Bicycle Mechanics - Cassette "clunking", cogset wobbles slightly
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09-30-10, 01:11 AM
I have a problem with my shimano hyperglide cassette, its on a cheap Alexrims DA22 I believe. I noticed a problem when coasting, I felt a clunking in the pedals, then took the wheel off the bike and determined it was the cassette that clunks about twice per revolution. It also wobbles ever so slightly on the axle/hub. Is there a cheap (read: free) and easy solution to this or will I have to take it apart, buy lube/and or clean it?
That the sprockets wobble about a little is functionally a non-issue. They do their useful work when stationary to the hub so that's OK.
The clunking OTOH sounds ominous. Could be that the freehub body isn't torqued down correctly, but to fix that you need to pull the axle, for which you need cone wrenches.
Disassembling bodies is doable, but rarely performed.
09-30-10, 11:20 AM
It may also be that your freehub is just gunked up. It's seems more likely that it's broken but it's worth the time to try to clean it out.
Generally you don't pull them apart. I've done it and it's messy getting them back together. I had to make my own tool to do this as well. There is no tool for removing the bearing cup which holds the freehub together so you're on your own if you want to try disassembling it.
To flush it clean you'll need to remove the axle and bearings, remove the cassete and remove the freehub from the hub spool using a 10mm hex wrench held in a vise or using a pipe extension. With the freehub off the wheel dunk it into a tube of cleaning solvent and work it while submerged. Then lift and work the ratchet some more while it drains. Repeat multiple times until the gunk stops flushing out and the freehub feels cleaner. You may need to replace the solvent with fresh stuff if it's really bad. Wear nitrile solvent resistant gloves during all this as you really want to minimize your life time exposure to most solvents wherever practical. If it was just gunked up all this dipping and flushing should clean it up. If the freehub doesn't smoothen up then realistically it is time to just buy a new one or canabalize a good one from a used hub. If it came out good the way I like to lube them is with some thick oil or oil and grease mixed to a thick oil consistency. Thin this lube with a bit of the mineral spirit solvent and dunk the freehub in it. Work the freehub ratchet to aid the entry and spreading of the lube soup. Then lift it out and work it more to flush the excess. Set aside end down on a tray or paper towel to let the excess drain for a while. Install and you're done. You do not want to use pure grease for this lube because it will make the ratchets pawls sticky and prone to not always engaging on the first possible tooth. It needs to be just a thin film of a "thick oil" so that the lube stays in the shells without migrating all over the place but is light enough to allow snappy pawl action.
If you do try to make your own tool and take it apart do so over a tub as there's about a gazillion loose bearing balls in these things.
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