[ICCARS]

Hi Stephen,

I sometimes feel like I'm the bearer of bad news as I see something like this and have to respond in an direct and open manner (part of being a Dutchy maybe)but I think you may have painted this chassis a bit prematurely as to me it would seem that you will require some additional lateral stiffening through the base section of your chassis in the form of cross bracing or similar.

What I would suggest is to do the torsional test now to identify any potential deficiency and engage an engineer nownot afterwards.
Question, do you have a front bulk head frame that provides a mounting point for your steering column etc.. as I would install this also and put all of the suspension back on and solid mount the suspension at the preferred ride height, then fix the rear solid to the ground at the widest point (the wheel studs are always a good mount point) then make a centre pivot support for the front somewhere suitable and you will be close enough to get the Engineer in to do the rest. This will save you some of his time and money and then you just need to have a good strong box section (100x50x3RHS) at least 4mtrs in length and work out your applied load in order to get to 4500Nm/deg of deflection and then your engineer can transpose or interpolate the rest of the figures out for you to see how linear and strong the chassis is as a start point. If it complies then all well and good, but if it does not then your engineer will need to advise you where to apply additional bracing or strengthening.

The second part is to perform a beaming test by supporting both ends of the chassis and then apply a specified weight to the centre (or seating positions) of the chassis and to measure the deflection or transitional beaming stresses and to see if the chassis is suitable in this regard.
I can send you some photos of how to set it up if you like in a PM.

Hope this helps you to move forward on your project.
Cheers
Wil