Musings on dragging rear wheel bearings.

[Its been a long time]

I have pulled the rear wheel assembly from my 650 again this morning to investigate the apparent bearing preload issue I mentioned yesterday in this thread.

https://www.xs650.com/threads/what-have-you-done-to-your-xs-today.32082/post-855842

First thing I noticed this morning is that the flange that acts as a dust shield on the outer sprocket side spacer was fitted incorrectly. The issue can be clearly seen in the picture below. I fixed it by taking a 32mm socket, fitting it over the spacer and gently tapping the flange straight with a 0.5lb hammer. This isn't the problem I was looking for but it's a good one to find and fix. I must pay more attention in future

 

[Its been a long time]

The good news is that I then found what I expected. In the picture below you can see the inner spacer that fits inside the inner bearing race. If you look at the tip of the scriber, above the scriber is the bearing race. Under the scriber is the inner spacer, it's surface is below the surface of the bearing. It shouldn't be like that. The spacer should be flush or slightly above the bearing race surface. What's happened here is that (most likely) the centre spacer over the years has deformed and is now shorter than it should be. That means (see the witness marking on the outer spacer) that the outer spacer when tightened is pressing on the inner bearing race and not touching the inner spacer like it should be. Result is bearing preload. Clearly, judging by the witness marking on the outer spacer inside face it has been like this for a considerable time. Picture -

 

[Its been a long time]

For completeness, I have checked the brake side bearing and spacer. The brake plate correctly bears on the end of the central bearing spacer. As a double check I put a piece of all thread through the assembly. Tightening the all thread causes the same effect as when the wheel assembly is installed and tightened.

Taken the sprocket off to clean everything properly before reassembly. Now I have to do a sketch and go across to a friendly machine shop to sort out the bearing preload. That's hopefully tomorrow. Unfortunately none of the parts I want are available from Yamaha.

 

[jaybar6]

For completeness, I have checked the brake side bearing and spacer. The brake plate correctly bears on the end of the central bearing spacer. As a double check I put a piece of all thread through the assembly. Tightening the all thread causes the same effect as when the wheel assembly is installed and tightened.

Taken the sprocket off to clean everything properly before reassembly. Now I have to do a sketch and go across to a friendly machine shop to sort out the bearing preload. That's hopefully tomorrow. Unfortunately none of the parts I want are available from Yamaha.

What about collar 19, that would separate the bearing from the load up? It would also be easier to make than the bearing separator.

 

[Bob Wegman]

You may want to make sure the bearing outer race is fully seated in the hub. If over time the axle had developed a little rust and when it was removed the friction between the axle and the inner race could have unseated the bearing outer race. Just a thought.

 

[Its been a long time]

What about collar 19, that would separate the bearing from the load up? It would also be easier to make than the bearing separator.

OK, that item, I referred to it as the inner spacer which is really what it is. On the picture of the bearing and the scriber above, you're seeing the outer face of item 19 inside the bearing inner race. That's what should be flush with or slightly proud of the bearing race. So that when you tighten everything up there's no pressure acting on the race itself. You want the load from the nut tightening to be carried on the spacers, not sideways on the bearings. Any side loading on the deep groove ball bearings will lead to reduced life and possibly unexpected bearing collapse. I have seen it happen on other bikes.

 

[Its been a long time]

You may want to make sure the bearing outer race is fully seated in the hub. If over time the axle had developed a little rust and when it was removed the friction between the axle and the inner race could have unseated the bearing outer race. Just a thought.

And that is a very good thought too. I checked that the centre spacer is lightly trapped between the two bearings. If one of the two bearings wasn't seated fully, the centre spacer would probably be rattling loose in there.

 

[jaybar6]

i get it, the photograph was deceiving, I thought one was looking in from the sprocket side at the bearing separator , but one is looking out at the collar 19.

 

[jaybar6]

i get it, the photograph was deceiving, I thought one was looking in from the sprocket side at the bearing separator , but one is looking out at the collar 19.

whoops, wrong again, I really get it now!

 

[Its been a long time]

whoops, wrong again, I really get it now!

 

[jaybar6]

Somebody has replaced the wheel bearing and the width is too wide! the bearing spacer and the bearing inner race should be flush, so the load is shared. it looks like a difference of 3mm.

 

[Its been a long time]

Close out here. The left side spacer I made which bears on the inner spacer within the drive side bearing inner race and doesn't preload the bearings is a complete success. I got the spacer made back in September but I've only just now installed the rear wheel and checked the rotation for drag. Spindle nut loose or fully tightened, makes no difference. Sadly, I forgot to take a picture of the spacer before I installed it. But it's the one here. I refitted the original press on shroud to the new spacer.

 

[arcticXS]

Did you ever check the following:
Are the outer races on both bearings fully seated in the hub? (most often this would require removing the bearings to check)
Are the correct bearings used?
(See earlier post regarding bearing width)

 

[Its been a long time]

Did you ever check the following:
Are the outer races on both bearings fully seated in the hub? (most often this would require removing the bearings to check)
Are the correct bearings used?
(See earlier post regarding bearing width)

I did yes, thanks. For reasons I'm not 100% sure why, the centre spacer comes up a bit short. As seen in pictures above. On other bikes I've seen this it is due to overtightening the spindle nut and crushing the spacer. The 650 centre spacer is very robust. So I'm not absolutely sure why the assembly is how it is. But the new spacer I made to engage on the centre spacer and not the inner bearing race has fixed it. No more dragging bearings when the spindle is tightened.

 

[arcticXS]

Is your new outer spacer ONLY touching the inner spacer?

 

[Its been a long time]

Is your new outer spacer ONLY touching the inner spacer?

Correct. Small gap between main diameter of the spacer and the side of the inner bearing race. So the bearing cannot move itself out from it's position.

Apologies for not taking a picture. But I think you understand OK.