Cars Technical Details Rolls-Royce & Bentley Motor Cars
-a record of manufacture from 1907-1991

by Peter Baines
General Secretary of the Rolls-Royce Enthusiasts Club

Club Silver Ghost 1907 – 1925.

Six cylinder engine in two blocks of three. Originally 7,036 cc but in 1909 the stroke was lengthened to 4 3/4″ to give 7,428 cc. The cylinder head is integral with the block. Side valves are fitted with exposed springs and tappet adjustment. Dual ignition is fitted, with a trembler coil firing one set of sparking plugs and a magneto the other set. In 1919 the trembler was replaced by a Rolls- Royce coil. Lubrication is by oil pump. Carburation is by Rolls-Royce two-jet carburettor. A starter motor was fitted from 1919, this drives the gearbox layshaft via a jaw clutch and chain. Lighting is acetylene but from 1914 electric lights via a dynamo were an optional extra. Gears were initially four but in 1909 a three speed box was fitted. This reverted to four in 1913. The gear box is separated from the engine and is driven through a cone clutch via a torque tube except on pre-1911 cars, which had an open propeller shaft. Petrol feed was by gravity with help from exhaust pressure on early cars, followed by pressure feed from a gearbox driven air pump. In 1919 the pump was moved to be driven off the distributor drive. Chassis weight without coachwork was approx. 25 1/2 cwt.
6173 Silver Ghosts were made.

20hp. 1922-1929.

The engine is a conventional six cylinder, single block with a detachable, cast-iron head. Overhead valves are operated by push-rods. A bore of 3″ and a 4 1/2″ stroke give a capacity of 3,127 cc. Oil pressure is by gear pump. Ignition is by Rolls-Royce coil with a stand-by magneto as an option from 1923 and as standard from 1924. The main distinguishing feature of the 20hp is its horizontal radiator shutters which were changed to vertical in 1928 at chassis number GFN71. The

transmission was initially by centre-change three speed gearbox with a central handbrake. The handbrake was moved to the right hand side in 1924 and a four speed right hand change box was fitted from 1925. The clutch is single dry-plate driving an open propeller shaft to a spiral bevel back axle. Fuel capacity 14 gallons with gauge on the tank. Fuel delivery by Autovac. Earlier cars in chassis form weighed 2,305 lbs. rising to 2,635 later.

2,940 were built.

New Phantom (Phantom I) 1925 – 1929.

The engine is of six cylinders, cast in two blocks of three with a single, detachable, cast-iron cylinder head which became aluminium in 1928. The bore and stroke are 4 1/2″ x 5 1/2″ giving a capacity of 7,668 cc. Twin ignition is fitted with coil and magneto each firing its own set of plugs. The cast-iron head engine carries all twelve plugs on the near side, the aluminium head has six each side. It has overhead valves operated by push-rods and the valves are interchangeable. A gear-type oil pump is fitted. The gearbox is separate from the engine and is driven by a dry-plate clutch. Final drive is by a torque tube and spiral bevel back axle. An 18 gallon fuel tank is standard but a 20 gallon tank could be ordered. The carburettor is a twin-jet Rolls-Royce internal expanding type. Fuel delivery by Autovac with gauge on tank. From 1927 a Hobson hydrostatic gauge was fitted. Chassis weight approx. 4,000 lbs.
3,514 chassis were built (2,271 Derby New Phantoms & 1,243 Springfield (USA) New Phantoms).

Phantom II 1929- 1935.

The engine is of six cylinders with two blocks of three with an aluminium cylinder head of 7,668 cc. with engine and gearbox as one unit. Compression ratio rose from 4.75:1 through 5:1 to 5.25:1 during this model’s production. Twin ignition systems of coil and magneto were used together, each system supplying its own set of plugs. Overhead valves were push-rod operated. Carburation by Rolls-Royce. A sequence starter is fitted which allows the starting gear to be engaged with the flywheel teeth before the full battery power becomes available to turn the engine. Petrol feed is by Autovac with an engine-driven vacuum pump. Fuel capacity 20 gallons rising to 28 gallons in 1933. A unitary gearbox is fitted with a conventional propeller shaft driving a hypoid bevel back axle. A chassis centralised lubrication system was fitted. Some oiling points needed an oil gun until 1931. Chassis weight approx. 3,810 lbs.
1,680 chassis were made, including the AJS and AMS series which were left hand drive. ( 1,555 RHD & 125 LHD)

Phantom III 1936- 1939.

The engine is a 60 degree V-12 of 7,340 cc. The cylinder heads are of aluminium and it has a compression ratio of 6:1. The valves are overhead operated by push-rods with hydraulic tappets. Troubles caused by poor oil maintenance and oil filtration caused these to be withdrawn in 1938. Most hydraulic tappet cars were subsequently modified. Ignition is by two coils, each supplying its own distributor with twin contact breakers in each. A twin choke down draught carburettor is fitted. The gearbox is separate from the engine and drives an open propeller shaft to the back axle which has hypoid bevel gears. This is the earliest Rolls-Royce with independent front suspension which is the wishbone type with oil encased-helical springs. A central jacking system is fitted operated by a pump under the driver’s seat. Marles cam and roller steering is fitted instead of the usual Rolls- Royce worm and nut. Chassis weight is approx. 4,050 lbs.

727 Phantom III’s were made.

20/25 1929- 1936.

The 20/25 engine is basically a 20hp enlarged to 3,699 cc. It has six cylinders with a separate cylinder head. The valves are operated by pushrods and the crankshaft is the usual Rolls-Royce type carried on seven bearings. There were three major changes during the life of the 20/25 which affected the carburettor, brakes, clutch, spring dampers and ignition. On early cars the radiator shutters were hand operated but in 1932 thermostat powered shutters became standard. The gearbox is of four speeds with synchromesh on third and top from 1932 at which time a centralised chassis lubrication system was introduced. Contemporary road tests gave the maximum speed as 67 mph in 1931 rising to 76 mph in 1935.
The number produced was 3,827.

25/30 1936- 1938.

The engine was again bored out, this time to 3 1/2” giving a capacity of 4,257 cc. Several changes were made from previous models. The familiar Rolls-Royce carburettor was dropped in favour of a Stromberg and twin S.U. petrol pumps replaced the Autovac. Marles steering was adopted and a Borg and Beck clutch was bought in as for the last of the 20/25’s. The magneto of earlier cars was also discontinued and twin electric coils were fitted, one acting as a standby. The longstanding Rolls-Royce braking system with servo assistance driven from the gearbox was still more than adequate for the increase in performance. DWS screw jacks, one at the front and one each side at the rear, were permanently fitted.

1,201 25/30’s were made.

Wraith 1938 – 1939.

The 25/30 Wraith continued with a 4 1/4 litre engine but the main difference was the fitting of independent front suspension controlled by coil springs. Road wheels were reduced from 19″ on the 25/30 to 17″. Built-in hydraulic jacks were operated by a hand-pump under the driver’s seat. The

Wraith was slightly heavier than it’s predecessor but cruising between 60 and 70 mph was possible. 491 were made before events of 1939 stopped production.

Bentley 3 1/2 1933 – 1936.

This model was basically a high-performance version of the 20/25 with a compression ratio of 6.5:1 instead of the 4.6:1 to 5.75:1 (depending on the year) of the former. Carburation was by twin S.U. carburettors. Gearbox and final drive ratios were changed and 18″ wheels fitted.
1,191 were produced.

Bentley 4 1/4 1936 – 1939.

Just as the 20/25 was increased in size to make the 25/30, the 3 1/2 was bored-out to make the 4 1/4. The compression ratio was increased to 6.8:1. The last two series, MR and MX, had changes to gearbox and final drive to give an overdrive top gear. Phantom II Continental There has been much argument as to what constitutes a “Continental”. The car’s designer, Ivan Evernden wrote, “the chassis is the standard Phantom II short model with a few modifications. These consist of a low steering column and specially selected springs of a type which permit of continuous high speeds over bad roads. The springs are supplemented with the standard Rolls-Royce patent hydraulic shock absorbers and additionally with adjustable, friction-type shock absorbers. The body is coachbuilt and it is so designed as to give a low centre of gravity and appearance and to provide roomy seating accommodation with ample provision for carrying luggage. There never was a defined specification of a Continental Phantom II. The series to series engineering improvements were applied to all chassis”.

Approximately 280 were built.

Bentley Mk V 1939-1941

Six cylinders of 4257cc, similar to the Wraith. Only 19 were produced, 15 as the standard Mk V and 4 as Corniche. Bentley MK VI & R-type 1946-1955 The engine is of six cylinders of 4257cc, but for the first time having overhead inlet and side exhaust valves to give a larger valve area. This was increased to 4566 cc in 1951 and 4887 cc in 1954 for the R-type Continental. Compression ratio 6.4:1 becoming 6.75:1 from chassis number B93TO. The Continental compression varied between 7.27:1 and 7.1:1. Usually twin SU carburettors were used but in some early left-hand drive cars a Stromberg down draught was fitted. In 1952 an automatic gearbox become an option, this became standard on left-hand drive cars in 1953 and right-hand drive cars in 1954. Front brakes were hydraulic with the Rolls-Royce servo-assisted mechanically operated rear brakes.

5201 MK VIs were built, 2320 R-types and 208 R-type Continentals.

Silver Wraith 1947-1959.

The Silver Wraith was basically the same chassis and engine as the MkVI but all had coachbuilt bodies. They continued in production until 1959 using the 4887 cc engine to cope with increasingly heavy bodies. 1,883 were made. Silver Dawn 1949-1955. Chassis and engine are almost identical to that of the MkVI but this car was the first Rolls-Royce to be sold with a standard steel body. Many were exported. A few were fitted with coachbuilt bodies and these are very collectable.

Total number built 785.

Silver Cloud I and Bentley S-type 1955-1959.

Using the previous 4887 cc engine a completely new body was designed. Automatic transmission was used but very occasionally one is found with a manual gearbox. The rear brakes were combined hydraulic and mechanical with the usual Rolls-Royce gearbox driven servo. Front suspension was

by unequal length wishbones and coil springs with semi-elliptic rear with electrically controlled dampers. Top speed 106 mph. Generally with standard steel coachwork. Most cars were produced with the standard 211 3/4″ in length but some were four inches longer.
Total built: 2359 – SCI, 3107 – S1 and 431 – S1 Continentals. The Continentals had higher compression ratios and larger bore SU carburettors.

Silver Cloud II and Bentley S2 1959-1962.

The Cloud II retained the same body as the Cloud I but was powered by a completely new V8 engine of 6230 cc with a compression ratio of 8:1. Self-adjusting hydraulic tappets were used, and the engine was all aluminium but with cast iron wet liners. Twin 1 3/4″ SU carburettors were used with automatic choke. SCII –
2116 were produced and S2 – 1922 and 388 Continentals.

Silver Cloud III and Bentley S3 1962-1966.

These cars have the same basic body shell as previous Clouds and S-types but the bonnet line was lowered and twin headlamps fitted. Engine power was increased and the maximum speed was given as 117 mph.
Total built: SCIII – 2376 of which 79 were coachbuilt and S3 – 1630, 312 of these were Continentals.

Silver Shadow I and Bentley T-type 1965-1976.

The V8 continued with a totally different monocoque body. A hydraulic system with pumps operated from the camshaft powered hydraulic dampers and automatic height control. Chassis numbers denote the type of car – SRH is the most common prefix standing for – standard – Rolls- Royce – home SRX means an export Shadow The Bentley is SBH or X CRH numbers indicate a coachbuilt car and DRH a drophead. From 1972 the third letter on export cars denoted the year of manufacture

Silver Shadow II and Bentley T2 1977-1981.

Shadow II and T2 were all improved version of the previous model with changes in external appearance, particularly wrap around black bumpers and an air dam below the front and with better

handling characteristics. Total number of Silver Shadows of all types built was 37,174 of which 2563 carried the Bentley radiator. Phantom IV 1950-1956. The rarest Rolls-Royce in the world – 18 were made, for Royalty and Heads of State only. A straight 8 cylinder engine was used with the usual 3 1/2 by 4 1/2 bore and stroke, giving 5677c. Manual transmission was used. Overall length was 229 1/2 in. Phantom V & VI 1959- 1991. Phantom V and VI were coachbuilt versions using the V8 engine and chassis remained in production after the monocoque Shadow was introduced as the or Royce to retain a proper chassis.
Total production of Phantom Vs was 516 and 373 Phantom VIs.

Peter Baines
 General Secretary of the Rolls-Royce Enthusiasts Club Copyright © 1999
 Rolls-Royce Enthusiasts' Club - Copyright Information