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Old 03-28-07, 10:52 PM   #1
jimmay
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Nexus regreasing

I have a Nexus 7-speed that I picked up second hand; I have no idea of its history. However, when I ride it, it sounds like a grinder in a couple of gears, and has more play than my other Nexus hub. This leads me to suspect that it needs its grease reapplied.

On his site, Sheldon brown says:
The Nexus hubs are packed with a very special grease. They are quite well sealed, and should only require service at very rare intervals. The great majority of mechanical problems that I've encountered or heard of have been the result of "preventive maintenance" including re-lubrication with incorrect grease.
The hub must be disassembled into its major components, solvent cleaned, dried and re-greased with Nexus hub grease (not to be confused with the similar Nexus brake grease.

Dismantling the hub is not as difficult as you might think, because of its modular construction.

If you unscrew everything that is screwed onto the left end of the axle, the whole mechanism can be pulled out of the right side as a unit.
I have the Nexus grease, so my question is: is this task as straightforward as it sounds above? Am I contemplating fixing something that ain't broke?
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Old 03-30-07, 07:30 AM   #2
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Hello? Anybody?
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Old 03-30-07, 12:49 PM   #3
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Sorry, I've never rebuilt a Nexus. Before I tried that, I would make doubly sure that it wasn't something else. Chain tension too tight, wheel set at an angle, rusted/sticky cable, kink in the cable, indicator alignment and wheel bolts too tight; all seem to cause some sort of noise with my Nexus 8.
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Old 03-30-07, 11:29 PM   #4
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Thanks for your reply. I am fortunate in that I was able to compare it in the same bike (i.e. same cable, chainline, different wheel) with my other Nexus 7. It is definitely grinding and less efficient, especially in 5. However, it is actually no big deal as it's on the hybrid.

The rebuilding part of the Nexus 8 on Sheldon's site looks a little more involved than the text Sheldon writes regarding the 7. I might have a look at loosening the locknut and seeing what's in there. I figure I can always buy another one for the price any LBS might charge to service it.
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Old 03-31-07, 06:28 AM   #5
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I've never done it either (and don't look forward to that day). The first place I would start is on Sheldon's pages about the various Nexus hubs.

http://www.sheldonbrown.com/nexus-mech.html

or

http://www.sheldonbrown.com/nexus8/index.htm

The Shimano website isn't much help on this as far as I can tell. There's stuff like this:
http://techdocs.shimano.com/media/te...9830609181.pdf

But I haven't ever found much useful information.
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Old 04-01-07, 10:45 PM   #6
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I forgot about those exploded views ... I'll pull it apart sometime and report back on what happens.
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Old 04-12-07, 07:39 AM   #7
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Just an update for those of you contemplating this.

I gingerly took off the locknut and outer shell. The main unit dropped out. At this stage I baulked at disassembling it further. I gave it a bath in some solvent to clean it. While wiping it, the rag knocked some pawls off from under a spring, so I had to put them back on with the help of a screwdriver. Then I liberally applied Nexus grease to all the bits that looked like they needed it. I put it together and installed the wheel back on the bike.

After adjusting the tightness of the locknut, I tested out the play in the wheel ... gone. Changing to the grinding gears, 5 and 7, the grinding sound has gone also.

The next test will be to ride it, but so far, so good.
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