Have you ever gotten a look under the skin of a round track car? It looks like a frustrated bridge builder's nightmare, with all the roll cage bars and gusset plates. Dirt trackers are even more gussied-up than asphalt cars, due to the surfaces they run on, and the driving style they're subjected to. Even those things flex, to the point that I've seen the left front wheel come several inches off the ground due to engine torque when a driver nails the throttle. Of course, it's not uncommon for a good dirt track engine to produce 700+ HP. Restrictor plates are for sissies- - - -Build it to run and let the NASCAR wimps hide under the grandstands!
All the concern about making a frame rigid is misplaced effort. Sure, add some gussets around critical stress points like motor mounts, but trying to keep a frame from flexing is a lost cause. We had a saying in the race car shop- - - - - -"Build it three times as strong as it needs to be, and don't be too surprised when it breaks!" After a long time trying to build rigid frames, I finally figured out they only need to be strong enough to have good weight transfer for suspension jacking adjustments. Making one super-rigid means it's going to break.
Jerry
