REAR SUSPENSION - PEUGEOT 407

Multi-link arm suspension by Peugeot 407

The first time in Peugeot's history they have decided to opt for a double wishbone suspension unit on the 407's front axle. On the rear axle, the latest generation multi-arm suspension still features dampers that are, in Peugeot tradition, inclined rearwards to optimize boot space.  Based on a structure exhibiting a high tensional rigidity, the choice fell naturally therefore on two high-tech architectures with the generous use of lightweight materials on a dual wishbone front axle with drop link, and on an integral multi-arm rear suspension with inclined spring/damper assemblies. The various constituent parts of the suspension and their functional criteria were not compromised in any way. Compared to the first generation multi-arm rear suspension that made its appearance on the 406, the all-new rear suspension of the 407 differs essentially by the inclusion of inclined spring/valve damper assemblies (more compact) and of a longitudinal arm decoupled from the hub carrier to ensure longitudinal operation only (absence of extraneous forces generating vibrations). 

Launched in 2005, the Peugeot 407 Coupe is the latest in a long tradition of prestige coupes produced by Peugeot, where style plays a key role, combining stature and refinement to create a product capable of long-distance touring with comfort and high performance development.

This stature is expressed initially through the coupe’s suspension dynamics, with dual wishbone and a drop link at the front and multi-arm rear suspension: the Peugeot 407 coupe produces’ superb road holding, is acknowledged for its grip, progressive control, dynamics and ride comfort.

 Component identification

The multi-arm rear suspension is supported by an aluminum cross member. It consists of two cast-iron sections connected by a profiled tube, to which they are welded. The assembled cross member weighs 14 kg and is joined to the structure by means of four flexible mountings with inbuilt radial stiffness and axial flexibility. This extremely rigid cross member provides the interface with each suspension unit. Each one has an upper wishbone, two lower transverse arms, one longitudinal arm, a hub carrier, a spring and damper assembly and a solid anti-roll bar (Ø 19 and 19.8 mm) that connects the suspension units.The anti-roll bar is maintained by two bearings rigidly attached to the rear floor. It is connected to each hub carrier by means of a link with two ball joints and plays an important role in load transfers in transferring loads during cornering.

System operation

Derived from the double wishbone one, the multi-link suspension uses three or more lateral arms and one or one or more longitudinal arms, which don't have to be of equal length and can be angled away from their natural direction. Each of the arms has a spherical joint or rubber bushing at each end, causing them to “work” in tension and compression and not in bending. The arms are joined at the top and bottom of the spindle. When this spindle turns for steering, it actually alters suspension's geometry by torquing all suspension arms. Don't worry though, as the suspension's pivot systems are designed to allow this. Multi-link arrangements are used on both the front and the rear suspensions, but the former replaces a lateral arm with a tie-rod that connects the rack or steering box to the wheel hub.Since there isn't a single multi-link setup in the industry, all big names have their own design. Audi A4's front suspension also has four links and it's extremely similar to the double wishbone one. 

Benefit of the technology

 The multi link suspension is seen as the best independent system for a production car because it offers the best compromises between handling and space efficiency and comfort and handling. Moreover, because such a suspension allows a vehicle to flex more, it's also a very good solution for off road driving.   The multi link is also advantageous for the designer who can alter one parameter in the suspension without influencing the entire assembly. This is a major difference compared to a double wishbone suspension. As with all good things, the multi-link system is costly and complex to design and manufacture. In fact, the suspension's geometry needs to be checked with design analysis software.