I've had three of these cars with the same damage on the passenger inner fender and core support. I have front clip off my 1968 GS 400. I'm cleaning my frame underneath and after a few passes with a flap disc it's looking like I've lost at least half the metal on the upper and side of the frame rail to rust. This is just under where the battery sits and looks to be the only place my frame has any rust. I already know I should at least get someone to fabricate a piece or three and cut all the rust away then patch it. This rust is pretty much only on the top and side as you can see below so I think it would be fairly easy to patch. It's interesting that the bushing actually prevented the metal from rusting underneath. At the inside of the hole its a full 1/8" thick, around that and to the side is about 1/16" thick. It seems like every forum post I see on Chevelle's with frame rust, their problem is usually under the bushing and not the surrounding frame. Anyone care to share what their rust experiences are with this model year? Pictures would be best. For someone like me who does not weld and can't bring my frame somewhere to have it welded, is there anything I can do myself? Is there anything to skim over pitting that may fix this? I'm thinking fiberglass reinforced epoxy would be an absolute nightmare on my frame but I also know it would be dumb to just believe POR is going to help my situation.
I have seen people with the Frame horn for sale I would get a cleaner one cut off and replace if the lower section of the frame is in better shape.
@Buicksky Thank you for the response. I'm looking for a short term solution to get the car back together so I can drive it. I haven't seen a clean frame horn for sale in a very long time and I don't have a welding resource I'd feel comfortable with doing all that. I guess I need to start thinking about parting out the car.
Sorry I didn't mean to discourage you. A short term solution is to cut out and weld up some patches. Depending on severity of the rot worm that could last you a few years or Much longer. You could put a parts wanted add up and a frame horn could be shipped. Another option is a complete frame swap.
Maybe you could bolt on a reinforcement, either some plates, or a piece of large angle iron or rectangular tubing on the inside. Don't try patching with epoxy or fiberglass, it's not strong enough and will be useless. Do treat the rust with a rust converter or specialty paint to keep it from getting worse. Having it welded is still the best way. You could likely find someone to come to your home to do the welding.
If you can clean the rust off ( out of the pits) with a sand blaster and or acid you could use 3M 8115 epoxy to glue patches of heavy guage steel to the top and sides of the frame horn and likely it would last for years without problems. you would need to make the laminate parts a bit bigger than a patch. fashion the parts before gluing. Use pins or screws to align your parts. Clean up and paint and put it back together. This is not ideal, but, will work and be somewhat safe. Everything will be squeezed together when assembled and the epoxy won't yield to vibration. Don't use any old epoxy - used 3M 8115.
Get a replacement frame horn. Attach it with steel plates bolted on, bridging the gap (aka 'fish plates'). That'll work as a temporary fix until you can get it welded.
Either replace the frame or frame rail. Your car is not safe to drive if you have a serious accident in front you’re as good as dead ! especially on the passenger side.