914 Chassis Stiffness, want input on chassis stiffness measurements Options

[Curbandgutter]

I want to check the stiffness of the 914 chassis two ways: the flexural stiffness (as in measure the shock tower movement as you lift it from the middle), and the torsional stiffness ( measuring the shock tower movement as you lift three wheels).

Then I want to input a 914 chassis into a 3d structural software that I use. I will design a tube chassis and check the flexural and torsional stifness with different tubing and thickness layouts.

Then construct the tube chassis and compare the real world results.

I want input from others as to how they would go about doing this. Or maybe give me some pointers. Or maybe someone already knows the factory stiffness?

What do you think?

[Dave_Darling]

It was either with Dwight Mitchell or Terry Zaccone (both well-knocn local autoXers) that they did the shaker-table analysis. They found some vibration node locations and were able to stiffen the car significantly accounting for those in their roll cage/bar design.

The internal truss inside the longitudinals is a very neat idea! Some parallels to Racer Chris' trailing arm stiffening versus the GT-type trailing arm stiffening. You will lose the heater channels, but it sounds like you aren't interested in any kind of heat so that's not exactly a loss.

I am told that a bar across the cockpit where the rear firewall meets the floor (i.e., just behind the driver's and passengers' butts) also helps stiffness in the chassis. No experience with it myself.

--DD