Swingarm question

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Just replaced the swingarm bushings with the bronze ones. No problem there. Somebody please explain to me (refer to pic below) why the outer shaft (#2) should rotate on the bushings and not on the pivot shaft (#6)? The outer shaft is not "captured", that is it's not stationary, it's not pinched by the frame or anything else so I would think it's tendency would be to rotate with the swingarm as much as inside it. The Pivot shaft IS captured in the frame. So I would think the outer shaft would have a tendency to rotate on the pivot shaft making the bushings at least in the wrong place. Am I missing something? I know the damn thing works, I just would like to know how?

swingarm-1.gif
 
The pivot tube (#2) is slightly longer than the assembled swingarm w/bushings. The tube does get pinched and held stationary between the frame when you tighten the pivot bolt (#6). That makes the swingarm w/bushings rotate on the tube.
 
The outer shaft is captured when you tighten the nut, the frame draws together till it tightens against the outer shaft. locking it in place. Not many care that Yamaha calls for shim washers to take up any gap between the frame halves and the swing arm. Without the shims, tightening the nut can force the frame halves in and torque the frame holes for the swing arm bolt out of alignment possibly causing stiction in the swing arm bushings. If you just get rid of the swing arm completely problem solved. It is always wise to check the base of the threads on the swing arm inner shaft for cracking, a cracked shaft has been reported a few times.
 
The pivot tube (#2) is slightly longer than the assembled swingarm w/bushings. The tube does get pinched and held stationary between the frame when you tighten the pivot bolt (#6). That makes the swingarm w/bushings rotate on the tube.

Um, not on mine. That's why the question.
 
Repeat
Yamaha calls for shim washers to take up any gap between the frame halves and the swing arm.
My 83 needed some shims to fill the gap when I put in bronze bushings. I could not get the outer shaft captured till I used the shims. Sounds like what you have going on also. IIRC I ended up using some shims from the local farm store or I may even have ground washers to the needed thickness.
 
Repeat
Yamaha calls for shim washers to take up any gap between the frame halves and the swing arm.
My 83 needed some shims to fill the gap when I put in bronze bushings. I could not get the outer shaft captured till I used the shims. Sounds like what you have going on also. IIRC I ended up using some shims from the local farm store or I may even have ground washers to the needed thickness.

Yeah, I've got new shims/seals coming (replacements from Mike's xs). you've pretty much answered my question. i thought it was important to do this, I'll work on this deal 'til it's right. thanks for the input.
 
OK, this is what I've got.............

swingarmbush001.jpg


This is about what I'd like to have..........

swingarmbush002.jpg


At first I thought the thickness of the powder coat was the culprit but even tho there are 2 coats (chrome and clear) I can't see that being enough. as soon as my machinist/son comes by I'll know more of what to do. i've ordered a new outer shaft and new bushings (if I have to machine the bushings they can't be in the swingarm and by the time I get these out they're gonna be junk).

To be honest I think the bushings are just too thick because with the way it is now and the outer seals/shims installed it just barely goes in the frame. We'll see.
 
IMHO Powercoat thickness could easily be the problem. There are a couple of ways to remove bushings without damage. Here's one that's cheap and easy to build out of hardware store parts. that's 3/8 or 1/2 iron pipe, couple of nuts threaded rod I think I used an engine mount bolt. cross slot one end of the pipe with a hacksaw about 1" bevel one nut on the grinder so it spreads the pipe when tightened. Insert it, tighten the nut till it spreads the pipe ends, tap out the bushing. put it in the other side tap out the second bushing. By the way a threaded rod and two nuts and washers is also a great way to install bushings. an in & out tool so's to speak.

swingarm.jpg
 
The shims are actually used if the pivot tube is too long compared to the swingarm/bushing assembly. They are installed inside the grease seals. They have an I.D. big enough to go over the pivot tube - they don't shim against it. This doesn't happen on most swingams so you don't find the shims very often. You need to thoroughly clean the old grease seals and look inside them to see if shims are present. Most probably get tossed out with the old grease seal because folks aren't even aware they might be in there. Out of the half dozen of so swingarms I've taken apart, I only found shims in one.

I agree with Gary - I'll bet the power coating is screwing you.
 
5twins is right per normal. You don't want the outer axle to stick out too far that would introduce side play.

Again I may be alone in the wilderness on this but if the assembly is narrower than the distance between the frame bosses by very much, shims to take up the slack rather than cranking on the pivot bolt is the way to go.
 
Y'll could be right. I'm gonna try to get the bushings out without hurting them, sand off the powdercoat and try again.

Pic of new seals with shims captured inside them, from Mike's SX

swingarmbush.jpg
 
Those aren't shims, the shims are separate thin pieces of hard steel that sit inside those as 5twins said the shim's IDs cause them to fit the outside of the outer pivot shaft to reduce clearance. I doubt mikes has shims.
 
pic of new and old.............

swingarmbush003.jpg


You can see where they have been riding on the pivot tube, not over it. Kinda goes against what 5twins said. Hmm.............should there be bigger ID shims as well?
 
Yes these are not shims, these are the seals which are made of steel with the rubber attached to it. The shims would sit inside these.
 
Yeah, Speed and Sport sells them although they only show 1 in stock. #4 in the pic below. If my swingarm assembly fits tight in the frame with no sideplay do I need them?

swingarm-1.gif
 
that outer shaft should only be longer than the brass bushings by a couple of thousandths of an inch. I would have to crack the manual for the exact spec.
 
The grease seal fits against the pivot tube, the shims would fit around the pivot tube and take up any excess space between the grease seal and bushing. There might be a shim in that old seal. Clean the inside real good and see if there's a thin separate washer (shim) that will lift out. The shims and the grease seals are separate parts. As Gary mentioned, I don't think Mike's sells the shims. As I said, they weren't needed very often. Even if you found some present, after you install new brass bushings, they may not be needed any more. It would all depend on how long your pivot tube ended up being in relation to the swingarm/bushing assembly. In your current situation, you don't want or need shims, just the opposite in fact. You need to create more space between the grease seal and bushing. Thinner lips on the bushings, removing the powder coat, or a slightly longer pivot tube are what you need.
 
The grease seal fits against the pivot tube, the shims would fit around the pivot tube and take up any excess space between the grease seal and bushing. There might be a shim in that old seal. Clean the inside real good and see if there's a thin separate washer (shim) that will lift out. The shims and the grease seals are separate parts. As Gary mentioned, I don't think Mike's sells the shims. As I said, they weren't needed very often. Even if you found some present, after you install new brass bushings, they may not be needed any more. It would all depend on how long your pivot tube ended up being in relation to the swingarm/bushing assembly. In your current situation, you don't want or need shims, just the opposite in fact. You need to create more space between the grease seal and bushing. Thinner lips on the bushings, removing the powder coat, or a slightly longer pivot tube are what you need.

:thumbsup:
 
These shims aren't made to adjust the fit of the swingarm into the frame, they're for adjusting the fit between the swingarm and grease seals on the pivot tube.
 
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