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Need advice on bottom bracket repair

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Old January 9th 17, 12:31 AM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 4,018
Default Need advice on bottom bracket repair

On Sun, 8 Jan 2017 17:27:33 -0500, Frank Krygowski

I too have had much better luck with PB Blaster or old-style Liquid
Wrench than with WD-40.

Same here. WD-40 may have 2,000 uses but it's only good at what it
was originally designed to do; displace water.

I hate suggesting ideas that I haven't tried, but if you're willing to
take the risk (and not sue me), this might actually work.

Better living through chemistry. In this case, we have a steel cup
and an aluminum frame and bottom bracket. My guess(tm) is the threads
are clogged with iron oxide (rust) and aluminum oxide (white crud).
The trick is to find a chemical that will attack both without trashing
the base metals. One thing *NOT* to use is CLR or various household
calcium/lime/rust removers. The acid will attack the two oxides, but
will also destroy the base aluminum threads. It may come apart, but
you probably won't have any threads left in the aluminum.

So, what to do. Oxalic acid and water mix will attack both the rust
and the white crud. It's a rather large molecule, so it may take some
soaking of the bottom bracket in the oxalic acid solution to get some
penetration. If you feel ambitious, heat up the bottom bracket
slightly, slop on the oxalic acid, and get out of the way. Tiny air
spaces in the threads will produce a partial vacuum as it cools, and
suck in the liquid. It won't suck much but it might be enough to
soften whatever is jamming the threads, especially if you can move the
steel cup with the now broken bottom bracket wrench. Oxalic acid will
bleach anything it touches, especially your clothes, so please wear
gloves and protective clothing.

When you put it back together, I suggest a little Never Seize:
to prevent a repetition of this exercise. However, if you do use some
kind of anti-seize or grease, be careful not to over tighten the cups.

Good luck.

Jeff Liebermann
150 Felker St #D
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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