In the whole history of pre-war sports cars, no vehicle had a greater name than the Bentley. This marque probably did more to further British prestige abroad than any motor-car produced. There was a time when the Bentley was absolutely unbeatable at Le Mans, gaining a most enviable name for sheer reliability and high-speed cruising. It was in 1923 that the name Bentley figured in the famous 24-hour race for the first time. A lone, privately entered 3-litre finished fairly well up in the awards list after running with the utmost reliability throughout the entire race. Encouraged by this, the same drivers, Clement and Duff, entered the following year and won—the first British drivers ever to win the Grand Prix d'Endurance.
Old Number Seven
For many years afterwards the big British cars continued to dominate the Le Mans scene. They gained a name for being virtually unbreakable, and certainly lived up to that description in the historic 24-hour race of 1927, when the entire Bentley team was involved in one of the most sensational multiple crashes that have ever occurred in motor racing. A French car seemingly slewed broadside at White Horse Corner when the cars were speeding through the night. It completely blocked the road, and driver after driver crashed in trying to avoid a collision. The complete Bentley entry, at one time, lay piled up at the same spot, and it certainly looked as though the chances of a British win were absolutely nil.
However, after some hectic physical endeavor, the pilots of "Old Number Seven" (running as No. 3) managed to extricate one very badly bent motor-car. S. C. H. Davis (" Casque " of The Autocar) and his co-driver, Dr. J. D. Benjafield, looked as if they were about to tackle the impossible. The car was driveable - just! The chassis was badly twisted, the front wheels faced in peculiar directions, steering was all haywire, battery clips broken, lights questionable, and a score or more of other things which Davis and Benjafield didn't particularly care to dwell upon.
The wonderful old car not only finished the race, but won it outright at an average speed of over 60 m.p.h. Pages and pages of Bentley history could be written. The successes at Brooklands, where for years they were the fastest cars on the track; their later demonstrations of high-speed reliability in the T.T., where Eddie Hall was the eternal second; in fact, the name Bentley is synonymous with all that is best in a sports car. The drivers of the Bentley era will never be forgotten. Names like Woolf Barnato, Sir Henry (Tim) Birkin, Jack and Clive Dunfee, Jack Barclay, Glen Kidston, Sammy Davis, Dr. Benjafield and the rest of the " Bentley Boys " will always be associated with the golden years of British sports-car racing.
However, let us go back to the end of the Kaiser war, when the marque was born. The Bentley first appeared in public in 1919, when the original 3-litre made its bow at the Olympia Motor Show, but it was not until late in 1921 that the first car was delivered to a customer. The intervening period was spent in development until its designer, W. O. Bentley, war-time engineer, was satisfied that it was a marketable proposition. When first shown, the car was virtually a Grand Prix road-racing machine of the period. Even to-day it would be unmistakably a Bentley; the almost identical distinctive radiator and high bonnet line were features retained during the whole period of its production.
The original experimental cars differed from the subsequent production cars in several respects. The early cars, although fitted with four valves per cylinder, had only two cams per Cylinder in place of the familiar triple-cam arrangement. Each cam operated a pair of exhaust and inlet valves respectively. A single magneto was mounted on the offside of the engine, and the other side of the cross-shaft supplied the drive for the water- pump. Later experimental cars were fitted with two plugs per cylinder and a twin-spark magneto, which was eventually replaced by the dual-magneto arrangement. Dry-sump lubrication was used, and the supply tank was located beneath the scuttle.
Transmission was via a leather-faced cone clutch, and a 3.53 rear axle was fitted. Engine dimensions were, of course 80 x 149-mm. (2,996-c.c.), pistons were of the hour-glass pattern, and power output was stated to be 65 b.h.p. at the modest engine speed of 2,500 r.p.m. Several varieties of Claudel Hobson and Zenith carburetors were tried, and maximum speed was stated to be 80 m.p.h. The Doubting Thomases shook their heads. 80 m.p.h. was an outlandish claim for a completely equipped road car, powered by an engine rated as low as 15.9 h.p. What the sceptics overlooked, however, was that the R.A.C. rating was based on the bore alone, the formula not taking the stroke into account. Also, the chassis was extremely light for its size, being around 13J-cwt„ the lightest it ever was. Incidentally, the four cylinders and head were cast in one, so Bentley didn't intend to have any possible cylinder-head gasket trouble. They adopted a compression ratio of 4.3 to 1 on early cars, which was sensible in view of the low octane rating of the fuels available at the period.
Clement drove the experimental cars at Brooklands, but Douglas Hawkes went over to America for the Indianapolis 500 Miles Race, running non-stop and finishing twentieth at over 80 m.p.h. Floyd Clymer, in his History of the 500-Miles Race, states that the Americans were very impressed with this new British car which was virtually a touring model. Also in 1921 was the first real production car delivered. This had the 9-ft. 9.5-in. wheelbase, dual-magneto system, triple cams with separate rockers, and dynamo driven from the rear end of the camshaft. Lubrication was of the wet-sump pattern, a five-jet Smith carburetor was used, and the back-axle ratio was lowered to 3.92 to 1. The “A-type" gearbox had ratios of 1, 1.33, 1.63 and 2.64 to 1.
Three of the cars were entered for the 1922 T.T. in the Isle of Man, and all finished. F. C. Clement was second, Bentley himself fourth, and Douglas Hawkes drove the remaining car. Towards the end of 1922 a long (10-ft. 10-in.) chassis was introduced, to accommodate various body styles. The power unit pushed out some 72 b.h.p. at 3,500 r.p.m., and the hour- glass type pistons were replaced by more conventional pot-type pistons. With the "A" gearbox a 4.23 rear axle was supplied for closed bodies and a 3.92 for the tourers.
Not long afterwards the T.T. Replica came into being, which was the forerunner of the famous Speed Model, which has passed into history as the "Red Label". In 1924 B.H.B. pistons were adopted and twin S.U.s fitted, but the biggest step forward was the adoption of the well-designed compensated four-wheel brakes. The following year was notable in that several of the rare 100 m.p.h. (" Green Label ") models were built. Engine compression ratio was 6 to 1, and power output was over 85 b.h.p. at 3.500 r.p.m. All the 100 m.p.h. Bentleys had the short or 9-ft. wheelbase.
The Speed Model was further modified in 1926, and duralumin valve rockers were adopted. Power output was stepped up to 88 b.h.p. at 3-5, and the special Le Mans cars were said to push out nearly 95 b.h.p. at the same revs. These cars were all un-supercharged. The 3-litre series culminated in 1927 with the Speed Weymann saloon with 4.23 axle and "C" gearbox (1, 1.36, 1.82 and 3.36 to 1). The valve gear was also modified - a separate rocker box being fitted to each cylinder. In all, over 1,600 3-litre cars were built, and a high percentage are still in everyday use. The Bentley-Owners' Club is reputed to have over 200 examples amongst its members, and the Vintage Sports-Car Club also can show an impressive list of the famous four-cylinder cars.
The big 4.5-litre Bentley was also very popular, and in blown form it won scores of events at Brooklands. In 1925 the 6|-litre six-cylinder car was made, which later became known as the Big Six, but it was not until 1930 that the famous Speed Six appeared, and this was the first six-cylinder Bentley to race at Le Mans. A few of the big 8-litre cars were made, and they were something of a sensation. A town carriage of undoubted smoothness and tractability, with the performance of a racing car, was really something. One or two 8-litres were converted to sports cars. A 4-litre car was also produced, mainly in closed form, and one such car owned by a certain Forest Lycett was one of the fastest sports cars then in the UK.
When the company was taken over in 1931 by Rolls-Royce, speculation was rife as to what form the new cars would take. They had to wait until 1933, when the 3.5-litre Bentley, often misnamed Rolls-Bentley, was announced. The car was completely new from radiator to tail, even although the familiar radiator was retained in a modified form. The rabid Bentley fans professed disappointment, as the Rolls-Royce people did not claim the car as being an out-and-out sports car. The purpose was to provide a comfortable touring car, which would have a performance in keeping with Bentley tradition, and yet accomplish this in perfect smoothness and silence.
As everyone knows, they certainly produced a high-performance car. Also, the 3.5-litre Bentley went on to gain a name for being one of the hardest-wearing sports cars ever produced. The power unit was based largely on the famous 25-h.p. Rolls- Royce engine, and had a capacity of 3669-c.c. (82.5 x 114-mm.). The similarity ended there, however, for the Bentley unit developed some 120 b.h.p. at 4,500 r.p.m., rather more than its Rolls counterpart. Twin S.U.s fed the six cylinders, and the overhead valves were pushrod-operated.
Best Car in the World
Unlike the old 3-litres, a detachable cylinder head was fitted, and, also unlike its predecessors, the engine was dead silent - so much so that the Bentley slogan became the " Silent Sports Car," a name that is now associated with the post-1933 cars. The original Rolls-made car was one of the first sports cars ever to be fitted with a four- speed synchromesh gearbox, and was assuredly the first to be offered with servo-assisted brakes, similar to those used on the " Best Car in the World."
As regards performance, the Silent Sports Car was no sluggard; even in closed form 90 m.p.h. was the rule rather than the exception. From 0-60 m.p.h. occupied a mere 18 seconds, while 29 seconds were all that were necessary to reach 75 m.p.h. from standstill. An early open tourer was tested by a leading motor journal, and, with gear ratios of 4.1, 5.1, 7.08 and 11.3 to 1, achieved maximum speeds of 57 m.p.h. in second, 77 m.p.h. in third, and 91 m.p.h. in top. Later models were fitted with an overdrive, which made them even more ideal for long-distance high-speed touring. Steering, suspension and road-holding were superb, whilst the 3 litre Bentley was one of the most economical 25-h.p. cars ever made.
The 3.5-litre was eventually superseded by the 4.25 litre cars, which were completely redesigned for post-war Bentley fans. The power unit was based on the then current Rolls-Royce engine, having o.h. inlet and side exhaust valves, chromium-plated cylinder bores, new-pattern synchromesh gearbox, well-designed i.f.s., and a host of interesting features. This car is known as the Mark VI, and at the time was only being marketed in closed form, particularly as a rather handsome four-door sports saloon with Bentley coachwork. The extremely fast aerodynamic car built before the war also provided room for conjecture. This Bentley was capable of 100-m.p.h. cruising without the least sign of fuss. |
