1947 Delahaye 175 (Henri Chapron)
|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 in the cockpit area, with its welded driveshaft tunnel and perimeter-welded stamped-steel floor that acted as a stressed structural member. It introduced the semi-monocoque chassis structure to the automobile realm. This revolutionary approach allowed the seat rails to be mounted on the bottom-plane of the chassis, instead of sitting on top of it, as competitors were doing. Their chassis had a heavy X-braced cruciform in the middle of the passenger compartment, with the driveshaft passing through a hole at intersection.. This methodology allowed a Coachbuilt Delahaye body to be lower in profile than the competition. The rigid chassis delighted France's coachbuilders for its remarkable rigidity, low profile stance, and its comfortably expansive completely rectangular passenger compartment.
The new 4.5-litre engine was visually very similar to the preceding Type 135, but significantly larger, and substantially 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 were specially made with twelve port heads). The larger engine was stronger and breathed better.
The new Type 175 chassis was completely different from the 135 in dimensions, proportions, and structural design. It had a larger. parallel-sided central structure, whereas the Type 135's tapered from the cockpit's rear cross-member forward, and was considerably narrower, both at its extremity, behind the driver, and the footwell forward. A very distinct feature of this new chassis, was the nearly completely round open hoop through both rear chassis-rails, through which the DeDion tube and the differential's splined half-shafts extended out to the hub-carriers, on to the rear leaf springs. The rear section of the chassis aft of the cockpit was visually similar to the Type 57 Bugatti in this respect.
More modern suspension than that of the Type 135 was featured in the 175/178/180 chassis-series. Delahaye's Type 135 had independent front suspension, a proprietary system it shared with Delage and Talbot-Lago. The new 4.5-liter chassis had a previously untried independent front suspension that was unfamiliar to Delahaye. This was the proven Dubonnet-licensed independent suspension system replacing the outdated proprietary system used in the Delahaye Types 135, 145, 155, and 165. The Dubonnet system was not unproven, since it was adopted by General Motors in 1933, as well as by Alfa-Romeo, and Vauxhall. Time proved the Dubonnet system to be problematical, unless it was fastidiously serviced and rigorously maintained. Oil-seal leaks caused component seizures, and notorious internal component breakage.
The new chassis's rear DeDion suspension system had earlier been employed by Delahaye, in its infamous Type 155 grand-prix (single-seat) "monoposto". Like the Type 155, 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 curve-formed large-diameter steel tube connecting both rear hubs. The rear wheels were driven by splined half-shafts. The semi-elliptical rear leaf-springs were conventional, and dampened by lever-arm hydraulic shock absorbers, instead of outdated friction-type. The new inline six-cylinder overhead-valve engine produced between 140 and 160 brake horsepower, depending on whether a single Solex carburetor, or triple Solex carburettors were fitted. The standard compression ratio was a modest 6.8:1. The optional Type 175-S had an increased compression ratio, for enhanced performance.
The Type 175-S racing engines employed by Charles Pozzi, and France's champion driver, Eugene Chabaud, had a claimed 9.1:1 compression ratio, and with its three horizontal Stromberg carburetors, was claimed to deliver over 220 brake horsepower. The higher performance Type 175S came with two factory options: Rudge wire-wheels; and, three Solex down-draft carburetors. The front's new grille designed by 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 new corporate grille design, although several of the more famous, such as Joseph Figoni (of Figoni et Falaschi), Jacques Saoutchik, and Henri Chapron were given artistic licence.
The new six-cylinder 4.5-litre engine in these cars carried the "183" casting code, and was made in two visually distinct forms. The first series were stamped Type 1AL-183, as were found in the six pre-production chassis known about by 1946; and, the Type 175S racing engines provided to Charles Pozzi and Eugene Chabaud. But the majority of the production motors were stamped as being Type 2AL-183. These came out of the same "183"casting molds, but of revised configuration, with modifications made for easier production, cost saving, and allegedly internal reinforcement of the bottom end. The transmission was a clever semi-automatic electrically shifted solenoid-actuated four-speed Cotal 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 was proven by racing-team owner Rob Walker.— '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, and a supposed source for incoming capital for French companies and the government's depleted coffers. 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 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 innordinate 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 four luxurious and 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; twenty-four each of pushrods, cam followers, and rocker-arms; three Stromberg carburetors (in the Types 145 and 155, but a single one in the detuned Type 165); two mechanical fuel-pumps, 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 front coachwork demonstrated the company's new postwar "face". It was one of very few totally new machines to debut at the first postwar Paris Salon in October 1946. 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 sheared rear half-shafts, due to hefty postwar enveloping-style bodies with hardwood body-frames under them, contributing excessive weight for the chassis' prewar 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 instrument panel on the cowl-scuttle. Production did not truly begin until early 1948, and some say, with reasoned conviction, that this chassis-series was never fully developed. The extended dealy was due to Jean Francois death in April 1944. There was nobody qualified to take his place. However, as most of the French grandes marques no longer existed after the war, the coachbuilders descended upon the Type 175S 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 175S Show-chassis. With it included, as it ought to be, the Type 175/175S total comes to 52 in all. 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 optional 175S came with three carburettors and like the 175, had aa 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 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, including the show-chassis, was 106 units. (substantiated by Club Delahaye president Jean-Paul Tissot, from archived company records) 
The Type 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 175S 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 of deeply finned cast-iron, actuated by dual master cylinders with a balance-bar.
The custom bodies of these cars were often much too heavy for what the chassis had originally been engineered for, leading to collapsing Dubonnet suspension, and sheared differential half-shafts. In dry conditions, these were fast cars, but 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. The real culprit, however was inferior postwar steel quality following the war. The engineer's specified grade had been completely consumed by the war, and what little could be gotten came through the French government, and it had not prioritized luxury car-makers. Due to buyer resistance and diminishing sales, the Types 175, 178 and 180 ceased production in 1951. And although Delahaye managed to introduce the seemingly more modern 235 in 1951, this was just an updated varaition of the Type 135, now equipped with three Solex carburetors and hydraulic brakes. It was too little, much too late to make any difference, despite being an excellent automobile. The company did not survive much longer. Its doors were permanently closed and locked in December 31st, 1954. Sixty years of car production had come to an ignominious end in defeat. Delahaye had been absorbed by arch competitor Hotchkiss, in 1953, and both Delahaye and Hotchkiss succumbed to the changing global circumstances, causing their absorption by the gian Brandt organization, for their assets to be converted into making other industrial and commercial items. The Delahaye automobile, and its captured Delage marque were relegated to history. Delahaye and Delage combined production dropped from 511 in 1949, to 41 in 1952; 36 in 1953; and 7 in 1954.
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