What is the best way to repair minor rust holes in frame rail

[bobs73challenger]

Hi everyone,

I continue to make progress cleaning the crap out of my inner fenders and frame rails for rust proofing/painting.

Recently discovered two small spots for concern on the drivers side. One on the engine bay side (to the right of the wiring in the pic), the other on the wheel side, right behind the shock. I've attached photos. The photos arent great, as I had to zoom in quite a bit to get them. They're very small, the one inside the engine bay is roughly the size of the quarter and the other one is longer than it is wide and is no more than 2-3 inches long.

They look bad, but I've knocked them the best I can and am confident that the rot is confined to those areas.  The rest of the frame seems sound.

My welder is coming out this weekend and we have time to tackle this, just wondering the best way to go about making these repairs.

I'm thinking, clean up the metal all the way around and plate over it. Is there anything wrong with that? Is there a better way? My car is not going to be a concourse resto or anything like that, its a resto mod that I'll be driving to and from work everyday. Interested in doing the patchwork correctly.

The exterior of the frame will be seeing por15 and the inside is getting treated with Eastwoods interior frame coating after I blow it out the best I can.

Thanks!

[shawge]

Hard to tell but it looks like a lot of scaly rust around the holes?  How far around does it go?

Auto Rust Technicians has frame caps. Not sure if plating over this would be good in the long term.

[daveh]

Cut the bad part out until you have clean steel and butt weld in a new piece, grind down and your done. Spray something like internal frame coating or anything to keep it from rusting.  Eastwood has these long tubes that will attach to any rattle can and allow you to reach the area.  I think they are like 6-7 bucks each but they are worth it.  Good luck

[HP_Cuda]

As someone who replaced frame rails.

It would be advantageous to find out how bad the rust is before trying to just repair something you can see. Maybe get one of those small cameras to put up in there and see how bad it is.

[rhamson]

As someone who replace frame rails.

It would be advantageous to find out how bad the rust is before trying to just repair something you can see. Maybe get one of those small cameras to put up in there and see how bad it is.

  These frame rails were barely enough stiffness when new. Just jack one up by the corner and look at the door gaps to prove it. If you can arrest what is bad with the Eastwood internal frame spray you will need to see what structure is not eaten out by the rust. I have successfully used the frame caps if you are just looking for strength and not looks.
 

[larry4406]

I cut out the rusted area until the metal was solid.  In  my case I had rust on both sides of the frame.  With one side open, I inserted a piece of steel plate into the frame against the back of the other side.  This was then plug welded thru the exterior face and then welded internally and coated with galvanized paint.  The rusted section then removed and welded to the internal plate and frame rail.  Lastly, I cut a new piece of steel to weld in the access hole (which was also rusted) and finished it all off.

Pictures attached to give you some ideas.

[jimynick]

Nicely done and it should be at least as, if not more, stronger than it was originally. 

[larry4406]

Thanks Jimmy.  I don't know if my approach was the "best" way but it worked for me.  Car unfortunately is on hold.