Yet Another Swingarm Bushing Thread

[YamadudeXS650C]

Note: I compiled the essential information from this thread into a newer thread, here:
http://www.xs650.com/threads/installing-bronze-swingarm-bushings-and-setting-sideplay.51077/

So, there have been numerous threads with this topic, but I thought it might be worthwhile to report on a bushing dimensional examination I did today while installing a set of Mikes' bronze bushings in my '80. When I did the same a few years ago on the '76, it was a difficult installation, and I had to do some machining of the ID and OD to get a fitment, so today I was curious about the product currently being sold.

The existing nylon bushes were quite stuck in there, but the recommended hacksaw cuts and heating with a torch (enough to boil the grease, but not enough to burn the paint) did the trick.

The proper dimensions of this bushing are:

Length 40mm
ID 22mm
OD 28mm
Collar thickness 2.6mm
Collar OD 34mm

Using a new, calibrated Fowler, I got these measures at 65 degrees F:

Bushing One:
Length 40.06 mm
ID 22.03 mm
OD 28.04 mm
Collar thickness 2.50 mm
Collar OD 34.07 mm

Bushing Two:
Length 40.03 mm
ID 22.05 mm
OD 28.05 mm
Collar thickness 2.60 mm
Collar OD 34.10 mm

I noted the largest variation in bold.

The OD increased on both bushes by .02 just in front of the collar.

After 24 hours in the freezer, the OD was reduced by .04 mm.

Reheating the arm with a torch,

I quickly assembled the bushings and recommended all-thread tool, and began cranking. They went in quite smoothly.

However, for the final 1/2" of bushing, the torque required increased dramatically, as the arm cooled and the bush warmed. Next time I do this (the '75 is up next) I'll press just one at a time.

The pivot tube fits well (whew!).

Lining up the tube and the bushing at one end,

....a measurement can be easily made at the other end with a feeler gauge. My sideplay measure came out within spec. No shims needed.

.
.

 

[5twins]

I'm going to hit you up again with the grease fitting line, only in this case, I feel it's required when installing the bronze bushings. If you look inside them, you'll find swirled grease grooves running from the front to back or rear. These bushings are designed to receive their grease supply from the rear .....

Now take a look at your original plastic ones. They have one grease groove running around the I.D. parallel to the top and bottom, about halfway into the bushing. They are designed to receive their grease supply from the side, and that's how the stock grease nipples on the ends of the pivot shaft are designed to deliver it. If you examine the pivot tube, you'll see holes about 1" in from each end (blue lines). They feed grease into the sides of the stock bushings. To get grease into the center of the swingarm from where it would eventually be forced into the backs of the new bushings, some additional holes would be required in the pivot tube (red arrows) .....

So, adding a couple additional holes at the center of the pivot tube will help get grease to the rears of the new bushings, but adding an additional grease fitting to the bottom, center of the swingarm works best. To assure adequate thickness for the fitting, put it at the edge of, but through the gusset plate .....

I use a 45° angled fitting and face it to the rear. I also implement both these mods when installing the bronze bushings now.

And here's a little tip for installing the extra grease fitting. Drilling and tapping the swingarm is going to fill the inside with metal chips. They can be difficult to clean out because there is often grease in there. Save the tube from a roll of paper towels. Slit it length-wise and roll it tighter so it will slip through the swingarm. About halfway down it's length, cut a V notch in each slit edge. You want to make them deep enough so that when the tube is rolled tight to fit in the arm, you'll get about a 1/4" to 1/2" diamond shaped hole halfway down the tube. Position that in the swingarm right under where you're about to drill and tap. All the metal chips you're about to generate, or at least most of them, will now fall into the cardboard tube and can be easily dumped out the end.

 

[YamadudeXS650C]

I like it !
Your timing on this is perfect, as I decided to put off the installation of the swingarm until tomorrow. I think I've got the appropriate grease fitting.
Thanks 5T.
.

 

[MaxPete]

This is terrific info Dude and 5Twins - many thanks!

Pete

 

[59Tebo]

Excellent write-up (and pictures, as usual, 'Dude) and tips, guys! Merry Christmas to all!

 

[YamadudeXS650C]

Excellent write-up (and pictures, as usual, 'Dude) and tips, guys! Merry Christmas to all!

Thanks Tebo, and Merry Christmas to you, too !

 

[Mailman]

Terrific write up Dude and great photos. I have the parts for this job just waiting to be done so this is very timely for me, I shall use this for a reference.
A couple of questions , when you were measuring clearance with your feeler guages, what amount of clearance are you looking for?
And you determined that you are not going to require any shims correct?
It’s the whole shim, no shim , what size shim, thing that has put me off about starting this particular job.

 

[fredintoon]

Hi 'dude,
that's just about how I did mine a decade or more back.
Except that Mr. Bodger got the bushings a tad out of alignment and had to go rent a 22mm adjustable hand reamer to make the bearing tube fit.
But the bushing replacement don't fix the bad design that relies on the throughbolt tension keeping the bearing sleeve locked from rotating.
Which it don't, more often than not which puts the actual bearing between the sleeve bore and the throughbolt OD to give the bike that all too familiar twiitchy cornering.
What I'd do these days is replace the bearing sleeve with a solid bar locked in place with an M16 Allen bolt each side.

 

[YamadudeXS650C]

Terrific write up Dude and great photos. I have the parts for this job just waiting to be done so this is very timely for me, I shall use this for a reference.
A couple of questions , when you were measuring clearance with your feeler guages, what amount of clearance are you looking for?
And you determined that you are not going to require any shims correct?
It’s the whole shim, no shim , what size shim, thing that has put me off about starting this particular job.

Thanks Bob,
I was measuring sideplay. That is, the distance the pivot tube emerges past the collar of the bushing when you set it up on the bench as I did in the photos. This distance becomes your sideplay. It should be .006" to .020". If it is larger than .020, then you need to use a shim. [see correction below]

To quote 5T,:
"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."

 

[YamadudeXS650C]

Bob,
This photo by Pregrid shows what you are measuring, altho a bit exaggerated.

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

 

[YamadudeXS650C]

"But the bushing replacement don't fix the bad design that relies on the throughbolt tension keeping the bearing sleeve locked from rotating."

Fred,
If you have the correct sideplay set up, the tension will be on the pivot tube, not the bearings, so there will be no forces at play to move them from their places in the swingarm.

 

[Mailman]

Thanks Dude! That was the info I was looking for!

 

[YamadudeXS650C]

Correction:

Altho other members have indicated a max sideplay of .020, and some have indicated .040,
5T posted this Yamaha bulletin which indicates the sideplay should be .005"

http://www.xs650.com/forum/showpost.php?p=342467&postcount=4

My sideplay came out to .006"
I will not lose sleep tonight.

 

[YamadudeXS650C]

Just now found a notation of sideplay ("swingarm side free play") being .040" in my Yamaha XS 650SJ Service Manual.
Hmmmm....
Discussion ?

 

[Mailman]

Ha! Well that seems a more reasonable allowance!

 

[5twins]

The manuals are rather vague on this. I was wondering where you got that first set of values you posted (.006"-.020"). All I've seen in the manuals is the .040" (1mm) spec .....

And they're not real clear on where to be checking for it. I would assume they mean at the pivot. I'm sure you could flex the ends of the arms even with good bushings.

If you measured .006" at one end with your new bushings, that means .003" at each end. Hopefully that's enough. When installing the swingarm, I would use the pivot bolt torque range given in the '77 torque spec chart (36-58 ft/lbs), not the single value given in some of the other years manuals (something like 47 ft/lbs). When you install one of these, the usual procedure is to torque the pivot bolt until it is in the specified range and so that the arm very slowly falls under it's own weight. That may not happen exactly at 47 ft/lbs (probably won't). It will probably require a bit more or less than that. If it stays loose above the max torque spec, you've got too much play. If it binds up completely before you even reach the minimum spec, you don't have enough play.

 

[fredintoon]

"But the bushing replacement don't fix the bad design that relies on the throughbolt tension keeping the bearing sleeve locked from rotating."
Fred,
If you have the correct sideplay set up, the tension will be on the pivot tube, not the bearings, so there will be no forces at play to move them from their places in the swingarm.

Hi 'dude,
you are absolutely correct, that's the way it should work. Alas that it ain't that way in practice.
What usually happens is that the throughbolt stretches in use and loses it's grip on the sleeve
so the sleeve is free to rotate with the swingarm. And because the sleeve to swingarm bearings' fit is far
tighter than the sleeve bore to throughbolt's fit the sleeve will rotate with the swingarm if it's free to do so.
My proposed switch from stock to a solid bar tapped M16 each end and retained by M16 capscrews each side
that are reefed up REAL tight will work far better.

 

[YamadudeXS650C]

I was wondering where you got that first set of values you posted (.006"-.020")

Thanks for the additional info, 5T; it is helpful.
I found the .006"-.020" in my personal notations, of which I have many, and I can't seem to find the original source at the moment.

I think I'll shave (file) a bit off the bushing to get to .008.

Since the manual info you just posted is an inspection procedure, it would make sense that the .040 is a max limit after some wear had occurred. A wear limit, that is.

 

[YamadudeXS650C]

The manuals are rather vague on this. I was wondering where you got that first set of values you posted (.006"-.020"). All I've seen in the manuals is the .040" (1mm) spec .....

And they're not real clear on where to be checking for it. I would assume they mean at the pivot. I'm sure you could flex the ends of the arms even with good bushings.

If you measured .006" at one end with your new bushings, that means .003" at each end. Hopefully that's enough. When installing the swingarm, I would use the pivot bolt torque range given in the '77 torque spec chart (36-58 ft/lbs), not the single value given in some of the other years manuals (something like 47 ft/lbs). When you install one of these, the usual procedure is to torque the pivot bolt until it is in the specified range and so that the arm very slowly falls under it's own weight. That may not happen exactly at 47 ft/lbs (probably won't). It will probably require a bit more or less than that. If it stays loose above the max torque spec, you've got too much play. If it binds up completely before you even reach the minimum spec, you don't have enough play.

5T,

How do you account for, or make sense of, this Yamaha Bulletin that you posted previously, indicating a sideplay measure of .005?

http://www.xs650.com/forum/showpost.php?p=342467&postcount=4

 

[5twins]

Yes, I think the .040" is the max wear limit. I've never seen a minimum spec listed in any of the manuals for the original plastic/nylon bushings. Maybe it's not a factor? Maybe the collar will compress some if need be when the pivot bolt is torqued, so the pivot tube protrudes out past it and can get pinched between the frame mounts. Maybe the minimum spec thing is more for the bronze bushings.

That tech bulletin doesn't really give a min and max, just one spec, .005". I don't like dealing with single number specs, lol. I prefer to be given a range.