Thread: boxing a frame

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You threw me for a second when you said you weld a plate across the "bottom" of the frame rails..........every boxing job I have known about entailed welding a plate to the "inside" portion of the frame, where the was no wall originally. But I am familiar with Ford frames, and I guess from reading this that Chevy frames of that era were open on the underside. That's interesting, didn't know that.

Anyway, regardless of what section is open, the procedure should be essentially the same. You would cut some flat stock of approximately the same thickness as the existing frame (or something like 3/16 thick steel) and shape it so it either caps the open wall, or so it is slightly smaller so it slips inside it, then weld it solidly in place. Some people only weld it in with lots of short welds, and some fully weld it in place. The latter is how we have always done it.

The reason for doing it is strength and rigidity. These old car frames, especially ones from cars like Model A Fords, were notoriously flexible.........and that was by design. They wanted the car to twist to conform to the rutted roads of that time. But as Richard mentioned, once we crazy kids started shoving a lot more HP into the cars than they were ever meant to take, we had to find ways to make the frames stronger.

My Kid just got done boxing the frame we built for his RPU. He elected to have rails bent up to simulate the appearance of a Deuce frame somewhat, and then box the back wall for more strength and a nicer appearance. The picture below will show how we slid the boxing plate slightly inside the frame before welding, which allows stuff like brake lines and cables to be hidden slightly in the inset portion.

Don