https://www.hdforums.com/forum/touri...le-solved.html

 

That's what prompted these questions/concerns I have now
I ordered the new bearings and to my discovery the bearings ID were not .750 dia. Or the shaft being 25mm dia.
Two totally different dimensions.
So now the question comes up as to why they are different?
if the bearings are not used to support the shaft what purpose do they starve other then an additional $50 cost to us...they searve no purpose at all if they do not ride on the shaft...
The only thing riding on the shaft that support the swing arm are the aluminum hat bushings and the trans. Journal...there are 2 each on each side of the journal you have a inner and outer which sandwich the bearing...
This my be alright having the swing arm shaft coming into contact with no more then the aluminum bushings but the big question is why the bearing...no need for the bearing...
Paul

 

The bearings don't support the shaft, the shaft supports the bearings. The bearings are in the swing arm. The swing arm rotates around the shaft. The ID of the bearings inner race is substantially larger than the shaft. There is a bushing that fills that gap. It's part number 48498-02. It's tight to the bearing, and a little sloppy on the shaft.

If you were to follow things out from the shaft you'd go shaft, bushing, bearing inner race, bearing *****, bearing outer race, swing arm.

 

Paul,
The bearing is supposed offer a precision pivot for the swingarm, but the sum of all tolerances of all associated components makes for a loose situation. You're right the bearings aren't doing anything if they're that loose, A solid chunk of material would do the same job. Don't forget to check for slop where the axle goes through the back of the transmission.

 

You might be able to make a few bucks or such by marking a new bushing Fabrik8r. Here's what I've found measuring my bike.

Bearing ID is 0.985.

Bushing OD is 0.095.
Bushing ID is 0.758.

Shaft OD is 0.748

The problem is that 0.010 difference between the shaft diameter and the bushing inside diameter.

The way the bushing is chamfered, I'd almost swear it's a drill bushing. But the flange is larger than any drill bushing I've seen or found. Odd size flange. 0.275 thickness by 1.374 diameter.

The oem new bushing is machined on the OD where it presses tightly into the bearing, and on the small end face. But everything else looks like standard powder metal casting.

 

I'll investigate mine when I have it apart but I won't pursue this issue for profit.

 

OK. There is a misunderstanding of how the swingarm shaft and the related components work.

The shaft actually is only there to basically support the items that center on it. All of those items are in compression of the two nuts which are torqued down. There is the transmission, spacers, the (offending) spherical bearing, more spacers, and the rubber mounts. All of these components are clamped together in tension. The center of the spherical bushing does not "ride" or move around the swingarm shaft, just as any of the other bushings or transmission doesn't "rattle" around. They are all clamped together in tension. The reason for the Spherical bearing is that the outer portion is the only alignment devise for the forward part of the swingarm. The outer portion of the spherical bearing keeps the forward portion of the swingarm from moving from side to side. The inner portion of the bearing does not move or pivot around the shaft. It is stationary and rigidly clamped.

Some of you will get this. Others I guess just won't.

 

Yep. That is essentially how it is supposed to work. Mine has not been working that way. The bearings were effectively frozen, and the bushings were rotating around the shaft instead. The sides of my transmission case are well polished from the rotation of the inner bushing.

Regardless of that rotational motion, the gap between the shaft and the inner bushing (new or old), let's the swing arm be pulled fore and aft, as well up and down, and a little cocking when I'd pull the rear wheel side to side. That side to side motion, with the metallic "think" was what got my attention. That's the easy one to detect.

With the rear wheel off, I could clearly observe the radial motion against the transmission case when cocking the swingarm side to side, as well observe the bushings rotating with the swingarm against the transmission case. The shaft was not moving at either end in the rubber blocks as I would **** the swingarm side to side. There was no axial play of the swingarm along the length of the shaft.

Removal and disassembly of the swingarm revealed the effectively frozen swingarm bearings, and the excessive clearance between the inner bushings and the swingarm shaft.

A closer examination of the components also revealed that while the bearings are properly spaced apart for fitment of the transmission, they are offset to the left sufficiently to create inadequate clearance between the outer bushing and the rubber block on the right hand side. This has been causing the swingarm to ride tightly against it on that side, creating a moderately tight drag on swingarm motion. This can be easily rectified with a bit of shim stock to space the rubber block out slightly from the swingarm. Only a few thousandths are needed. Alternatively, I could check and even reset the bearings if I had the harley insert tools. However, I suspect that the bearings are properly placed in the swingarm. The belt is riding well on the pulleys, and the bearings are sitting identically in relation to the set marks in the swingarm.

To address the play allowed in the swingarm by the excessive clearance harley has apparently specified with the inner bushings, I'm going to either have to make my own inner bushings, or use essentially a speediesleeve on each side. A single long speediesleeve or thicker shaft will not work as the transmission case bore is slightly tighter than the bushing bores. I do not care to drill out the transmission case to fit a larger diameter shaft.

 

It's been awhile when I was last digging into this. I am building a FXR that utilizes modern twin cam touring drivetrain. As I remember it the pivot shaft itself has tapered ends that limit the outer spacer clamping. A shim between the outer spacer and the bearing/ spacer could provide that tension. As you said I don't think it would take much.

Good luck with this and we all want to know what you will come up with.