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Need info on manipulating Aluminum for repair

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Need info on manipulating Aluminum for repair

Old 06-24-15, 12:24 PM
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Need info on manipulating Aluminum for repair

Hey all, I have a GT XCR3000 which from what my research shows has a 6000 Al frame. According to the "all-knowing" () wikipedia, "6000 series are alloyed with magnesium and silicon. They are easy to machine, are weldable, and can be precipitation hardened, but not to the high strengths that 2000 and 7000 can reach. 6061 alloy is one of the most commonly used general-purpose aluminium alloy." I don't know how accurate the information is, but it seems as though I would be able to repair this by bending and/or heating.

Here's what the problem is. The rear shock upper mount/seat post tube that is welded to the frame has been bent. It has cocked the alignment off to one side and now the shock is in a bind because it's not directly in line with the lower shock mount.

I was wondering if there's anyway I could repair this without cutting the piece off the frame, straightening it, and then re-welding it (which I would have to have someone else do - I don't have a TIG, nor CAN I TIG).

Any info or advice would be much appreciated.

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Old 06-24-15, 12:47 PM
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I would try it. 6061 bends ok. Not sure about the other members of the 6000 series
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Old 06-24-15, 02:03 PM
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I agree it can be bent back. In my experience, aluminum needs to be bent in one very fast motion. If you go too slow you could snap it. People may disagree but it's what I would do with it.

An example: https://www.instructables.com/file/FEFLORGGYVDJTS5

This aluminum lever has a pretty substantial bend. If you took a new lever and tried to bend it like that, it would break. Drop the bike on the ground and the lever bends just like the picture. I have straightened levers like these and other aluminum objects but only while trying to replicate the forces that bent them in the first place. You know that mount was bent in a violent way. Bolt a long rod to the mount and go for it.

Hope you get it lined up better!

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Old 06-26-15, 02:27 PM
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NB: you can find an aluminum welder easily in FLA. .. Boat Repairs ... to Aluminum Boats ..
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Old 06-26-15, 07:55 PM
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I can't see the bend in the photo. But, perhaps take it apart. Put the frame in a vise, and try bending it back with a large Crescent wrench.
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Old 06-27-15, 01:30 PM
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Marine alloys are different. This would need a complete heat treat if one wants near to original specs, which is unlikely to be a factor in boat welding. Hulls can be made of 1/4" plywood right up to 35 or so feet, but the same boat would have an aluminum version that would be quite a different structure.

6061 is used in boats, but I doubt they do much heat treating. One could weld up a casting platform or bimini structure without it requiring heat treating, I would imagine.
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Old 07-10-15, 03:59 AM
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Hmmm... okay lots of different opinions, but the general consensus seems to be that it CAN be repaired and quite possibly by me at home. Thanks guys, I really hope it works. Can't wait to ride this thing.

Turns out though, that's not gonna be a possiblity either though because I need to rebuild the dinosaur Rock Shox SID dual-air that is on it... and I can't seem to find a kit for it.
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