Seat post fused into seat tube.

[Zippy]

Well I've decided to take my chemical warfare on my seat post a little further. I sawed the anvil end off my seat post so I could guage how far in the post goes with a stiff wire; about 7 inches

Then I removed my BB, plugged the seat stem with BluTack and turned the frame upside-down so I can pour caustic soda right up to the top of the down tube.

Lots of aluminium sludge coming out of the tube and having to drag a rag through the tube to ream out every now and again so I can get more lye in.

Something's gotta give!

It was worth removing the BB though as it was starting to "weld" in as well!

 

[Zippy]

peanut

think I'll take a bit of time burning it out with caustic and twisting the seat post before I go drilling holes in things!

 

[Coreyhoward]

You can try all the wacky approaches above but please please please be carefull of using either ammoia' or caustic soda ( don't put caustic soda in the post or encourage anyone to! ( mental (illegal) and dangerous) Both are degreasers (only). 1st of all make a cup of plasticine/bluetak around the neck of the join - and then fill will a good spray of wd-40 or similar. 2nd leave in a warm room overnight -in the morning give it a couple of good whacks (laterally) the go to work-when you get back from work take off the saddle and put a piece off wood ontop of the stem the whack it ( vertically)with something heavy (lump hammer) (it should shift but don't send it all the way in - to make sure place mole grips a bit higher up the stem ).3rd use the mole grips or the saddle in a vice technique as described in the earlier postings.If that dosen't work (which it should) then use a heat gun or dangerous chemicals/hack saw to make a new cut at the back of the post and ruin the bike ....( but i had to laugh at the "put the bike in the freezer technique - how big of a freezer does he have!??? Mr Iceland perhap's? Haha! Anyway good luck- there are e few other tec's if you have no luck - you can try drilling through the seat stem (technique for this as well if needed) and inserting a bolt to twist against for grip or the chisel tech' ( but be carefull of your hands)- If you want to use heat (use the right technique) same goes for freezing- otherwise its usless.

 

[raindog]

Knowing that I would not sleep thinking if my bikes where OK, I got dressed went downstairs and checked my old Trek 1.2, which I have not touched the saddle post for about 6 months, and guess what it was stuck solid! Twenty minutes of twisting finally got it moving but I was making that much noise in the shed I would have woke the street up.

Why do some people seem to get stuck seat posts and others not? Could be the subject of another thread.

Good luck as always to zippy.

 

[Zippy]

Coreyhoward - don't worry about the caustic soda thing. I've been a lab rat in my time and I know the dangers and precautions. By the way it ain't illegal to put lye in your downtubel but don't put it in your aluminium frame!! Steel only please.

Whacking it hasn't worked simply because I think the aluminium oxide is sticking the seat post to the downtube the entire 7 inches in the frame so nothing's gonna crack that easy. I've tried all the penetration oils by the radiator softly approaches.

PS - don't use a lump hammer to "crack" the chemical bond, use a claw hammer - its percussive shock you need not a bent frame :-)

 

[hubgearfreak]

put a 1/2" stainless steel rod up through the seat tube into the seat post and smash the seat post out that way.

thing is peanut, is that it's stuck. an interest in knocking it out seems to make sense, but if you could move it, at all in either direction, then the battle is won - you'd have cracked it.

but if it's not moving down, why do you think it'll move up?

good luck

 

[e-rider]

I've seen loads of seatposts stuck over the years. Never seen the heating approach work; just lots of burnt paint so I'd not recommend that.

You could take it to a frame builder such as Mercian or Argos - both charge relatively small amounts to remove them - I'd be interested to know how they do it.

The hacksaw blade method works but it's very risky.

 

[Zippy]

put a 1/2" stainless steel rod up through the seat tube into the seat post and smash the seat post out that way.

this would work if the seat tube was just overtight, but this one is chemically bonded between Alu and Steel (Aluminium Oxide. What is likely to happen is the softer Aluminium will bunch up at the head of the striking steel tube and eventually cause a bulge in the cycle's downtube and still need to saw or chemically erode the stem out.

Pouring caustic down the tube rather than throught he drink bottle lug enables a more energetic reaction and keeps the embedded end of the seat tube submerged in the solution for longer, so I am hopeful for this to work without risking damage to the frame.

Sorry about the italics - couldn't switch 'em off!

 

[hubgearfreak]

why is it that if it doesn't move with some hammering from above, do you seriously believe that hammering it from below will move it?

 

[Zippy]

I hope this is not going to turn ugly

The reason the seat post will not respond to hammering in either direction is because I think every square inch of the embedded post is fused by the reaction between aluminium and steel.

Either enough of this needs to be chemically dissolved with caustic (or ammonia - but definitely not both together due to the liberation of Chlorine gas) along with regularly twists with the wrench until the chemical bond is sufficiently weakened.

the last resort will be to carefully (I take your point about tube depth peanut) cut several grooves in the seat post until it can be peeled away and pulled out piecemeal.

I'll keep you all posted

 

[Panter]

Just to say, Zippy, that I wish I had something to add, but I just don't.

Anyway, you're thread has made epic reading and I feel a real flutter when I see there's new responses on it, has he freed it yet? has he not? the suspense is quite enthralling.
So, don't be put off by any negativity, the NaOH will chew through it eventually I should think.
I really admire your perseverance and wish you the best of luck.

I take it this frame actually fits you?

 

[hubgearfreak]

zippy
i understand that it's stuck, that hammering does nothing
i understand that chemical removal is your best hope, followed by the hacksaw.

sorry if i've caused any ill feeling on your thread, i was simply wondering what good drilling big holes in the BB would achieve, to do hammering - given the fact that hammering doing nothing is a given
frankly i'm astounded at peanuts's over-reaction

good luck, and thanks for the thread, i'm going to grease mine at the weekend, if it's not too late

 

[raindog]

sorry if i've caused any ill feeling on your thread, i was simply wondering what good drilling big holes in the BB would achieve, to do hammering - given the fact that hammering doing nothing is a given
frankly i'm astounded at peanuts's over-reaction

+1
Drilling a hole in the bb and tapping from below isn't going to work if belting it from the top doesn't move it.
Chemicals seems to be the way to go, although I would've given up by now I think.
As always, good luck zippy.

 

[02GF74]

+1
Drilling a hole in the bb and tapping from below isn't going to work if belting it from the top doesn't move it.
Chemicals seems to be the way to go, although I would've given up by now I think.

agreed - you'll just weaken the BB.

use a scriber between the post and frame to clean out the interface - then use tape to make a funnel around it to pour in the chemical.

repeat process to allow the chemical to work its way into the gap and try to twist post in the frame.

given enough time, this may free it.

 

[Panter]

By 'eck, I think he's shifted it......