Paul Magès Note 39 (13 May 1963): alert regarding the reinforcement of rear anti-roll bars

In this document

The note of 13 May 1963 (p. 36)

Paul Magès writes a note numbered "39" to Mr. Cadion. He reports having tested "this morning" a car belonging to Mr. Nougaron equipped with a "P1 powertrain assembly", fitted with a rear anti-roll bar stronger than the standard one ("25 mm, it seems") p. 36.

He asserts that, given the "play we are aware of", one cannot "modify, in this direction, the anti-roll ratio on the DS without risking irreparable consequences" p. 36. He specifies that one can experiment freely in mechanics "as long as it does not touch upon safety issues".

His recommendation: to limit the car's inclination, one must reinforce the front bar and the rear bar at the same time, while maintaining the same ratio. He adds that in the case of a stronger front tyre, this ratio would need to be reviewed (increasing the front bar or reducing the rear one) p. 36.

A box in red pencil contains a handwritten response from a correspondent (reading uncertain, signed "V 13/5-63") indicating agreement with Magès and that "it is not prudent to touch the rear [roller]" p. 36.

The subsequent reminder (p. 37)

A second document, addressed to "Mr. Castion", recalls "Note No. 39 of 13 May 63" regarding the diameter of the rear anti-roll bars "of Mr. Nougaron's cars" p. 37.

The author points out that, about three months earlier, "there was a fatal accident with a car from this department" p. 37, and asks: "Did this car have a reinforced bar?". He renews his warning and raises the question of responsibility: "Which person can take, in full knowledge of the facts, the responsibility of leaving reinforced rear bars on cars" p. 37. Several passages on this page are crossed out and illegible.

Context

The Citroën DS, equipped with the hydropneumatic suspension invented by Paul Magès, relied on a fine balance between front and rear anti-roll bars to ensure road holding without compromising safety. The "Mr. Nougaron department" mentioned here likely refers to an internal testing team at Citroën, but this point is not specified in the document.

Archivist's perspective

This two-part piece illustrates the role of technical vigilance that Magès exercised beyond mere invention: he alerts his hierarchy to a specific risk, documents his personal test, then reissues the alert after a tragedy that he explicitly links—in interrogative form—to the initial subject p. 36-37.

The pressing tone of the second letter, with its question of responsibility left open, suggests that he seems not to have received a satisfactory answer after his first note. This document echoes other safety alerts from Magès in the same file, notably Note BEA 43.027 to Mr. Duclos on the operational safety of the hydraulics and Investigation No. 5.719 on hydraulic leaks, confirming the engineer's constant concern for user safety in the face of uncontrolled modifications to his systems.