Jack,
Thanks for posting that link, I don't usually go to the drag racing sites but I do watch the fuel shows on ESPN2 and they did show Cory Mac's frame failure at least 100 times!!! also Branden's tire failure. If you make some fairly basic assumptions, i.e. the wing makes 6000 lbs of down force, the wing lift/drag ratio is approx 3:1 and the engine makes about 6000 lb-ft torque you can find that the bending moment being put into a dragster chassis is around 30,000+ lb-ft! I am sure that if you did a quick stress check it is probably more than 50-75% of the material yield strength and this equals low fatigue life. Throw in the additional flexing from a rough track and maybe scrape .010 off the bottom rails by hitting the track and you are inviting failure. One thing that the guy was wrong about is that as the chassis flexes the angle of attack of the rear wing actually decreases and the front wing's increases, which is probably a good thing. Just to keep the front wheels planted and resist the engine and rear wing forces it needs to make about 1800 lbs of down force!
It seems obvious that NHRA could fix this problem with a hack saw! just keep cutting an inch of each side if the rear wing until they can only go 300! Down force is proportional to the square of the speed so going from 330 to 300 should reduce the wing down force by about 20%. Sure the crew chiefs would have to learn an new tune up put they wouldn't have to change big parts. Maybe they wouldn't need those 130 gpm fuel pumps!
Just my two cents worth.
Rex