Extending Motorcycle Swingarm

[UnfinishedProjects]

When I return from this deployment I would like to start working on my bike again. First thing I want to do is weld a swingarm jig so I can stretch the swingarm about 2" or so.

The problem is I have air suspension on the bike and when the bike is lowered the tire comes in contact with the seat pocket. The swingarm is made of 1.25" dom tubing, .120 wall.

What is best way to do this mod?

Should I put a solid slug inside the tube as well as the filler tube piece?

Place a couple plug welds on each side of the filler section? When I drill down through the existing swingarm to place the plug welds, should a drill into the slug as well to help penetration?

I hope to purchase a Longevity TIG when I get back, but if I cannot, do you think a 140 amp, 110 Volt MIG is capable with the .120 wall tubing? I think I would be fine, especially with a fillet at the butt welds.

Thanks for the help.

-Kev

[tigqk]

Start from scratch and build a new one from more common materials-alloys,chrome molly, stay away from aluminum, mag,etc.and you may be able to do it yourself, got a picture of it?Is it going to be on the road or is it for racing?My belief is 140 amp welder doesn't have the power to do the job,again it depends on your prep, and electrode dia. I spend alot more time prepping to a standard than anyone I know, because I like wire feed and Tig, but sometimes it isn't practical to Tig. check here for good prep and engineering info,
info;Effective Area & Size
also aws.org
Also to be quite honest this may not be the right forum for this question maybe your best information may be on a motorcycle forum and see if someone has done it for your bike.
What may be a fast and quick solution for you is to fabricate a bump stop to keep your swingarm from hitting the seat, a reactive bump stop like autos have. I am sure it did not come from the factory hitting the swingarm but without seeing it it is difficult to give advice.
Absolutely,get yourself a Longevity Tig, good value for money.

[odleo]

My brother had a new new swing arm for his bike made, the bike shop told him it would be cheaper build a new swing arm than to stretch his old one. He needed a 2.5 inch extension so that he would not hit the seat pan on his bike.

[SICFabrications]

in my honest opinion, a 140 amp mig machine wont get it.... aint enough juice... 110 amps on a dc tig machine will get much better results with a smaller HAZ (heat affected zone) to accomplish that with a mig, you would need close to 200 amps with .035 er70s-2 wire to get decent results... also, your (not tryin to put ya down, just sayin) technique and welding ability is going to play a huge role in this as well.... better safe than "crashed"

[mdkrusemark]

I think you will be fine with the 140 amp machine. I welded up my whole rear frame rails on my 67 firebird with my little hobart handler 140. I wouldn't use a solid bar to sleeve it, I would just use .120" or 3/16" wall. I would sleeve it as long as you can and plug weld it along the sleeve, prob each plug weld 120* away from the other. Then v grove the butt weld and use a weave pattern to weld it up. You'll be fine.

[SICFabrications]

krusemark, no offense, we arent talking about a mild steel component that rides around on 4 wheels.... (which ive seen my fair share of knuckleheads that have a lil mig welder and think they can weld the world and end up killin peeps) we are talking about 4140 hot roll annealed dom tubing.... before you give ill gotten advice, know what youre talking about. 140 amp mig machine will cold lap before you get enough penetration... what i fear is lamination tear or weak grain boundry failure when using a small mig machine on 4140 hot roll...its simple physics

---------- Post added at 08:07 AM ---------- Previous post was at 08:05 AM ----------

as to the OP, unfinished, the best bet is to build an entire swing arm from scratch... that way there arent any splices to fail... its what i would do

[mdkrusemark]

we are talking about 4140 hot roll annealed dom tubing.... before you give ill gotten advice, know what youre talking about. 140 amp mig machine will cold lap before you get enough penetration... what i fear is lamination tear or weak grain boundry failure when using a small mig machine on 4140 hot roll...its simple physics

Where are you getting that it is 4140 hot roll annealed dom tube?

Most 1.25" .120" wall dom tube that you see is 1020 or 1026 cold form.

[SICFabrications]

i may be wrong, but i build mine from 4140 and wont accept less.... either way, splicing is not ideal and using a 140 amp mig machine in my opinion wont cut the cheese. not when code calls for 200 amps... i aint tryin to start a flame war, but be it as it may, better safe than sorry... codes are in place for a reason....

[tigqk]

When you get it done please post the pics would love to see it done.This is a good job for Tig, this is the thing about giving recommendations on a 115volt, 140 amp machine, prep your metal for a weld and when it is done how are you going to tell if their is sufficient penetration when the penetration is limited by electrode size and electrode size is limited by machine amperage, you get only one crack at welding it properly and will only know when it fails if it was correct.Another reason you may want to consider Tig is the appearance will be consistent, slightly convex where a mig may be considerably convex in trying to get penetration to where you want it, round surfaces require stop and go and you have cold joints.Also will you be dressing the mig welds for appearance?

[SICFabrications]

you said what i was trying to say.... im tired and under some serious stress.... i think i might have too many irons on the fire right now with building bridge parts, 300 linear foot of iron fence for a cemetary, 900 linear ft of railing for a different bridge, 14 spider arm rests and 4 more water transfer manifolds... and then the occasional aluminum boat and exacavator boom repair that walks in.....

well said, tigqk