jur

My one (old) bike's rear hub feels gritty as it turns; it says something like "sealed mechanism" on the hub; is it possible to open these and replace the ball bearings? Sure gonna be a lot cheaper than to buy a new hub and get LBS to build the wheel.

mtbikerinpa

For the purposes of this post I will attempt to define the terms used for hubs, since it is not often clear.

Sealed Mechanism generically is used for a majority of Shimano-parralax style hubs that use conventional ball-and-cone bearings that are merely covered with a boot or a contact seal. These are servicable in exactly the same manner as thier "unsealed" relatives.

Sealed Cartridge is when each bearing is a cartridge assembly with balls and races sealed with tight tolerance lip seals. These are far lower maintenance and in my view simpler to work on(not all share this view). They are usually press-fit, and the cartridges themselves are not adjustible to any large extent. This means an out of tolerance condition requires replacement of the cartridges. Not expensive if you go to a commercial bearing supplier(sample in hand).

To identify which you have:
Check the cone(stationary) part of the hub. If it is soft or movable, move it off to expose the bearing. The Parralax ball-cone will be visible as a normal looking bearing set. If it slides off to reveal a flat face, that is a cartridge.

Regardless of the type, both are servicable.

sydney

Well actually, shimano and other brand 'sealed' hubs cover alot more territory than the specific paralax type with the rubber booties. Even Shimanos supposedly unsealed relatives as you incorrectly put it have seals ranging from very good to barely adequate.

mtbikerinpa

Parralax style. Generalization, not specific model. I have yet to see a 'sealed mech' hub that is not sealed cartridge that is anything more than barely adequate at keeping the junk out. But this is beside the point of this thread.

sydney

You need to look beyond the MTB cr@p.

Eros

sydney, does someone piss in your wheaties every morning?

KrisPistofferson

mtbikerinpa, you look EXACTLY like that girl from "Smallville".

sydney

Actually,probably BS.

sydney

Actually, the simple answer is .....yes.

sydney

This is just nonsense and confusing to the poster. You are talking about a specific shiamno Paralax hub. His reference to 'sealed mechanism' could just as well apply to an older hub that has nothng but a metal shield with a lip to keep rocks and big scorpions out.There ae aloso other types so marked with the metal cover and rubber seasl inside.Even on a paralax hub,moving the rubber bootie out of the way does not expose the bearing.It only allows access to the locknut and adjusting cone,which have to be removed to get to the loose servicable bearings.

roadbuzz

"Gritty" feeling can come from incorrectly adjusted hubs, usually too tight.