Talk:Dubonnet suspension

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Fundamental errors

The post-WW2 Vauxhall Wyvern and Velox inherited the leading link front suspension of the 1937 Model H 10-Four, and did not, as stated, employ trailing links. Also, the suspension promoted and funded by former racing driver André Dubonnet was not invented by him, but developed by Frenchman Gustave Emile Chédru (US Patent No. 2,054,063, filed on March 8, 1933). Heckmotor97 (talk) 16:56, 18 July 2018 (UTC)

Yet Motor Sport describe it thus, "The suspension, torsion-bar Dubonnet independent at the front, conventional 1/2-elliptic at the back, " [1] Andy Dingley (talk) 17:00, 18 July 2018 (UTC)

There are some drawings here [2], but it's hard to tell which way round they are. Can we confirm if this is a leading or trailing link?

If it's a trailing link, that suggests that Dubonnet is a fair description. If it's a leading link, is Motor Sport being too inaccurate in calling it one? The article already states that Vauxhall never claimed this themselves (licencing?). Andy Dingley (talk) 17:12, 18 July 2018 (UTC)

I was driving a 1937 Model H 10-Four two days ago. I have recent pictures of the suspension units of two examples and of the post-WW2 Wyvern's identical leading-link torsion-bar units. The cars rise under heavy braking, due to the anti-dive geometry that contrasts so fundamentally with the 'curtsey' always associated with Dubonnet trailing link 'Knee-action' when braking. The units fitted to the six-cylinder Vauxhall DY and DX cars of 1935 - the first British use on production cars of independent front suspension - appear also to be leading link - double leading-link, in fact, as the upper link is controlled by enclosed horizontal coil-springs and double-acting dampers while a lower link resists braking torque. I, too, have found contemporary and subsequent drawings and explanations surprisingly unclear.Heckmotor97 (talk) 08:54, 19 July 2018 (UTC)

See Talk:Vauxhall Wyvern#Talk:Dubonnet suspension? Andy Dingley (talk) 08:57, 19 July 2018 (UTC)

I think the key aspect here is really cleared up by the German Dubonnet article, and the use of the term "synchromous". Dubonnet's key feature is to make the natural frequency of each end the same, avoiding the problem noted for many other 1930s IRS systems of them "pattering away" and "herding a chorus of tap dancers" as one of the big Brit names of motoring writers once described them. By using soft damping on a low mass front system, Dubonnet achieved a similarly low frequency to the greater mass of the rear axle. The downside is then the well-known Dutch roll problem with heavy cars.

The physical construction, and how Vauxhall / Opel deviated from the "true Dubonnet", is much less important. From today's viewpoint, that's how we first see it - but at the time, their natural frequency (and its unusual nature) would have been more noticeable in comparison to the contemporaries. Of course reversing the link direction would also give the different braking behaviour you describe. Andy Dingley (talk) 09:25, 19 July 2018 (UTC)

References