Ammonia?

[Daddybus]

As predicted (on here) the seat post & stem on my Sun are both stuck solid. Apparently, or so I've read, ammonia can dissolve the bond between the steel & the alloy.
So if I turn the bike upside down I can fill the head tube & (after removing the bottom bracket) the seat tube & soak?.... Anyone had any success with this method? I really don't want to resort to sawing them through, especially the rather nice GB hiduminium spearpoint quill stem!

 

[mjr]

For the stem it will just pour out, so you would need a pretty big container full to get it immersed.

I may be being dense but if you seal around the top of the expander bolt, where's it going to leak out from?

I've never resorted to ammonia. Penetrating oils or cola have always worked so far... but I've not done it much.

 

[ian c]

Before using chemicals I would try some heat first to expand the outer steel - I use a hot air gun as I can get things up to a good heat without affecting paintwork.

 

[Daddybus]

The seat post has a plastic top to it so that's sort of sealed off. The expander bolt is loose but if I just gaffer tape it all on the outside would that not stop it leaking out? I might chuck some cheap 'roller' cola in the head to soak a while... Unfortunatly i dont have a heat gun... I'll ask around

 

[Daddybus]

Btw doesn't matter about the paint.. That's all got to come off anyway.

 

[ian c]

I bought my Bosch heat gun to strip down some doors in a house - it never got used for that but it's always called into action to free off stubborn parts on cars, bikes and bicycles!

 

[Daddybus]

It leaks a little but I'll keep pouring it back in... Good job the wife isn't back in till 10pm!!

 

[ian c]

I'd watch the amount being leaked - if it starts leaking a fair bit more then chances are it has broken through down the sides somewhere and could be moveable.

 

[ian c]

Oh, and I would NEVER get away with doing that in the kitchen, other half would crucify me!

 

[Hugh Manatee]

Will it not act like caustic soda and just eat the aluminium? Try the heat gun. Own brand products don't cost a lot at the DIY chains.

Look at some of the comments here:

http://www.instructables.com/community/Ammonia--Aluminum/

They mention a stuck stem.

 

[Yellow Saddle]

Search for stuck stem / stuck seatpost here. We've discussed it often. Your solution is not with ammonia.

 

[biggs682]

@Daddybus seen a few you tube videos looks messy

 

[classic33]

I take it that the wedge shaped nut is now free?

 

[Daddybus]

....as a bird

 

[classic33]

Tried knocking it back into the stem?