How to Stretch the swingarm?

[synergy]

Hi, cause the yamaha sr 250 is very small, i want to know how to stretch the swingarm. You know...low and loong
The swingarm is this:


But as you notice, there is no straight zones, so im in doubt. Maybe this solution could be right? (but have problems with the inner pipe mount...)


I´m concerned about the way of doing with maximum security (inner piece with welded holes, type of welding...)
I have this schem (the orange is the weld, the blue and yellow the inner piece, is enough if this piece is welded, or better machined?, best solid machined?
The type of welding i have is MMAW welding "electrode", is fine?? (with supply inner pipes) or only MIG/TIG?

The MIG is waay better in resistence and durability terms? Can i do with MMAW with the same security?




How do you guys made it? please explain, it´s a serious structural mod, so i think this info would be great, well explained for the forum.

 

[synergy]

Nobody stretch his swingarm?

 

[crazypj]

plenty of people have stretched swingarms, just not THAT swing arm.
Post some measurements, there will be something out there thats easier to adapt.
I measured a Suzuki 250 swingarm, about 8" across pivot, 3.75" space between pivot bushings and 22" long

 

[chrisf]

OK, I've done a few of these before. What you do is weld three pieces of steel to the axle plate to keep it nice and rigid. You can't have that moving around. Then chop the swing arm in half, tap in some bungs and weld in a splice piece. When you're all welded up, cut the pieces off that you held the axle plates in position.

I've done this using TIG and MIG, and honestly, I like MIG a lot better for this application. I would never use a stick welder for this job--or any job for that matter.

--Chris

 

[synergy]

Thanks both.

Ok, motofiaccone; a sketch would be right. The way i explained in the first post do you think is worse than yours? what are the main differences?

I ever thought the stick welder has the same resistance (and more ductility)as MIG, am i wrong?

 

[crazypj]

You can have problems with hydrogen embrittlement and also free nitrogen from air causing nitrides to form with a stick welder.
If it was heavier section I wouldn't worry about it but swing arm extension isn't a good idea with a stick welder
Making a new swing arm would be safer

 

[synergy]

Ok, understand. The way is MIG welder.

Otherwise, do you think the method i wrote is correct?