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Old 03-17-06, 08:51 AM   #1
TallRider
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freehub body not aligned correctly to hub - how much of a problem?

I've got a used Shimano 105SC rear hub with 8-speed freehub body, Uniglide- and Hyperglide-compatible (threaded on the outside and inside of freehub). Takes 9- and 10-speed cassettes too, of course. It had about 8,000 miles on it when the rim cracked, and I just built a new wheel with it. The bearings had been adjusted too tightly (so, it was properly tight when the Q/R was not tightened, got too tight when Q/R was tightened) and I had to replace one of the bearing cones. But the hub is in good shape, and just built it into a nice wheel to work with an 8-speed cassette and down-tube shifters that I had sitting around.

Now, with the bike in the stand, when I spin the wheel forward (so the freehub is clicking), I can notice the cassette weaving slightly side-to-side and up-and-down. Slightly. Probably 0.5mm to 1mm side to side, about the same up-and-down, when looking at the largest (23t) cog. What this means is that the freehub body is not in perfect alignment with the main hub body - it either screws in on a very slight angle, or it has gotten bent. My money is on the first explanation - just a slight manufacturing imperfection.
I've got a recent Ultegra rear hub on my good road bike now, and its freehub is in perfect alignment with the hub, judged this same way.

I've noticed this sort of thing with freewheels before, but there it doesn't indicate any real problem; it just means taht the freewheel threads on the hub aren't perfectly aligned, and so the freewheel is very slightly misaligned, but not enough to cause shifting problems.

On a freehub, since the drive-side bearing races on which the hub spins are in the freehub, it means that the drive-side bearing race isn't perfectly aligned with the non-drive-side bearing race. This may have been part of the problem with the cone wearing out after 8,000 miles, too.

I don't think it's a big problem, but wanted to fish around and see what people around here think. Have you seen this sort of thing before? How common is it? Does it generally point toward bearings wearing out? (The bearing races themselves seemed just fine when I overhauled the hub last summer.)
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Old 03-17-06, 09:04 AM   #2
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It might be worth the trouble to take the hub apart again and remove the freehub body. Most I've seen have a very thin washer between the freehub body and the hub shell. If this washer is missing, that might contribute to the mis-alignment.

Another fix would be to reorient the freehub body on the shell, say 90 ot 180 from it's current position as that may reduce or eliminate the wobble.
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Old 03-17-06, 09:17 AM   #3
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I think the fixes you proposed might reduce the wobble, but my guess is that the threads in the hub body, into which the freehub body screws, are slightly misaligned. I may give it a shot though. But I'll need to buy a 10mm allen wrench to unscrew the freehub body.
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Old 03-17-06, 04:47 PM   #4
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All recent Shimano freehub bodies are located by the splines on the hub shell and the mating splines on the body itself. The hollow bolt merely holds everything together so if it is a bit out of line that shouldn't matter.

If the freehub body doesn't seat squarely on the hub shell you could get runout problems. That's why I recommended checking the washer and re-indexing the body relative to the hub shell to see if either helps.
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Old 03-28-06, 04:01 PM   #5
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An update for those who'd watched this thread: I just got me a 10mm allen wrench, disassembled the hub and removed the freehub body (which did take the 10mm allen wrench, not a splined tool). Cleaned everything out at the interface, reconnected the frehub body to the hub, repacked the bearings, and put the cassette on. There is now no side-to-side fluctuation of the cogs when the wheel rotates while the cogs do not (so, you hear the clicking of the pawls while freewheeling).

So, I conclude that the freehub body just needed to be seated correctly and tightened down. It was pretty easy to loosen the bolt holding the freehub body to the hub initially, which tells me that it was a bit loose too. It's now tightened up properly.

Thanks to HillRider for useful comments here.
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