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Shimano XT hub: uneven bearing count?

Old 04-12-11, 12:42 AM
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Shimano XT hub: uneven bearing count?

I am hoping someone could verify or explain this.

While disassembling a Shimano XT rear hub (FH-M700) I noticed that the number of ball bearings on the drive and non-drive side are different. Is this supposed to be this way?

Also, the Shimano manual says that the total number of bearings to be a qty of 20. But I counted 13 for the drive side and 11 for the non-drive side.

Thanks!
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Old 04-12-11, 04:47 AM
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I don't know about your specific hub, but I have in the past encountered hubs having different numbers and sizes of bearings on the two different sides.

If in doubt about the number of balls to put in a race, I'd go by what fits. Just be sure to get the diameter correct. Look at the balls that came out and check to see whether they are two different sizes.
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Old 04-12-11, 10:20 AM
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There was probably a bearing retainer in the NDS, which was replaced with loose balls during the last overhaul. To fill the space previously occupied by the retainer more balls are required.
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Old 04-12-11, 10:34 AM
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I dont think Shimano made a M700 XT hub.
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Old 04-12-11, 11:13 AM
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Originally Posted by ryker View Post
There was probably a bearing retainer in the NDS, which was replaced with loose balls during the last overhaul. To fill the space previously occupied by the retainer more balls are required.
If so, it would be the first Shimano hub with a retainer I've ever heard of.
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Old 04-12-11, 12:35 PM
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Originally Posted by hillrider View Post
if so, it would be the first shimano hub with a retainer i've ever heard of.
fh-m770

fh-m775
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Old 04-12-11, 02:56 PM
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Thank you all for the responses. The correct part number, as ryker astutely points out, is the FH-M770. I forgot to mention that this is a practically new hub with only 600kms on it. Yes, the NDS does have a bearing retainer. Not sure why they didn't put one on the drive side.

The number of ball bearings mentioned in the Shimano service page for the hub on their website and the actual the number of bearings in the hub hve a disparity. I was surprised by this, but I suppose it could be chalked up to a simple error.
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Old 04-12-11, 04:07 PM
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In fact there is an inconsistency between Shimano's breakout diagram for the FH-M770 and the description in the accompanying table. If you count the bearings in the diagram, you get 11 and 13. I don't think you have a problem at all.
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Old 04-12-11, 11:06 PM
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I just serviced this very same hub myself and found what you described. Unfortunately I bought new 1/4" balls from my LBS while this uses 3/16" balls. Oh well, I reused the existing.

Paul
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Old 04-13-11, 07:02 AM
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Originally Posted by paul2432 View Post
I just serviced this very same hub myself and found what you described. Unfortunately I bought new 1/4" balls from my LBS while this uses 3/16" balls. Oh well, I reused the existing.

Paul
If the old bearings were still shiny they are still good. A dull finish is an indication of wear.
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Old 04-13-11, 07:06 AM
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Originally Posted by ryker View Post
fh-m770

fh-m775
Thank you. Now I've heard of one. As you might guess, all my Shimano hubs are road models and, so far, they all have non-retainer bearings and symetrical ball counts.
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Old 04-13-11, 11:26 AM
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Is this the new model XT with the oversized aluminum axle?
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Old 04-13-11, 10:09 PM
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Originally Posted by ryker View Post
In fact there is an inconsistency between Shimano's breakout diagram for the FH-M770 and the description in the accompanying table. If you count the bearings in the diagram, you get 11 and 13. I don't think you have a problem at all.
Exactly! That's for the sanity check!
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Old 04-13-11, 10:11 PM
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Originally Posted by silver_ghost View Post
Is this the new model XT with the oversized aluminum axle?
Yep, it is the new XT model. I believe they went to the smaller 3/16" ball bearings from the 1/4" ones because of the over sized axle.
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