Dubonnet suspension

Dubonnet suspension was a system of trailing arm independent front suspension and steering popular mainly in the 1930s and 1940s. Not very durable unless exactingly maintained, it was soon replaced by other versions. It consisted of a rigidly mounted axle beam in 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 from the kingpins. The system featured an encased coil spring and shock absorber, 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.

The system was invented by French engineer and designer André Dubonnet (heir to the Dubonnet vermouth fortune), and built into his Hispano-Suiza based special of 1933. He sold it to General Motors who adapted it as their "Knee-action ride", but the system was also used by many others including Fiat, Alfa Romeo, Simca, and Iso Rivolta.

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 of 1949 reintroduced a similar trailing arm suspension which is widely described as 'Dubonnet' suspension. However this suspension used torsion bars rather than coil springs and so Vauxhall themselves denied that this was the 'true' Dubonnet.

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