Last year’s victory by the new 2-litre Aston-Martin at Spa is still talked of by Aston-Martin enthusiasts, and with a team of aerodynamic Aston-Martin saloons in course of preparation for this year’s Le Mans and Spa races we deemed it time to call on designer Claude Hill at Feltham and discover a few things about the present 2-litre Aston-Martin car.
Hill was, at it were, born and bred on Aston-Martins. He started with Bertelli and Renwick as a lad, somewhere about 1924, and recalls commencing the engine of the first Bertelli production, the R and B. He migrated to Feltham with Bertelli and has been with Aston-Martin ever since, for upwards of twenty years, with two small lapses when he went to Morris and Vauxhall for a while. To-day he is Technical Director of the Company.
Quite a while before the Hitler war R. Gordon Sutherland, who has recently resigned from the Board of the Company, but who was then the power behind the scenes, decided that the current 2-litre Aston-Martin was rather out dated, being low, heavy and complicated. So he set Hill off on designing the “Atom,” with comfort, a flat floor, and good roadholding and steering as the primary aims. Hill produced a revolutionary chassis frame of steel tubing and fitted the car with a semi-aerodynamic saloon body of unstressed alloy panels. The o.h.c. 2-litre engine was retained, a Cotal gearbox was employed, and a system of trailing-link coil spring i.f.s. was evolved. At the rear half-elliptic suspension was retained but with comparatively soft springs. This prototype “Atom” was completed in 1939 and used extensively thereafter by Mr. Sutherland. Indeed, it has now done something like 90,000 miles and, we are assured, will still do its 90 m.p.h. and displays no trace of body rattles. As a matter of fact Aston-Martin have done plenty of experimental work on their 2-litre cars, for prior to the “Atom” they devised “Donald Duck,” which was the original 1936 2-litre saloon, endowed, in 1938, with an all-steel saloon body and such departures from standard as Lockheed brakes, new mountings for the o.h.c. engine, amidships fuel tank, etc. This purely experimental car — EML 132 — encouraged its sponsors by doing 90 m.p.h. at 4,650 r.p.m., and some 22 m.p.g. when endowed with twin Zenith carburetters and suction advance and retard control.
During the war Hill concentrated on a further development of these cars and finished up with an entirely new 2-litre Aston-Martin, the car we know to-day and which proved itself at Spa last year, in company with Peter Clark’s H.R.G. team which took the Roi de Belge Cup. “What,” I asked Hill, at his office in a disused fire-station on Hanworth aerodrome, “were the main requirements you had in mind for the new car?” “Mainly,” he replied, “a simple construction that would lend itself to comparatively small-scale production, first-class steering and roadholding, and a car capable of a genuine 90 m.p.h. and really comfortable riding.”
So Hill evolved the now familiar framework of rectangular and square steel tubing which replaces the old-style deep-section whippy channel-section chassis. It is so simple that two men can make up a complete frame in ten days, yet it is so rigid that suspension seemingly ridiculously flexible for a fast car can be employed with exceedingly satisfactory roadholding qualities. Hill told me that he had purposely chosen rectangular or square tubing as being so much more easy to handle, and to attach things to, than round tubing. He showed me how tubing of different sizes is jointed by cunningly cutting the ends so that equal lengths of diagonal are formed, and he proudly said that ordinary low-carbon, mild-steel tubing suffices. The joints are gas or arc-welded according to their position, and the lower tubes, forming the sidemembers, are of 13-gauge, those of the superstructure of 18-gauge. The depth of the main tubes is 3 inches, to which 2 1/2-inch deep extension tubes are attached, terminating in 2 1/2-inch deep tubes at the rear of the frame. The bulkhead was arranged as a main cross-member and the superstructure was purposely made sufficiently wide to enable a three-abreast seat to be installed. Hill made no attempt to fit the body panels to the chassis frame; these panels are carried on special adaptors, so that they can be shaped as required.
The suspension for the new car was another complete breakaway from prewar Aston-Martin practice. “I felt it essential,” Hill told me, “to employ really soft springs to obtain truly comfortable riding and I was confident that I could do this without destroying sportscar controlability, by employing a frequency of 90 cycles per minute at the front and 100 at the rear of the car.” An improved version of the “Atom” trailing-link i.f.s. is used, the 7-inch links being pivoted on really substantial needle roller and ball bearings accommodated in a tubular, light-alloy chassis crossmember, filled with thin engine oil, which not only keeps the trailing-link bearings properly lubricated, but which provides a bleed for lubricating the bearings of the steering bell-crank. A torsional anti-roll bar runs through the centre of this cross member. “Can the customer replenish this oil supply?” I queried. “Oh, yes,” said Hill, unfolding a drawing, “we provide a filler plug but we have found that no leakage occurs and that the oil remains in good condition after prodigious mileages.” Indeed, I was told that after 20,000 miles the grinding marks were still plainly visible on the trailing-link bearings. Thus the accurate functioning of this i.f.s. system is assured, while obviating much laborious servicing routine.
The coil springs used in this i.f.s. system are some eight or nine inches long, of 4 1/2-inch outside diameter and of -inch gauge. Armstrong hydraulic shock-absorbers are used, their arms forming the upper link of the suspension-system parallelogram.
In conjunction with this i.f.s., Hill plotted a very accurate steering geometry, the two separate tie-rods overlapping and moving, as it were, as part of a cone. As previously mentioned the bell-crank to which they are linked runs on needle-roller bearings lubricated from the oil reservoir formed in the front cross-member. The steering box is of Marles manufacture.
In the matter of rear suspension while retaining a conventional hypoid rear-axle, Hill evolved a system of trailing members to carry it and sprung it on coil springs, “because they are neater than leaf springs, less affected by the weather, etc., and help to solve the problem of countering brake torque reaction.” The springs are of the same size as those at the front, but are of 1/2-inch gauge. To obtain the high degree of roadholding required Hill kept the new chassis low and arranged the roll centres to be at ground level at the front and at hub-level at the back. An anti-sway bar is used, and Armstrong shock-absorbers are mounted on the axle. Reverting to the simplicity of the chassis from the manufacturing angle, nothing in the i.f.s. layout is handed,” everything except the shock-absorbers being interchangeable off side to near side and vice versa.
The engine for the new car Hill evolved during 1944, between dodging flying bombs and worrying as to whether his wife and three children had dodged also. “Why,” I said, “did you drop Bertelli’s special head and o.h. camshaft valve gear in favour of push-rods?” “Because,” replied Hill, I sought simplicity, as I have already told you. I could get the same power more quietly and more smoothly from my new pushrod 82.5 by 92 mm. engine with its special valve positioning as we got from the o.h.c. 2-litre. Moreover, it is easier to manufacture, is easier to maintain and by eliminating dry-sump lubrication, saves the cost of one oil-pump and obviates long warming-up periods, oil-joints that might leak and a vulnerable oil tank.” With internal webbing in the sump, I was told, the oil temperature keeps in the region of 70 degrees C., while just recently horse-power figures have been attained on the bench that are very satisfactory. Pressure-cooling is considered by Hill to be another unnecessary complication. The engine is, of course, mated to a David Brown synchromesh gearbox, not to a Cotal box.
To stop the car, Hill relies on 12-inch Girling hydraulic brakes of 2LS type at the front.
So was born this new 2-litre Aston-Martin. In a chassis form it weighed some 16 1/2 cwt., and underwent its tests in the hands of St. John Horsfall most satisfactorily. The loss of Brooklands Track, incidentally, is still lamented at Feltham when there is serious testing to be done.
It was during this testing that the Spa project materialised. Freddie Dixon and Tony Rolt tried the prototype chassis and Fred said “Why don’t you race her?” or sentiments to that effect. Horsfall put the matter to Hill, and David Brown, whose Tractor Group had absorbed Aston-Martin, Ltd., and Lagonda, Ltd., consented. That was nine or ten weeks before the race, before a single complete Aston-Martin had been built. So there was something of a hustle
In the end the third chassis to be constructed was used and Hill designed the body for it. This necessitated altering slightly the width of the chassis superstructure, cutting off the rear frame members, removing the battery from its location in a front wing and placing it beside the fuel tank in the tail, and making the new 30-gallon tank. Everyone worked with a will. Lucas checked over the standard electrical equipment, and Gallays made the new tank which was mounted on rubber and strapped down with cables. There was no time available in which to shorten, and so lighten, the chassis, so the 9-foot wheelbase had to be retained, this helping with the installation of the big fuel tank. No higher axle ratio than 3.9 to 1 was available, scant improvement on the normal 4.1 to 1 ratio, so 19 by 5.50 rear tyres were used, with 18 by 5.50 tyres at the front, in place of the 16 by 5.75 tyres normally used on all wheels. The engine was virtually standard, with two oversize S.U. carburetters. As first it was thought that at Spa as much benzole as competitors wished to use would be permitted, so a new head giving a compression-ratio of 9 to 1 or 9.5 to 1 was planned. There was no particular difficulty about this, because a 10 to 1 compression-ratio was possible using flat-topped pistons. Before the car left England news was received that Belgian fuel would have to be used, so a compression-ratio of 8.5 to 1 was adopted. The standard compression-ratio is 7.3 to 1.
Jack Sopp prepared the engine, assisted by Fred Lowne, and the car was assembled and shipped just in time. St. John Horsfall asked Leslie Johnson to partner him as driver and it is now history that the Aston-Martin made the fastest average speed in the race, winning at 72.07 m.p.h., covering 1,729 miles in the 24 hours. The, car had a net weight in the region of 19 cwt., and went through the entire race on one set of racing Dunlop tyres. The standard Lucas headlamps, fitted with 48-watt bulbs and backed by two Lucas spot-lamps, materially aided the drivers during the fog and throughout the night spell. The other Lucas electrical equipment also functioned impeccably and the Lucas screen wiper kept going all the time. Hill himself was in the pit, together with Dinsdale (his head draughts-man), Johnson Ferguson (the s.v. Aston-Martin enthusiast), Mrs. Eve Johnson (who operated the chart with Hill), R. A. Jackson and P. A. L. Stretch. Mr. David Brown also visited the pit for a while.
With the racing car went the first Aston-Martin three-seater, as tender car, and a Guy works lorry. Something like 20 m.p.g. was averaged throughout the race and when the engine was stripped afterwards, not even a valve spring was broken.
Since this convincing Aston-Martin victory the first three-seater model has been delivered, to Automobile Distributors, Ltd., of Dublin, who sold it to a private owner the following day. At Earls Court last year a “Spa Replica” model was exhibited, as reported and illustrated in Motor Sport at the time. The price, with p.t., is £3,109 10s.
Naturally, the eyes of enthusiasts the world over will be on the Aston-Martin team in this year’s races. Excellent as was last year’s performance at Spa, victory had to some extent to be shared with the H.R.G.s, which won the coveted Roi de Belge Cup, while a Simca in the 1 1/2-litre class averaged 71.08 m.p.h. against the Aston-Martin’s 72.07 m.p.h. So we may expect a determined attempt to be made to win the Biennial Cup at be Mans at the end of June. Le Mans is a great Aston-Martin stamping ground, for the make won the Biennial Cup there in 1931-32, 1934-35 and again in 1937. Best wishes go out to the team from Feltham for this year’s race and I shall hope to see them make a keen bid for renewed success at Spa as well.
At present not much is known about the cars, except that two will be 2-litres, one will have an experimental 2-litre engine, and that closed bodywork will be used, on chassis reduced to a wheelbase of 8 feet 8 inches. This wheelbase will also be used in future for the “Spa Replica” model. The drivers have been nominated as Charles Brackenbury, “Taso” Mathieson, Arthur Jones, Nick Haines, Leslie Johnson and Pierre Marechal. Besides Mr. Sutherland, St. John Horsfall has also severed his connection with Aston-Martin, Ltd., but it is to be hoped that Claude Hill will not relinquish development of his most intriguing motor car. — W. B.