A MASTERPIECE OF SPORTS CAR CONSTRUCTION
A MASTERPIECE OF SPORTS CAR CONSTRUCTION
To get into a motor car one has never driven before, to take it up to its maximum revs, in all its gears, and to brake and swing round corners with the utmost joie de vivre, one has either to be lacking in imagination or very confident of the car’s controlability. The second needless to say was the reason when we first took the wheel of the new Bentley. From the start we felt perfectly at home in the car, and the ” rightness” of direction and handling were such as one only expects in a car tuned for racing. A speed of 90 m.p.h. quickly attained on unfamiliar roads confirmed this impression, all the more remarkable because of the quiet, almost inaudible exhaust note.
A second trial of the car was made under very unfavourable conditions. Visibility was poor, and the roads were wet after a long spell of fine weather, and the surface was covered in many places with a treacherous coating of grease. After a gentle beginning to get the feel of this low-built car, we discovered that under all circumstances the front wheels kept to the intended path, and the tail showed no tendency to slide. Encouraged by this, speed was increased to 80-85 m.p.h. without any feeling of insecurity, and fast bends at 75 m.p.h. seemed quite safe. These speeds were quickly reached using the excellent gear-box with its quick changes and its silent running ratios. The top-gear acceleration is distinctly good too, and the gear-lever need seldom be used unless one wants an unusual performance. The maximum speed of over 90 m.p.h. is as much as the average man wants in England, but a higher axle ratio could be fitted giving 100 m.p.h. at 4,500 r.p.m. The car ran without snatch at 7 miles an hour on top gear if required, but with
the easy-change mechanism fitted to the gear-box, there is no point in not changing down. The wide speed-range is attained on any good spirit, Shell No. 1 being generally used. The suspension is good over the car’s entire speed-range. Going slowly over a rough surface, one does not get those jabs associated with a fast car with tight “shockers,” yet at 85 m.p.h. there is no swinging or rolling at corners. This must be due largely to correct weight distribution and a stiff chassis, for on the majority of cars fitted only with hydraulic shock-absorbers a certain amount of movement takes place before the steadying effect is felt. Actually at 90 m.p.h. on a wavy road a little extra friction might have been useful, and we understand that supplementary adjustable
friction dampers will be fitted on future cars.
To maintain a good average, especially in England, where nearly all the roads pass through numerous villages and towns, a well-silenced car is essential if one wants to avoid trouble with the police. The Bentley is fitted with two silencers, one of which can be cut out by moving a small lever beside the front seat. The exhaust note then is that of a quiet sports car, while with the two silencers in operation one might almost be in a 25 Rolls-Royce. This silence is particularly pleasant when closed bodywork is fitted, and only reduces the maximum speed of the car by about 3 m.p.h.
The joy of driving a thoroughbred car is the way in which it responds to the controls. The steering of the Bentley was light and positive, with the right amount of caster action. It was pleasantly highgeared, and yet easily locked over, and there was no kick-back on rough surfaces.
The car was as comfortable on Brooklands as on the road, and the speedometer which was accurate, showed 93 m.p.h. on most parts of the track. The speed over a timed half mile was 91 m.p.h., and with the windscreen raised the maximum was reduced by 3 m.p.h.
Acceleration on the road seemed unusually good, but was so smooth that one could not make comparisons until this had been tested by stop-watch. As the acceleration chart shows, its performance is well in advance of other four-seater unsupercharged cars up to its capacity, while a standing half-mile was covered in 331 seconds.
The maximum engine speed is 4,500 r.p.m., and with an axle ratio of 4.1 the speeds on the gears are 94, 75, 55, and 34 m.p.h. The caris ordinarily started on second gear, which is a silent ratio. Third and top gears have a synchro-naesh mechanism which makes a bad change impossible
and synchronises the pinions in an unusually short time with a velvety action. The average Bentley owner will probably prefer to drive the car as though it were fitted with a normal gear-box, and used in this way delightfully quick and decisive gear-changing can be effected. The easychange mechanism is there if one is feeling lazy, and is a great convenience in traffic. The clutch is light and smooth, The reverse catch release projects from ‘ the top of the gear-lever handle, and feels a little strange to anyone accustomed to a
smooth knob, but grasping the handle between the thumb and two -fingers, which is all that is required, one does not notice it. On our first test the brakes were extremely powerful, but the servo-mechan ism was progressive, so that one could control exactly the braking effort required. On the Second occasion it seemed that
water had got into one of the drums when it had been washed, but it dried out by the end of the road-test. From 40 miles an hour the car pulled up in 57 feet. The engine is carried on slightly flexible mountings, and is .vibrationless through
out its range. The mechanical silence is remarkable, aided by a very large airsilencer, and the car might have been propelled by an electric motor. The driving position is good, the driver sitting in an upright position with the controls all wit.hin easy reach. The windscreen is quite low, but yet is placed so that even a tall driver looks through the middle of it. The off-side wing is corn
pletely visible, and the lamp on top of the near-side one is a guide to the car’s width. The front passenger’s knees sometimes
come into ‘contact with the bottom of the facia board, but this is being raised on bodies now being built. The front seats slide easily on Lever°11 fittings. The back seats, like those in front, have pneumatic upholstery, and are roomy and well padded. There is a centre
armrest which folds, and three fairly small passengers could be carried if necessary. The foot-wells have inclined ramps, and altogether the back passengers should be as comfortable as those in the front.
The A.T. rev.-counter, which has a clock-face on the lower part of its dial, and the speedometer, are both 6 inches in diameter and are mounted on the dash under the driver’s eye. The usual instruments indicating water-temperature, oilpressure, charging, and petrol level, are mounted together in the middle of the facia board, together with the switches, and have the high finish which one associates with Derby. By pressing or turning a knob, the indirect lighting is switched on momentarily or for as long as required.
There are four controls in the centre of the steering column. They operate the lamp dipping mechanism, the mixture control for starting, the throttle control, and the spark advance and retard. This last lever is only retarded for starting or idling, otherwise being set at full advance, as the ignition timing is varied by a centrifugal governor. By reason of its low build, the Bentley looks remarkably neat and handy. Actually it is only 4 inches shorter than the old 4f litre, but the passengers sit closer together, and gain the advantage of being carried within the wheelbase. This ” close-coupling” seems to be reflected in the way the car handles, for one can dodge in and out of traffic or swoop round right angle bends in a way usually associated with an 8 foot 6 wheelbase. The radiator is of the vee-type always used on Bentleys, and with the header tank almost flat on top, the familiar badge, and the thermostatically-controlled shutters is like a small edition of that fitted
to the 8 litre. The open Vanden PlaS body which was fitted to the car we tested was a handsome and practical production in
keeping with the high quality of the chassis. The long and well-louvred bonnet and scuttle, two-door body cut away for the front passengers, and. straight line quarters and hoods are sporting in line, and the long sweeping wings afford excellent protection. The rear panel, which carried the spare wheel, is hinged at the bottom. When opened it discloses a luggage space large enough for several suit-cases. The hood side-screens are carried in a pocket on the inside of the hinged panel. The petrol filler-cap, which is quickacting and 3 inches in diameter is reached by opening a hinged flap by the side of the rear panel. The tools are carried on a tray inside the scuttle. The cylinder dimensions of the Bentley are the same as those of the 25 h.p. Rolls Royce, and one might have imagined that the new car was but a modification of the old. The true facts were revealed to us by Mr. W. 0. Bentley, the designer and originator of the fam
ous marque, who for many months past has been testing the new cars on the fast highroads of France ; the only part common to the two engines is the sump!
The pistons are longer, and so is the block, the cylinder head is entirely new, likewise the camshaft, and a stronger crankcase and a heavy crank shaft are needed for the powerful engine. The gearbox is specially built, as also are the front and back axles, and the braking lay-out, while the chassis is shorter with a lower centre of gravity. Nothing in common except the skill of the designers and the Rolls Royce standard of craftmanship !
The weight has been kept down by the use of high-grade steels and the light alloys developed by Messrs. Rolls Royce, but the chassis is very solidly built and weighs 22 cwt. The surprising performance has been secured by the high power (120 horse power) in conjunction with a moderate chassis weight and the small frontal area made possible by the double-dropped frame. The chassis specification of the Bentley
was given in last month’s issue of MOTOR SPORT, but some additional details are now available. The chassis incidently is guaranteed for three years. The chassis frame is double-dropped with a level platform space in the centre
part. It is braced by a number of tubular cross members, and a very stiff pressing through which the propellor shaft passes —_
strengthens it at the front mountings of the rear springs. The camshaft is gear-driven from the front of the engine, and a chain of gears drives the water-pump on the off side and the dynamo on the near side. The contact breaker is carried verti
cally on the off side, with the coil beside it, and a spare coil is mounted on the dash. 2 S.U. carburetters are used and 14 mm. Lodge plugs. There is a very large Burgess silencer and air cleaner above the rocker casing, and the oil fumes from the crankcase enter the cleaner through a duct and pass through the carburetters on. to the inlet valve stems. The crank-case is replenished through an accessible filler on the near side, with a quick-action cap. The sump holds 14 gallons.
The output of the dynamo is regulated by a constantvoltage regulator mounted on the dash, and a fuse-box with fuses for each unit of the lighting system are fitted. A relay switch for operating the starter-motor is mounted close beside it. A special slipping clutch mechanism. on the starter pinion protects that vulnerable part. Lucas Bifiex headlamps of a special light pattern are fitted. ‘I he rev-counter drive is taken off the dynamo, and. close beside it is the jack
handle, while the jack is carried on the dash. Luvax one-shot lubrication is standard, and this and the two-gallon reserve petrol tap are operated from the driving compartment.
A Klaxon windscreen wiper is used, and the electric motor is carried on a rubber block on the dash. A flexible drive comes through to a gear-box at the off-side of the screen and an enclosed shaft drives the two blades through rack and pinion gear. The blades drop below the level of the glass when out of use so that the screen can be folded down when required.
No effort has been spared to perfect the 3i litre Bentley, and it is indeed the car for the connoisseur of fast travel. From every point of view the new car meets the modern need for a fast, lively and smoothly running sports car of the highest quality, and the interest with which its coming was awaited has been equalled by the enthusiasm of its reception by those who have tried it.