Originally Posted by Galizien
The boxed frame is nothing more than the company trying to gain a marketing advantage over the other. The boxed frame does however add alot of extra weight, and a C frame has proven to be more than enough on light to medium duty trucks. It provides proper flex and enough strength for most any job these trucks will see. Its also lighter, and much cheaper to make.
Look at how straight and low profile that frame is, closer to a tractor trailer frame. No uneeded bends or twists.
Damn the new dodges look hot as hell.
Galizien:
The boxed frame- as used by D-C in the 2500 and 3500 actually weighs LESS than the C section Ford due a lighter gauge steel. You are correct about flex though- All other things being equal, box section frames tend to be stiffer up to the point where they fail- and C section frames handle deflection better.
The trade-off is that a frame that flexes will make a poorer handeling truck- soft. But stiff frames tend to fail when abused.
I guess one probably makes sense for lighter trucks where overloading is not going to be a significant issue and the other frame makes sense once you are in the range of trucks where frames simply have to flex in order not to fail.
-Mike