1972 Citroen DS21

Citroen had a tradition of stunning the world with revolutionary models including the 'Traction Avant,' followed two decades later with the strikingly styled 'DS.' Its low-drag bodyshell had an aerodynamically efficient shark-like appearance, concealing an all-independent, self-leveling, hydro-pneumatic suspension and power-operated brakes, clutch, and steering. Its advanced hydro-pneumatic suspension was unrivaled for comfort and ride quality and continues to be used by present-day top-of-the-range models. It was one of the first mass-market cars to use electronic fuel injection and front disc brakes that were mounted inboard on either side of the differential. Additional mechanical sophistication included a semi-automatic transmission, variable ground clearance, power steering, and was effectively a mid-engined, front-wheel-drive car. The gearbox was mounted ahead of the engine and the differential sandwiched between the two. Developmental improvements made along its two-decade lifespan included swiveling headlights, a five-speed gearbox, and a restyled front end. The original 1,911cc, overhead-valve, long-stroke engine was replaced in 1966 by a short-stroke 1,985cc unit, also available in 2,175cc and 2,347cc capacities.

The Citroen DS was unveiled in 1955 at the Paris Salon and it was revolutionary in every sense. Within the first 15 minutes of the show, 743 orders were taken, and sales for that first day totaled over 12,000. Over a million examples were built during its production lifespan, with everyone from middle-class families to heads of state counted among the proud owners (a total of 1,455,746 examples built in six countries, with 1,330,755 manufactured at Citroën's main Paris Quai de Javel).

Two years after the introduction, a simplified version known as the ID19 (in French ID is pronounced 'Idée'- idea) was introduced and was essentially a DS19 but without the hydraulic steering, brakes or gearbox. The engine had a lower output and the interior was a little less luxurious. The ID was replaced by the D Spécial and D Super in 1970, but these retained the lower specification and position in the range. The D Super was soon made available with the 2175cc engine and a five-speed gearbox and named the 'D Super 5'.

Citroen pioneered its hydropneumatic suspension on its top-of-the-line Traction Avant 15CV-H a year prior to its use on the Citroen DS. Developed in-house by Paul Mages, the self-leveling system was innovative and offered very high ride quality and sharp handling. It was proven effective in motorsports, especially rallying, where it was able to sustain high speeds on poor surfaces for prolonged periods. A DS won the Montey Carlo Rally in 1959 and a DS19 was driven to victory in 1962 at the 1000 Lakes Rally. The DS repeated its victory at Monte Carlo in 1966, and a DS 21 placed first in 1969 and 1970 at the Rallye du Maroc.

The semi-automatic transmission required no clutch pedal, although the gears still needed to be shifted by hand. The shift lever operated a powered hydraulic shift mechanism in place of a mechanical linkage. The innovative centerlock wheels were able to be changed quickly in the event of a puncture. A captive allen bolt was used as the central fastener while a hexagonal protrusion transferred the drive to a matching recess in the wheel. Behind the wheels were the disc brakes, with the front being positioned inboard. This, along with the independent suspension, helped reduce unsprung weight.

An air-cooled flat-6 engine was considered but development costs, technical problems, and the French tax horsepower system favored smaller engines. Instead, the DS received a derivation of the 11CV Traction Avant engine - an overhead-valve four-cylinder unit with three main bearings and wet liners. It had a 3.1-inch bore, a stroke of 3.9 inches, and a volumetric displacement of 1911 cc. With an aluminum cross-flow head and hemispherical combustion chambers, the engine powering the DS 19 offered 75 hp at 4,500 RPM (compared to the 60 hp of the 11C). In 1965, the engine was replaced by a 1,985cc five-bearing wet-cylinder unit, which birthed the DS 19a, and from September of 1969, it was called the DS 20.

The DS 21 was introduced for the model year 1965 and came with a 2,175cc, five main bearing engine offering 109 horsepower. In 1970, a Bosch electronic fuel injection system boosted output even further. Larger inlet valves on the carbureted versions also increased output slightly.

The DS 23 of 1973 used a 2,347cc engine in both fuel injected and carbureted configuration, with the fuel injection being the more potent and rated at 141 hp.

by Daniel Vaughan | Jul 2022