Chassis Stiffness and Suspension Tuning for Track Cars (i.e. Miata, Cayman, 911)

[ksw100]

I'm aiming to deepen my understanding of how chassis stiffness influences suspension tuning in track-focused cars like the Mazda Miata, Porsche Cayman, and Porsche 911.

Specifically, I'm interested in:

General Guidelines: What are some fundamental principles or rules of thumb regarding chassis rigidity when optimizing suspension settings for these types of vehicles?
I would greatly appreciate any insights, experiences, or resources you can share.

Thank you!

For reference:

 

[cibachrome]

Don't make the assumption that a chassis 'torsional stiffness' is a constant that you might see in a home ladder. It can be quite a staircase function and also depends on whether the chassis is 'dressed' or not.

Plus, how would you rate your kitchen table if three legs sit nicely on the floor and the forth is short and you wind up with spilled food? What if your kitchen floor is not straight & smooth, but your $1000 table is perfect ? The ability of keeping 4 tires well connected to the road surface is the fundamental strategic problem you face. Thus enabling springs and dampers to work with tires is a high priority. This being a very nonlinear problem, btw... Meanwhile most weekend warriors don't appreciate that the steering column is connected via bridgework to the vital steering mechanisms, and this is also a consideration from a stability & control feedback loop.

You didn't name your source for the graph, but the test method plays a part in this, too. K&C, modal analysis, racking test fixture? And the fixturing technique. Easy to do in Nastran (for exampe) using 'inertia relief' Solution-2

Quite a few SAE papers on this subject...