View Single Post
Old January 9th 17, 05:48 AM posted to
John B.[_6_]
external usenet poster
Posts: 2,202
Default Need advice on bottom bracket repair

On Sun, 08 Jan 2017 20:41:16 -0800, Jeff Liebermann

On Mon, 09 Jan 2017 08:34:44 +0700, John B.

There is a recipe for "home made penetrating fluid" I found on the web
- equal measures of kerosene, ATF, mineral spirits, and acetone - that
worked really well the time or two I tried it. The problem with it is
I cold never find a bottle to store it in that the acetone didn't
evaporate :-(

I'm surprised that this concoction works. There are quite a few
claims that ATF+acetone works best, but I don't see how. None of the
comments I read talked about using it with aluminum, or an aluminum
and steel combination. If the idea is to attack the oxides, which
requires an acid, none of the mentioned ingredients will do anything
useful, except lubricating the parts of the threads that are already
broken loose.

I'm not sure what the kerosene and mineral spirits actually add to the
concoction as neither have much lubricity and are both of a higher
viscosity than acetone so I suspect that the 50% ATF and 50% acetone
mix that I've also seen recommended probably works as well.

Seems like a popular concoction:
The last video claims that acetone breaks down rust (at 1:32), which
it doesn't.

What the ATF brings to the table is a detergent, a rust inhibitor,
anti-foaming agent, an anti-oxidant, and some kind of lubricant, none
of which seem useful for breaking loose rust or aluminum oxide.

Forget the detergent, the anti-foaming, the anti-oxidant and
concentrate on the lubricant. If you mix acetone with ATF you get a
lubricant that initially has a viscosity of approximately 1/2 - 1/3
that of water (water centipose = 0.89,. acetone = 0.31) so it flows
into some pretty small cracks. Then the acetone evaporates leaving at
least some oil in the joint. And the crux of the argument - it works.

As for aluminum and steel joints. Yes iron and aluminum in the
presence of an electrolyte results in some pretty spectacular
corrosion but even a little insulation prevents that. Grease in the
threads for example. A favored insulation for sail boats where one has
a considerable amount of stainless in contact with aluminum spars is
lanolin for some reason.

I wanted to read the original Machinists Workshop Magazine article,
but couldn't find any back issues or copies online. This was the
earliest reference I could find:

which describes the torque loads using different penetrating oils.
From the Machinist Workshop Magazine, April 2007, issue.

Or the magazine at
But they don't seem to allow searching back issues.


John B.


Home - Home - Home - Home - Home