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Discussion in 'Old's Cool' started by AnnieGS, May 1, 2004.
Having broken about 10 rear sub-frames on various BMW bikes over the years, as well as pannier mount brackets and the like, I have a bit of experience of various fixes.
Sometimes I have only been able to get brazing done and it's gotten me home. Sometimes I have done Arc welding to get me home and it's stayed like that until I've either sold the bike or broken the weld somehow.
I once broke down in the middle of nowhere and the old guy at the end of the town who seemed to repair almost anything reckoned that the strongest fix for this kind of break was straight Oxy-Acetylene welding. The reasons he gave were that the surrounding metal was heated up gently (compared to Arc) then the two pieces were joined together in a controlled manner by an experienced hand, then allowed to cool down slowly.
This he said allowed for the best type of weld in strength, durability and depending on the hand doing the work, looks.
Well his Oxy Acetylene weld outlasted two others on the bike so I had to agree. That was in 1984 and I then did a welding course where I learnt to Arc and Oxy weld. Since then I have repaired a few bits and pieces as one does and I think that the old guy was correct.
Arc, Mig, and Tig are also various types of intense quick heat which may or may not have applications on various pieces of broken bikes. They all have one important setback in that they create localised warpage and or shrinkage due to their quick working time.
Oxy, either straight welding or brazing, will heat the metal up slowly and evenly, it should in the right hands damage the metal the least and allow for a very strong repair.
Do not know the answer.
But I have a pair of older /6 /7 brackets sitting unused. If you wish it, and they will fit, I will send them out your way.
As the man said, torch welding is the way to go in this application. The metal type plus the continous flexing that is inherent to bikes makes this kind of weld just the ticket.
Annie, find an old guy that runs his own shop, and will do it himself, not farm it out to a kid who just burns rod. Best chance of a proper job going that way unless you have some way of finding out who does good work in town.
Just had an idea for that one. Do the local old car guys get together once a week? Almost everywhere, guys that have restored cars unofficially just meet somewhere for coffee. They'd be the guys to talk to. They will know who's good, and who should be shot. And they'll love to chat with a 6' blond on a bike.