Bottom bracket corrosion: can this bike be saved?

Dear all,

I've had problems with the bottom bracket of my 2001-vintage touring bike for the last couple of years. I'm already considering acquiring a new bike, but I wonder whether the old one is absolutely beyond repair.

Here are some pictures:
http://radio-bip.qc.ca/Palier/photos.html

The original Shimano cartridge-type bearing assembly began to wobble about two years ago (pictures 13 and 14). This initial trouble was caused by the ball bearing itself.

I thought it would be a simple matter to replace the faulty part, but I was wrong.

I purchased a replacement cartridge (not cheap, if I remember well), and the corresponding crank extractor (pictures 2 and 3), and attempted to remove the crank.

After screwing the tool into the crank (pictures 4-6), I carefully started rotating the wrench in order to pull the crank, but to my horror I realized that I was actually very carefully stripping out the thread. (I think it was more a design flaw than an error of mine).

I tried in vain to extract the crank using other means, so ended up bringing the bike to the shop. The part was replaced, but the mechanic told me he cussed a bit during that job.

The old bearing showed signs of aluminium [a.k.a. aluminum] corrosion [pictures 8-13], see the pitting on the ring, in addition to the rust desposits from the frame on the threads, or what seem to be left of them. I remembered at that point my engineering school lectures and the stern warning putting dissimilar metals into contact. But, hey, if there are millions of bikes like that out there, why should I worry?

I had no complaints about the replacement bearing until it conked out around Christmas 2007. The threaded fastening cup on the replacement Shimano part [which played the same role as the one on picture 9] was made of plastic, and now that I thought of it, the mechanic hadn't screwed it in entirely, probably because the rust prevented him. Now the bearing assembly was resting on only one side, and there was a huge amount of play.

This time I was decide to do it myself. I tried to remove the crank, but the thread was still gone from the time before, and no amount of cajoling or violence could get the crank unstuck (pictures 15-16). I tried heat and WD-40, too.

I bought a replacement Shimano crank assembly of a different design for about 55 EUR, including which seemed of a better design (see pixes 17-25), and included cranks and sprockets.

Here's an exploded view:
http://radio-bip.qc.ca/Palier/EP1342656.pdf

Since I had a replacement for everything, I felt I could let loose my butcher instincts, and hack away at all that junk which had made a pedestrian of me for some weeks (pictures 29-38).

With the old bearing assembly out of the way, I was finally able to inspect the damage (pixes 39-41). I had never before disassembled a bottom bracket, so I wasn't sure whether this amount of rust was normal.

Ah yes, the pictures also explained why the lighting system shorted out a few weeks before the trouble with the bearing reoccurred. I had attached a new wire on the frame's surface with tie-wraps a few weeks earlier.

After cleaning the socket with a wire brush (#47) and applying some rust-remover, I was able to see that many threads were entirely gone (pixes 50-51), and the ones which remained were not in very good shape.

I installed the new assembly (discovering that there was a prescribed torque for the screws and cup). The cup on the drive side had very little thread to catch, so I put two of the three O-rings on the left side. The third one was not necessary for the socket width.

The result can be seen on pictures 52-54.

Alas, the repair held only a few weeks. The right cup fell out of its thread, but is still held in by the crank, so the bike can be ridden [pictures 62-63]. So I'm back to wobbly cranks and front sprockets perpetually stuck at the middle setting.

So what can I do now? Is the thing ruined forever? Is the bike dangerous? I can ride around the neighbourhood on that thing, but not much more. It's a shame, as I think I maintained this bike generally correctly. (Some tell me my problem stemmed from a manufacturing error, as the socket should have been drowned in grease. Others tell me I should have regularly greased the saddle tube to prevent water from seeping in, an idea which I found rather curious in earlier days).

Another mechanic suggested I drown the thing in two-component epoxy glue formulated for metals - that would last me for the remainder of the bike's useful life. I found a product in the Uhu catalog, but no retailer seems to carry it. I found a putty of the brand "Pattex", but the load would quite probably exceed its specified limit, and there is the problem of properly filling the gap between the cup and the socket with something of the consistency of, well, putty.

Any ideas? Is there a way to save this bike. BTW, I'm a big, heavy, and strong guy.

Thanks,

Alexandre
ps: sorry for the saga-like explanation, I could have started with the current situation, but I thought that the full story would better convey my current, frustrated, state of mind.
.

Relevant Pages

  • Re: Bottom bracket corrosion: can this bike be saved?
    ... new bike, but I wonder whether the old one is absolutely beyond repair. ... The original Shimano cartridge-type bearing assembly began to wobble ... about two years ago (pictures 13 and 14). ... remove the crank. ...
    (rec.bicycles.tech)
  • Re: Bottom End Questions...
    ... model year that The Motor Company went cheap on the crank and left-side bearing on the TC88? ... I'm pretty sure my 2003 had the pressed crank and lousy bearing, but wasn't sure if that was the first year for either or both. ... The way I ran that bike is one of the reasons I traded it on the '09 and why the '09 will stay stock. ...
    (rec.motorcycles.harley)
  • Re: clunking sound from crank
    ... have a kickstand or a chain guard on the bike would you? ... else that's near the crank during it's rotation? ... I know that this sounds stupid since the bike is only 3 months old, but the first thing I thought of when I read the original post was a BB bearing or loose race or maybe a small adjustment to the locknut or something like that. ...
    (rec.bicycles.tech)
  • Re: which bike shop is correct?
    ... crank bearings and crank quite loose ... crank-might require replacement of pedal crank (or whatever it's ... They probably mean putting in a modern cartridge bearing, ... Doesn't matter if you got the bike cheaper than that--it's worth ...
    (rec.bicycles.tech)
  • CurlyMans Summer Road Trip Days 26 thru 33
    ... I have pictures but since Internet ... After Zion I made my way to Jacobs Lake just inside Grand Canyon Park ... I did get into a conversation with a local Bandido, whose bike I ... a beer since it was the only bar I knew of. ...
    (rec.motorcycles.harley)