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Old 02-09-12, 08:14 PM   #1
elguicho 
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stuck alloy post on alloy frame, can anything be done?

Hello, I did a search of the forums to see if anyone had answered this already but I had no luck. I have an alloy seatpost stuck in an alloy frame, ammonia would ruin the frame and the post, is there anything that can be done? Thanks.
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Old 02-09-12, 08:16 PM   #2
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I like to use copius amounts of pb blaster. and lots of time/ patience
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Old 02-09-12, 08:22 PM   #3
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I was not aware that ammonia would ruin everything, from what I read it just dissolves any aluminum oxide. I hope it doesn't, as I'm going to try it soon with an aluminum stem in stuck in a steel steerer tube. In addition to the steel seatpost rusted into the steel frame....
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Old 02-09-12, 08:53 PM   #4
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I was not aware that ammonia would ruin everything
I don't know if it ruins everything but I have read that it might compromise the bike tubes.
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Old 02-09-12, 09:25 PM   #5
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I don't know if it ruins everything but I have read that it might compromise the bike tubes.
It won't anymore than they might already be compromised by corrosion.
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Old 02-09-12, 09:36 PM   #6
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Assuming you tried all the usual stuff, cut it out.
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Old 02-09-12, 10:17 PM   #7
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heat the seatpost. This should not be too much of a problem to get loose
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Old 02-09-12, 11:17 PM   #8
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Alloy/alloy? Sacrifice the post and go at it with a pipe wrench. It's not that tenacious.
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Old 02-10-12, 01:41 PM   #9
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Lay the bike sideways. Get out the Windex bottle, spray the seat post insertion area. Avoid getting on other parts. I assume you removed the seat post clamp or have slid it off so it exposes the notch in the seat post. Keep the seat tube flat. Flip frame and let it soak for a while. Come back and spray it again after an hour. Wait some more. As long as the BB is at the same elevation or even a tiny bit higher, the fluid should be drawn in, but not flow down to the BB. Shouldn't destroy the tubes. But this way, it avoids having Windex or ammonia get down into the BB and force an overhaul of that part too.
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Old 02-10-12, 03:18 PM   #10
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Get out the Windex bottle
Really? That's the kind of easy idea I was looking for. I want to try all the non-violent methods first otherwise I guess I'll get the saw out...
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Old 02-10-12, 04:22 PM   #11
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Really? That's the kind of easy idea I was looking for. I want to try all the non-violent methods first otherwise I guess I'll get the saw out...
Windex and most glass cleaning solutions contain ammonia. Others suggested ammonia above and I've used this before with exactly your problem, although I think the liquid did more lubrication than ammonia did clearing the oxide layer. I still ended up with big scratched seat post after muscling it out. If the seat post was stuck in a steel frame, I'd recommend using coke/pepsi and letting it sit all night. It contains phosphoric acid which reacts and loosens rust. I guess know your chemistry and read labels on household products!
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Old 02-11-12, 12:11 AM   #12
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Kroil. Soak it for a while...it will come undone eventually. Best to take off bottom bracket and drip some in through the hole from bottom bracket to seat tube....
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Old 02-11-12, 01:09 AM   #13
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Windex and most glass cleaning solutions contain ammonia. Others suggested ammonia above and I've used this before with exactly your problem, although I think the liquid did more lubrication than ammonia did clearing the oxide layer. I still ended up with big scratched seat post after muscling it out. If the seat post was stuck in a steel frame, I'd recommend using coke/pepsi and letting it sit all night. It contains phosphoric acid which reacts and loosens rust. I guess know your chemistry and read labels on household products!
there was some crazy guy on here before who poured some ammonia onto his aluminum tabbed, aluminum steerer carbon fork because he was trying to loosen a stuck stem. No surprise, but the aluminum tabs were dissolved enough that they wiggled in the fork.

I'm guessing the Al2O3 and Al reacts with dissociated ammonia, NH4+ or NH2-, which then becomes AlN, Al(NH2)3, H2, H2O, O2 or something to that nature. I haven't seen any good documentation of what reaction actually takes place, but I doubt ammonia only eats the aluminum oxide top layer, because aluminum is quite high on the reactivity series, which makes it fairly weak against acids.
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