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Old 11-01-11, 07:21 AM   #1
robbied196
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Can you fix a fracture in a steel 531 tube?

I've found a nice 1954 Claud Butler 531 frame, but unfortunately it has a crack near the bottom of the seat tube just above the fillet braze. It runs about halfway around the diameter of the tube.

I don't really want to go to the expense of having a new seat tube fitted, plus it kind of sacrifices its vintage credentials. I'm wondering if the crack can be brazed and smoothed back down. What would be the strength implications of going down this route?
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Old 11-01-11, 09:17 AM   #2
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You could certainly extend the fillet well beyond the crack and it would LOOK ok, but there's no way that I would trust it.
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Old 11-01-11, 10:44 AM   #3
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Probably best to have the tube replaced- it looks like the tube may be compromised by rust. Full vintage cred only holds until the first repaint anyway.
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Old 11-01-11, 10:51 AM   #4
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if there wasn't a fillet so close to it, you could have it tig welded without sacrificing strength. The problem is that the brass might contaminate the weld. I would try to find a welder that is comfortable with TIG (GTAW) on thinwall tubes and see if they think they can do it. A butted joint is not a good candidate for brazing. If you could sneak a tube inside and braze it, there might be some hope, but that is a thesis in and of itself.

The other thing that needs to be done is to drill drainage holes in the bb shell for the seat tube, down tube and bb shell itself. I assume there was none, and this caused the failure.
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Old 11-01-11, 02:54 PM   #5
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A close look at the pics makes me think the tube rusted out from inside. I'll bet the BB shell doesn't have a large drain hole at the bottom of the seat tube and it held water.
I'd replace it.
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Old 11-01-11, 05:52 PM   #6
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That seat tube is a goner. Replace it or use the frame as wall art.
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Old 11-01-11, 08:14 PM   #7
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Originally Posted by unterhausen View Post
if there wasn't a fillet so close to it, you could have it tig welded without sacrificing strength. The problem is that the brass might contaminate the weld. I would try to find a welder that is comfortable with TIG (GTAW) on thinwall tubes and see if they think they can do it. A butted joint is not a good candidate for brazing. If you could sneak a tube inside and braze it, there might be some hope, but that is a thesis in and of itself.

The other thing that needs to be done is to drill drainage holes in the bb shell for the seat tube, down tube and bb shell itself. I assume there was none, and this caused the failure.
Supposedly, 531 is not amenable to TIG welding, part of the reason Reynolds phased out 531 and went to 525 (CrMo) . Internal sleeve is an interesting idea, probably could work as the ID of the top and middle of the seattube is likely slightly larger than the butt section at the bottom, would make it relatively easy to "drop" the sleeve in from above and then braze it in place.
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Old 11-01-11, 10:06 PM   #8
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Called my old master builder about this one... the old man is 82 y/o so pretty much have seen it all in 60+ years in the bussines, he is retired now.

This reminds me old miyata pro fix, those frames cracked in the same place than this one, well even lower. This is the fix and hope you find somebody able to do it... u need a pretty skilled guy with the torch... he said... clean, put a sleeve inside from the BB in, then heat and braze it from the outside, the bronze will go wherever u put the heat so thats why he mentioned like 3 times that if the guy is good with the torch it should be a pretty fast fix. He mentioned too about going from the inside with the bronze rod and heating from the outside just to play safe.

Hope this helps and hope you find a good builder to get your frame fixed, who ever it is I would recomend to add more filler in the area to re inforce it. Not a builder here ok?

Good luck.
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Old 11-01-11, 10:11 PM   #9
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I assume it has a solid shell, so getting it clean enough to braze is going to be really hard
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Old 11-02-11, 05:29 AM   #10
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Thanks for all the advice. I've had a closer look and Cassave is right, there is no drain from the bottom of the tube. Although the steel feels quite strong, you'd think the kind of rust that would rot through the tube would mean I could poke my finger through it! Unfortunately, this ruins the rather brilliant sleeve idea, I guess it could be dropped in from the top, but wouldn't the inside of that tube have to be spotless?

I'm in the UK and I've made a few enquiries, all of them point towards a new seat tube which seems to be around 80. I think I'll completely strip off the paint next and try to make sure there's no other issues!
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Old 11-02-11, 06:15 AM   #11
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Originally Posted by GrayJay View Post
Internal sleeve is an interesting idea, probably could work as the ID of the top and middle of the seattube is likely slightly larger than the butt section at the bottom, would make it relatively easy to "drop" the sleeve in from above and then braze it in place.
Getting the inside of the tube clean enough to braze might be tricky, though.
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Old 11-02-11, 10:21 PM   #12
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If you can clean up the area around the crack enough, you may be able to
externally splint a bit with some more steel tube, a parch , lay more brass down
over the area , but then I would not smooth it down, as the big bead of brass
is what you are relying on to have it not open up again.

forget pretty , you are going for the tractor repair practicality.
then ride gently for a while as you save money the to do it right ..
or just have a builder start putting together a new fillet brazed replica.

Last edited by fietsbob; 11-02-11 at 10:29 PM.
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Old 11-02-11, 11:39 PM   #13
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This does not appear to be a "stress crack." As others have said, it appears that the seat and down tubes have rusted through at the BB connection. AFAIK the only way to fix this without replacing the seat and down tubes would be to clean up the rotten parts of the tubes, insert an internal steel sleeve (that will be an interesting job in itself) and braze it all together and then grind the seam smooth so it's not too noticeable when you paint it. You could more easily fit an external sleeve and braze it together. That could be strong enough, but would look like c**p.

That assumes that the BB ain't rusted out, too.
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