Passenger Vehicles 1905-1914
The demand for single cylinder vehicles in 1905 was strong, a reflection of their qualities of simplicity, ease of maintenance and, above all, economy. Each year between 1905 and 1910, the company always had at least two models available. For 1911 and 1912 there was a single variant on offer; thereafter customers had to settle for a twin cylinder or four cylinder, as single cylinder production had ceased.
The most significant change on chassis design over the ten-year period covered here was the transition from steel tubing to pressed steel sections. From January 1905 the only Type that was launched with steel tubing was the Type AL (see image below), the model that was to be the exception to all the subsequent innovations that the company launched. Steel tubing was still used on many models, but only for cross members. A waisted (or cranked) chassis design was adopted for all models from 1905 onwards in preference to the parallel frame that was used for some of the larger- engined, three-speed models before 1905. The choice of springs for each Type continued the pattern that had been established previously: all chassis had semi-elliptic springs on the front, the smaller chassis best suited to lighter coachwork, had three-quarter elliptic springs on the rear, whilst the longer wheelbase models had semi-elliptic springs attached to an inverted transverse spring at the rear, or just semi-elliptic springs for the later models.
From an aesthetic perspective one of the most significant changes occurred in 1907 with the Type AU when the familiar sloping coal-scuttle bonnet was replaced with a horizontal centrally hinged bonnet. This was a direct consequence of the adoption of the honeycomb type of radiator, which was considerably more thermally efficient than the previous finned-tube version that was slung between the dumbirons.
The adoption of a rigid (or live) axle with the driveshafts to the wheels enclosed in the same metal casting that held the differential was a significant change from late 1909, and this became the norm for the smaller cars thereafter. The previous year the Type BO had its gearbox mounted away from the differential, establishing a trend that culminated in the amalgamation of the engine, clutch and gearbox into a single unit in the Type DE1 in 1911. This approach was then adopted for many of the twin cylinder models and some of the smaller four cylinder types.
Previous mention has been made of the influence of voiturette racing on technical development from October 1905 (with the first Coupe des Voiturettes event), and subsequent innovations such as magneto ignition, improved compression ratios, higher crankshaft speeds and longer engine stroke, the latter a result of the regulations on weight and bore. The impact of some of these developments was felt in the design of engines for passenger vehicles, but their engine dimensions between 1905 and 1911 were very consistent (generally with 100mm bore and either 120mm or 130mm stroke), although a Type de Course with a 160mm stroke was available in 1910 and the 1911 Type CP did have a 150mm stroke. One of the principles that was established from the usage of the small De Dion Bouton engines for racing was that these single cylinder cars were desirable not just for their economy, but also for their performance and reliability. A customer had the option of purchasing a twin or four cylinder De Dion Bouton, but with their heavier superstructure improved performance was not always guaranteed.
The engine installed in the Types Y, Z, AL/AL2 and BN was a direct descendant of that used in the early tricycles and voiturettes, and visibly similar. There was a cast iron cylinder body and a vertically split aluminium crankcase containing the same arrangement of heavy internal flywheels. All other components are characterised by their light construction. These engines were equipped with an automatic/atmospheric inlet valve. Following the demise of the Type Y in 1906, there was a period of a further six years before the next 6hp vehicle (according to the revised hp ratings), the short-lived Type DE1, the final ‘one-lunger’, appeared on the market. Along with the continuity of engine design, there were a series of changes that were made to the technical efficiency and appearance of individual models. The Type Z, for example, which received its Type Approval in December 1904, was the first single cylinder to be equipped with the metal plate clutch and sliding pinion gearbox, a permanent feature thereafter, while the Type BN, launched in late 1908, had a cone clutch, a feature that was restricted to that particular Type and the Type CD of 1910.
The 8hp engines of the Types AU and BG, available in 1907, were markedly different from their single cylinder predecessors both aesthetically and functionally. They were the first single cylinder engines to be equipped with mechanically operated inlet valves, which helped to both reduce engine noise and increase the power output of the engine by an estimated ten per cent. The cylinder is cast with a bottom flange and the cover is formed with the water jacket delivery pipe. Two chamber caps enable access to the valves. There is also some change from the previous design in the way the engine is mounted in the chassis: the aluminium, vertically split crankcase has four brackets incorporated into its shape, which now rest on the chassis members, to which they are bolted.
The demand for more substantial accommodation and coachwork, however, was increasingly well catered for, culminating in the production of the Type BO, whose wheelbase options (2.34m and 2.6m) were similar to those of its larger four cylinder relations. The Type BO engine, introduced in September 1908, was the first single cylinder to be equipped with a magneto, containing a contact breaker and a distributor in the high-tension circuit. As with the Type BN arrangement, the carburettor float chamber and jet are situated near the base of the engine and are connected through a vertical pipe to the mixing chamber adjacent to the water jacket on the top of the engine. The air that passes over the jet is drawn from a jacket that surrounds the exhaust pipe, and the rich mixture is diluted in the mixing chamber by the action of an automatic auxiliary air valve. The engine has forced lubrication: an automatic pump, driven off the camshaft, forces the oil through tubes and channels to the main crankshaft and bearings. The overall design of the engine is different from its predecessors in that the conventional circular crankcase has been replaced with one with tapering sides, although the four mounting brackets introduced with the Type AU are still present.
The angular design of the Type BO engine was relatively short-lived: by the time of the launch of the Type CD and long stroke CP engines (in September
1909 and September 1910 respectively) the original circular crankcase design had been restored, complete with mechanical valves, magneto and splash lubrication. The decision to discontinue with the mounting lugs, as seen in the Types AU and BG, in favour of bearer arms, may have had something to do with the latter’s greater tolerance of torsional stresses of the chassis, but cost considerations undoubtedly dictated the omission of forced lubrication, hot tube feed to the carburettor and the auxiliary air valve.
The Type DE1, launched in 1912, may have been the end of the line for the company’s production of single cylinder vehicles but it was not without interest since it did incorporate a number of innovations. For the first time the company integrated its engine (84mm bore x 130mm stroke), clutch and gearbox into a single unit. This was novel for Puteaux but Bayard- Cle?ment, with its 10/14hp model and Darracq with its 7hp car, had offered this option early in 1907. The 6hp engine had valves enclosed within a dust-proof cover plate, the camshaft was driven by silent chain, there was forced lubrication and a combined oil level gauge and drain tap fitted. The Type DE1 had an accelerator pedal, akin to most other vehicles produced in Europe, but very different from the philosophy of the decelerator that De Dion Bouton had installed in its cars for more than a decade, and continued to use for some time on the larger engine variants. The Type DE1 continued with a number of features previously introduced: the leather- faced plate clutch, quadrant gear change, forced engine lubrication and magneto.
The one exception to the trend in technical development was the Type AL, which was launched in July 1905, and evolved into the Type AL2 from 1908. It appeared in French sales catalogues until 1909, was still available from the factory in 1910, and continued to be featured in the English sales catalogues even as late as 1911. This particular model had a 100mm bore and a 120mm stroke engine that first made an appearance on the Type K2 in 1902, and throughout its existence it sported the same tubular chassis, coal-scuttle bonnet, automatic valves, contact breaker ignition and expanding clutch. Its existence was both testimony to the quality, simplicity and ease of use of the original cars, and of the company’s awareness of what some customers really wanted.
The quintessential single cylinder car that appeared in so much of the promotional literature was the light-bodied two-seater, often without a windscreen or hood in the earlier period, although good sense and experience ultimately led to windscreens and folding hoods becoming a regular feature for enhanced weather protection.
The company launched fewer Types of twin cylinder cars than any other engine configuration in the period between 1905 and 1914. The engine numbers of extant vehicles, of which there are perhaps 50, suggest an output of little more than 3,000 over a ten-year period. The very limited coverage in contemporary press and literature supports the view of low production. The 1905/6 vehicles were similar in design and specification to the 1904 cars.
For 1904 the twin cylinder vehicle was the most powerful that De Dion manufactured and it had a chassis and general construction suitable for the most substantial of coachwork. For 1905 and 1906, even with four cylinder cars available, this view still prevailed and the longer wheelbase twin cylinder cars were of equal length to the standard four cylinder models; they were all equipped with the more robust pressed steel chassis, with the exception of the Type AB. From early in 1905 all twin cylinder vehicles were equipped with the revised front wheel hubs, incorporating C-shaped axle ends and pivot joints, the profile of which evolved throughout the period. The rear springs were semi-elliptic in design, attached to an inverted transverse spring by two sets of double shackle joints, the traditional method employed by the company for those cars designed to carry heavier coachwork.
The 10hp Type AB and the 12hp Type AC that were both produced in 1905 were very similar to their predecessors, the Type W and Type S, except that the most recent models had the latest sliding pinion gearbox and plate clutch. When the twin cylinder models were first launched in 1903 they represented both a considerable investment and a significant departure for a company that hitherto had only produced single cylinder models. The company tested a range of power units in 1903 to ensure that the new approach to engine lubrication, using an engine-driven pump, was fully effective, and thereafter the engines were substantially unchanged, and retained their simple automatically operated inlet valves and had twin blade ignition. The Type AB, the continuation of the Type W, retained the existing steel tube chassis arrangement, although the Type AC was equipped with the pressed steel chassis. With the arrival of the pressed steel chassis rails, the role of the traditional dumbiron disappeared and so simple shackle bolts were used for attaching the standard semi-elliptic front springs to the tapered front of the chassis rails.
From early in 1906, the Type AN was available as a direct 12hp replacement for the Type AC, but with some significant changes. The track was reduced from 1.36m to 1.24m, whilst the wheelbase was substantially longer: 2.58m in standard form, and 2.88m for the Type ANL, making it the longest twin cylinder vehicle that the company ever produced. Some of the chassis fittings also differed with the Type AC having a gear change and brake lever mount underslung below the chassis, and for the Type AN the mechanism operated through the frame. The engine had the same dimensions and output but the fittings changed: the earlier Type AC has ‘vertical’ chassis mounts that were changed to ‘horizontal’ mounts for the new model. The ignition was also revised, with the earlier ‘two-bladed’ affair replaced with the standard contact breaker.
Comprehensive changes were eventually made in August 1907 with the Type AV, which had a wholly new engine with a smaller 80mm bore and a lengthened 120mm stroke. This was to be the only time that this particular cylinder configuration was ever used in any pre-war passenger vehicle. It was equipped with mechanical valves as were all subsequent two cylinder Types. As with the single cylinder Type AU that received Type Approval three months before the Type AV, the coal-scuttle bonnet disappeared, replaced with the horizontal, centrally hinged design. The presence of dual ignition by high-tension magneto, supported by coil and battery for starting, a sliding pinion gearbox, plate clutch, and the pressed steel chassis, all confirmed the full makeover of this model.
De Dion Bouton actively reduced the pricing of the four cylinder vehicles between 1905 and 1907, at which point the twin cylinder option was withdrawn. By 1907/8 these vehicles sat uneasily between the cost efficient and, for many individuals, entirely adequate performance of the single cylinder offerings, and the recently developed four cylinder variants, whose power output was similar (at least on paper), but whose more substantial chassis offered greater flexibility. The differential between the price of a single cylinder car and a four cylinder dropped very significantly at the same time. When the lower-powered twin cylinder Type CQ appeared in 1911, following the decision to reduce (and ultimately discontinue) single cylinder production, it was repositioned with a chassis-only price of just FFr4,800.
When the Type CQ appeared in the 1911 catalogue, it was clear that the role of the twin cylinder car had evolved: it was now designed to meet the needs of customers interested in a smaller economy model, and for this reason the wheelbase was shortened, the track reduced, and the engine was less powerful. Three-quarter elliptic springs now graced the rear of the car. From that time until the end of 1914 there was always a twin cylinder option available to customers.
In common with the other smaller-engined cars of 1911, and in contrast to its own twin cylinder forebears, the Type CQ had a rigid (or live) rear axle, the gearbox was separate from the differential, and there was direct drive on top (third) gear. The significant difference with this engine was the adoption of a ‘single-throw’ crank. The earlier twin cylinder engines had cranks that were situated at 180 degrees to each other, which offered improved mechanical balance, but at the risk of torque irregularity derived from the challenge to a conventional carburettor of balancing the mixture for both cylinders. A double-barrelled two jet carburettor initially solved the problem for De Dion Bouton, but the ‘single-throw’ crank offered the opportunity to both simplify carburation and produce a more compact (and cheaper) power unit.
The differences between The Type CQ and its successors (Types DE2, DW2 and EJ2) were significant but beneath the surface. The last three iterations of the twin-cylinder had a smaller engine of 66mm bore and 120mm stroke (the same as the four cylinder Type CR from the previous year), producing 6hp under the new formula. The engine, plate clutch and gearbox were formed into a single unit for the first time, in the interests of compactness and stiffness.
The Type DE2 received its Type Approval on November 28, 1911, the same day as that of the single cylinder Type DE1, with which it had much in common. The DE2 was built on a smaller chassis than its predecessor, the Type CQ, and its wheelbase and track were correspondingly reduced; in fact, the wheelbase of 1.95m and the track of 1.15m were the same as the Type DE1. The Types DE1 and DE2 both had the same integrated engine, gearbox and clutch arrangement, and they shared the same power output rating of 6hp, although in some of the company literature the twin cylinder vehicle is sometimes referred to as a 7hp vehicle.
The Type DE2 had a leather-coated metal plate clutch. It had quadrant gear change, forced engine lubrication and a magneto. The magneto for the twin cylinder vehicle had a distributor as an integral part of it. The pressed steel chassis had a tubular cross member at the front and was upswept over the rear live axle, and in respect of suspension and the fitting of springs it was identical to the single cylinder car described previously.
The Type DW2 of 1912 had an extended wheelbase of 2.13m. The Type EJ2 received Type Approval on July 30, 1913. It was the last twin cylinder produced by the company, and may not have been available outside France; certainly, there is no mention of the vehicle in the 1914 catalogue produced for the British market, and The Autocar noted that only six De Dion Bouton models (a third of the range) were to be offered for sale in the local market: three of the four cylinder Types and three eight cylinder models. The only visible structural difference between a Type DW2 and a Type EJ2 is that the latter does not have the rear suspension bracing rods.
Between 1904 and 1914, 46 four cylinder passenger vehicles went into full production, although Type Approval was sought for 81 different models. Of these, 15 were powered by engines of 7-12hp; 19 were mid-sized 14- 18hp, and 13 were rated 24-30hp. There were 17 different cylinder size configurations, involving cylinder blocks cast individually, in pairs, or as monobloc, depending on Type.
With the exception of the early Types (AD, AO, AI and AP), they all had mechanical valves, and utilised magneto ignition. All Types had the sliding pinion gearbox, although the larger-engined vehicles from 1908 generally had the stronger double-sleeve upgrade. Various clutch mechanisms were used from metal to metal-plated ones to leather-faced metal plates to Thermoid-coated metal plates.
Along with the options of power output, different chassis lengths were available for many models, and up to six factory-offered body styles existed for the larger wheelbase cars. Customers also had the opportunity to buy a bare chassis for which coachwork could be commissioned from independent suppliers, an approach that was particularly prevalent for the larger-engined models, and some magnificent examples of the coachbuilders’ skills resulted.
For each year, the bulk of the vehicles produced would have similar design characteristics, superficially noticeable in the style of radiator or front wheel hub, suspension, elements of the engine layout, and the choice of carburettor. The decision in 1909–10 to adopt the Zenith-style carburettor, after experimentation with numerous other designs and formats, was a landmark moment for a company that so frequently chose to plough its own furrow regardless of industry-wide conventions.
From the outset, all four cylinder chassis were of pressed steel construction with some models having cross members made of tubing. Throughout the period, the chassis was tapered at the front and, initially, at the rear too. Between 1905 and 1910, the design of the transmission evolved from one where the gearbox and differential were integrated and drive to the wheel was through Cardan shafts, to one where the gearbox and differential were separate but drive was still through Cardan shafts. Late in 1910 (initially with the Type CF), a rigid rear axle was employed for the first time on a four cylinder vehicle.
At the beginning of 1905 De Dion Bouton had on offer one four cylinder model, the 15hp Type AD. This model received Approval from the Service des Mines on December 1, 1904. It was the first passenger vehicle to be equipped with a four cylinder engine, although various prototypes had been tested; indeed, one of the participating cars in the Marquis de Dion’s tour of southern Britain in the summer of 1904 was a four cylinder. The Type AD was available for the prosperous few who could afford the FFr12,700 (chassis only) price tag, three times the price of the Type Y entry level vehicle. It was innovative in many ways and received extensive media coverage. Over the next two years this 15hp model was produced (as the Type AO and AX) with various upgrades, including mechanical valves and revised cooling arrangements, and the familiar coal-scuttle bonnet was replaced. At the same time, a larger engined, 24hp model was launched in 1906 (the Type AP), which gave way to the Type AY a year later, this time with magneto ignition.
The Type BH, introduced late in 1907, was destined to be one of the company’s most successful models, and contributed significantly towards the ultimate decision to focus on a range of four cylinder vehicles. The overall design recognised that many people could not afford, or needed to own, a substantial, powerful motor car, when a smaller, two or four-seater model was thoroughly adequate for their needs. The engine (75mm bore x 100mm stroke) was of a new (and more technically efficient) construction with the cylinders cast in pairs instead of separately, as in all previous four cylinder cars. This created a more compact engine, requiring a shorter crankshaft and the opportunity to reduce the number of main bearings from five to three. The impact was reduced vibration, improved cooling, and lower manufacturing costs. The engine was equipped with mechanical valves and a magneto. At a cost of FFr7,650, the Type BH chassis was FFr3,850 cheaper than the smallest four cylinder car of 1907 and only FFr1,000 more expensive than the twin cylinder Type AV of 1907.
Eighteen months later, in 1909, twin cylinder cars were no longer produced, and there were five of the four cylinder models available, from the 10hp Type BQ to the 30hp Type BU. From that point onwards, the bulk of De Dion Bouton’s vehicle manufacturing capacity was dedicated to the production of four cylinder models with various engine configurations. For the period 1909–12, the company produced three categories of vehicles: small cars had engines of 10-12hp; mid-sized cars were equipped with 14-18hp power units, and the top of the range vehicles had 25-30hp options, entirely adequate for formal landaulet coachwork. From 1912 rigid rear axles were chosen for the smaller cars, and by the end of 1914 only the largest-engined chassis had Cardan shafts.
The Type BQ, launched for 1909 and the Type CF, available at the end of that year, were the successors of the Type BH, and reflected the policy of manufacturing a small four cylinder vehicle designed to meet the budget and needs of the twin cylinder market; it was ten per cent cheaper than the last twin cylinder model, the Type AV, and twenty per cent cheaper than its Type BH predecessor. In contrast with the Type BH, the Type BQ only had one chassis option, which was 5cm longer than the standard Type BH wheelbase, and its track was narrower. Both Types had the same clutch and gearbox, which were also fitted to the earlier single cylinder Type BG. The Type BQ engine was of twofold significance: its overall capacity of 1368cc was the smallest of any four cylinder vehicle produced to date, but it was also a four cylinder monobloc design, (66mm bore x 100mm stroke), and this was the first time that such an engine configuration had been used by the company.
By 1911, De Dion Bouton had developed a standard approach to their four cylinder production: in each year there was a choice of 10hp, 14hp, 18hp, and 25hp models, and either the 14hp or the 18hp models would have both three- and four-speed variants (the latter at extra cost). It is discernible in the four cylinder De Dion Bouton vehicles that left Puteaux between 1912 and 1914 that a more considered approach was taken; for example, the 10hp Type CR launched in 1911 had an engine configuration that remained in all subsequent 10hp Types until the end of 1914, and the same gearbox was utilised amongst most of the product range in 1913 and 1914.
At this time, some of the coachwork installed on De Dion Bouton chassis marked a significant departure from that previously used. With fully enclosed body and lack of division, the design was focused around an Left: Following the publicity created from the Peking to Paris race in 1907, Le Matin joined forces with the New York Times to set another challenge, that of travelling 35,000km (22,000 miles) through Alaska in winter. Six cars started, including the De Dion Bouton of G. Boucher de St. Chaffray. By the time five of the cars reached Siberia, the lack of fuel became critical, and St. Chaffray tried to reach an accord with any team that would get him to Paris first in return for his fuel supplies. The Italian team accepted his fuel but refused to have him on board. The Marquis de Dion insisted that St. Chaffray retire from the race. owner/driver (or as the advertisements suggested, ‘a gentleman driver’) not a chauffeur. The design was described as having more window space and a better rear view than a landaulette; some models had a central side door that when opened gave access to the front and rear seats. One motoring magazine writer acknowledged that many motorists of the ‘old school’ would not be well disposed to a closed vehicle of this kind, although within a very few years, of course, the design became a common sight on the roads.
Subsequently, for the mid-range four cylinder vehicles, Types DJ/EK in 1912, Types EA/DZ in 1913, and Types EO/EN in 1914, customers had a choice of a rigid rear axle or Cardan shafts on the same chassis with the same power unit. Finally, in 1913/14, the smallest-engined-vehicles (Types DW4/EJ4) had an integrated engine, clutch and gearbox. The larger horse-powered vehicles were only ever available with Cardan shafts. Only one model, the Type EB2, had an option of worm final drive.
The 8hp Type DW4 represented a very new and distinctive model for De Dion Bouton. It was approved on the same day as the twin cylinder Type DW2, with which it shared the same chassis. The wheelbase was 2.13m and the track 1.15m, making it significantly smaller than any other four cylinder vehicle that the company ever produced. The inclusion of an 8hp model in the product range for the first time meant that there were four of the smaller four cylinder Types listed in the annual catalogue with 8hp, 10hp, 12hp and 14hp engines, and only one of the larger four cylinder, 25hp-engined chassis available (the Type EB2); the clear expectation was that demand for larger-engined machines would be met by the supply of V-8 models.
The configuration of the Type DW four engine was unique, with its 54mm bore and 110mm stroke. It was the first four cylinder vehicle to have an integrated engine, gearbox and clutch arrangement, something that had only previously been seen in the twin cylinder Type DE2, and was used in the 1914 replacement for the Type DW4, the Type EJ4. Cooling was by thermo-syphon. As with all of the small vehicles at this time it had a rigid rear axle and three-quarter elliptic springs. By 1913/14, there was a large degree of harmonisation in the chassis produced for passenger and commercial work. The Types DX/EJ4 passenger models with their 66mm bore x 120mm stroke engines were the same as the Types DQ/ DR for small commercial vehicles, while the larger 100m bore x 140mm stroke engines were extensively used for all types of commercial activity requiring larger chassis.
Requirements around noise levels and smooth running always imposed limitations on the cylinder size of four cylinder engines. Six cylinder cars had the theoretical advantage over their smaller relations of increased torque and the attractive necessity for fewer gear changes, but the longer crankshaft, with inherently lower torsional stiffness inevitably led to torsional oscillations, with broken crankshafts and engine failure as the final outcome.
The earliest development work on eight cylinder engines had taken place in France as early as 1903 with the straight-eight of CGV and the V-8 designed by Cle?ment Ader; the former never went into full production and the latter was created with the 1903 Paris–Madrid race in mind, and never offered for sale. Rolls-Royce made three Legalimit V-8 cars in 1905, and in the same year Darracq produced a 22.5-litre V-8 that took the Land Speed Record at the end of the same year. The French Antoinette company designed a V-8 engine in 1906 that was declared suitable for aircraft or motor cars.
Thomas, in his 1914 article for The Automobile, reported that De Dion Bouton had installed six and eight cylinder engines of 50hp in separate chassis in 1906 for a 10,000 mile test to determine the best option for larger capacity motor vehicles. The V-8 was unanimously deemed to be the better choice and the six cylinder prototypes were stored in the basement of the factory in Puteaux, where they were badly damaged during the floods of 1910. The V-8 engine that De Dion Bouton subsequently developed was for motor vehicles and aircraft. In the weekly company newspaper, Le de Dion- Bouton, published October 2, 1909, and generally used for communicating the latest company news, the front page carried two photographs of the engine prototype. The article emphasised the advantages of its compact design and its power to weight ratio for aircraft usage. Whilst the article made no reference to the engine’s usage in motor vehicles, the necessary development work must have taken place because Type Approval had already been secured in July 1909 for the first V-8 vehicle, the 35hp Type CJ. Several months later an example of the engine was displayed at the Turin Motor Show, and the 1910 brochure, dated September 1909, carried summary details of the car.
De Dion Bouton was the first company to manufacture and market a V-8 motor car for consumer use. The launches of the first single, twin and four cylinder-engined vehicles made by De Dion Bouton had previously been met with a warm welcome, and subsequent commentators had only added to the sentiment that the products were innovative, well-engineered and satisfied a consumer need. There was good reason to expect that the launch of a V-8-engined vehicle would follow this well-trodden route. The appearance of the V-8 engine was indeed met with considerable press interest, but also general scepticism amongst other motor manufacturers, none of whom followed De Dion Bouton into this sector of the market.
Previously, De Dion Bouton had avoided the premium sector of the motor car market; indeed, the Marquis de Dion had remarked on many occasions that, in his considered view, the small passenger car and commercial sector presented the most reliable source of prosperity. The Marquis himself was regularly seen in small motor cars, and even in the late 1920s, his regular transport (chauffeur-driven, of course) was a Type JP, one of the smallest four cylinder cars the company ever made. It would seem that the foray into V-8 motor cars was driven by the synergistic benefits to be gained from the parallel technical development and production of power units for aircraft and motor vehicles.
The first 35hp unit of 1909 had its 90 degree engine in two banks of four cylinders, cast in pairs, with side valves on the inside of the V, operated by a single central camshaft and roller-ended rockers, the timing gear being driven by silent chain. Bore and stroke were 90mm x 120mm, giving a capacity of 6107cc and power output 35bhp at 1500rpm. The two banks of cylinders were in the same plane on the aluminium crankcase, forked connecting rods (patented by De Dion Bouton in 1908), which shared the same wide big ends, were used, while the crankshaft ran in two broad main bearings only. There were two high-tension magnetos, one for each bank, mounted on the rear of the unit, with their contact breaker ends visible through the dashboard and accessible through two folding doors.
The carburettor was an early example of a twin-choke, with one jet chamber to each bank of four cylinders. Engine lubrication was through a forced system with a gear-type pump in the crankcase. The aim was to achieve reliability with effortless torque and smoothness for a vehicle that could cope with substantial coachwork. The engine was three-point mounted in the frame, the single front mounting was a ball joint to allow for flexing, while the rear mounts embodied vibration-damping coil springs. A single- plate clutch and a universal-jointed propeller shaft transmitted power to the separate four-speed, pressure lubricated gearbox, which was also three-point mounted. Inevitably, drive to the wheels was through Cardan shafts. The springs were three-quarter elliptical and the final drive housing was clamped to a cross-tube bracketed to the chassis but insulated by thick, circular rubber washers to eradicate any vibration.
Some writers (notably Maurice Hendry, the author of the standard work on Cadillac) have expressed the view that the 1909 launch was the start of the decline of the company, remarking that “the trouble with De Dion V-8 was that it was half-baked, a brilliant design with serious shortcomings ...”. There is some truth in this conclusion. The engine was designed for reliability and not performance: its breathing passages were restricted; the valves were tiny and the exhaust pipe even smaller; effectively the engine design was focused on ‘throttling back’ performance to improve driver and passenger comfort. The persistence of the ‘decelerator’ pedal and the provision of a hand throttle did little to dissuade some that, for all of the innovation behind the De Dion Bouton V-8, it was rather anachronistic.
Nevertheless, the engine set the standard and was the template for Cadillac’s own V-8 (79mm bore x 130mm stroke), launched in late 1914, albeit with a three-speed gearbox in unit with the engine, distributor ignition, a three- bearing crankshaft, a higher crankshaft speed of 2400rpm, with a much higher output of 70bhp, and a conventional accelerator. The launch was a great success, and ultimately persuaded European manufacturers after the 1914–18 conflict, that V-8 engines were eminently viable.
Examples of the Type CJ were produced in 1910, although perhaps not in any quantity until the end of that year. There is a photograph that appeared in several French journals of the Austrian Emperor climbing aboard a 35hp V-8 vehicle in December 1910. Throughout the period of pre-war production, six different engine configurations were released. The arrival of the small capacity, four-litre Type DM at the very end of 1911, saw the advent of two banks of four cylinders per casting; this variation continued for all the smaller V-8s, whilst the 7.1 litre models continued to have two cylinders per casting. After 1913 the engines had twin-choke carburettors. All Types retained their Cardan shafts. From February 1913, the cars were offered with a choice of bevel or worm gear final drive. The ‘decelerator’ mechanism was retained for all the eight cylinder cars.
It is clear that from the earliest stages the USA was considered an important market. In an undated American De Dion Bouton catalogue, there is reference to a 100hp model with 120mm bore and 130mm stroke, a specification not referred to elsewhere.
The actual production numbers of V-8s are uncertain but, in an unpublished manuscript of memoirs, Edgar Duffield related that by the time he left the British agency in July 1914, 277 vehicles had been sold in Great Britain and “he had orders in hand for as many more of the V-8 cars and chassis as Puteaux could ever hope to let us have up to the end of that year”. Nevertheless, it is likely that pre-war production of the larger-engined V-8 motor cars was limited, and that many of these chassis were custom built to the specific instructions of each customer. The limited production helps to explain the small number of surviving examples. It is likely that very few individuals at the time ever had the opportunity of seeing an example of a V-8, let alone driving one.