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Discussion Starter #1
Hi,

I just pulled off my blower today and I always go over things now in case something needs work before we get to play in the snow again.

On the drive mechanism (it hangs below the seat), there is a shaft that has two bearings and a rather large pulley on the top and a smaller pulley on the bottom.

Today I noticed some movement in the bearings. It is visible and I'd say you can move the outside of the large pulley maybe 1/16" inch parallel to the shaft axis.

Is this a concern? I don't hear any grinding and no evidence of grease leakage. The part is GXH47901. Are these a standard bearing of the infamous extended race?

I have some tools to replace the bearings but I need help determining if its even needed.

Thanks

Mark
 

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Mark, Lateral movement (parallel to the shaft) of a bearing usually means the bearing is shot, a spacer has worn (excessively !) or a locknut has loosened. Dismantle & inspect shaft for wear from bearing possibly moving on shaft. Check bearing movement between inner race & outer race...should be about .001 max. Do some inspecting and get back, Bob
 

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Discussion Starter #3
I got this apart far enough to make some educated guesses.

Bolts were all tight. I had to get a bearing separator on the small pulley to dislodge it after getting hit with some PB Blaster for a few hours.

Once part I found the bearings seem tight and smooth and it feels like good grease. No slop.

I did notice a little wear on the shaft where the inner race of the bearings sit. The unworn part of the shaft mics up at about .783 but more like .780 at the bearings. I would assume this should be is a slip or interference fit. Why the shaft is wearing or even moving in relation ship to the bearing is not known. The bearings are a standard 6204RS and they have a 20mm ID. When I look up the shaft part # ($70 bucks) it specs an OD of .787. That would be about right for the 20mm bearing. My shaft is 3 to 4 thou short of getting to .787.

I wonder if this shaft was just small to begin with and always was a little sloppy. It'll more than likely cost $70 t find out.

I think I'll Just let this one go and when it gets real bad just replace it then.

Any thoughts? Some bearing mount like Loctite 609? That would lock the shaft to the bearing. I've not had experience with this stuff. I do use some thread lock sometimes. Would that work?
 

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Discussion Starter #4
No here's something interesting.

I gave this a little thought about why and how the shaft wore at the inner race of the bearings. I noticed previously that the spacers in the "stack" were loose on the shaft. Then I thought about how the shaft could be held to the bearing so that there was not play.

After examining closer, I realized that the bolts that hold the pulley on the shaft was bottoming out on the shaft before the pulley was tightened. In other words the pulleys were not tight to the shaft. All the spacers were free to rotate and every thing just moved and was sloppy.

The one assumption I made was that this was designed to be a tight assembly.

Pulley/spacer/bearing/spacer/bearing/spacer/ pulley (I call it the stack) was meant to be solid and all would ultimately "bear" on the bearing inner race. In the ideal sceanrio the only movement would be between the inner/outer race of the bearing. Nice!

So with that in mind I measured the spacers. Bingo! The one spacer specs at .650 and measures the same. The other spacer mics at .227. The spec on that one is .50. I don't see any unusual wear on the spacers so I'm thinking one spacer is the wrong one since it was built.

I could get a new spacer but I could also find a washer to add a little to the depth of the stack (I wouldn't need much. I could also add a large washer on the outside of a pulley hat would accomplish the same thing. I don't have a large enough steel (7/8" ID) washer but I did find a fiber washer that would work. I tried that and sinched everything up and it felt great. No more slop and when I spun the assembly I felt just the smooth workings of a wall greased bearing.

When this health think passes and the hardware store reopens I'll get a washer and reassemble it.

I doubt this ever worked as designed.

Am I OK in my thinking. Its hard to argue with success.
 

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Your line of thinking is correct...you get an A++ !!

Keep your numbers handy, .50 length and 7/8" ID. If you know someone with a lathe, I think a piece of 3/4" pipe will work...faced to the correct length. Maybe a local school has a machine shop that can do it too ! What you've got now will work, but you'll be better off with correct parts. Also, with me not knowing where the wrong spacer is in the stack, check alignments. You're 1/4" short and possibly 1/4" out of alignment with ???
Again, good job! Bob
 

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Discussion Starter #6
Thanks Bob,
a .50 spacer would give me around 1/8" more room on either side to tighten the stack down. As I stated it might be easier to just put a spacer on the outside of the pulley which would require a 7/8" ID as well. If I had the thickness of a washer it would be more than enough to fix this and cheaper. The wrong spacer is at the top, under the large pulley. In the big scheme I doubt changing things that much since this is a belt drive system and very tolerant of things that are out of allignment a little. Gears would be another matter. I may still get a proper spacer. It is part GXH46754.

Mark
 
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