The Silver Wraith, launched in 1947, was an evolution of the pre-war Wraith and was offered in the traditional chassis form ready for the fitting of Bespoke coachwork. The 4,257cc overhead-inlet, side-exhaust engine developed before the war was used, as well as a modified coil and wishbone independent front suspension. Hydraulic brakes were used for the first time on a Rolls-Royce with hydraulic brakes.
Following their pre-war tradition of manufacturing a rolling-chassis only, Rolls-Royce delivered these cars to be bodied by independent coachbuilders. Some rationalization however was apparent because the sister model Bentley Mark VI incorporated into a 7 inches shorter frame the same major technical components. The Silver Wraith outlived the Mark VI and in fact survived until 1959 having been modernised step by step with vital improvements like automatic gearbox becoming an option in 1952 and power assisted steering in 1956. An engine bored out to 4,566 cc had been phased in in 1951 and in 1954 capacity was increased to 4,887 cc. The Silver Wraith was the last Rolls-Royce model to show a vast variety of coachwork styles.
The Silver Wraith differed from the Mark VI in that, rather than being offered as a complete car, the tradition of manufacturing a rolling-chasses only was maintained, the body being erected by a coachbuilder.
The England of the post war era had more urgent requirements than luxury motor cars. The economy had suffered and production was severely handicapped by shortages of raw materials. Further, the high priced, high quality car had become subject to a prohibitive purchase tax. To add to the misery petrol was rationed and only available on coupons.
Rolls-Royce, therefore, approached the subject of production of the Silver Wraith with not only hesitation but great care. It had been decided that Rolls-Royce s and Bentleys should not continue to be built in strictly separate series. Instead, it had been agreed essential that as many parts of the chassis, engine and gearbox should be identical for the different makes and thus interchangeable. The fitted hydraulic jacks shown on the chassis drawing were never fitted. In this regard the Silver Wraith illustrated the company’s new philosophy that complicated components did not belong on a chassis, whichshould be realiable and easy to maintain anywhere in the world.
In respect of the engine there were no notable differences between the Silver Wraith and the Mark VI. A camshaft with lower lift than that of the Bentley, and asingle Stromberg carburettor instead of twin SU carburettors were the only modifications.Thus more torque was gained at low revolutions.
One technical sophistication proved to be a shortcoming. The upper cyinder liners were polished and chrome plated. In theory this should have helped the engine in achieving extraordinary mileage. It was hoped that a rebore would not be necessary before 100,000 miles (160,000 km) was reached, which could then be carried out during a general overhaul. In practice the quality of chrome plating did not live up to expectations. Many of those engines which were used for town traffic became unserviceable after very low mileages. After a short time this problem, which was common to the Silver Wraith and the Mark VI, was solved.Cylinder lines of hardened steel with a chrome content were pressed into the engine blocks.
The price and economic conditions prevailing at the time when the new model was launched limited the production of the Silver Wraith which, from 1946-59 was only 1,783 examples.These were fitted with a variety of different bodies and were the basis for new heights being reached in the craft of coach building. In the course of 1955 the Silver Wraith was equipped with an engine the capacity of which was 4,887 cc. Mixture was provided by first a single carburettor and then, from 1956, by twin SU carburettors.
The need for yet more power had become inevitable because the weight of the additional equipment had eroded the car’s performance. By the end of 1954 all Silver Wraiths were fitted
with automatic transmission and in late 1956 power steering became an optional extra.
6 cylinder in-line engine, bore x stroke 88.9 x 114.3 mm (3 1/2 x 4 1/2 in), capacity 4,257 cc (from 1951 bore x stroke 92.08 x 114.3 mm (3 5/8 x 4 1/2 in), capacity 4,566 cc; from 1954 bore x stroke 95.25 x 114.3 mm (3 3/4 x 4 1/2 in), capacity 4,887 cc); cast iron cylinder block, aluminium alloy cylinder head, Stromberg carburettor (from 1951 Zenith carburettor, from 1956 twin SU carburettors); single dry plate clutch; 4-speed gearbox (from 1952 4-speed automatic gearbox optional), hypoid bevel final drive, independent front suspension with coil springs, semi-elliptic springs rear; drum brakes servo-assisted; wheelbase 3,225.8 mm (127 in)(from 1951 wheelbase 3,378.2 mm (133 in); tyre size 6.50 x 17 (from 1951 tyre size 6.50 x 16, for export cars tyre size 7.50 x 16 optional, for long wheelbase cars standard).