I'm trying to figure out which type of SFCs to get, and have spent hours reading through all the messages/archives here.

Does the actual welding of the SFCs along the floorpan make a difference in the rigidity of the car, or am I better off just ensuring that it is welded at the ends?

I've been emailing sales people from the various vendors, and of course, I am getting different responses. Part of me thinks that it would be fine with just welding at the points it attaches, because the flex you are trying to eliminate is focussed on the chassis (and not the floorpan).



As well, do I have to worry about possibly causing the floorpan to crack under stress if there are welds attached to it?

 

IMHO, stitch welding vs just the ends, would be like comparing a 4 pt roll bar, to a 6 pt cage/bar. More attachment points (ie:the stitch welding) certainly be of any harm. I don't feel it would be a waste to do.

 

If you were to look at any of the formulas to determine stress or deflection of a member (like round or square tubing), you might find that the 'unsupported length' is directly related to the deflection. Having a weld on one or two sides to a relatively flexible piece of sheetmetal isnt exactly ideal but its better than nothing... and those telling you its just to connect the chassis and the floorpan apparently isnt part of that dont know what they're talking about. The floorpan of the car is a huge factor in the chassis, the load is not transferred by the rockers and roof alone.

 

My Global West SFC instructions suggest stitch welding.

JamesC

 

My spohn-like home made sfc:s are stitch welded to rocker panels and floor pan.
Think about this: pro stock tube chassis won't get it full stiffness until floor etc panels are attached to the chassis.