I've decided to box the frame on my '66 C10 and while I'm at it I want to add an X member to limit how much the frame is able to twist. I've already started making patterns for the boxing plates but need some help on the X member. I've been looking over a few different frame builders' pics and came across Fatman Fabrication's Tri-Five frame, and really like their X member design.
http://www.fatmanfab.com/55_57chevy.php
It's got a full tube center section instead of an open square tube design. Round tube is really strong against torsional twisting so I think that would be a good idea to integrate into my X member.
I'm starting from scratch and have the ability to build it myself. I also have a tubing roller so I can make arches. Would the arched tubing have any strength benefits over straight tubing? And what about round tubing vs square tubing? I'd like for it to be able to accomodate dual 3" exhaust, and keep in mind that a '66 has trailing arms instead of leaf springs.
As you can see in the pic below, with only one of the rear bags inflated there's quite a bit of frame flex. I'll be boxing the frame from the C notches up to the steering box, and welding around the rivet heads that hold the crossmembers in place.
Any ideas/comments/input would be greatly appreciated!
