford's Race |url=https://www.caranddriver.com/features/a29790131/ford-v-ferrari-mose-nowland/ |archive-url=http://web.archive.org/web/20230306213644/https://www.caranddriver.com/features/a29790131/ford-v-ferrari-mose-nowland/ |archive-date=2023-03-06 |access-date=2025-04-28 |website=www.caranddriver.com |language=en-us}}</ref>

Thanks to its streamlined aerodynamics, the car proved to be fastest in the field at Le Mans in 1967, achieving 213&nbsp;mph on the 3.6-mile [[Mulsanne Straight]].

Dan Gurney, who was 6 feet 4 inches tall, requested a bubble-shaped bodywork extension over the driver's seat to accommodate him. Gurney also complained about the weight of the Mk IV, which was {{convert|600|lb}} more than the Ferrari 330 P4, and, combined with its higher speed, put more stress on its brakes. During practice at Le Mans in 1967, in an effort to preserve the brakes, Gurney developed a strategy (also adopted by co-driver [[A.J. Foyt]] who had just won the [[1967 Indianapolis 500]]) of backing completely off the throttle several hundred yards before the approach to the Mulsanne hairpin and virtually coasting into the braking area. This technique saved the brakes, but the resulting increase in the car's recorded lap times during practice led to mistaken speculation within the Ford team that Gurney and Foyt, in an effort to compromise on chassis settings, had hopelessly "dialed out" their car - despite Gurney having been the fastest GT40 pilot in the 1966 practice and race. Also, Gurney was developing his own Eagle V12 F1 car with which he would win the [[1967 Belgian Grand Prix]] the very next weekend.

The Mk IV ran in only two races, the April [[1967 12 Hours of Sebring]] and the June [[1967 24 Hours of Le Mans]], and won both events. Only one Mk IV was completed for Sebring; the pressure from Ford had been increased considerably after Ford's humiliation at the [[1967 24 Hours of Daytona|1967 Daytona 24h]] in early February, when Ferrari staged a 1-2-3 finish, honored later by naming a road car the [[Ferrari Daytona]]. [[Mario Andretti]] and [[Bruce McLaren]] won Sebring, Dan Gurney and A. J. Foyt won Le Mans (their car was the Mk IV that was apparently least likely to win),{{according to whom|date=August 2024}}{{why|date=August 2024}} where the Ford-representing Shelby-American and Holman & Moody teams showed up to Le Mans with 2 Mk IVs each.<ref name="supercars.net" /> The installation of the roll cage was ultimately credited by many with saving the life of Andretti, who crashed violently at the Esses during the 1967 Le Mans yet escaped with minor injuries. Gurney later described the Mk IV as "''half-way between a road-legal passenger car and a race car; it was reliable and comfortable, but heavy''".<ref>{{cite web | url=https://www.youtube.com/watch?v=A6Kj3n-NDt0 | title='Behind the Headlights' the story of the Ford GT40 | website=[[YouTube]] | date=11 February 2019 }}</ref>

Unlike the earlier Mk I - III cars, the chassis of which were built in Britain, the Mk IV car was built entirely in the United States by Kar Kraft, Ford's performance division in [[Detroit]]. Thus, Le Mans 1967 still remains both the only all-American victory in Le Mans history — American drivers ([[Dan Gurney]] and [[A. J. Foyt]]), team ([[Carroll Shelby International|Shelby-American Inc.]]), chassis constructor ([[Ford Motor Company|Ford]]), engine manufacturer (Ford), and tires ([[Goodyear Tire and Rubber Company|Goodyear]]) — as well as the only victory of a car designed and built entirely (both chassis and engine) in the United States. A total of six Mk IVs were constructed.<ref name=isr />

One of the Mk IVs was rebuilt to [[Group 7 (motorsport)]] rules as the [[Ford G7]] in 1968, and used in the [[Can-Am]] series for 1969 and 1970, but with no success.<ref name=isr />
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