Swing arm oops

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Buddy called me up in a panick saying he fubared his rear swing arm on his bike the axle adjusters were seized and to get them out he was heating the tube up with a oxy acetyl torch I guess he didn't realize how thin those swing arms really are lol Attached Images
Reply:Fixt well repaired actually should last till next time he decides to take a torch to it lol Attached Images
Reply:I wonder if that aluminum arm was heat treated?Miller Dynasty 200 DXBuildPro TMA52238 (38" x 22")Miller MP-10 & Jackson Nexgen EQC20 Ton Press & Swag HD Press Brake
Reply:Throw that arm away if you like your buddy.....Miller Dynasty 200DXMiller Spectrum 250DMiller Millermatic 200Bunch of old blue dinosaurs....
Reply:Looks like he destroyed the axle slider holes too. Hes wrong, that aluminum isnt that thin. He put that much heat into it. Throw it away.
Reply:No the swing arms arnt heat treated there 6061 extrusions they are anodized. The axle sliders are still in good shape I had to drill out and fill the adjuster holes he mangled those nicely. It's a definite repair not fixt kinda thing as for welding it key part is to finish the welds clean and don't weld across the tubes. And yes where he heated was thin only the axle slots and front are solid on these the tubes are only 1/8
Reply:Originally Posted by abecNo the swing arms arnt heat treated there 6061
Reply:Almost looks like a yzf swingarm.
Reply:It's off a 03 crf450
Reply:The D1.2 Structural Aluminum code has some good information / guidelines on heat input limitations for various aluminum alloys so that you don't degrade their strength and corrosion resistant properties.In general it limits the preheat and interpass temperatures of the heat treatable alloys (and 5xxx series alloys containing more than 3% Mg) to 250 F.  Time at that temperature not to exceed 15 minutes.According to section 4.18 all straightening is to be done with mechanical means at ambient temperature when ever possible.   If heat has to be used, time and temperature has to be limited to the values given in Table 4.5   Which for 6061-T6 says no more than 450 F. for no more than 5 minutes.   A maximum of 400 F. is allowed for 30 minutes and a maximum of 375 F. is allowed for 1 to 2 hours.If these guidelines are followed a T5 or T6 tempered material will not lose more than 5% of it's strength.  A T4 tempered material will actually increase in strength if subjected to these times and temps.
Reply:Originally Posted by 4956If these guidelines are followed a T5 or T6 tempered material will not lose more than 5% of it's strength.  A T4 tempered material will actually increase in strength if subjected to these times and temps.
Reply:rlitman,I fully agree, that swing arm is toast and belongs in the scrap bin.   I was just trying to shed some general light on the effects of time and temperature on heat treated aluminum alloys.
Reply:It will be fine. I fixed many bikes from the local track that go wrecked. Swing arms, frames, sub frames. As long as its a good weld that doesn't make any vertical stress risers it will be okay. If you couldn't weld on these frames 3/4 of the bikes at the race track would be scrapped.
Reply:Same as above. We have a place for dune riding called the Oregon dunes.  Thousands of people ride in the dunes every summer.  during my 20 years of welding in Roseburg, I have probably extended upwards of a couple hundred swing arms. Plus lengthening frames and general repairs. I never had a single one comeback because of welding weakening the material. If they brought one back it was because of crashing into someone coming up the other side of the dune.  Mac
Reply:Originally Posted by sbchp355It will be fine. I fixed many bikes from the local track that go wrecked. Swing arms, frames, sub frames. As long as its a good weld that doesn't make any vertical stress risers it will be okay. If you couldn't weld on these frames 3/4 of the bikes at the race track would be scrapped.
Reply:u can find one on ebay fairly cheap, from the dealer it would coast as much as the bike.....my son's sized also, very common with aluminum swing arms, as ya probably know.........
Reply:Originally Posted by Tool MakerSame as above. We have a place for dune riding called the Oregon dunes.  Thousands of people ride in the dunes every summer.  during my 20 years of welding in Roseburg, I have probably extended upwards of a couple hundred swing arms. Plus lengthening frames and general repairs. I never had a single one comeback because of welding weakening the material. If they brought one back it was because of crashing into someone coming up the other side of the dune.  Mac
Reply:Lmfao I've stuck a few sleds into the back sides of hills always a good laugh. Yeah I have no worries about the swing arm I've done my fair share of Alu welding
Reply:If he hadnt torched the arm, i would have no qualms with that repair. But because it wastorched, I, personally wouldnt feel comfortable riding on that again, let alone repairing it. To each his own.