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Tiggin a harley swing arm Questions

Posted: Tue Jun 27, 2017 3:01 pm
by Just Nick
Okay so I have a swingarm that at some time the bolts for the pulley had backed out. It came to my shop for repair and the customer does not want to spend the big bucks to just replace it. So my questions are what grade of metal should I use to weld in a replacement section. Keep in mind that there will be a axle adjuster spacer in the middle of the swing arm where I have to make and wend in this replacement section. The axle will be torqued at 65 ft lbs of torque and that is why I ask what grade of steel. I was looking at all the metal I have around the shop and I figured it was too soft but I don't know.


swing arm milled.png
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swing arm damage.png
swing arm damage.png (115.08 KiB) Viewed 1384 times

Re: Tiggin a harley swing arm Questions

Posted: Tue Jun 27, 2017 5:59 pm
by thespian
You can bet if it's Harley it isn't anything special. I ride one,but they boast old tech.
Is that swing arm off of a touring bike? I ask because if it is my rear 1" axle is torqued to 105 foot pounds, and mine is an 03.

Re: Tiggin a harley swing arm Questions

Posted: Tue Jun 27, 2017 7:16 pm
by cj737
Many motorcycles use fairly thin carbon steel, nothing special. I'd simply match the wall thickness and use ER70S2 filler wire with a TIG.

Re: Tiggin a harley swing arm Questions

Posted: Tue Jun 27, 2017 7:54 pm
by Just Nick
No it is off a Dyna 3/4" axle and trust me I know all about Harley and there Tech I have been wrenching on them for over 15 years professionally and own my own shop working on nothing but HD's. On the Dyna Models with the 3/4" axle the torque spec. is 60-65 ft lbs. I figured to use 70s2 but was not sure if I should use something stronger then the carbon steel I have laying around. I will machine out the new part tomorrow to be welded on the swing arm where I milled out the rusted section. Now I am a Harley tech/ Tuner not a welder but I can weld good enough for this part. Hopefully if not he is buying a new swingarm Lol


Edit to add. And thank you both for the reply's "Insert Thumbs up symbol right here"

Re: Tiggin a harley swing arm Questions

Posted: Tue Jun 27, 2017 8:07 pm
by thespian
Just Nick wrote:No it is off a Dyna 3/4" axle and trust me I know all about Harley and there Tech I have been wrenching on them for over 15 years professionally and own my own shop working on nothing but HD's. On the Dyna Models with the 3/4" axle the torque spec. is 60-65 ft lbs. I figured to use 70s2 but was not sure if I should use something stronger then the carbon steel I have laying around. I will machine out the new part tomorrow to be welded on the swing arm where I milled out the rusted section. Now I am a Harley tech/ Tuner not a welder but I can weld good enough for this part. Hopefully if not he is buying a new swingarm Lol


Edit to add. And thank you both for the reply's "Insert Thumbs up symbol right here"
Yeah it's not like you cut the end of the swing arm off, and are trying to graft in a piece in a strange place , it will be just fine.

Re: Tiggin a harley swing arm Questions

Posted: Wed Jun 28, 2017 4:34 pm
by Just Nick
Swing arm spacer.png
Swing arm spacer.png (124.04 KiB) Viewed 1284 times
Milled out swingarm section.png
Milled out swingarm section.png (129.54 KiB) Viewed 1284 times
Got the new piece fabricated and milled the slot for the axle adjustment. Then I decided to make a heat sink/ spacer so I know the stock axle adjuster will move freely inside the swing arm. Only thing left to do is weld it up and I will do that tonight and post more pictures of the finished product if my welds don't look like fidos butt LOL

Re: Tiggin a harley swing arm Questions

Posted: Wed Jun 28, 2017 7:21 pm
by Just Nick
welded 1.png
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welded 2.png
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welded 3.png
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All welded up I wet ahead and did a couple beads over the main weld just to fill in some metal. Not my best looking welds but hey I am a self taught (with Jody's Help) and only for about a year and a half. 120 amps 20cfh gas lens with a number 8 cup. Would there be anything you pros would have done different ?

Next I have to weld a forward control mount on a frame for a chopper but that one I am going to call in one of my friends that was a welder for 35 years doing welding for GM on tool and die.

Re: Tiggin a harley swing arm Questions

Posted: Wed Jun 28, 2017 10:40 pm
by thespian
Not weldporn quality, but you probably will grind most of it off anyway, and they should function just fine.
It looks like you got plenty of penetration.