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Stuck seatpost - Caustic Soda after Penetrating Oil?

Posted: Sat Aug 03, 2013 11:45 am
by iamalex
For £65 I thought a Serotta built steel frameset with a stuck seatpost was worth trying to save. It's Spirit steel with an alu post. I turned upside down, plugged holes and filled the seat tube with penetrating oil and soaked for a day and a half. It's still stuck solid though did get about 5mm rotation before snapping the top of the post off. The next step would be to corrode it out using caustic soda - I've picked up goggles and overalls.

Any scientists out there - Is the heat from the caustic soda reaction likely to cause the penetrating oil residue inside the frame to combust??

Thanks

Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 12:39 am
by LEC135
There is another sort of 'caustic soda' to try first and thats Coke. Let that eat away at it for a few days. Worked for me.

Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 12:39 am
by Weenie

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Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 12:41 am
by vfb
I havent tried it my self, but i have heard that cola could do the job with a seatpost stuck in the frame. Turn the frame upside down, and fill the cola inside the frame and give it around 24 hours, and try again.

Hope it helps and good luck, and :thumbup: for trying to save a nice frame :-)

Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 1:10 am
by Paniagua
A lot of "mechanical" solutions before going Caustic, but really time and patience are your friends, re-applications of a thin penetrating oil (mineral oil for bad cases) over time (more than a couple days, maybe a week or even more) This works, something I do for all kinds of "stuck" situations.

Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 1:43 am
by moshinho

Re: Stuck seatpost - Is Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 7:56 am
by iamalex
Thanks for the suggestions - I think I've got plans A, B and C now!
The frame's continued to soak in penetrating oil for another night so later today I'll give it hell with a pipe wrench. (before toping back up with oil I expect).

Turned into a bigger job that I anticipated but not looking to back down now. Cranks seized to bottom bracket, bottom bracket seized in frame. Penetrating oil + old mtb handlebars attached to huge spanner for leverage + a few hours did the job on those.

The frame is a Glider Tupelo, built by Serotta for the bike shop Cycle Fit in London a few years back. I'll get some pics of mine at some point but here's a nice one from the internet.

Image

Re: Stuck seatpost - Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 8:11 am
by Monkeyboy3333
I'm sure it will be worth it , patience allowing!

Re: Stuck seatpost - Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 8:11 am
by Monkeyboy3333
would chucking it in a walk in freezer do anything? I'm thinking expansion and contraction here....

Re: Stuck seatpost - Caustic Soda after Penetrating Oil?

Posted: Sun Aug 04, 2013 8:11 am
by Weenie

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