Frame Swelling

[Eternal]

The 73 fj40 is now down to frame and sand blasted. The inner frame, bottom, on the boxed section has swelled considerably. The outer main frame is in good condition. I have pulled out all the swelled metal and there are parts where 3-4 inches along the bottom of the box that are not there anymore. I have been cleaning it out but not to sure how to proceed to repair it without removing the inner frame channel. The upper section(closest to the tub) is in very good condition.
I was thinking of removing the inner frame completely and replacing with 1/4 wall tubing over the whole length.
Or just adding plates where the inner frame is missing and then capping the whole thing to make a sealed frame? Is that allowed on a street vehicle? Is it advisable to seal the whole frame off?

Need some guidance from those who have been there. Thanks.

Eternal

 

[ken_79-fj40]

mine was like this too. The inner rail was actually rotted through from the rear spring hangers to about a foot ahead of the crossmember. I used an air chisel to bust out all the expanded rust, then pounded the frame back where it should be (where there was a good inner channel) and welded the seams (between the inner and outer channel) top and bottom. For the rotted sections, I cut the whole channel out and welded 1 inch flat stock to the inside of the framerails, flush to the inside edge. Then I plated those sections. Then I plated over them again about 8 inches over the repair in both directions. Its all welded all the way around. I'm not a frame expert, but it sure seems to be strong now.

 

[Eternal]

Is it OK to weld to the frame or will there be problems if I have to get it inspected? I am Cutting a load of stuff off right now that the PO put on.

 

[ken_79-fj40]

you'll have to check with the local inspection station on that one. I live in NH, inspection is pretty lax here. I don't think i've actually had a legitimate inspection on any of my cars for about 10 years. It helps to know a few mechanics.