A 1924 Grand Prix Sunbeam by Anthony S. Heal the present owner
After their historic victory in the 1923 Grand Prix at Tours the Sunbeam Company were not content to rest on their laurels but made a determined effort to produce another world-beating design for the following year’s race. The piece de resistance of the event at Tours had undoubtedly been the employment of forced induction on the 8-cylinder Fiats. Although they were easily the fastest cars in the race the teething troubles, which so often beset new mechanical devices when first subjected to the acid test of Grand Prix racing, eliminated the entire Fiat team before the end of the course. But Louis Coatalen and Bertarione clearly saw that the supercharger had come to stay and they set-to to make their successful 2-litre 6-cylinder engine give 35 per cent. more power without sacrificing its reliability. Mercédès and Fiat, the only European firms to have employed blowers on their racing cars up to this time, both used their kompressors to drive air through the carburetter only when the throttle was fully open. The 1924 Sunbeam broke fresh ground, and incidentally set an example which has since become almost normal practice, by having its Roots-type blower, which was driven direct off the end of the crankshaft, aspirating through the carburetter and delivering the mixture under pressure to the induction ports.
Apart from the addition of the supercharger, the rest of the engine was hardly modified. The six steel cylinders (67 x 94 mm.) had welded-on water jackets. The twin overhead camshafts, which were gear-driven from the rear of the engine, operated two large valves per cylinder through pivoted steel fingers. The valves were inclined at 90 degrees. The unusual split race main and big-end roller bearings (a vestige of Bertarione’s earlier association with Fiat’s) were again used. The advantage of this form of construction was that it enabled a one-piece crankshaft to be employed. The engine developed 145 b.h.p. at 5,000 r.p.m., which should be compared with the 107 b.h.p. given by the same motor in unsupercharged form in 1923. The clutch and 4-speed gearbox were built in one unit with the engine, while a large-diameter torque tube located the rear axle and took care of driving and braking stresses. The braking was assisted by a mechanical servomotor driven by skew gears from behind the gearbox. On account of the extra length of the power unit (due to the addition of the supercharger) the wheelbase was 4 in. longer than the 1923 cars, but the chassis frame was 2 1/2 in. lower.
The story of Sunbeam’s misfortunes at Lyon during the 1924 Grand Prix is now ancient history, and probably everyone knows that although they were the fastest cars entered they lost all chance of winning through having been persuaded, on the eve of the race, by the representative of Robert Bosch A.G., to fit a new type of magneto. The result was that both Segrave and Resta suffered intermittent misfiring throughout the race. Segrave led for the first three laps but fell back to 14th due to magneto trouble. He demonstrated the Sunbeam’s potential form, however, by gaining six places in five laps, eventually finishing fifth after putting up the fastest lap of the race at 76 m.p.h. K. Lee Guinness lay second to Ascari’s Alfa-Romeo for ten laps, and when the Italian car stopped to refuel on the 16th lap K.L.G. actually led the race. Unfortunately he had to retire on his 21st lap with bearing trouble.
Although it failed to achieve a win in the 1924 Grand Prix de l’A.C.F. the 2-litre Sunbeam has to its credit a very long line of successes in all kinds of events, including Grands Prix, world’s and class records, hill climbs and Brooklands races. Here is a list of some of the more important achievements. A full list would occupy far too much space.
1924. Grand Prix de l’A.C.F.: 5th, H.O.D. Segrave (and lap record). Spanish Grand Prix: 1st, H.O.D. Segrave – 64.09 m.p.h.
1925. Grand Prix de l’Europe: 3rd, Count Masetti.
1933. Co. Down Trophy Handicap: 1st, T. McCalla (scratch) – 67.94 m.p.h.
1924. Dario Resta. Class E: 1 mile – 119 m.p.h.; 1 km. – 121 m.p.h.
1925. H.O.D. Segrave. World’s Records: 3 hrs. and 500 km. – 102 m.p.h.
1928. K. Don. 7 Class E Records up to 200 miles (1 hour-116 m.p.h.).
1929. K. Don. 2 World’s Records: 200 km. and 200 miles – 115 m.p.h. K. Don. 3 Class E Records: 5 km. – 126.1; 5 miles – 125.8; 10 km. – 125.7.
1927. Brooklands Gold Star: 1st, K. Don – 118.58 m.p.h.
1928. Lightning Long Handicap: 1st, K. Don (from “owe 7 see.”) – 118.46 m.p.h.
1930. 500-Mile Race: 3rd, Purdy and Cushman – 104.74 m.p.h.
1924. Aston Clinton: Dario Resta. Fastest time and new record.
South Harting: Dario Resta. Fastest time.
1925. Kop Hill: H.O.D. Segrave. Fastest time.
Shelsley Walsh: H.O.D. Segrave. Fastest time.
Klausen Pass: Count Masetti. Fastest time and new record.
From the foregoing brief outline of the 2-litre Sunbeam’s performance and achievements it may well be imagined that it was with a good deal of pleasurable anticipation that a group of “vintagents” forgathered in Birmingham during the “phoney” stage of the war for the purpose of making a trial run on one of these famous Grand Prix cars. The machine which was to be sampled was No. 3 of the team (DA8667), which was driven by Kenelm Lee Guinness in the 1924 race at Lyon and by Count Conelli in the 1925 Grand Prix de l’Europe at Montlhèry. Subsequently it was used by Count Masetti to put up a new record at the Klausen Pass in Switzerland and by H.O.D. Segrave to secure fastest time of the day at Kop Hill and Shelsley Walsh. From 1927 the same car became well known at Brooklands as “The Cub,” achieving numerous successes and taking many world’s and class records.
On arrival at our rendezvous we found the Sunbeam had already been pushed out of its garage. Although fitted with large helmet-type wings and an additional silencer, the low battleship-grey car still bore the purposeful look that distinguishes the veritable voiture de course. After a short tow we gained the open road, clear of the city’s traffic. The engine was then started, and after running rather hesitatingly at first it was soon firing evenly and was allowed to warm up gently at about 1,500 to 2,000 r.p.m.
Sitting in the driving seat, the spring-spoked steering wheel with its leather-covered rim seemed to be in exactly the right place to suit the writer. The centrally-situated gear lever was short and rigid and it was only necessary to move the left hand a very short distance from the wheel to reach the lever, which moved in a pleasingly positive manner. The gate is so arranged that to change to third one pulls the lever towards one. The outside handbrake was within comfortable reach of the right hand and a 6-in, lever, moving on a quadrant mounted in the centre of the dashboard, controlled the advance of the two magnetos, whose distributors projected into the cockpit. The Jaeger revolution counter was mounted on a series of radially disposed spiral springs to insulate it from vibration. A thermometer, and air, oil, and blower-pressure gauges were the only other instruments provided. The small, rather closely-spaced pedals called for narrow shoes if the driver was to be sure of hitting the right note at the right time.
The first thing that occurred to the writer as he moved off was the extraordinary lightness of the clutch compared with other cars of contemporary vintage. Due to the light flywheel, the engine accelerated and slowed down with a rapidity which was rather disconcerting to a “vintagent” brought up on “30/98″ Vauxhalls and Bentleys. The timing of the gear change was, however, soon mastered and, with second gear engaged, engine speed quickly mounted to 4,000 r.p.m., when a change was made to third. Becoming a little emboldened the throttle was opened a bit wider, the blower gauge (which hitherto had registered zero) mounted to ”3 hectogrammes,” and with the whine of the timing wheels and gearbox plus the skirl of the blower the Sunbeam was very quickly travelling at what many people would feel was une allure exageree. Over one hundred and fifty horse-power can produce quite a startling effect with a motor-car weighing only 16 cwt.! Possibly the most shattering sensation is to sit in the mechanic’s seat while the driver accelerates really rapidly, using the gearbox in the manner the makers intended. The writer, who is rather blase where acceleration is concerned, certainly felt that he had never experienced anything like it.
After a short run the machine was stopped to allow the tender car with the other members of the party to catch up. Everybody, naturally, wanted to try the Sunbeam, and a suitable stretch of road was selected to enable them to do so. Once warmed up, starting could be effected by one brisk half-turn of the handle, which was just as well, as it is all too easy to stall the engine when getting away on the high bottom gear with a motor which produces very little torque below 2,500 r.p.m. The get-away from a standstill was found to require a little practice, but once mastered it was possible to make a pretty rapid start.
Our short trial run soon had to be terminated, but it so happened that we were able to renew our acquaintance with the Sunbeam not very long afterwards. The new owner decided to bring the car by road from Birmingham to his home not far from London. As this involved a journey of just over 90 miles the same party forgathered again a fortnight later and the writer had an opportunity of driving the Sunbeam for a large part of the journey. Coming out of Birmingham, the servo-operated brakes seemed quite inadequate, but this was due to the comparatively low road speed being insufficient to bring the servo mechanism into full operation. As the speed was increased so the potency of the braking improved until out on the open road the retardation was better than that of many modern cars. The higher the speed rose the better the braking became. There was no difficulty in driving amongst the normal main road traffic provided intelligent use was made of the gearbox and the ignition lever. Incidentally, hardly any pinking occurred despite the fact that “Pool” petrol, with an admixture of oil, was being used. In this connection it is interesting to recall that it was usual for “The Cub” to be driven from the works at Wolverhampton to Brooklands on ordinary No. 1 spirit, although petrol-benzole mixture was used for racing.
On this occasion no attempt was made to drive very fast as the motor-car was too valuable to be endangered on its first outing in the hands of its new owner. Nevertheless, we proceeded at a pace which meant that our modern saloon, which acted as a tender car, had its work cut out to keep the Sunbeam in sight. Travelling at about 60 m.p.h. with the throttle barely open, the blower gauge scarcely registered at all. A long, inviting straight stretch of road tempted the writer to press gently on the loud pedal. About half throttle was all that was necessary to achieve the century. Round corners the car seemed glued to the road (as they say in all the best road-test reports) although indiscreet use of the throttle would result in the tail sliding outwards slightly. This power-slide of the rear wheels always appeared to be perfectly controllable, and with a little practice the technique might be usefully developed. Passing through a county town the racer was driven almost like an American saloon in order to avoid arousing the ire of the local Gestapo. The volume of sound produced by the mechanism when revved up on the lower gears is very pleasant to the enthusiast, but there are some Philistines who are so devoid of good taste as to be unable to appreciate it! In consequence of our appeasement policy it was not unnatural that a plug should oil up, and once clear of the town a stop was made to change it, and to take some photographs. A change of drivers was also made and the writer then wrestled with the tin buzz-box in a vain attempt to keep the Sunbeam in view. That his efforts were unavailing is not surprising, as it was afterwards learnt that the racer had held 100 m.p.h. up one of those deceptive main road gradients that take the stuffing out of all but the most potent touring machines. Incidentally, at this speed the only sounds the driver is concious of are the slight whine of the blower and the rushing of the wind.
The popular idea of the old-fashioned racing car is a rather fierce machine with very hard springing and steering that calls for a good deal of exertion on the part of the driver. The Sunbeam is the very antithesis of such a car. Its steering is very light and the suspension gives a much more comfortable ride, even at touring speeds, than most vintage sports cars. An outstanding feature of the whole design is the light touch required with each control. It is, in fact, not unlike an organ, no more pedal pressure being required to bring forth the full diapason of 150 b.h.p. than to produce the shrill tremolo of the four tyres under the heaviest braking. The Sunbeam is a machine which needs to be driven with all the finesse and sympathy of which the driver is capable. Once the velvet-glove technique is acquired the car can be made to perform in the most soul-satisfying manner.