1947 Delahaye 175
|Body and chassis|
|Engine||4,455 cc type 183 I6|
|Transmission||4-speed pre-selector (Cotal)|
Delahaye 175 was an automobile manufactured by Delahaye between 1947 and 1951. The last of the large Delahayes, the type 175 was essentially a brand new chassis and engine. The chassis bore little resemblance to the preceding Type 135, other than the cockpit area with its welded driveshaft tunnel and welded stamped-steel floor. The assembly formed a rigid stressed-steel semi-monocoque structure. This allowed the seat rails to be mounted on the plane of the bottom of the chassis, instead of on top of it, as competitors were doing, since their chassis had X-braced cruciforms instead of Delahaye's semi-monocoque cockpit. This made the completed Coachbuilt Delahaye body lower in profile than its competition. The rigid chassis structure also delighted the coachbuilders.
The new 4.5-litre engine was visually similar to the Type 135, but significantly improved. It had seven main bearings versus the Type 135's four, and its cylinder head had six intake and six exhaust ports, twelve in all, versus nine in the standard Type 135 ( albeit a rare few Type 135 racing engines had twelve port heads). The larger engine was stronger and breathed better <Club Delahaye archive data, obtained from its Bulletin>.
The new chassis was completely different from the 135 in its dimensions, proportions, and structural design. Even in the cockpit area, the new chassis had a large parallel-sided central structure, whereas the Type 135's was tapered from the cockpit's rear cross-member forward, and it was considerably narrower. A very distinct feature was the nearly round open hoop through both rear chassis-rails, through which the DeDion tube and splined half-shafts extended, out to the hub-carriers attached to the rear leaf springs. The rear section of the chassis aft of the cockpit, was visually quite similar to the Type 57 Bugatti in this respect.
More modern suspension than in the Type 135 was featured in the 175/178/180 chassis-series, with an entirely new previously untried Dubonnet-licensed independent system up front, replacing the outdated proprietary system used by Talbot-Lago, Delage (also produced by Delahaye from 1935), and the Delahaye Types 135, 145, 155, and 165. The rear suspension was not a new concept, its DeDion system having been earlier employed by Delahaye in the Type 155 grand-prix (single-seat) "monoposto". The Type 175, 178, and 180 DeDion system featured a rigidly mounted differential in a cast aluminum housing containing a Gleason hypoid final-drive gear-set, with a curved large diameter tube connecting both rear hubs. The rear wheels were driven by splined half-shafts. The semi-elliptical rear leaf-springs were conventional, and damped by lever-arm hydraulic shock absorbers. The new inline six-cylinder overhead-valve engine produced between 140 and 160 brake horsepower, depending on whether a single Solex or triple Solex carburettors were fitted, and the standard compression ratio was a modest 6.8:1. The optional Type 175-S had an increased compression ratio, for higher performance. The Type 175-S racing engine employed by France's champion driver, Eugene Chabaud, had a claimed 9.1:1 compression ratio, and with its three horizontal Stromberg carburtors, produced 220 brake horsepower <DELAHAYE Sport et Prestige by Francois Jolley; and, DELAHAYE, Tout l'histoire, by Michel Renou>. The higher performance Type 175-S came with two factory options: Rudge wire-wheels; and, three Solex down-draft single-venturi carburetors. The front-end and new postwar grille's design were executed by Delahaye's young in-house designer, Philippe Charbonneaux, in a corporate effort to develop a particular Delahaye "face" after the war. Delahaye required coachbuilders to use the corporate grille design, although several of the more famous ones such as Joseph Figoni (of Figoni et Falaschi), Jacques Saoutchik, and Henri Chapron were given some leeway for artistic license. The new 4.5-litre engine used in these cars carried the "183" engine-block casting code, and was made in two visually distinct forms. The first series were stamped Type 1AL-183, as were found in the six preproduction chassis known about by 1946; and, the Type 175-S racing engines provided to Charles Pozzi and Eugene Chabaud, but the majority of the production motors were Type 2AL-183, produced from the same but revised engine-block casting mold, with modifications made for ease of production, modest cost saving, and internal reinforcement of the bottom end. The transmission was a Cotal, this being a semi-automatic electrically shifted solenoid-actuated four-speed epicyclic gearbox. The shift lever protruding from the transmission operated forward and reverse only, the car being capable of being driven in either direction with the same four gear-ratios - only to be attempted by the brave or fool-hardy, as proven by racing-team owner Rob Walker <an Autocar magazine article>.
After having spent World War II building railroad rolling stock (train cars) for the German occupiers, Delahaye was included in deputy director General Paul-Marie Pons' 1945 plan Pons for French industry and engineering. His plan Pons was a five-year program for the reconstruction of French industry. The plan allotted Delahaye the position of building covetable sports and luxury cars for the export market. Over 80 percent of the company's automotive chassis were exported to France's colonies, including those in Africa. The plan's objective was to generate much-needed foreign currency for France's struggling postwar economy. The outdated prewar Types 134, 135, and 148L were revived, but Delahaye still needed a "halo car" like the 165. In consideration of the inordinate expense of producing the complicated V-12, with its exotic alloys, as used in the Type 145 sports-racers, the solitary Type 155 monoposto (all five were made exclusively for Lucy O'Reilly-Schell for her team Ecurie Bleue), as well as in the five luxurious and very impressive Type 165 grand touring cars, production of the V-12 ended in 1938, with just twelve sets of engine parts made. The excessively complex V12 had three camshafts in the block; four overhead rocker-shafts; three Stromberg carburetors (in the Types 145 and 155, but a single one in the detuned Type 165); two mechanical fuel-pumps, and dual Bosch ignition. The V-12 was replaced by a new, much less complex inline overhead-valve six-cylinder of the same displacement. The new Type 175 debuted as a glitzy show-chassis with partial frontal coachwork demonstrating the company's new postwar "face". It was one of very few to debut at the first postwar Paris Salon in October 1946, and it garnered considerable attention. It would also be Delahaye's first left-hand drive model.
The chassis however, was not yet fully developed (in October 1946), nor adequately performance tested, before being put into production. Problems were encountered with the Dubonnet front suspension, and shearing rear half-shafts, due to postwar enveloping-style bodies with hardwood body-frames under them, contributing excessive weight for the chassis' prewar designed and developed engineering. The same unchanged Show-chassis reappeared on Delahaye's stand in 1947, again in 1948, and finally in 1949, with somewhat more but still limited frontal coachwork. There was nothing whatsoever aft of the instrunment panel on the cowl-scuttle. Production did not truly begin until early 1948, and some say, with conviction, that the three-wheelbase chassis-series was never fully developed. However, as most of the French grandes marques no longer existed after the war, the coachbuilders descended upon the Type 175-S, in particular, to prove their art.
The company's Production Build List verifies that 51 Type 175 chassis were built (numbers 815001 to 815051 inclusive), but that excludes the Paris Type 175-S Show-chassis. With it included, as it ought to be, the Type 175/175-S total comes to 52 in all.< Club Delahaye archive, Jean-Paul Tissot president> with no differentiation explaining which of these were Type 175 or optional 175-S chassis. While not a grand success in the marketplace, a Type 175S won the 1951 Monte Carlo Rally, the same car finished in twelfth place in the Carrera Panamericana, while a second Motto-bodied 175-S coupe was disqualified on a technicality.<DELAHAYE Sport et Prestige by Francois Jolly) The 175-S came with three carburettors and a 2.95-metre wheelbase; two longer wheelbase versions with single carburetors and 140 HP were also built: The Production Build List confirms that there were 37 of the 3.15-metre wheelbase Type 178 built, and 17 Type 180 chassis  and 180 (333.5 cm) were produced, mainly for heads of state, dignitaries, and the like. Two Henri Chapron-bodied, fully armoured 180 limousines with divisions were built for the leadership of the French Communist Party in 1948. A prototype "Delage D180" was also developed on this basis, but never entered production as Delahaye focused its Delage production on their D6 model. The total produced in the three-chassis series was 105 chassis. (substantiated by Club Delahaye president Jean-Paul Tissot, from archived company records) name="Rousseau"/>
The 1AL-183 and Type 2AL-183 engines, when equipped with a single carburetor, produced 140 horsepower, allowing a top speed of 130 km/h (type 180), 140 km/h (type 178) and 145 km/h (type 175). The triple-carbureted 175-S raised this to about 160 km/h (99 mph), although naturally these figures were subject to variation depending on which sort of body was fitted, and which coachbuilder made it. Coachbuilder Jacques Saoutchik seemed oblivious of weight, and applied flamboyant heavily chromed brass embellishments on his extended enclosed fendered bodies.
The rear-wheel drive Type 175, 178 and 180 chassis is considerably more sophisticated than its 135 predecessor, the front suspension being independent with pivoting horizontal cylinders that contained a powerful coil-spring and hydraulic shock absorber in an oil-bath Dubonnet. The rear was by de Dion, with semi-elliptical springs. Brakes were hydraulic type made by Lockheed. The brake-drums were deeply finned cast-iron, actuated by dual master cylinders with a balance-bar drums all around.
The custom bodies placed on these cars were often much too heavy for what the chassis had originally been designed and engineered for, leading to collapsing Dubonnet suspensions and sheared differential half-shafts. Wet-weather handling was considered unpredictable. A shortage of time and money for development may have been a cause of the 175's failure. Delahaye's reputation for solidity took a serious hit in consequence, and although Delahaye managed to introduce the seemingly more modern 235 in 1951, the company did not survive much longer. Delahaye and Delage combined production dropped from 511 in 1949, to 41 in 1952, 36 in 1953, and 7 in 1954.<Club Delahaye archive> 
- Hull, p. 524.
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- Hull, p.524.
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- Adatto, Richard S; Meredith, Diana E. (2006). Delahaye Styling and Design. Deerfield, IL: Dalton Watson Fine Books. ISBN 978-1-85443-221-6.
- Hull, Peter. "Delahaye: Famous on Road and Race Track", in Ward, Ian, executive editor. World of Automobiles, Volume 5, pp. 521–524. London: Orbis, 1974.