Topic: Swingarm help

[fmctm1sw]

I have a CB650 I just put back on the road.  During my initial ride I sensed something wrong in the handling, especially in and out of turns.  At a gas station, I grabbed my rear wheel and had play in the swingarm.  Yeah, play with the wheel and shocks still on it     I have it all apart with another swingarm from a parts bike to put on it.  The one on the parts bike felt tight.  The question I have is the collar and bushing.  The collar is supposed to move freely in the bushings right?  The sloppy one does, the tight one doesn't.  Like if I put my finger inside it it should spin right?  It doesn't.  I planned on not pulling it all apart but I may have to...  any thoughts?

[fmctm1sw]

I never could get the bushings out of the parts' bike's swingarm so I let them be.  One of the bushings and associated collar surface looked scuffed so I did what I could to smooth it out and was able to get it into the bushes and turn it (although it's nowhere near as smooth in turning as the "bad swingarm" collar.  I measured everything and here's what I came up with (in inches). 

Bad swingarm
left bush:  .927
right bush: .927
collar left: .922
collar right: .922

Parts bike swingarm
left bush:  .928
right bush: .926
collar left: .921
collar right: .922

After looking at Hondaman's book, he says .008 was the service limit for the 750 (although he states this much clearance would create a lot of play at the end of the swingarm) so I assume the 650 wouldn't be much different.  I'm at .005 give or take.

Here's the weird thing though.  The play I have is side to side.  The swingarm moves horizontally left to right as if the frame is too wide for the swingarm or some shim is missing from the ends of the swingarm itself.  I looked at the parts fische and I'm not missing anything on the swingarm.  I think I read somewhere that when tightened, the swingarm should slowly fall down if lifted.  It certainly did on the 350 and 550 swingarms I worked on.  This one flops right down if you lift it.  I have yet to try the "bad swingarm" on my parts bike. 

So I'm right back where I started except for that parts swingarm on the bike now.  I'm taking a break for now.

[70CB750]

I seem to remember that the swingarm bolt is supposed to squeeze the swingarm - i.e. there is a play when the bolt is out and no play when tightened down.

Anyway, on the K3F the swingarm with new, flanged bushings had too much play, I ended up using washers to eliminate the play.  There was not enough room for those original cap washers that go with felt washers - so I searched my washer bin and ended up opening the right thickness washers on lathe to accommodate the long swingarm bolt.  It seems to be nice and tight, but since the K3F is not on the road yet, that is the only feedback I have.

[fmctm1sw]

Thanks 70.  I believe I also read that the collar becomes an immobile part of the frame once that swingarm bolt is tightened.  No amount of tightening is going to take up the slack I have though.  I should have time later this week to look at it again.  I think I'll try putting the other swingarm on the parts bike and see if it exhibits the same play.

[MCRider]

Thanks 70.  I believe I also read that the collar becomes an immobile part of the frame once that swingarm bolt is tightened.  No amount of tightening is going to take up the slack I have though.  I should have time later this week to look at it again.  I think I'll try putting the other swingarm on the parts bike and see if it exhibits the same play.

The collar is longer than the swingarm tube is long. So when you tighten up the swingarm bolt, the collar becomes pinched between the frame bosses and thrust washers, leaving the swingarm free to...swing. The smingarm should only move in the vertical plane. If it moves horizontal teh bushes/collar/thrustwasher dynamic is compromised. No amount of tightening will fix it.

[fmctm1sw]

Well, here's how I solved this issue or at least created less of a problem than I had.  The collar and dust caps fit snugly in the frame.  The problem started when I added the swingarm to the equation.  The swingarm slid left to right on the collar.  I added a picture of the dust seals on the swingarm with those shim looking things near the end of the swingarm as references points to give you an idea of how far it was moving.  I took up that play between the bushing ends and the dust seals with a washer (I'm pretty sure it was a 350/400F steering stem washer) that I grinded down.  There is no side to side play anymore and the swingarm no longer flops down if you lift it.  BUT, is not loose enough where it will fall down by itself either. 

[70CB750]

Looks good!

[MCRider]

I looked at a CB650 fish and it shows that you have the "tophat"style bushings with no thrust washers, other than the dust caps. I can't really tell from your pictures if that's the style of bushing you have or not. What you've rigged up will probably work.

"Tophat" style bushings have a flange that locates the bushing keeping it from going too far in. It also acts as a thrust. The other "plain" style bushing is just a barrell shape with no flange.

[70CB750]

I like the tophat better since it provides bronze surface for the movement between the frame and the swingarm.

The positioning of the bushing is a nice bonus.

[MCRider]

I like the tophat better since it provides bronze surface for the movement between the frame and the swingarm.

The positioning of the bushing is a nice bonus.

The more I look at his pictures it would seem he has the non-flange (non-"tophat") style bushings which are wrong for his bike. The makeshift washers take the place of the tophat flange and may work OK.

[fmctm1sw]

I looked at a CB650 fish and it shows that you have the "tophat"style bushings with no thrust washers, other than the dust caps. I can't really tell from your pictures if that's the style of bushing you have or not. What you've rigged up will probably work.

"Tophat" style bushings have a flange that locates the bushing keeping it from going too far in. It also acts as a thrust. The other "plain" style bushing is just a barrell shape with no flange.

That's what I have.  The tophat style.  I was actually able to remove the bushing by grabbing the little flange.

edit:  If I could change anything (and I may when I replace the chain), I might make that washer a hair thinner to get that "slow drop" out of the swingarm.  I went on a 50 mile ride yesterday and I didn't feel that "hinged" feeling so it's a vast improvement. 

MC, thanks for the explanation of how the swingarm works.  That helped immensely.

[MCRider]

I looked at a CB650 fish and it shows that you have the "tophat"style bushings with no thrust washers, other than the dust caps. I can't really tell from your pictures if that's the style of bushing you have or not. What you've rigged up will probably work.

"Tophat" style bushings have a flange that locates the bushing keeping it from going too far in. It also acts as a thrust. The other "plain" style bushing is just a barrell shape with no flange.

That's what I have.  The tophat style.  I was actually able to remove the bushing by grabbing the little flange.

edit:  If I could change anything (and I may when I replace the chain), I might make that washer a hair thinner to get that "slow drop" out of the swingarm.  I went on a 50 mile ride yesterday and I didn't feel that "hinged" feeling so it's a vast improvement. 

MC, thanks for the explanation of how the swingarm works.  That helped immensely.

I remember when I figured it out. IT was a revellation. Same principle set up for the rear wheel. The "spacer stack" as I call it, goes from one side to the other, includes the internal bearing races, and is smashed firmly by the axle nut. The outerraces of the bearings then spin around the immobile spacer stack.