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PostPosted: Thu Jan 24, 2013 3:31 am 
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So before buying my giant I checked most places that would crack and all seemed good Until just now when I cleared so mud off if, turns out i have a crack in an X shape where there are holes in the little bridge attaching the chainstays together. Its a good crack but it has not reached the welds as yet.
ImageImage

Would welding this heat up the welds close by making them weaker ?

Any thoughts on what to do from an engineering point of view would be great, if not does anyone have a set of ATX DH chain stays floating about im very interested.


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PostPosted: Thu Jan 24, 2013 9:58 pm 
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Gutted.

I was always under the impression that aluminium does not like to be rewelded once it has been welded and heat treated hence my Tazer being destined for the wall.

I personally would try and find a replacement part. Weren't these pretty famous for cracking? I can't remember to be honest.


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PostPosted: Thu Jan 24, 2013 10:26 pm 
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Pretty bad looking. How about getting some plates put in to strengthen it?


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PostPosted: Thu Jan 24, 2013 11:06 pm 
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Gutted. I've just been to my dads house and shown him this (he's a fabricator/welder) and he said looking at that a decent fab/welder would cut it out and weld in a new alu section. The holes on the cross section are to let air in while welding other wise the welds would burst while being welded and it wouldn't be as strong. He said the biggest problem is all the paint....as much as pos needs to be removed otherwise it will weld like shit. Failing having a new section welded in you could grind all the paint from around the cracks and just get a welder to fill it in as much as he can, or even have a plate welded on top...soming thick like 4/5/6mm.

Anyway from what he said he seems confident it could be repaired so i'd try to get it done!! Rear ends don't come up that often....


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PostPosted: Fri Jan 25, 2013 1:02 am 
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Whats the coiled spring directly above it for :? looks like a canti spring


The bridge is there to space the rear and give it a bit of rigidity.I think in theory you could take it out and fit or in some way bolt on something else :?


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PostPosted: Fri Jan 25, 2013 9:05 am 
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No problem to repair that for a decent fabricator.

As your dad says best route would be to repair the crack so it doesn't spread further and then add material to make sure it doesn't happen again.

I would hazard a guess that the frame had a poorly drilled hole or not de-burred and that will draw the stress to the rough/mid shaped part of the hole.

Seen it in examples of poorly built aircraft when I was at college.


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PostPosted: Fri Jan 25, 2013 9:28 am 
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dyna-ti wrote:
Whats the coiled spring directly above it for :? looks like a canti spring


The bridge is there to space the rear and give it a bit of rigidity.I think in theory you could take it out and fit or in some way bolt on something else :?


Spring is for the AC chain device.


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PostPosted: Fri Jan 25, 2013 11:06 am 
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Joined: Sun Jun 27, 2010 9:37 am
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yeah any welder could fix that no worries.

having spoken to some one who wleds up space frame aluminium chassis' for racing land rovers, he was shocked to hear how many cyclists are worried about re welding alloy frames. you may not get it looking exactly the same easily and as strong as original but it will be very close.


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PostPosted: Fri Jan 25, 2013 11:19 am 
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It's interesting to hear that ali is ok to reweld. I was always told that it's a pain and not a good idea due to the heat treating etc.

May be there is hope for the Tazer once have more cash!


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PostPosted: Fri Jan 25, 2013 11:28 am 
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Joined: Sun Jun 27, 2010 9:37 am
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at the end of the day if its already cracked why not try re welding? i think that s aluminium is more tricky to weld, due to set up rather than anything, a lot of people dont want to try. with a lot of the new wave of pulse wave thingy welders, its much easier to do than it was a few years ago. the heat developed during a small repair weld is no where near that generated by doing a long continuous dress weld, so heat treating isn't as much of an issue, but a good welder/fab guy/gal may heat treat any way.


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