Swingarm Play (pivot bolt damage)

The swingarm shim is very thin, as mentioned. It's size is given in some of the older parts manuals and is 26-34-0.3. 0.3mm is only about .012". These shims were installed on a "as needed" basis, which from what I've found, wasn't very often. I've only run across a couple in all the swingarms I've pulled apart (maybe a dozen or so).
Yes, I found it in the thread @gggGary linked to. I’m going to McMaster-Carr for the ‘79 bushings and this one if I have to.
 
That might be a bit much. I think we normally shoot for about half that, so you may need a shim. If it sticks out too much, you won't be able to achieve the proper "tension" (bare swingarm slowly drops under it's own weight) within the pivot bolt's torque range.
 
That might be a bit much. I think we normally shoot for about half that, so you may need a shim. If it sticks out too much, you won't be able to achieve the proper "tension" (bare swingarm slowly drops under it's own weight) within the pivot bolt's torque range.
Now, I’m a bit confused. What is the ID of the OEM shim? I thought it was 16 mm. It’s not?
 
Now, I’m a bit confused. What is the ID of the OEM shim? I thought it was 16 mm. It’s not?
Marty, that shim sets the side to side play.... your .020" you stated in #62 above.
It fits around the pivot tube... fills the gap between the bronze bushings "hat section" and the grease seal.
It doesn't address the "pivot tube to frame" gap you're trying to eliminate.
 
Last edited:
I'm not sure where it comes from but I know I read it somewhere. Maybe not in an actual manual, maybe in some magazine article on bike care, heck, maybe even from a Joe Minton article. It's the way I've always mounted them.

The shim I.D. is 26mm, taken from that shim size spec I mentioned a few posts back. It fits OVER the pivot tube, not against it, and allows you to adjust the difference in length between the tube and the swingarm w/ bushings. In your case, you'd want to add maybe .010" worth of shimming to reduce the .020" difference you have now.
 
Too bad I screwed that up. I had it set to .020, it could have been anything.
Not really. That's determined by the thickness of the bronze bushings hat section (after they're fully seated) and the length of the pivot tube. Once those bushing are pressed in, the gap is what it is.
All you can do at that point is use the shim(s) Yamaha uses to close the distance down.
 
..... or file the face of the bushing if the difference is too small. This issue has been reported with some of the bronze bushings. Apparently the flanges are a little too thick. Installing the bushings into a freshly, heavily painted arm could cause issues as well, as could powder coating. Best to clean the paint or powder off the edge that the bushing flange is going to bear against.
 
Got an extra grease seal? cut the rubber off and there's your shim. Will be about .005" too much, but that should make a snug, hand tight fit.
OK. That is what I did. .005" interference was fairly easy to assemble. What I was trying to do broke the grease seal.
IMG-1648.jpg


I found a shim amongst my junk and installed it.
IMG-1647.jpg
IMG-1652.jpg
IMG-1653.jpg


Anyway, it's done and it's as close to perfect as I could get it. 47 ft lbs is set and there's no free play. Thank you to those who helped me figure this out.
 
By "47 ft lbs is set .....", do you mean that's how much torque it took to get the arm so it slowly fell under it's own weight?
 
After pressing in the bronze bushings on my 81 XS 650 the pivot tube protruded .013" past the bronze bushing. I know this is within the .005" to .020" range but I wanted to get it closer to the .005" but I didn't have any shims even close to the .008" so after a day looking through my junk pile and finding nothing I was taking the trash out and spotted a empty canned bean can in the recycle bin. The bottom was .008" thick so with nothing more than hand tools I made a .008" shim. Took me a few hours but it fits nicely over the pivot tube and into the end seal.
 
Swing arm pivot shim made from tin can. The cheaper the can the thinner the tin.
 

Attachments

  • 20230210_152053.jpg
    20230210_152053.jpg
    307.1 KB · Views: 65
Back
Top