Frame rot - HELP!!

This weekend I was surprised (I know I should have expected it!) to find an eraser sized hole in the frame while replacing my trailing arm bushings. I was cleaning off all the undercoating the PO had sprayed on to inspect and found a "blister" which revealed the hole. Poking and banging I find the weakened portion (that which would give under the force of a 5#ball peen)only extends to about a quarter sized patch.

Here's the question: Do you think a small repair plate bolted or welded to the side of the frame will last? I'm hoping this repair method would last about ten years. What do you think? Any experiences here? /ubbthreads/images/graemlins/confused.gif

If there is one bad place there can be many more. Check everywhere. For me welding is the only solution. Not bolting a plate. Best of luck and I hope it is just that one place. It would not be a bad idea to wax-oil the insides of the frame or an equivalent rust inhibitor. Obviously don't oil them and then weld. My cars have samll holes drilled in frames and then sprayed inside of frame. Then a plug is used to cover the holes.

If it is just one place and only 1/4 inch you could drill it, clean it flat and use a plastic plug. Also good access for interior spraying.

Clean up all the bad metal then weld a patch over it. Welding is the only way to do this.

So I'm seeing that a welded plate is going to have to go in -- any idea how thick the frame material would have been originally ? I could use that info to help me guage how far back to cut out the section - without going too far.

The frame is around 14 gage or so,quite easy to weld if cleaned up well. While your about the job, notice the nice extra holes the factory left in the side rail above the rust, yes they are the problem. Take a suitable bolt & washer and insert it,with a nut on the other side. Presto , problem licked(repeat as needed)
MD(mad dog)