Fortification is the Club Magazine of the GT40 Enthusiasts Club
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THE FORD GT40
Background to the Le Mans Entries In the summer of 1962 Henry Ford II decided that Ford Division should participate in the International Competition field. Ford Division operate their own Engineering Department which is concerned with future design, and they are also responsible for marketing the cars carrying the name of Ford. Production of cars is not part of their responsibilities but they are, of course, able to call upon other divisions such as Research, Engine and Foundry, Styling and so on, so that when given this new task they could seek success with the force of the entire organisation.
It is a matter of history that considerable success has since been won, in rallies and track events all over the world and rear engined Indianapolis cars powered by Ford engines have in the past two years revolutionised the design of these track cars.
In parallel with these excursions into Rally and Classic American races Ford decided in 1963 to enter the road racing field in GT prototype class, wherein h might be possible to secure success with power units resembling those supplied en masse to the American market, and in which the lessons learned in reducing drag and increasing road stability might have long term application on production cars.
In order to get into the business of racing with minimum delay, a subsidiary company called Ford Advanced Vehicles was set up at Slough in England under the Managing Directorship of John Wyer, well known for his long and successful association with Aston Martin, who won the Manufacturers Championship in 1959 including victory in the Le Mans 24 hour race. In order to reduce time spent on design and development the two 1962 Lola GT cars, into which Eric Broadley had fitted V8 Ford engines, were purchased together with retention of the whole time services of Broadley himself during this introductory period of 1963/64.
Serious engineering work on the project began in August 1963 and between then and February 1964 the frame design was wholly revised and became a spot welded hull stiffened longitudinally by square tubes running downwards from the scuttle to the front suspension elements. A separate assembly attached at the back of the car supported the tail and rear engine mounting.
The core of the car was, in a sense, the transverse bulk-head which formed the back of the seats with seat pans themselves an integral part of the floor adjustments - leg room being adjusted by shifting the pedals.
The rear suspension layout, with very widely spaced transverse links and long radius arms, is of the type originated by Broadley, and since generally adopted in the motor racing world, and the front wishbone and coil system was used in conjunction with rather short arms.
As originally set up, the engine fitted was the all aluminium Indianapolis version of the Ford Fairlane 4.2 litre engine (95.5 x 72.9 mm). This gave 350 bhp at 7200 rpm which was transmitted to an unsynchronised Colotti 4 speed gearbox, giving intermediate ratios of 1.29; 1.70 and 2.50 to 1. Top gear (1:1) was 3.09:1.
When the cars appeared first, at the Le Mans training, only 8 months had elapsed since work had commenced and `work' had not only meant the development of cars but the building up of entirely new organisation from scratch, securing suppliers, installing quality control and so on.
The Ford engagement on this particular front was not on the massive scale which one might associate with the second largest builders of motor cars in the world. On the contrary so far as the GT cars were concerned, the policy adopted was like that of Mercedes Benz who, when they appeared in the Mille Millgia in 1952, intended, in Professor Nallinger's words, `to open a little window on the racing scene`. The total strength at Slough was never more than two dozen on the floor with an office staff of less than ten.
During 1964 cars were entered for the 1,000 km race at the Nurburgring; the 24 hour race at Le Mans; 12 hours at Reims and at Nassau. In these events, and after some modifications to the profile and adjustments to the trim of the car after the Le Mans training period, very high speeds were demonstrated and the official Le Mans lap record went to Phil Hill in 3 mts. 49.2 seconds or 131.37 mph, with Ginther a little slower at 3 mts. 51 seconds. Only the 4 litre Ferraris were able to approach these speeds but in the course of 110 laps the leading Ford had secured a 1% margin over its nearest rival and had been timed on the straight at 207 mph.
As in the 1,000 km race earlier, the cars were eliminated by transmission failures and the prime effort during the winter months of 1964/65 has been to remedy this weakness.
During 1965 the GT40 won its first race at Daytona, was lying second in the Targa Florio when eliminated by an accident and was lying third in the 1,000 km race at Nurburgring when eliminated by an engine mounting failure.
At the 1965 Le Mans training, effort was concentrated on tyre testing in the course of which Attwood lapped the circuit in 3.49.0 without fully extending the car.
THE 1965 COMPETITION CARS
It will be seen from the attached specification that the architecture and general dimensions of the Ford GT cars remained unchanged as between 1964 and 1965. There have, however, been two considerable changes in that the engine and gearbox are new.
The engine now has a swept volume of 4736 cc with a bore and stroke of 101.6 x 77.9, this being the unit fitted to the Fairlane 500 model in the USA.
The production form with a compression ratio of 9.3:1, and with a maximum torque of 2400 ft. min. with a single double choke carburettor, this engine gives 203 hp. It gives 271 bhp in conjunction with a 10.9:1 compression ratio at 6000 rpm, with a peak torque at 3400 rpm.
As installed in the GT40 model 380 bhp is realised at 6500 rpm with 330 lb ft torque at 5500 rpm. The compression ratio is 1 0:1 and the main difference is the use of 4 Weber 48 IDA double choke carburettors so that in effect each cylinder is provided with its own choke and jet assembly.
Broadly speaking, the effect of installing the 14% larger, and somewhat heavier, engine has been to raise the maximum power by around 10% at approximately 10% less rpm, and to increase the maximum torque by 20% at the same crankshaft speed.
To meet these demands the Zahnradfabrik Friedrichshaven have designed and supplied gearboxes which are an almost miraculous combination of compactness and load carrying capacity. The former must be related to the introduction of 5 synchronised speeds giving ratios of 0.85; 0.96; 1.09; 1.47 and 2.42 to 1 in conjunction with the option of 3.33 or 4.22 to 1 in the final drive, which is also a ZF production.
The gear case is only 21.0 ins long and the complete weight of the transmission, including the transaxle a mere 127 lb.
This notwithstanding it has endured extreme overload conditions including sustained maximum torque at twice the maximum speed at which this normally will be delivered; that is to say, twice the power that can be expected will be transmitted through the gear case. And this for over 10 hours.
Experiments are continuous with wheels, tyres and shape. In respect of the first, the cars will run at Le Mans with cast spoke alloy wheels but no fixed decision has yet been made about the tyres mounted upon them.
The nose shape of the Ford GT40 is somewhat compromised by the forward mounting of the spare wheel which, at Le Mans, must be removed and replaced during the pit stop. Shape must therefore in some degree be sacrificed to ease the wheel removal, but certain lessons were learned during April training period and an extended `DROOP SNOOT will be seen on the cars on June 19/20th.
On last year's cars the aerodynamic lift phenomenon relieved the rear tyres of 240 lb of weight, or around 20% of the load that they would be carrying statically The introduction of a transverse spoiler has converted this upward thrust into a net load of 140 lb which adds about 1 0% to the present static load and considerably improves high speed stability.
The 4.72 litre engine has a wet sump and for racing purposes on some circuits the oil is circulated through a heat exchanger mounted in the tail. Provision is also made for circulating the gearbox oil from the pump normally fitted through an additional tail mounted heat exchanger.
The present purpose of Ford Advanced Vehicles is to explore within relatively limited means the problems peculiar to high speed motoring.
To do this on a base which will have some statistical significance it was decided, once the design had reached the stage when it could be offered with complete confidence, to set up a production line for the manufacture of 50 cars.
The line is now in being at Slough where final assembly takes place of components derived from international sources.
In brief, the main steel body pressing comes as a hull from Abbey Panels Ltd of Coventry. The nose, tail and door sections are derived from Fibre Glass Engineering Ltd of Farnharn, and when they have been brought together to form a complete shell the whole car is upholstered, trimmed and painted by the well-known coach builders Harold Radford, who also fit up the Marchal lights imported from France.
It is received in this form at Slough for the attachment of the running gear, that is to say front and rear suspension elements, Girling disc brakes and steering mechanism. At the same time the engine from Dearborn is coupled to the transmission from the Bodensee and the whole assembly then mounted on Borrani wire wheels imported from Italy.
The cars presently being made are specifically intended for Competition and a large part of the sanction has already been sold at £5,200 each. lt is probable that during the year a road version with a variety of owner amenities, will be introduced to supplement the existing design.
FORD ADVANCED VEHICLE PERSONALITIES
In the first half of this century the only British car to achieve GP success was Sunbeam, and it was in the racing division of this concern that John Wyer served a large part of his time. He later worked with Solex Ltd and Monaco Engineering Ltd, but from 1955 to 1963 he was in the employ of Aston Martin Lagonda Ltd, being firstly their Competition Manager and subsequently General Manager and Technical Director.
Roy Lunn was in the Design Office of Aston Martin in 1949/50, after which he became Chief Engineer at Jowett, and then joined Ford at Dagenham from where he transferred to Dearborn in the Research Division. His present position is Manager of Advanced Concepts, and in this capacity he worked with Ford Advanced Vehicles at Slough from August 1963/64, supervising the development of the cars up to the completion of the first prototype, and the modifications made for them in the early part of the 1964 racing season.
Those presently concerned under John Wyer for the development and production of the vehicle include:
Apprentice toolmaker at Seimens Bros of Woolwich. 2 years in R.A.F. Tool designer at Cape Asbestos and S Smith & Sons. Chief designer at John A Smith of London and Wolverhampton, Design Consultants. Chief Tool Designer and Methods Engineer at Marconi. Director of Ascott-Murphy, Hainault, Design and Production Engineering Consultants.
Engineering apprentice at Austin Motor Co. Development Engineer in E R A. Engine Designer at Daimler and Rover. Engine and Chassis designer at Austin. Chassis designer at Ford of Canada. Engine and Chassis designer at American Motors. Chassis designer at Ford of USA.
Trainee Dunlop Rubber Co and later Technical Service Engineer in South Africa and New Zealand. Partner in Rootes and Chrysler dealership in New Zealand.
M.A. (Cantab). Pupil apprentice David Brown & Sons. Development Engineer and Assistant to General Manager, Aston Martin Lagonda.
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