The Aston Martin DB 4, 5 & 6

Aston Martins seem to be the post-war embodiment of the vintage Bentley in being big, beefy and thoroughly British. Not for this company the mid-engined design of their exotic Continental rivals, but the engine in the front, under the bonnet, where it should be!

As with Bentley, Aston Martin’s reputation was gained on the track and reflected in the road cars. Although it was not until 1959 that an Aston Martin finally won Le Mans and also the World Sports Car Championship, it had been a decade of glory for them.

The success had started in 1950 when one of the first DB2s won the Index of Performance at Le Mans bringing the company to the attention of many influential people, particularly in America. Since the DB2 was a particularly fine car it really helped the company pull through the lean years after the war.

Interest in the marque was further bolstered in 1953 by the introduction of the DB2-4, one of the earliest GT hatchbacks, almost nine years before the advent of the E-Type. Success on the track with this 6 cylinder model led to the introduction of the company’s first sports racing car, the DB3, first raced at Dundrod in 1951, which in turn was succeeded by the rather more successful DB3S, one of the truly great sportscars of the Fifties.

Aston Martin had been using twin overhead sixes since 1950 when WO. Bentley’s 2.6 litre Lagonda, designed for David Brown’s other car firm, was adapted to the DB2 coupe.

It was the advent of the Sixties, though, that was to bring to Aston Martin the prestige which enabled it to be mentioned in the same breath as Ferrari, Jaguar and Porsche. So distinctive were the ensuing models from Newport Pagnell that they brought with them universal recognition.

The DB4 was the product of a team of talented men employed at Aston Martin and was the British answer to the Ferrari. Harold Beach was the engineer-in-charge who created the chassis around which the Milanese coachbuilder Touring designed a body while Tadek Marek’s fine new aluminium engine powered it. As General Manager John Wyer was in charge of the day-to-day business and smoothed the may so that the project went ahead as quickly as possible especially as the company had wrung as much as it could out of the 10 year old DB2 and desperately needed a replacement.

Work on the six cylinder, twin overhead cam, seven bearing engine had commenced in 1955, first run in 1956 and raced a year later in a DBR2. The 3670cc all-alloy engine had a bore and stroke each of 92mm and was fed by twin SU HD8 carburettors. It had a compression ratio of 8.25:1 and developed 236 bhp at 5500rpm, a great improvement on the 162 bhp of later DB2/4s. During its early life the sump capacity of 15 pints of oil was increased to 17 before being finally settled at 21 pints. Overheating was the biggest problem of the earlier engines and caused bearing failures, so in order to overcome this an oil cooler was also available from the second series on.

Touring’s beautiful body was of their `Superleggera’ construction system by which the aluminium body panels were attached to a tubular frame built onto Beach’s rigid platform chassis. After initial work at David Brown’s Yorkshire factory, production was transferred to the Tickford works at Newport Pagnell where the cars were later built.

The close co-operation between England and Italy ensured the rapid advancement of the project so that the first prototype DB4 was running in July 1957 prior to its first maiden appearance at the 1958 London Motor Show. Its Italianate good looks allied to good performance ensured the car was a success, but at almost £4000, including purchase tax between 1958 and 1960, it was appealing to a very specialised market.

The DB4 went through a number of constant modifications throughout its life from October 1958 to June 1963. Apart from the series 1 cars, the bonnet was hinged at the front, the rear lights kept changing position, the series 1-3 cars had a deeper air scoop on the bonnet and the Vantage engine with three SU HD8 carburettors, 9:1 compression ratio and larger valves, developing 266 bhp at 5750rpm, was offered as an optional extra from the series 4 (Sept 1961 to October 1962) and installed in cars with a restyled front with sloping headlights and known as the DB4 Vantage. A twin-plate 9in Borg and Beck clutch became standard on the series 4 as did the wide-ratio gearbox.

At the same time as the DB4 was in production, Aston Martin introduced a more powerful version of the car known as the DB4GT at the London Motor Show in September 1959. Although similar in styling, the car was 5in shorter than the series 1 and was sold mainly as a two-seater. The engine was fed by three twin-choke 45DCOE4 Weber carburettors, it had a twin plug head with twin distributors, a compression ratio of 9:1 and a power output of 302bhp at 6000rpm. It thus had an excellent power-to-weight ratio being almost 2001b lighter than the normal DB4. In some cars the bore was increased by 1 mm to give a capacity of 3750cc. The gearbox used was the David Brown close-ratio fourspeed gearbox mated to a Borg and Beck 9in clutch.

A special Zagato-bodied DB4GT was introduced at the London Motor Show a year later. The Italian stylist managed to combine beauty with purposefulness, but unfortunately only 19 were made, although even today all are in existence and known about. Although none of the 19 was identical, the engines in these ‘Zagatos’ had a compression ratio raised to 9.71 and a claimed power output of 314bhp.

Extra leg room and boot space were achieved on the series 5 DB4 by increasing the length by nearly 4in to give an overall length of 15 feet. The roof was higher but not the overall height as smaller 15in wheels were fitted. Except for the first 50 cars, most had the Vantage engine and GT headlamp treatment and were in effect the DB5. Of the 1110 DB4s made, 70 were convertibles which were introduced at the 1961 London Motor Show.

The DB5 was a logical development of the DB4 and is perhaps today the most desirable of all the DB Aston Martins, combining greater power with even more refinement. The main external difference was that it had twin fuel fillers, but there were a great number of detailed improvements underneath the handsome body.

An enlarged 3910cc engine, with the bore increased to 96mm, was installed. Fitted with triple SU 2in carburettors and a compression ratio of 8.9:1 it developed 282bhp at 5500rpm. From September 1964 the DB5 also came with the Vantage engine with triple Weber carburettors which developed 314bhp at 5750rpm.

The all coil suspension, which was independent at the front, was derived from earlier cars and race-bred features included power disc brakes and rack and pinion steering. There was now synchromesh on all forward gears and on the DB5 a fifth ratio was added as well as a twin clutch plate. Other refinements were electric windows and on later DB5s, electrically controlled dampers.

In 1966 the DB5 gave way to the DB6 which continued the styling theme but with improved aerodynamics. By now, though, it was becoming a little bit long in the tooth. It was not keeping up with the times on top of which it also suffered from quality problems. Sales slumped alarmingly in 1967 but the model remained in production from October 1965 to July 1969 in which time 1327 saloons of which seven were shooting brakes.

Many DBs have now reached the age when they are undergoing restoration. The DB5 being revived at Middlebridge Racing was one of 1021 made, of which 123 were convertibles and 12 were shooting brakes. Imported from the States in August 1988, it was still on its Virginia plates when it arrived back into the country. Corrosion was the major problem, so much so that Middlebridge was forced to take the body completely off before bead blasting the chassis. Since the brief from their Japanese client was to restore it to better than new, no expense was spared in carrying out these commands.

Apart from the roof, every other panel of the car was closely examined. As rear ends are difficult to obtain, it was decided to restore that section by letting in metal in the lower sections. The front end was new and bought from a local company who had fabricated it from original specifications. The rear valance was also a problem. Almost all Aston Martins of this age suffer from corrosion in this area due to the chemical reaction which takes place between the valance and the body after the protective cloth tape has rotted away. In most restorations the original cloth is now replaced by tank tape which is of far better quality than the original material. The engine has been completely rebuilt as has every other mechanical part except the strong ZF gearbox. Fortunately the block had not cracked, a common enough problem with this model, as a factory replacement would have cost a further £5000 to the restoration bill.

The wheels are new and come from India where they are made under licence from Dunlop. The interior is being completely re-trimmed to original specification by an ex-Aston Martin man and the steering wheel is being reconditioned. The only outstanding problem, and the one likely to hold up presentation of the car at the AMOC St John Horsfall meeting in June is that the customer has requested an air conditioning unit, but which must be hidden out of sight. In fact air conditioning could be specified for the DB5 but it was not very effective by modern standards.

Aston Martin still make fine motor cars and with Ford’s financial assistance, it can be said that for virtually the first time in its history it has some security, but its reputation as the manufacturer of some of the finest Gran Turismo models was forged in the Fifties and Sixties and it’s the cars from that era which are still remembered with affection and reverence today.