Suspect bent swing arm

Colmol

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Hi Guys, has anyone ever had to deal with a bent swing arm?
I have an almost finished project bike that seams to be "crabbing" as bit when I test rode it. I have stripped it down and string line / plum bobbed the frame to find the steering head was misaligned. Cut it out and rewelded it, reassembled the bike, took it for another test run but still have the feeling of the bike not riding straight. I have run a straight edge from the front wheel to the rear and the rear is out of line by an inch or more so conclude the swing arm is bent.
Has anyone ever straightened one?

Attached is a photo my rebuild. If you look hard at the rear end it looks a bit like what I'm talking about.

Appreciate any help / feedback

Col
 

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Hi Guys, has anyone ever had to deal with a bent swing arm?
I have an almost finished project bike that seams to be "crabbing" as bit when I test rode it. I have stripped it down and string line / plum bobbed the frame to find the steering head was misaligned. Cut it out and rewelded it, reassembled the bike, took it for another test run but still have the feeling of the bike not riding straight. I have run a straight edge from the front wheel to the rear and the rear is out of line by an inch or more so conclude the swing arm is bent.
Has anyone ever straightened one?

Attached is a photo my rebuild. If you look hard at the rear end it looks a bit like what I'm talking about.

Appreciate any help / feedback

Col
It really needs to go in a frame jig to get correct measurements. More than likely there'll be a problem getting it straight after cutting & welding the steering head. Checking alignment by string line alone isn't really enough as the wheels need to be vertical. I worked for a mate of mine some time ago at Bob Martin Motorcycle Engineering here in Melbourne. The quick way is to use the center stand or a rear race stand using a level get the rear wheel vertical placing shims under one side of the stand. Once vertical place the level on the front wheel & move the bars until the level is centered. Then get right down on the floor & look down both sides of the front tyre in a straight line comparing the overhang of the rear tyre.
The best way is to put it into a jig to center the frame & then the swing can be checked for straightness.
 
Providing the radial centre line of the rear wheel is parallel to the centre line of the bike then being slightly offset is not a problem.
It is not uncommon for bikes with shaft drive to have the rear wheel offset and doesn't affect the tracking of the bike when riding.
If the two centre lines are parallel then IMO it is unlikely that if the arm has been bent if it only affect the radial axis. I'd have thought it would also affect the radial one as well.
If the vertical centrelines of wheel and frame are the parallel then I'd doubt the swinging arm is the issue.

Have you checked that the wheel is straight and runs true?
 
Thanks all for your comments.
@Dunc, pretty well what i have done only a bit agriculturally. I ended up buying a swing arm off gumtree, but have yet to swap it over and recheck. Managed to distract myself by cleaning up my workshop by building a Hardtail Bobber from all the left overs from various bike projects :)
 
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