Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing The Trad Supension Basic

"Helicoidal and leaf springs having the same stiffness" This is only an assumption for this small exemple showing that the spreading of the forces concern only the section between the 2 linkages of the leaf spring.
For this exemple you can choose a girder with an oversized section or a small section or different sections between the 2 linkage of the leaf spring, the conclusion is the same, there is a difference around 20 % between the 2 configurations.

Yes Morgan trads have a flexible chassis, mostly in torsion due to the ladder configuration. In pure bending this is not a today car, but...

"A flexing chassis is PART of the suspension and a very important one " … perhaps in the case of Morgan with their short suspension travels, but the chassis acts like a massive rate spring and don't have itself any internal dampering. Imagine a nude chassis fixed on a bench, you bend it or distor it and you suddently release it. What append ? In fact you add a massive spring over the suspensions with a non negligible travel if your chassis is very flexible.

Except for the trucks which have very rigid ladder chassis, at the moment all the cars have a rigid chassis : touring, rally, Formula 1 etc. and have tuned suspensions for their purpose improving the driving.
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Some years ago I modelised the chassis of my PLUS 4, I was curious to verify the MORGAN chassis legend. I am a normal driver, not a pilot and I like sciences, so I use stress analysis program, this is less dangerous than extreme driving and keeps exercising my mind.
Stress analysis on the main girder gives an idea of the constraint values. The most critical part begins at motor & door level. Under a 3g vertical impact the constraint is roughly 12 daN/mm² (~3,82*3) inducing a security coefficient of roughtly 3 (depending on the used steel).

I love my MOG, and use it for touring, with speed limitatios you can keep driving sensations we can all share, but each with his own methods. Experience is the final complement of the theorie.