Swing arm Pivot tube

[David Toll]

Good morning Ladies and Gentlemen
Am working through a basic restoration of my '78 SE and have arrived at the brass bushing replacement part. Whipped the swing arm off only to find that the PO has already done the job - not surprising as there was little side movement in the arm, but I had to look. After several self-congratulatory high fives and a prayer for the continued good health of the previous owner, I adjourned to my deck with a cold beer and computer and searched this wonderful forum for details on this replacement, to make sure that everything was done right and that the arm would stay in place at the less than excessive speeds I expect to demand of my motorcycle.
After reading a number of expert opinions, I have developed a concern. My pivot tube does not extend beyond the end of my bushes - they sit flush.
XS Leo posted this response to an inquiry.
"The tube #2 has to be just a bit longer than the swing arm so the tube #2 gets locked into the frame and the swing arm and bushes pivot around the tube #2."
Leo, are you referring to the swing arm body itself or the swing arm with bushes in place? Does this mean that the bushes have not been pressed into the swing arm sufficiently? There does not appear to be a gap between the bush and the arm. Do I need to pull the whole thing apart and try again? Should I remove the pivot tube and attempt to press the bushings further in? Can I ride it as it is without making my wife a widow? Was I too hasty in being happy??
All advice sincerely appreciated

 

[Michaelo]

Gidday fellow Aussie, flush is good, gap is not good you will need to shim it, what are the seals like?

What's the condition like, was it "wet with grease" ?

Have a look at this thread, 5 twins nails the mod in this thread, my swing arm parts, bushes, shims, pivot bolt, tube, and seals are on their way from Hieden Tuning (Geoff didn't have a new bolt so I ordered everything from Heiden Tuning) and my plan is to do his mod.....

http://www.xs650.com/threads/rear-swingarm-pivot.2887/

Cheers Mick

 

[figure8]

The pivot tube shouldn't stick past the bushings. I can't tell in your pic but if there is a gap by all means get them pressed all the way in. While you got it all apart get everything greased up good. If your feeling really ambitious drill a small hole, tap it and add a grease zerk the pivot tube shaft. 5twins has some good detailed pics of what I mean. Maybe he'll pop up soon.

 

[David Toll]

Hey Mick. Good to hear from a fellow enthusiast from the Land of Leisure, particularly a swinging spot like Airlie.
When you say "gap", are you referring to the gap between the end of the seal/pivot set up and the frame? When I pulled it to pieces, it was a fairly tight fit. Would you still recommend shims under the seals?
Through bolt was well greased but I will replace the seals as one was a bit chewed. Waiting for delivery is the worst part, I find I start something else and lose the train on my original job. Oh well, I suppose patience is a virtue.
Will check out the attached site and see what it has to offer.
Cheers Mate

 

[David Toll]

The pivot tube shouldn't stick past the bushings. I can't tell in your pic but if there is a gap by all means get them pressed all the way in. While you got it all apart get everything greased up good. If your feeling really ambitious drill a small hole, tap it and add a grease zerk the pivot tube shaft. 5twins has some good detailed pics of what I mean. Maybe he'll pop up soon.

Thanks 8. I love to hear what I want to hear. Yes I have seen 5twins grease nipple mod and am considering if I can fit the thing without interfering with the pivot shaft.
Cheers

 

[grizld1]

OP, you might want to hear it, but it's incorrect. If the tube does not extend past the bushings you will lock the swing arm in place when the the swing arm axle is torqued down. In the design used on the XS650, the tube locks against the thrust plates (grease seals) leaving the swing arm and bushings free to rotate around the tube. This is only possible if there is clearance between the bushings and the thrust plates, and that clearance can only be achieved if the tube ("inner bushing" in Yamaha's terminology) extends a bit past the flanges of the outer bushings. If the axle is undertorqued to allow the swing arm to move, excessive flex will occur at the swing arm pivots. There are plenty of posts detailing procedures for correcting clearance. Search and you will find.

 

[littlebill31]

As I just delt with this, and took the knowledge of Grizld and others, the aftermarket bushings usually need to be altered. I had to remove some material from the swingarm (which is soft, but needs to be done before bushing installation) and the bushings themselves to get enough tube protrusion.

 

[grizld1]

Bill, if you have a blind hole bearing puller, it's easy to remove the bushings and do the needful to the swingarm.

 

[littlebill31]

Thanks. I didnt have one and was extemely close anyway, so I just filed the bushing down a hair. I think I had .5mm on each end. 45 ft/lb got the swingarm to hold itself up and slowly, ever so slowly, drop.

 

[David Toll]

Ok, I have two for the tube sticking out past the bushings and two against it. I have done a bit of a search as grizld1 suggested but the consensus appears to be roughly the same. Without appearing to cast dispersions on anyone's opinion, I find myself somewhat confused.
If I were to adopt grizld1's recommendation, could I simply remove material from the outside of the bushing to give me the .0004" required exposure?

 

[650Skull]

Exactly the information stated and some very good pics of how it should be.

http://www.xs650.com/threads/swingarm-question.7607/

Read the whole thread ................Probably the best thread on this on the whole site.....

 

[littlebill31]

And then you have aftermarket pivot tubes that are even shorter than the originals. This causes even more headaches.

 

[weekendrider]

To add to your state, some brass bushing flanges were made too thick, some too thin. It depended on the maker. So are your flanges thick or thin?

 

[650Skull]

Poat #31 in the link has pics of the bushings and the measurement of the flange on the correct sized ones and one a set of wrong ones

 

[David Toll]

You're right Skull, an excellent and detailed thread. Let me see if I have this right. My pivot tube sits flush with the outside of the bushing so I remove a couple of thou. from the face of each bushing. I then buy shims which I put in place to take up the gap I've created between the face of the bushing,(swing arm), and the grease seal!?? Why did I bother to take material off the bushing in the first place? Am I being blonde? Do I risk ostracism for compounded stupidity??

 

[Michaelo]

Exactly the information stated and some very good pics of how it should be.

http://www.xs650.com/threads/swingarm-question.7607/

Read the whole thread ................Probably the best thread on this on the whole site.....

That's the best description in 7607, Gaz is correct, you need the shims, thanks Skull for posting that up, it's "the ducks nuts"

 

[David Toll]

To add to your state, some brass bushing flanges were made too thick, some too thin. It depended on the maker. So are your flanges thick or thin?

Weekendrider, my flanges appear thin. (Perhaps I should reword that?). I don't have a micrometer but they appear to be just over the 2mm mark on my steel draftsman's rule. Well within the 2.66mm shown in pregrid's post.

 

[650Skull]

5Twins covers this in post #18. Seems the shim is there to take up excess play. If the tube is protruding enough for the grease seal, not to catch the swing arm, so it will pivot on the tube, it seems the spacer will not be needed.............Spacer = the amount of tube protruding.

If the spacer is only a couple of though each side and they weren't used, because the tube was that much shorter, i would think, there was enough flex in the frame in that area, to tighten everything up as per normal without any adverse affects

 

[David Toll]

OK Skull. I will attack the bushing face with a file and remove enough face for the tube to protrude. I will use post #7 on the thread you sent me as a guide. My thanks and sincere appreciation to all.

 

[grizld1]

David, go to www.biker.net for a free download of the factory manual with torque specs. You want the swing arm to be free enough to fall under its own weight or with just a slight nudge. Shims will defeat the purpose of establishing clearance for the outer bushing (tube); there has to be a small amount of side play for the swing arm to work freely. If you put in shims to "close the gap," you'll only wind up taking them out when the swing arm locks up.

A 12" caliper is a big help on this job.