The 3-litre Super Sports Sunbeam

Having written about the 36/220 and 38/250 sic Mercedes-Benz, the Brooklands-model Riley 9, the Gordon England Brooklands-model Austin 7 and the Amilcar Six, it seems appropriate to follow up these articles with something on the 3-litre Super Sports Sunbeam. In the first half of the 1920s there were two main British exponents of the larger kind of sports car, namely the 3-litre Bentley and the 3-litre Sunbeam. The former requires absolutely no qualification, but the Sunbeam from Wolverhampton was made in smaller numbers and was in some respects the more exclusive car. Whereas the Bentley used a four-cylinder, sixteen-valve, overhead-camshaft engine that might have come directly from under the bonnet of a number of 1914 Grand Prix racing cars, the Sunbeam, stamped all over as the brainchild of Louis Coatalen, used a power unit much more closely related to a contemporary racing engine.

Indeed, with a six-cylinder, twelve-valve, twin-overhead-camshaft engine the 3-litre Sunbeam was an exciting sort of motor car, which can be likened to an English version of the Type 43 Grand Sport Bugatti. Admittedly, the Bugatti was even more nearly related to pure racing car practice and naturally its supercharged straight-­eight cylinder, twenty-four-valve, overhead­camshaft engine gave it a higher speed, some 112 mph against the 90 mph or thereabouts of which the Sunbeam was capable. (I think we can quote 82 mph as the maximum speed of a 3-litre Speed Model Bentley.) The Type 43 Bugatti was also shorter in the wheelbase than Coatalen's Super Sports Sunbeam, but there is similarity nevertheless.

The 3-litre Sunbeam tends to be thought of as a car typical of the later 1920s. This is because although it was announced publicly in 1924 it did not go into production until late in 1925, not being catalogued until October that year, or early in 1926. The announcement about a new Super Sports Sunbeam came, in fact, in May 1924. It had a six-cylinder engine of 75 x 110 mm (2,916 cc) with twin o/h camshafts driven by a train of eleven helical gears at the front of the engine, operating the valves inclined at 90° via light rocker-fingers -the sort of engine to appeal to Griffiths Borgeson, who has just written a very learned book about twin-cam engines and exasperate Anthony Blight who has recently expressed the view that "camshafts are expensive, heavy, and difficult to drive properly, and the less of them there are the better" -it can be assumed that Mr. Blight does his personal motoring in a Mazda RX-7 .... 

The engine of this 1924 Super Sports Sunbeam was a sophisticated one. It used dry-sump lubrication (very rare for production cars, although Bertelli used it for a time for his 1½-litre Aston Martin) with the oil carried in a large tank between the frame and the crankcase, on the n/s, the carefulfy balanced crankshaft ran on eight plain bearings, block and head were integral, and to obviate camshafts-snatch three double-cams and spring-dampers were used on each of the o/h.-camshafts. A single plug per cylinder, mounted centrally, as the twin-cam engine permitted, was employed, with a BTH magneto driven by a cross-shaft at the front of the engine, the opposite end of which drove the water-pump. The Rotax dynamo was driven from the nose of the crankshaft, as on a 12/20 Calthorpe, and a Claudel-Hobson carburetter on the o/s fed into a Y-manifold that supplied the cylinders through two three-branch upper manifolds. The ribbed exhaust manifold was on the opposite side, with a rear off-take.

Obviously this fine engine owed much to the Bertarione-designed 2-litre Fiat-like six-cylinder 67 x 94 mm Sunbeam with which Henry Segrave had won the French Grand Prix in 1923, although the cylinder block was of cast-iron instead of steel and plain bearings were used instead of roller bearings throughout as in the racing engine. For this reason some surprise was expressed that Coatalen put his new sports engine into a chassis resembling that of the current 16/50 hp touring Sunbeam, with a wheelbase of 10' 91/2" and cantilever back springs. The engine drove through Coatalen's now-favoured plate clutch and unit gearbox, and Coatalen's also- favoured torque-tube, and the wire wheels were shod with 880 x 120 mm tyres. Hartford shock-absorbers were fitted to both axles and Sunbeam Perrot-type four-wheel brakes featured in the specification. Typical of the period was the right-hand lever controlling the four-speed gearbox. 

What was presumably a prototype (Reg No DA 8206) had a two-door four-seater body, but differing from the accepted style of later production 3-litre Sunbeams were the running-boards and long, flowing front mudguards. Two spare wheels were mounted at the back and all-weather equipment was provided. The axle-ratio was quoted as 4.5 to 1, giving a speed of about 87 mph at 4,000 rpm in top gear. Even a price was quoted -£950 for the chassis, £1,100 for the four-seater, at a time when a 3-litre Speed model Bentley chassis cost £925 and a Vanden Plas four-seater £1,225. 

Although at first sight the long touring-car chassis of the 3-litre Sunbeam seemed out of keeping with its racing-type engine, the reason behind Coatalen's thinking is not, I suggest, difficult to interpret. In 1923 the first Le Mans 24-hour race had been run, and this endurance contest was originally for "production touring cars". Ignoring the Rudge Whitworth Triennial aspect of the scheme, the winner was a 3-litre Chenard-Walcker, wtih another in second place and a 2-litre Bignan third. The race had caught the imagination of the British and John Duff had entered his privately-owned 3-litre Bentley, which he shared with the works-driver Frank Clement. They came home 5th, beaten only by the aforesaid cars and the 4th-placed Bignan. WO Bentley was extremely interested and determined to have a real stab at the 1924 race. Louis Coatalen thought the Bentley an old-fashioned sports car concept and there could have been little that would have pleased him more than for a Sunbeam to show a Bentley the way round the Le Mans circuit, in those days very much a road course.

It must have been for this purpose that the 3-litre Sunbeam was envisaged, surely? Previously Coatalen had kept a low profile where sports cars were concerned, preferring to build high-grade touring cars that benefited from experience gained with the racing Sunbeams. He never went much beyond offering sporting versions of these touring models. The 21/60 and 24/70 Sunbeams were fine sporting cars, and there was even a sporting edition of the 14/40. But until goaded by the new 3-litre Bentley, Coatalen offered his clients nothing of a truly sports car nature. In 1921 he had unexpectedly announced those mysterious substitute single-­overhead-camshaft, four-valves-per-cylinder engines for the 16 hp and 24 hp Sunbeam cars, notwithstanding that sporting versions of these were available and that they were to receive push-rod overhead-valve engines in 1922 anyway (see Motor Sport, August 1980). I suggest that it was to challenge Bentley at Le Mans that the formidable Louis put down the twin-cam 3-litre Super Sports Sunbeam. It would endorse his edict that his racing cars benefited his production models, the new 3-litre power unit being of the same form as that of the winning 1923 French GP Sunbeam.

Indeed, it is said that 25 of the new 3-litres were intended: The Le Mans regulations in those days actually called for 30 cars similar to those raced to have been built, stocked, or sold, so perhaps what was intended was 25 cars plus a race-team, plus the prototypes? 

Cars of over 1,100 cc had to have full four-seater bodies, so Coatalen, who liked to economise when possible probably saw no good reason why his expensive new engine should not be installed in. the existing 16/50 hp touring chassis. The new 3-litre Sunbeam was to have made its debut at the Kop hill-climb of March 29th 1924, before running in the Le Mans race on June 14th/15th. It failed to appear, nor was any comment made about this that I have seen. The intention was to allow AH Pass of the Car Mart to drive this prototype car at Kop and it was carefully explained that its presumably "rather French" body would be replaced by one more suitable for touring before production commenced. The two Le Mans entries, for which Lee Guinness and Resta had been nominated, never materialised either. Nothing more was heard, for nearly a year. 

It seems likely that Coatalen was too occupied with supercharging the 1923 Sunbeam GP engine for the 1924 season and getting out the new version of the successful 1½-litre supercharged Talbot-Darracq racing cars, to build enough 3-litre sports cars to comply with Le Mans homologation. Unless, of course, he had run into technical difficulties, which seems unlikely, or had not realised that the Le Mans regulations required so many duplicate cars to exist; even though this was apparently left to the entrants' honour! 

Anyway, for whatever reason, the Sunbeam entries were withdrawn and Coatalen had the unwanted experience of knowing that Duff and Clement, again privately entered, had won the 1924 Le Mans marathon for WO Bentley, trouncing the push-rod ohv La Lorraines. He just had to run in the 1925 race! Meanwhile, between March and June 1924 Bentley and Coatalen waged a bitter if gentlemanly correspondence in The Autocar, sparked off by WO daring to criticise Coatalen's pet dogma that racing improved the breed of motor cars and benefited subsequent touring cars. I recommend anyone who has not seen this splendid slanging-match to try and do so; it was summarised by "Balladeur" in Motor Sport many years ago. There are some very interesting asides in it. Rather surprisingly, Coatalen mistakenly thought the 3-litre Bentley had dry-sump lubrication. He otherwise attacked it as merely a rehash of the racing cars of 1913/14, its design that which Coatalen had used himself at that time (he makes no mention of cribbing from Ernest Henry and Peugeot) but had abandoned from racing experience. Bentley remarked on Coatalen building his special racing cars in special factories using special personnel for the purpose, presumably thinking of the facilities in Wolverhampton, Acton, Paris and so on, which Coatalen cunningly met by saying his racing and touring cars were built together in the experimental departments of  the Sunbeam and allied factories. WO got in a nice dig when he said that he was clearly wrong in his assumption and that if he were building special racing cars, which he hoped he would never be called upon to do, he would try to get the best man from Fiat's or Sunbeam's (a crack at Bertarione designing the 1923 GP Sunbeams, Ernest Henry the 1922 cars) but that he would never let such people come near his production models. The arguments duly brought in Hotchkiss versus torque-tube transmission, Bentley claiming the latter to be cheaper, which I have never understood. 

The point I want to make here about this illuminating correspondence in the public prints is that at one stage Bentley tried to rile Coatalen by saying his twin-cam racing engine in a chassis of short wheelbase fitted, all round, with half-elliptic springs, were not to Sunbeam's touring-car specification. So not only would victory over the Bentleys at Le Mans in 1925 be very sweet for Coatalen, but for whatever reason he had used a long-wheelbase chassis with cantilever back springs for his 3-litre sports car, it would ram WO's comment down his throat if a car so endowed did well in racing! This time, it happened. Two Sunbeams were entered, to be driven by Segrave/Duller and Davis/Chassagne. Both started. Duller retired with clutch trouble but after many difficulties the Chassagne/Davis 3-litre Sunbeam (Reg No DA 8206) came home second, at 55.96 mph, for the 1,343 miles it covered, eight miles behind the winning Lorraine-Dietrich, 45 miles ahead of the Lorraine-Dietrich which finished third. Both the 3-litre Bentleys retired, so Coatalen's cup must have been full. However, neither he nor WO can have overlooked the fact that a car with simple push-rod-operated o/h-valves had won ....

For Sunbeam's it had been a near-run thing. On the journey over very rough roads to Le Mans, the two green cars running in formation, Segrave's in the lead, the chassis side-member of Chassagne's car cracked (some reports say) by the rear engine-bearer. Both cars were taken to the Darracq factory in Paris (which probably made WO smile!) for repairs, Chassagne's in a lorry, and strengthening of the chassis frames. Why a chassis that sufficed for the 16/50 hp Sunbeam now gave trouble can presumably be attributed to the greater weight of the twin-cam engine, the higher speeds attained, and the bad roads. Incidentally, the new engine was very long and as a four-seater body had to be used, maybe Coatalen had little option over wheelbase length. A big Darracq chassis was sent for the drivers to practice on - could it have been a 28/70? With no practice on the 3-litres, the drivers started the race. Segrave had trouble with sticking throttle-barrels in the Claudel-Hobson carburetters, Chassagne had the same problem, and later, forced into a ditch, the back axle was bent and the car began to break up, the dashboard with its duplicate instruments collapsing so that it had to be steadied by hand (which no modern racing driver, at Le Mans or anywhere else, could cope with), the back tyres nearly touching the body, the brakes weakening, and the throttles still sticking open - suggesting that the chassis had broken again, a trouble that dogged production 3-litres. The engine was the best part of the car, running crisply up to 3,700 rpm right to the end.

That Le Mans race vindicated the complicated 3-litre Sunbeam. It remained an exclusive car, in specification and the small numbers built, and also in its racing, for it did not run in many events. WO Bentley got his revenge in 1927, of course, when Davis and Benjafield won in a 3-litre Bentley, covering 1,472.5 miles at 61.35 mph, after the 4½-litre and another 3-litre had retired. But in 1926 the three 3-litre Bentleys entered all retired, two with valve failure, one car breaking a rocker which couldn't have happened with Sunbeam-type twin o/h-camshafts, the third crashing due to lack of brakes. It is difficult to understand why Sunbeam did not contest that race. Money may have been running out, but Coatalen was still able to build a team of new 11/2-litre straight-eight GP Talbots and the V12 4-litre Sunbeam LSR car and one would have thought that enough finance might have been found to do Le Mans again. After 1926, of course, as Bentley made Le Mans his own preserve, STD affairs were such that no further racing was possible. 

When It re-emerged in 1925 the 3-litre Sunbeam was seen to have undergone some changes. Apart from twin carburetters, the magneto, protruding forward, was now driven from the main timing-train. The camboxes were now ribbed but the exhaust manifold was plain. The former carbon-steel crankshaft was replaced by one of nickel-chrome, to make revving to over 4,000 rpm safe, and the water flow across the block was altered to obviate cracking around the bores. The wheelbase was increased to 10' 101/2'' and the tall radiator and cycle-type front mudguards turning with the wheels, in conjunction with abbreviated running-boards, gave a very sporting appearance. At Le Mans these mudguards were obviously unsuitable and blade-type front wings, full-length running boards, and side-mounted spare wheels were used. Tuned for power the engine gave 90 bhp at 4,400 rpm. 

The 3-litre was shown at the 1925 Olympia Show, and The Autocar took one up to Scotland to the Glasgow Exhibition. By 1926 specialist coachbuilders had been busy with the 3-litre chassis. For instance, Maythorn made a coupe for Sir Thomas Devitt, Bt, cellulose-painted in grained walnut, with brown morocco upholstery, Warwickshire Motors had supplied a similar car to Ernest Taylor of Bournemouth, Sunbeam's themselves had put a Weymann saloon body on a 3-litre chassis for Herman Bradley of Hilston, Lord Ridley had taken delivery of a four-door tourer by HJ Mulliner, and Lord Curzon had an aluminium boat-tailed car with streamlined running boards (YL 3570). The Surbiton Coach & Motor Works made a rakish sports-saloon, Park Ward mounted a very touring-looking all-weather body on a 3-litre chassis with conventional mudguards, Dr Bury of Deptford had an Alford & Alder sports-tourer with bulbous tail, Gordon England fitted one of his lightweight 4-door tourer bodies, in blue leathercloth, with Brooks fitted trunks in the special tail, a smart two-door Weymann saloon was supplied by E Maul & Son to J Gyers of Stockton-on-Tees, Freeson & Webb did another Weymann saloon, and Bamber's of Southport got Car Bodies to make a sports-coupe with concealed head when open and in 1927 Weymann's did a 2-door saloon with trunk and hood-irons on a 3-litre; not all these cars had the cycle wings, although Col Warwick Wright's four-door Weymann saloon retained them. Altogether, Coatalen must have thought his advanced 3-litre well worthwhile.

Full all-weather equipment was supplied for the standard four-seater in 1926 and Dewandre vacuum-servo brakes were available for an extra £30. AH Pass, of Pass & Joyce Ltd, had taken a 3-litre (it had streamlined-shape steps instead of running-boards; Reg No XY 1) to the South of France and into Italy to inspect the Fiat factory. 

By April 1925 The Autocar had published its findings, having had a short run, I suspect accompanied by Segrave (who in spite of his racing-ace status used to demonstrate cars when occasion demanded), in DA 9485. They said 90 mph was decidedly attainable, which might even be exceeded on the road (a ploy to suggest they didn't break the 20 mph speed-limit, perhaps), and 10-30 mph took 4.2 sec in 1st, 5 sec in 2nd and 7.8 sec in 3rd, top not being used below about 11 mph (a reminder, I fear of how staid even vintage sports cars were!). The 3-litre braked from 40 mph to rest in 66'. The gear ratios were rather low, the maxima in the gears being 30, 45 and 71 mph. The cantilever springs caused a little rear-end float until the shock-absorbers were tightened. The body was still cramped for the rear-seat occupants but it was noted that the cycle front wings had been well tested in France and never broke from their brake back-plate mountings. By the early summer Pass' car was tried, from Euston Road to Brockley Hill, which it did in top gear. The gear change was no longer sticky, the exhaust note more pleasant, the engine now extraordinarily smooth, cold starting taking but a minute.

Motor Sport and "auntie" Times had to wait until a Weymann saloon was available. Like WO Bentley, Coatalen realised that many clients wanted a closed body even on a sports chassis but he at least offered a light one. After a 6-light body, a 4-light, 4-door fabric saloon, using the cycle front wings and short running-boards, was listed, at £1,250. It weighed 33 cwt. Motor Sport's road-test car (UK 3525) lapped Brooklands at 77½ mph, touching 86 mph, although the car had a low axle-ratio, having been run at Shelsley Walsh by Perkins, with an open body. From 40 mph the Sunbeam stopped in 90' on the wet track and it did 10-40 mph in 12 sec in top, in 8½ sec using the gears. The Times man spoke of a comfortable maximum of 80 mph and an engine, which had run 12,000 miles, that was "not noisy but could be heard because of the gearing and the wide valve clearances", This car was geared at 45 mph at 2,000 rpm. Along the years small improvements were made, such as more modern tyres (5.25 x 31 straight side, then 5.25 x 21 well-base), central, plunger chassis-lubrication, bi-metal pistons, adjustable front seats, and dipping headlamps, etc. By 1930 the price of the four-seater was down to £850.

Although he missed Le Mans in 1926, Coatalen ran two blue 3-litres in the 1927 Essex MC Six Hour Sports Car Race at Brooklands, entrusting them to Segrave and Duller, with Perkins as spare driver. In those days I didn't have a Press pass and so couldn't get near the cars. I was as keen on Bentleys as most schoolboys but also greatly admired Segrave and the Sunbeams. So I was troubled when I saw the latter. They had very substantial touring-type mudguards, full-length running-boards and big windscreens. I felt they might have tuned 20/60 push-rod engines instead of twin-cam power units. They were twin-cam cars all right, and perhaps the heavy mudguarding was to prevent breakage on the Brooklands bumps. Segrave refuelled away from the pits and was disqualified (Posthumus has a theory that the "fastest-man-on-earth" was bored with sports-car racing on an artificial road-circuit and did this deliberately), but Duller won on distance, averaging 64.3 mph for 386 miles. Jackson (who ran a variety of older Sunbeams at Southport), partnered by Turner, brought another 3-litre home in 6th place, at 59.6 mph. Duller won the Pass & Joyce Cup, and the Barnato Trophy presumably intended for a Bentley. Of the Bentleys Birkin's Bentley was 3rd, the rest retiring with rocker failure, so again Louis could afford a Gaelic smile! 

Supercharged 3-litres of very "competition" appearance were prepared for Phoenix Park in 1929. Curiously, in view of Sunbeam's long experience of making their own Rootes blowers, Cozette compressors were used (for technical details, see Motor Sport, Vol. XXVI, page 29), so perhaps an outside influence was at work? Malcolm Campbell (in UK 7145) retired with clutch failure, this component being hard put to cope with 138 bhp at 3,800 rpm, but I have heard that Campbell's brutal gear-changing didn't help! In the 1930 Irish GP BO Davis drove the supercharged car but retired when the blower casing cracked (disguised as a jammed Bendix pinion and broken oil-pipe) and Manders' normal 3-litre retired much later. The prototype of these blown cars apparently had a Weymann saloon body, the other five the very attractive, lowered open bodies, HW 7813 being used for practice and then sold to Walter Hammond, the cricketer. Davies in his smoke blue (sic) 3-litre got a 3rd place at Brooklands in 1930, lapping at 107-110 mph, which compares with a lap at 80.33 mph by Fortlage's normal sky-blue 3-litre, the only one of these Sunbeams to run in a BARC handicap race, I think. Hammond's car was acquired by CLW Barker, who gained two third places with it in BARC races during 1938/39 (best lap = 101.64 mph).

Production of the 3-litre had ceased in 1930. As appendices to the above I have asked AS Heal to recount his experiences with a 1926 3-litre and the STD Register (Secretary: Jeremy Grammer, 39 Broad Walk, Wilmslow, Cheshire) to give us a breakdown of the Sunbeams of this type among its present membership. - WB.

A 3-litre appreciation

WB asked me to write something about my 36 years' experience as a private owner of the 3- litre Sunbeam. On June 9th, 1945 John Wyer and I took the train to Liverpool to collect from J Blake & Co Ltd the 1926 3-litre Sunbeam (YP 7363) I had arranged to buy from them. £175 seemed an extravagance at the time but proved, in the succeeding 36 years, to be a sound investment. Mr GV Halpern was extremely helpful in preparing the car for the 200-mile journey to Buckinghamshire, fixing a mirror, providing a jack and filling the petrol tank in exchange for all our coupons for the next three months. Considering its age, the car was in good condition and had not been altered or cut about by previous owners. It is one of the F seris (Chassis No 4082F) from which the maim shortcomings of the earlier E series had been eliminated. 

The engine is astonishingly flexible, the acceleration is all one can rightly expect from a 46- year-old 3-litre four-seater, the gearbox is delightful, giving rapid changes from second to third and from third to top. The steering, like all vintage Sunbeams, is light and positive under normal road conditions but for racing or on slippery surfaces there is a tendency to understeer. I fitted a Ki-gas and starting from cold has been no problem. For competition use I fitted SU petrol pumps in place of the standard Autovac but I have not sought to improve the performance of my car beyond what it gave when new. 

The 3-litre Sunbeam stands to be compared with its two great contemporaries: the 3-litre Bentley and the 30/98 Vauxhall. The latter with its 4¼-litre overhead valve engine gave better acceleration and higher top speed. Compared with the 3-litre Bentley the performance of the Sunbeam shows up favourably. The following times recorded at a meeting of the Bentley Drivers Club in 1949 are of interest:-   3 laps 

Fastest Sunbeam 3-litre 35.98 sec (½ mile ss). 11.08 sec (1/4 mile fs). 7 min 9.4 sec (3 laps)  Fastest Bentley 3-litre 38.04 sec. 13.01 sec. 7 min 28.0 sec. 

It is on the open road that the 3-litre Sunbeam is seen to best advantage as the extraordinary flexibility of the engine and its excellent top gear acceleration in the middle range enable very satisfactory average speeds to be achieved. I have never greatly exceeded 80 mph with YP 7363 as with the ever increasing rarity of major spare parts, I have always tempered valour with discretion. Slow running shows up well as the following times, recorded during the 1954 VSCC Anglo American Vintage Rally, reveal.

That this was no freak performance may be judged from the Sunbeam's achievement in the 40 minute speed test at Goodwood on the last day of the Rally when the 3-litre carried off the award for the greatest distance covered.

To anyone like myself, with experience of the 30/98 Vauxhall, the Sunbeam's six-shoe Perrot brakes seemed more than adequate. Apart from a cracked cylinder block, for which I blame myself, in 36 years of varied use, comprising touring, rallies, races, speed trials and towing a trailer carrying my 2-litre Grand Prix Sunbeam, my 3-litre has been a model of reliability.

In its competition days, John Wyer ministered to its needs but when Sir David Brown claimed his full time and attention at Aston Martin, his mantle fell upon Len Gibbs of Slade's Garage, at Penn who has looked after it ever since. 

£175 may have been an extravagance in 1945 but, as Sir Henry Royce so truly said "the quality remains long after the price is forgotten". I gladly pay this small tribute to Louis Coatalen, Vincent Bertarione and all those at "The Sunbeam" who produced the car that has given me such unfailing service and so much enjoyment during the last thirty-six years. Anthony S Heal.