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help requested for free hub rebuild

by Dr Livingstone
Wed, Apr 22, 2015 19:05
2

Due to some worrying noises and chain snagging I have partially stripped down my rear wheel. I was worried that the free hub was grunchy but this proved untrue. Upon reassembly with a new cassette I find that the rear wheel does not spin as freely as before - I have not yet fitted the chain. Does anybody have ideas as to why?

Tech Spec:
Specialized Sirrus 8 speed with Sora rear mech
HG50 cassette
Freehub with ball bearings in outer race (not cassette bearings)
ball bearings in race on other side of wheel.
Both sets of 9 bearings are identical at 6.35 mm diameter.

Freehub seems to spin well enough in the wheel.

Questions:
when reattaching the cones on the hollow spindle tube what torque should I use - currently just a bit more than hand tight
when attaching the 17mm lock nut what torque? I am currently using just less than I would for a wheel nut

as a last question - how easy to convert to sealed cassette bearings?

thanks for your attention

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2 comments

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DaSy | 9 years ago
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It is most likely you have over-tightened the cones. It is a real art getting them just right, and you should account for the fact that the whole thing will slightly tighten when the QR is tightened, so have to allow a tiny amount of play in the hub adjustment to account for this when the wheel is off the bike.

This link to Parks How-To guides is pretty good - http://www.parktool.com/blog/repair-help/hub-overhaul-and-adjustment

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MKultra | 9 years ago
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No you can't really convert a Sora hub to sealed bearings as a cartridge bearing hub has a smooth axle with square shoulders machined into as does the hub body and the free hub body in order to let the cartridge bearing seat.

Shimano cup and cone hubs come with a rubber labyrinth seal on them which are very good at keeping the crap out, my advice is not to strip Shimano cup and cone hubs down as the cones and and their lock nuts are extremely difficult to re-position correctly by hand, it's not about the torque settings it's due to the fact that a machine tool has held that axle in a fixed position with a stop of some sort on the machine to prevent over insertion of the cone into the body of the hub as it gets threaded on during assembly, then another part of the machine has wound the lock nut down onto it, you can't reproduce that by hand even with a torque wrench, it's simply a case of trial and error until you get a hub that spins freely with no play, the lock nut it self needs to be welllied down as hard as sensibly possible, it's keeping the cone in one place while doing so that's the trick, even with two cone spanners it's not easy to get right, the rubber seals also tend to go baggy if removed and refitted.

I would go for a new wheel, Shimano sora hubs while very good for the money are not what I would describe as being user servicable. When they do reach the stage where they get rough it's time to replace rather than rebuild, the way they come from the factory is fine for the life of the hub in my experience.

This is why I dislike the current craze for torque wrenches, they are not the answer to every mechanical problem.

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