This is a shameless attempt to save the the most advanced civilization in
history from imminent self destruction by eliminating carbon emission,
dependence on foreign sources of fuel,obesity, hypertension and diabetes.
Cycling accomplishes all those things at once and helps us develop a better
understanding of ourselves, each other and our relationship to the cosmos.

Oh, horse puckey!
I like to ride bikes, have been doing it all my life.
The rest of that crap is just a fringe benefit,
and the blogosphere gives me a chance to share my interior
monologue with virtual rather than imaginary friends.

Thursday, March 31, 2011

My broken Shimano Nexus hub

You might recall from my post about a month ago that "the black box" broke.  That black box being the confusing mass of technology called the Shimano Nexus hub from my winter commuter bike.  I set it aside since I was ready to put Byron together and winter was nearly over.  It looked like the hub had broken the seal on the drive side somehow.  Somebody on the internet saw it and suggested a catastrophic weld failure, but the cap on that side of the hub is really a pliable plastic seal.

So I consulted with the disassembly instructions from Sheldon Brown's website.  Armed with that, forty years of wrenching experience, my considerable ignorance of IGH systems, and the confidence I could only get from knowing I don't need it for 8 months, I decided to take it apart.
   The instructions for disassembly are simple: remove all the nuts, seals and bearings from the non-drive side
set them aside,

and slowly remove the entire unit from the housing.
Klink! Damn!
    Something fell out onto the floor and scurried away to hide in the filth that is my garage. I didn't imagine there were loose bearings in there, and there probably weren't supposed to be.  I grabbed my famous terry towel, placed it under the unit and tried again.  Several more loosened bearings fell out from somewhere. but I caught them before they could hide.  As I expected the unit's innards looked as sensible as the guts of any watch I had seen.
And even though I don't know what I am looking at, it is quite obvious that something is wrong.  Although my intitial fear that the axle broke seems to be unfounded, there is obvious side to side play in the entire unit.
I also noticed that loose looking spring type wire thingy inside the drive seal.  I don't think that should look that way, and it's really loose.  On the other hand, the bearings that fell out came from seal itself which has a series of clips molded into the housing, being a part of  the housing seal, they are pliable and replacing them should not be a problem.
  Hmm, well I'm not in Kansas anymore, can't just grease the bearings and slap it together.  It appears to be well beyond the oil bath and reassembly notion also.  Fortunately, I don't see any sign of water contamination and whole mechanism rotates quite freely around the axle without binding.  Even the grease looks pretty clean, so the seal was effective up to the last.  That's impressive after 4 years.
   I'll dig deeper into the tech stuff and see what I can see in the coming months; the adventure continues.

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