"Jon Elson" wrote in message
...

bob prohaska wrote:

In searching for methods to free an aluminum steering stem
from a steel bicycle fork the ideas of using either auto
antifreeze or aqua ammonia have come up. I think the antifreeze
idea is a leftover from the days before aluminum radiators, but
haven't been able to confirm it. The aqua ammonia idea seems
consistent with the chemistry (NH4OH attacks Al(OH)3) but
nobody seems to have any substantive accounts, either of success
or failure.

Does anybody on this group have experience with either method
they'll share?

Thanks for reading!

bob prohaska
The aluminum bar is inside the steel tube? If so, freeze it. The aluminum
will shrink more than the steel, making it looser. If you can get dry ice,
that will work best, but just putting the whole assembly in a freezer (if it
will fit) should do it. Otherwise, pack ice around it, let the cold soak
through to the aluminum, and then tap it out.

Jon
================================================== ======

I'd start with heat first, a heatgun or propane torch. Don't go anywhere
near red hot, just make sure the heat soaks all the way through to fully
expand the aluminum and crush any corrosion between aluminum and steel. I'd
aim for 450-500F, maybe where a drop of water sizzles and floats on steam.
Then quench it in water and cool it all the way back to room temperature and
try tapping on the aluminum to see if it moves. If not, then try the dry
ice.

--
Regards,
Carl Ijames