Dubonnet suspension was a system of

leading arm A (semi) trailing-arm suspension, sometimes referred to as (semi) trailing-link is a vehicle axle or wheel suspension design in which one or more horizontal arms (or "links"), perpendicular to and forward of the axle, are connecting the axle or w ...

independent front suspension Independent suspension is any automobile suspension system that allows each wheel on the same axle to move vertically (i.e. reacting to a bump on the road) independently of the others. This is contrasted with a beam axle or deDion axle system in w ...

and

steering Steering is a system of components, linkages, and other parts that allows a driver to control the direction of the vehicle. Introduction The most conventional steering arrangement allows a driver to turn the front wheels of a vehicle using ...

popular mainly in the 1930s and 1940s. Not very durable unless exactingly maintained, it was soon replaced by other designs. It consisted of a rigidly mounted axle beam from which the sprung steering and suspension arms pivoted around kingpins mounted on the ends of the axle. The wheels themselves were mounted onto stub axles, suspended by self-contained suspension units outboard of the kingpins. The system featured an encased

coil spring A selection of conical coil springs The most common type of spring is the coil spring, which is made out of a long piece of metal that is wound around itself. Coil springs were in use in Roman times, evidence of this can be found in bronze Fib ...

and

shock absorber A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Most sh ...

, which sealed in the oil needed to lubricate and protect the suspension parts. This was also the weakness of the layout, as any leaks would have negative effects on ride and durability. Dubonnet-Federung

One advantage for a comfortable ride was the reduction in

unsprung weight The unsprung mass (colloquially unsprung weight) of a vehicle is the mass of the suspension, wheels or tracks (as applicable), and other components directly connected to them. This contrasts with the sprung mass (or weight) supported by the ...

, as the kingpins and steering gear were inboard of the suspension, and not thus counted as sprung mass. This in turn led to 'synchronous' behaviour in many cars with this suspension, where the

natural frequency Natural frequency, also known as eigenfrequency, is the frequency at which a system tends to oscillate in the absence of any driving force. The motion pattern of a system oscillating at its natural frequency is called the normal mode (if all par ...

of the front wheel suspension now, unusually for the time, matched that of the rear suspension and their solid driving axle. The mass of the driving axle was greater but with the now softer springs of the lightweight front suspension, their frequencies became comparable. This was a feature of Opel patents and advertising in the 1930s. Hispano-SuizaH6CXenia

The system was invented by French engineer and designer

André Dubonnet André Dubonnet (28 June 1897 – 20 January 1980) was a French flying ace, athlete, race car driver, and inventor. He was the grandson of Joseph Dubonnet, founder of the Dubonnet apéritif firm, from which he inherited substantial wealth. Early l ...

(heir to the

Dubonnet Dubonnet (, , ) is a sweet, aromatised wine-based quinquina, often enjoyed as an aperitif. It is a blend of fortified wine, herbs, and spices (including a small amount of quinine), with fermentation being stopped by the addition of alcohol. ...

vermouth fortune), and built into his

Hispano-Suiza Hispano-Suiza () is a Spanish automotive–engineering company. It was founded in 1904 by Marc Birkigt and Damian Mateu as an automobile manufacturer and eventually had several factories in Spain and France that produced luxury cars, aircraft en ...

based special of 1933. He sold it to

General Motors The General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. It is the largest automaker in the United States and ...

who adapted it as their "Knee-action ride", but the system was also used by many others including

Fiat Fiat Automobiles S.p.A. (, , ; originally FIAT, it, Fabbrica Italiana Automobili di Torino, lit=Italian Automobiles Factory of Turin) is an Italian automobile manufacturer, formerly part of Fiat Chrysler Automobiles, and since 2021 a subsidiary ...

Alfa Romeo Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." ...

Simca Simca (; Mechanical and Automotive Body Manufacturing Company) was a French automaker, founded in November 1934 by Fiat S.p.A. and directed from July 1935 to May 1963 by Italian Henri Pigozzi. Simca was affiliated with Fiat and, after Simca bough ...

, and, possibly in its last incarnation, the 1953 Iso Isetta which carried forward to the 1955 BMW Isetta, the 1957 BMW 600 and the 1959 BMW 700. The General Motors connection led to one of the suspension's most numerous uses, with a return to Europe for the pre-war Vauxhall Twelve and Vauxhall Fourteen from 1935 to 1938. The post-war

Vauxhall Velox The Vauxhall Velox is a six-cylinder executive car which was produced by Vauxhall from 1948 to 1965. The Velox was a large family car, directly competing in the UK with the contemporary six-cylinder Ford Zephyr, and to a slightly lesser extent, ...

of 1949 reintroduced a similar leading arm suspension which is widely described as 'Dubonnet' suspension. However this suspension used

torsion bar A torsion bar suspension, also known as a torsion spring suspension, is any vehicle suspension that uses a torsion bar as its main weight-bearing spring. One end of a long metal bar is attached firmly to the vehicle chassis; the opposite end termi ...

s rather than coil springs and so Vauxhall themselves denied that this was the 'true' Dubonnet.

References

{{automotive handling Automotive suspension technologies