Seized seat post and stem

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garygkn
Posts: 1472
Joined: 16 Aug 2008, 8:59pm

Seized seat post and stem

Post by garygkn »

I inherited a Trek 930 it looks to be a useful bike but it came with a seized seat post and the recessed quil stem bolt won't budge - I don't want to round off the bolt as there is no way to get a grip on it as it is recessed by about 30mm.

I'm going to try the boiling hot water method on the seat post and leave the bike out in the freezing cold over night and see if that budges it.

The only thing I thought of trying for the stem which may not be appropriate is to turn the bike upside down and pour in some oxalic acid to eat away the rust?
Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Seized seat post and stem

Post by Brucey »

the quill stem bolt could be drilled out if needs be, but that it won't move is indicative of something evil somewhere that drilling out won't necessarily rectify.

I'd recommend soaking everything using a penetrating solution of some kind. For a few weeks.... some folk use diesel.

If you are in no hurry you can leave it soaking for weeks or months if necessary.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
maxcherry
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Joined: 22 Mar 2011, 5:53pm

Re: Seized seat post and stem

Post by maxcherry »

Honestly chaps, I'm a female!
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NATURAL ANKLING
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Re: Seized seat post and stem

Post by NATURAL ANKLING »

Hi,
If only life was so simple.................
NA Thinks Just End 2 End Return + Bivvy - Some day Soon I hope
You'll Still Find Me At The Top Of A Hill
Please forgive the poor Grammar I blame it on my mobile and phat thinkers.
garygkn
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Joined: 16 Aug 2008, 8:59pm

Re: Seized seat post and stem

Post by garygkn »

I have time - no hurry.
Would just like to free it up.

I have a steel frame and an alloy post - perhaps blow torch on the alloy post?

https://www.youtube.com/watch?v=wUzFj2K8Ti4
Last edited by garygkn on 21 Jan 2015, 11:08am, edited 1 time in total.
pwa
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Joined: 2 Oct 2011, 8:55pm

Re: Seized seat post and stem

Post by pwa »

I don't have a great record with this kind of thing. I have resorted to sawing off and filing out a stuck seat post in the past! But I think the wisest first step would involve some sort of penetrating lubricant and lots of patience. The temperature treatment also sounds reasonable. Let us know how you get on.
garygkn
Posts: 1472
Joined: 16 Aug 2008, 8:59pm

Re: Seized seat post and stem

Post by garygkn »

Yes it may take some time but I'll post the results.
I'm aiming for a happy ending!
Keezx
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Joined: 20 Dec 2014, 10:44am
Location: The Netherlands

Re: Seized seat post and stem

Post by Keezx »

Penetrating oil does n't do anything to aluminium oxide, is useless.
Ammonia does....
rjb
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Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Seized seat post and stem

Post by rjb »

There's a whole topic on this problem in the "technical section Too good to lose" area. Lots of info and advice there. :wink:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
gerrymcm
Posts: 450
Joined: 30 Oct 2012, 2:52pm

Re: Seized seat post and stem

Post by gerrymcm »

I've cut off and sawn a stuck stem off, I opted for this route as
A: The stem wasn't particularly desirable and
B: I thought it was safer than wrecking the forks clamping and twisting the stem out.
C: Simpler than the chemical solution, which to me looked risky.

Of course a quill stem is easier than the seatpost as it's shorter.

If you go the mechanical route of hacksaw blade and cutting down the length of the seatpost there's a good article on the "internet" somewhere. The chap who wrote the article made quite a good but simple tool out of a bit of wooden dowling with a slot cut in it and a hacksaw blade glued into the slot. I wish I'd had one of these when I cut my stem out.

Good luck
Gerry
blackbike
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Joined: 11 Jul 2009, 3:21pm

Re: Seized seat post and stem

Post by blackbike »

I used the caustic soda method for a seat post. It worked very well.
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Vetus Ossa
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Location: Plymouth

Re: Seized seat post and stem

Post by Vetus Ossa »

Re seized seatpost.
I had one once that was well and truly stuck, even turning the bike upside down and putting the seatpost in a vice and twisting the frame wouldn’t budge it. I found some advice online mentioning ammonia as a freeing agent so tried it, and it worked a treat. Here’s, for what it’s worth is what I did. Obviously it’s easier to handle with the frame completely stripped down, so did that first. Then I turned the bike upside down and secured it in my bike stand. I then poured ammonia in through the bottom bracket until it came level with the bottom bottle cage boss, and left it in there for a week. The seatpost had a solid end so no leakage there. Then it was back to the vice and clamped the post in the jaws and twisted the frame, once it started to move it was fairly easy to twist it all the way out with no damage done to the frame or post, I was well chuffed.
Of course the smell was terrible, if you’re as old as me you will be familiar with the smell of nappies soaking in the stuff, so defiantly best done in the garage or at least outside.
Good luck with whatever method you choose.
Beauty will save the world.
garygkn
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Joined: 16 Aug 2008, 8:59pm

Re: Seized seat post and stem

Post by garygkn »

Thanks all. Much appreciated.
I'm going to put some of these suggestions into action starting this weekend.
garygkn
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Joined: 16 Aug 2008, 8:59pm

Re: Seized seat post and stem

Post by garygkn »

I have just a few questions:
I don't go to shops a lot as they never seem to have what I want.
Where can you buy ammonia?
Would soaking in paraffin work?
What is the best penetrating oil?

Many thanks.
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Vetus Ossa
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Joined: 22 Oct 2012, 7:32pm
Location: Plymouth

Re: Seized seat post and stem

Post by Vetus Ossa »

I got my ammonia in Boots, comes in a plastic container as I remember.
Forget penetrating oil for that job, but if it’s a general question for other parts, you want plus gas.
Beauty will save the world.
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