Shimano Deore XT HB-M785 retainer vs loose bearings



ThingBlob

New Member
Dec 25, 2013
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My question has to do with the way loose bearings look in an HB-M785 hub. That's the 2012* Deore XT front hub with the plastic bearing retainer (w/11 bearings) and a 14mm** hallow axle. The lock nuts are a nut/adapter (reducer) combo with a 5mm socket head.
I can almost fit 13 - 3/16 bearings in there, but they bind. If I put 12 in there (all new by the way), without the seal, and manually turn the axle, I can sometimes see a gap of almost one bearing diameter (minus the difference caused by the compound angle) in group***.

Is that ok, or, should I put the retainer back in?

The reason I ask is because the reducer part of the lock nuts no NOT seem centered. I recently sized up the loose balls and it seems that the original Shimano bearings are a tiny bit bigger. Perhaps that's the lot they came from?

Am I just being paranoid?

*I think it's 2012.
**I read somewhere that it's 14mm.
***I'm pretty sure I have the cones properly adjusted - a little drag with no rattling.

PS: I originally posted this in a not so appropriate place. When I copied it here, I removed one thing and added another.
 
IF the "plastic bearing retainer" to which you are referring is simply a carrier ring which holds the 11 bearings, then it is merely a convenience which was introduced to facilitate assembly ...

carriers are typically not used for hubs, but I haven't dis-assembled a Shimano through axle hub ...

but, why not use carriers for hub assemblies?!?

FYI. The carrier rings are not found on bikes before ~1980 +/- ...

again, it is a convenience for assembly and/or dis-assembly ...

but, if the "plastic bearing retainer" is some type of shroud to keep water/mud/dirt out, then you need it.

So, you should be "okay" with the 12 loose bearings sans "retainer."
 
As Alf stated, 12 loose balls should be good to go. Make sure you are not just adding one more ball from a different/new bag of bearings. Add twelve new balls all from the same production bag or container.
 
Thank you for your input.

This is the first time I've seen this kind of configuration. This is also first set of hubs I've ever seen with 3/16 bearings in the rear hub too. And they appear to both have the same diameter hollow axle.

I probably shouldn't be so paranoid, since the cones are quite large, and are not likely to fall into a gap with 12 bearings.

Thanks again.
 
Thank you for you input.

And yes I did. So ALL of the new bearings are about 5 10,000ths of an inch smaller than the original Shimano.

Thanks again.
 
5 tenths makes a difference! I take it that you own and know how to use a micrometer...uncommon trait these days. 99.9% of the people on the planet could not figure out that half a thou in a bearing is big enough to park a semi in! Hat's off to you, OP! Good call.