Framebuilders - Looking for repair direction/ideas
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07-23-12, 10:38 AM
1973 Raleigh Grand Sports 531 Reynolds. Off CL for decent price, even checked the lugs and bb for brazing defects not uncommon with the older Raleighs. I did notice the rust at the seat tube lug and even loosened the st bolt and rotated the post to check for frozen post(difficult but not frozen) but did not take the post out, oops! It appears there was a void in the brazing then rust occurred causing a separation of the st and lug (that's headscratcher, the "flapping" st). The separation goes down just below the lug and is limited to this area. So, anyone have a solution(if possible) or direction on how to approach a repair?
07-23-12, 10:59 AM
I'm not sure how you can repair that other than to replace the seat tube. I'd say ride it that way, but it's hard to see how to make that work. I always thought that a seat tube repair looks easy, but Dave Moulten says it's the hardest tube replacement, so I tend to think it's not worth it for yout
07-23-12, 12:29 PM
One way would be just to either braze on or use a tube clamp on the lower section of seat post. There is a demountable travel frame that uses the seat post and two clusters to join the frame at that point. We had a thread recently. The seat post becomes a structural element, so you don't want to use some whimpy carbon post, but you presumably wouldn't anyway.
07-23-12, 02:40 PM
... either braze on or use a tube clamp on the lower section of seat post. There is a demountable travel frame that uses the seat post and two clusters to join the frame at that point. We had a thread recently. The seat post becomes a structural elemen.... .
I did a couple of searches but no luck. If anyone can supply a link I'd appreciate it, I'm having a hard time visualizing it.
Andrew R Stewart
07-23-12, 03:27 PM
A long time ago I repaired a frame with torn and collapsed binder ears. I cut/filed off the bulk of the ears with a mitered shape to fit a binder barrel. Brazed it all together and slotted the barrel as usual. Maybe i was lucky in that the old filler stayed put. I'm glad I had a sand blaster to aid the pre braze clean up. Still today i'd pass on such a repair. Andy.
07-23-12, 03:36 PM
You should be able to get that to form back out if you make a cone shape on a hardwood dowel(like oak or mahogany) and sand it smooth. Sometimes you can use a wrench socket to form it as well, but those tend to be blunt faced and harder to get started. You should be able to rebraze the metal if needed, and sometimes a mig welder can work. I had my double butted steel mountain bike repaired with a whole new tube section in the thin part of the butting via mig welding. Mind you it has to be a pretty good operator to do it that thin, such as a sheet metal welder from a body restoration shop.
07-23-12, 03:54 PM
re-brazing is going to be tough given the rust. The demountable idea is interesting, but in the end it's the same amount of work as just replacing the tube. The Ritchey breakaway uses the seat post as a structural element. Someone that posts in here intermittently made a similar travel bike, but I forget their username
On edit: I suppose you could remove the part of the seat tube in the lug and replace it with a sleeve on the seatpost.
do a google image search for the term
ritchey breakaway seat clamp (https://www.google.com/search?q=ritchey+breakaway+seat+clamp&hl=en&client=firefox-a&hs=crR&rls=org.mozilla:en-US:official&prmd=imvns&source=lnms&tbm=isch&sa=X&ei=6cgNUNutBeHj0QG33uXgCw&ved=0CEUQ_AUoAQ&biw=1544&bih=894#hl=en&client=firefox-a&hs=8rR&rls=org.mozilla:en-US%3Aofficial&tbm=isch&sa=1&q=ritchey+breakaway+seat+clamp&oq=ritchey+breakaway+seat+clamp&gs_l=img.12...3391.6319.2.109302.2.2.0.0.0.0.38.184.108.40.206...0.0...1c.8AdDR_b7YQ8&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=c9bce066b5d7808e&biw=1544&bih=894)
and you will find some good pictures
07-23-12, 05:08 PM
Thanks all for the ideas and info.
07-24-12, 09:00 AM
Ritchey Breakaway system. And I was not suggesting anything that would be nearly as complex as a tube replacement. Just a clamp on the tube top, however nasty, and go with that. It would be posible to trim out a short section of the tube, so that one could slide the clamp over the top. Then a small tube section could act as a collar spacer, or even another clamp. The two clamps on the seat tube would restore integrity, should not look too bad if you get creative with your choices. You could also braze your lower clamp in if you prefer.
07-24-12, 02:39 PM
Maybe try cleaning out rust form the tube/lug void by soaking in oxalic acid and then throughly flush out with clean water and then compressed air. Once you have it somewhat clean, flip the frame upside down and it should be possible to flow some braze into the gap from the bottom of the lug toward top of the frame. Even if the braze cannot penetrate completely through the gap and the area was still somewhat dirty , it should still be pleny strong enough to ride on. Once the seat binder is clamped shut, it is not like the seattube is likely to slip within the lug.
07-24-12, 03:56 PM
Since the bike was clearly brazed with bronze, I would think you could get in there with silver and just replace the tube without disturbing any of that great workmanship. Or getting any on you for that matter. I'm not convinced those seat stays are attached very strongly.
I'm not going to volunteer to do the job though.
07-26-12, 09:31 AM
Decided to replace the st, I've built frames but never replaced a tube. Here's the planned removal sequence(after taking accurate measurements):
1) cut a 4-6" section from the st center
2) heat the st/ht lug and stay tops untill I can remove the seat stay attachments, then slide/remove the lug towards the rear, using the st still attached to it to help in the pulling/removal.
3)heat bb and remove remaining section of st
Seems pretty straight forward, comments?
07-26-12, 11:17 AM
I don't see why you wouldn't just remove the remnants of the ST from the seat lug and BB shell with a dremel or die grinder. I wouldn't use heat at all. You have good access to the sockets. Just go at it with abrasives. Taking a tube out of a lug with heat is not a trivial thing to do, especially with brass. I see no reason to detach the seat stays. The brazing is horrible, but it seems to have lasted this long.
07-26-12, 12:11 PM
"Taking a tube out of a lug with heat is not a trivial thing to do, especially with brass."
IIRC the brass needs a higher temp to remelt/flow, so you think the tt would get toasted and/or deformed by the heat at the lug during removal? I don't think that would be a problem for the stays or the bb end of the st since the st will be completely removed. I want to get rid of the ears and use a different type of pinch bolt so the lug will be heated for that installation anyway, although the tt area will certainly not reach the same high temps as I first planned. I will, however, start the process as you suggest, going at it with dremel, and see how it goes.
07-26-12, 12:46 PM
even with silver, the lugs get so hot during tube removal that it is easy to damage them and, by extension, the top tube. It takes a lot of heat to reflow all of the filler at once.
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