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kf6pfk 11-07-10 05:37 PM

Repairing a weld in a aluminum swing arm assembly
Hi all,
I am the owner of a Trek Y22 mountain bike. I have found a small crack that runs along one of the welds in the rear swing arm assembly near the pivot point. I like the bike, but have been told that the swing arm is no longer available. Could it be a reasonable repair for someone familiar with welding aluminum? I was going to try to find someone at one of our local small aircraft repair shops who might like to take it on. I fear that the heat generated when TIG welding the bad seam will knock everything out of alignment. If that happens, I have no way of getting things back to normal, so I don't know if it's even worth bothering with. Any ideas?

merlin55 11-07-10 06:54 PM

hard to say without seeing the creack. If you could find out the exact alloy, 7005 or 6061 or whatever that would be a big help for the welder. A good repair would be to fix the crack with a weld and to weld on a extra gusset on both sides of the swingarm to reduce the load....but a poorly shaped gusset could make it weaker..

kf6pfk 11-08-10 09:14 AM

I can't really tell by looking; so I've emailed Trek tech support for the answer.

kf6pfk 11-08-10 02:24 PM

From Trek TS " That is 6061 and then is annealed and aligned then aged to T6." , So it Sounds petty hard to fix to me.

ftwelder 11-16-10 04:38 AM

Do you have any photographs?

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