stuck seatpost

[baz]

I have an aluminium seatpost stuck in a steel frame. I'd like to seperate them without destroying either. Brute force is not going to work, and I've read in a couple of places that ammonia inserted into an upside down seat tube will remove the oxidisation that's making the post stick and free it up.

Is this an old wives tail or has anyone actually tried it, before I make myself look like a stupid terrorist by buying ammonia and then ruining my bike with it*.



*Ok, not as stupid as NOS in your fuel tank guy but not far off.

[JAC]

I'd guess that if you've got oxidisation that bad then your seat post is probably ruined anyway, I wouldn't want to put too much stress on it when it was refitted.

Frame will probably be ok with a bit of cleaning after removal.

Never heard of ammonia being used to separate the two, but that doesn't mean it can't be done

[Zig]

Havent tried it but ammonia would remove the corrosion off aluminium ok.

You would have to get it in to the gap between the post and the tube though.

I guess upsidedown, block up the exposed end of the seat post, fill seat tube enough that it fills more than the seatpost (ie overflows the bottom of the seatpost inside the tube)

Leave for a bit and try wiggling the seat...

Clean the alu after you get it out though as ammonia and alu dont get along....


If you are still wanting to look stupid you could always try wizzing on it and hoping there is enough ammonia in you wizz*



*There isnt..

[Cyclone]

had a post like this many years ago in a 2nd hand bike i'd bought
i tried everything from wd40,3in1,parrafin,diesel...etc etc nothing shifted it apart from nipping it off at seat tube and running a hacksaw blade down remaining seat post,takes time but stick at it.

[Zig]

had a post like this many years ago in a 2nd hand bike i'd bought
i tried everything from wd40,3in1,parrafin,diesel...etc etc nothing shifted it apart from nipping it off at seat tube and running a hacksaw blade down remaining seat post,takes time but stick at it.


Ahem

I'd like to seperate them without destroying either.
:rolleyes::rolleyes::D

wd40 etc would work on steel on steel but aluminium just ignores it..

[Cyclone]

Ahem

:rolleyes::rolleyes::D

wd40 etc would work on steel on steel but aluminium just ignores it..

i guess a drop of grease in the first place and you wouldn't be in this situation now :eek: i'm away to paint my nails and have some milk AHEM:D

[gaulty]

Pigs piss is full off ammonia, just trying too collect some may get tricky, will it no shift if you hit the seat with your palm in a rotation sorta way (or hammer it).

[AndyL]

clamp seatpost in vice, then use frame as leverage to give it a good swift tweak...

Good luck!

[JAC]

Don't think grease between alu & steel would stop corrosion long-term, you'd need anti-electrolytic paint.

I'd give it the seatpost in clamp & twist treatment too, maybe put a brush shaft down it first if you can to stop it crushing

[simon]

plus gas is worth trying

heat or cold can break the bond too. freeze spray released one in an old frame of the wifes. blasted the post with the spray and poured boiling water on the frame then cave it a tweak in the vise


Is this the on one barry? and what post?

[Rob]

sounds daft but, a thump down on post with big hammer might break the bond and it will move then..
if not-
flatten the post with block hammer, clamp in vice then sharp tugs on frame.

[jimjam]

sounds daft but, a thump down on post with big hammer might break the bond and it will move then..
.

Mjolnir?

[JAC]

Mjolnir?

But he'd need to be wearing his Thor goggles

[Rob]

if its coroded you have to break the lock in any direction doesnt matter.. up down twist left right.. once ifs free it should twist out, its just the inital move that can be hard..

[nathan-stp-0]

Use the force young padaone

[Cyclone]

Don't think grease between alu & steel would stop corrosion long-term, you'd need anti-electrolytic paint.

I'd give it the seatpost in clamp & twist treatment too, maybe put a brush shaft down it first if you can to stop it crushing



have a 15year old steel frame with a USE alloy post in it originally greased up all those years ago and still able to remove,i guess that must have been special grease i used? NOT::yikes::

[hughsuffern]

i had the same problem . used placticine to create a reservoir around the top of the seat tube . filled it with vinegar and leave overnight , came out the next morning with a good twist

[JAC]

So why do I use anti-electrolytic paint when I'm assembling aluminium to steel components? Surely slapping some grease on would be cheaper.

Perhaps it's because when aluminium & steel are put in contact with each other for a period of time, as it seems has happened with baz, they will react.