The Rapide pioneered developments in three key areas; engine, transmission and rear suspension - all were later applied to Aston Martins from the DB5 through to the DBS. From its launch in 1961 the Rapide took its power from the 3995cc straight six double overhead camshaft engine, at a time when the DB4 still had the 3700 cc engine.
The engine specified for the Rapide, was designed to give more torque than the DB4 unit and ample power. With the use of two Solex carburettors, this gave maximum 236 bhp at 5000 rpm, and effortless acceleration up to a top speed of 130 miles an hour. The same engine in the DB5/6, in more a highly tuned state and with three SU carburettors produced ca. 270 bhp and in the final Vantage model with three Webbers, 325 bhp and a top speed of ca. 150mph. Interesting, some of the very last Rapide’s produced also had 3 SU’s as standard, possibly with a higher output DB5 engine specification as well.
The engine bay of the Rapide is impressive, and sometimes highly detailed especially in some of the motor show cars. Features seen include polished cam covers (normally these were painted), and chromed or painted cam cover nuts. The carburettors bodies on a few cars were painted the same as the body colour and with chrome linkages, normally these were a silver-grey colour. The bonnet stay rods could also be chromed rather than the normal galvanised finish and the carburettor air-box was occasionally painted body colour rather than the normal black finish. All show highly detailed customer or motor show specifications and it would be true to say that no two Rapide's are alike, all are unique. Early Rapide's had cam covers with single nut fixing as used on the the DB4, however by the time LR140 was produced in late 1963 the cam covers had double fixings as used on the DB5. These features on the Rapide were simply mimicking that of current Aston DB5 production, and what the works were then using.
Mated to this engine was a three speed Borg-Warner automatic transmission, which was standard on the majority of Rapide’s and did not become an official works option for Aston Martins until the DB5 was introduced. A number of cars were also built with the David Brown four speed manual gearbox, as also used on the DB4. Since then a fair number of cars have been either converted to 4-speed automatic or to a manual transmission.
The car deviated significantly from standard Aston Martin practice at the time, incorporating De Dion rear suspension, not seen until the DBS appeared in 1968. This allowed for improved handling and ride quality by reducing the unsprung weight. However, the most important reason for the use of the De Dion axle, was it allowed for a significant increase in rear passenger space. The springing at the rear of the car, was by transverse torsion bars, a system pioneered on the 1950’s 2.6 and 3.0 litre Lagonda saloons. Another first with this car was the use of telescopic shock absorbers.
The braking system was advanced for its day with twin servo assisted dual system all round discs brakes, early cars were fitted with Dunlop callipers whereas later cars used Girling. A bellows type servo system operating directly on the brake pedal was used for the first few cars produced.
The cars were built by hand-forming an aluminium outer skin over a Superleggera frame mounted on a steel chassis. Apart from the wing vents and bumper the front of the car looks very different to the DB4, which is 14” shorter. A rear view however, shows its common heritage with both the DB4 and DB5, with delicate shark fins and inset rear light clusters. Viewed from the side the car clearly shows its breeding as a grand-touring 4-door saloon. The famous front end with its multiple chrome grills gives the car a unique look, and this it could be argued, is best highlighted on darker coloured cars.