Paul Magès' note to Bercot on the AP 3: beyond hydropneumatics (May 1966)

In this document

An expanded mission entrusted to Magès

The draft opens with an address to Mr. Bercot (President of Citroën), dated 18.5.66 with an earlier mention "10.5" p. 68. Magès reports that Mr. Grosseau conveyed to him the wish to see him take charge "more directly" and "more actively" of everything concerning vehicle comfort and suspension p. 68. He specifies having already made contact with Messrs. Hondel (Hendet), De Lassus, Roche, Bellier and Sezuer to organize a collaboration, a contact "warmly accepted" by those concerned p. 68.

The case of the AP 3

Magès mentions a meeting he initiated "at Mr. Sernec's around Feb 1st, 1966" to present findings made on an AP 3: a "significant anomaly" had been brought to light in "the design of the front subframe - Body and engine suspension" p. 69. Following this, Messrs. De Lassus and Hendet (Hondel) reportedly launched experiments to verify the vehicle's behavior, subsequently continued with Lapierre: precise measurements, calculations on the rigidity of the shell, the front subframe and the tuning of the engine suspension to the frequency of the body p. 69.

Measurements on horizontal reactions

Magès mentions recordings made according to a "reproducible and identical method for all vehicles", comparing the accelerations undergone by a point on the chassis when passing over defined obstacles p. 70. These measurements show, according to him, that the brand's cars are "very bad" from the point of view of horizontal reactions — a defect previously assumed, now quantifiable p. 70. He adds that the reduction of vertical jolts seems to apparently amplify horizontal reactions p. 71.

The call for a strategic decision

Dated 20.5.66, the second part of the note asserts that "the application of the hydropneumatic suspension cannot be sufficient" if nothing is done for the "horizontal components of shocks" p. 71. Magès notes with regret that "some of our direct competitors" have already partially solved this problem, and urges management to set a clear objective to progress on the road-holding system as a whole p. 71-72.

Context

The acronym AP designated at Citroën, in the 1960s, study prototypes intended to prepare for the renewal of the range (from which the GS project would later emerge). The hydropneumatic suspension, developed by Magès for the DS from 1955, excelled in absorbing vertical shocks but remained less efficient against longitudinal and transverse accelerations — a challenge that several competing manufacturers, particularly in the high-end segment, were also seeking to solve at the time.

Archivist's perspective

This handwritten note, in two parts (18 and 20 May 1966), shows Magès in a role that goes beyond mere technical invention: he acts here as a coordinator and whistleblower to management. He seems to want to formalize already informal collaborations with the departments concerned (calculation, structure, testing), probably to carry more weight in decisions.

The document extends a reflection already present in the note on the AP suspension of February 22, 1963, and echoes road tests mentioning anti-roll and damping in the report of April 2-5, 1962. One perceives, as early as 1966, the awareness that hydropneumatics alone would no longer suffice — an intuition that would find an echo, a few years later, in Citroën's research on global road-holding.