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automotive fraem strength

Any ideas on the proper way to box in a car frame? I need to box a frame for a 1967 Cutlass convertible and have recieved conflicting info.

1 welder says run the bead all the way around the metal pieces I am using to box in the fourth side. 2 say I won't gain anything by that, I should run a 4 inch bead, leave an 8 inch gap, run another bead util I have encircled the piece. Any isuggestions?

Also can I add strength by adding a piece of flat stock to the outside or inside of the frame over this span?

Thanks,

Reply to
dafalcon
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First, why? How thick is the plate you are going to use? But, getting back to why, the application would determine method. (Demolition Derby, or rot-out, or something else?)

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Reply to
Tom Gardner

I have a great non-boxed frame that I will use to replace a rotted out boxed frame for a restoration. Evidently this is usually done since boxed frames are usually too rotted to save. This is something I want to be strong and last. I don't know off hand the thickness of an auto frame but that is what I would use to box it in.

Reply to
dafalcon

Tom

He's working with a 67 Cutlss convertible. Most likely not a car for demolishion derby. I have seen Convertible cars benefit from "boxing" their frames. I have no info on just how much benefit.

Continuous welds will provide the maximum strength. But the time and effort may not result in enough additional ridgidity to make the time to weld worth it to you. I'd say that the frame will look better when continuously welded. The welds may be very difficult to see after the body is in place.

Jerry

Reply to
Jerry Martes

You probably want to leave regular gaps as you weld it up to keep from imparting stress & twist to the frame in the process. I'd set it on a flat surface, check that it is straight and flat. Weld, leaving gaps. Allow to cool, then check for straightness to the same reference points (As listed in the FSM). Then go another round, leaving less gap. Check again, then finish the seams and grind off the excess. Be sure to leave some drainage holes for condensation. If it warps after all is done, take it to a frame shop to be straightened.

Reply to
Rex B

dafalcon wrote in article ...

The OEM convertible frame was actually "boxed" with a "V"-shaped section, and was stamped from a heavier guage material.

I don't have my 1967 GM service manual handy here in the office - but I DO have the 1968 GM manual here, and rear body mount locations differed by several inches between the wagon, sedan and convertible.

Use of a "boxed" sedan frame will NOT provide the OEM frame strength, nor will it provide a convenient, well-designed replacement for the original and it is ill-advised.

Even ignoring any possible safety issues, the sedan frame will likely sag, causing poor fits of the doors.

Reply to
Bob Paulin

Boxing the frame is mainly for torsional rigidity, weld all along. But only weld ~4-6" then move the heat somewhere else for a while then come back to the gaps. Pat

Reply to
Pat Ford

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