Sorry I'm late to the party!!!

I believe you guys are talking about two different things.

Torsional rigidity of the chassis, and deflection of the suspension.

Torsional rigidity is pretty easy to test, you need to lock one end down (rear) you generally need a pivot fulcrum and a big ass lever!!!

You don't need a lot of weight, you can measure how far it deflects for how much weight, calculate that into degrees and pound feet, done.

That is done solid to the chassis and not attached to the suspension.

As Peter said XVM did that 10 years ago and developed an entire chassis stiffening package around that.

Suspension deflection is a whole lot more complicated.

Suspension deflection has to be done dynamically. Twisting a car around the shocks and springs really tells you nothing. The suspension reacts to speed and distance, like pot holes and expansion joints... etc

Tests like that are done on a vehicle driving and or on a test rig like a 4 post.. etc..

XVM also did that 10 years ago and developed the Level II suspension from that data..

CR