A bad welding job, or a broken frame ?

[Billythekid]

I honestly don’t see anything out of the normal here I live in Florida we have a lot of humidity that happens offen especially where gunk has sat piled up for years when you clean it off sometimes it has a lot of oil or grease and some times there is no oil or grease in the built up gunk and when you remove it it takes the paint with it leaving what you see above and if your talking about the welds they look normal schwinn to me it has to do with the welding process they used I forget what it’s called tho

 

[coasterbrakejunkie1969]

I honestly don’t see anything out of the normal here I live in Florida we have a lot of humidity that happens offen especially where gunk has sat piled up for years when you clean it off sometimes it has a lot of oil or grease and some times there is no oil or grease in the built up gunk and when you remove it it takes the paint with it leaving what you see above and if your talking about the welds they look normal schwinn to me it has to do with the welding process they used I forget what it’s called tho

Electroforging, I thought the joints looked like what you see on most Stingrays. Maybe due to the high volume of them being made at the time they may have let the quality relax a bit. 10 year old kids are less discerning.

 

[SirMike1983]

To me, that looks like a combination of an imperfect weld, rust, and hard use. I've seen a few Schwinn 1960s-70s era frames where something looks off about the chainstay welds to the bottom bracket. I saw one frame where they actually did not even seem to line up - like they were pushed together but didn't match up straight. I would not be surprised if every so often there was a frame where the weld was not as good as the others at that pair of joints. It doesn't help that if the bike is ridden hard, or jumped, that joint sustains a great deal of stress. That is also a low spot in the frame where moisture can collect. Given the type of steel, it might be possible to clean it and have it re-welded, but that depends on the corrosion and what's left by way of metal there. The bottom bracket joints proved more difficult to electro forge weld than some of the other frame joints, and you see hybrid construction bikes in the 1940s and 50s where some joints are welded and some around the bottom bracket are still fillet brazed.