Comparative tests of the Lavoix suspension against the Citroën A.6 (5 Nov. 1948)

In this document

This two-page document is a report of road tests dated 5 November 1948, carried out "at La Ferté", along the property wall p. 71.

Tests conducted

Two tests are reported, both dedicated to the Lavoix car suspension:

• First test: two people (50 kg), driven by Mr. Boulanger, with Mr. Cadiou as a passenger p. 71.
• Second test: four people (50 kg), driven by Mr. Lavoix, with Messrs. Boulanger and Cadiou in the back p. 71.

Observations noted

In both cases, the testers note more significant pumping than in the Citroën A.6, deemed "too great" p. 71-72. They also note shocks felt in the legs, appearing to come from the front of the vehicle — one of the testers suggesting the absence of "front dampers" — with no shocks perceived from the rear p. 71.

Conclusions formulated

At the request of Mr. Lavoix, Mr. Boulanger formulates two written conclusions: the excessive pumping is qualified as a "defect", with the explicit recommendation not to exceed the level observed on the A.6; the jolts in the legs, coming from the floor and appearing to come from the front, are "to be eliminated" p. 72.

A handwritten annotation in red bears the name "M. Magès" at the top of page 71, as well as a mention in parentheses, partly uncertain, evoking a "unique tandem spring" p. 71.

Context

At the end of the 1940s, Citroën was working on the development of new suspensions intended to succeed existing models, with a view to what would become the DS in 1955. This period is located shortly after the first tests of the 2 CV with hydropneumatic suspension conducted by Magès in May-July 1946 (Notebook of the first 2 CV hydropneumatic suspension tests (May-July 1946)), and well before the test of the 15-Six H in April 1954 (Road test of the 15 Six H (ELV 412) by Paul Magès, 3-5 April 1954). The Citroën A.6, cited here as a comparison reference, is a model from the Traction Avant range of the time.

The name "Lavoix" likely refers to a supplier or technical partner associated with an alternative suspension solution tested by the Citroën teams — but the document does not specify the exact nature of this collaboration.

Archivist's perspective

This report illustrates the comparative work carried out by the Citroën development teams, where Boulanger — head of the brand — himself participates in road tests, alongside Cadiou and Lavoix.

The handwritten mention of the name "Magès" p. 71 suggests that this document probably circulated to the engineer — then technical writer and later deputy head of the Super-Control within the design office (Draft letter from Paul Magès to Mr. Sarre and interview plan of 11 May 1969) — perhaps to inform him of the limits observed on solutions competing with or complementary to his own research on hydropneumatic suspension, initiated as early as 1944 (Hydropneumatic suspension plans with differential interaction (17 February 1944)).

This document is part of a period when several suspension avenues were being explored in parallel at Citroën, as evidenced by other pieces in the same collection, such as the folder "Theoretical study – hydropneumatic suspension 1943/44" or the manufacturing schedules 1945. It constitutes a valuable and precisely dated testimony of the comparative testing activity conducted at that time.