Any suggestions for loosening a seat post? Alum inside Steel

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wxm said:
Any progress?
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Not so far. It's hanging upside down right now in the garage under an a-frame ladder. I took the bottom bracket out and filled it up with ammonia. Then I hung a 5 gallon bucket from the seat post and filled it with water about an inch off the floor. I figured if the post fell it would catch the ammonia in the bucket. It's been there for about 3 weeks.

I think I'm going to give up on the Ammonia. It's not working. I guess I can give coke a try next. Is coke better than pepsi or is there another pop that is better? I'm getting pretty close to just cutting it. I guess I'll give the coke a try for a while and see where it gets me. Then I might buy a little dry ice, and cool it way down, then try some heat on the steel and see if I can get it to break free. Ofter that I guess I'm going to give the hack saw a try.
 
Jetboy said:
Then I might buy a little dry ice, and cool it way down, then try some heat on the steel and see if I can get it to break free.
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Give it a go, but in reverse order. Heat the steel first. The aluminum will cool so much faster. Get the steel hot, then put dry ice on the post. Aluminum conducts heat MUCH faster than steel. The post will get COLD and contract well before the steel has a chance to cool and contract.

Butt
 
did you try to hammer the thing IN? should not damage the frame I would think and may be enough to loosen things up. Use a fitting cap.
 
let us know how the coke worked, please.
turns out I have to deal with the same exact issue....
 
Today I took it down and drained the Ammonia. It's been sitting for about three weeks. I didn't realize how fast it evaporated. There wasn't a whole lot left in it. Probably about a cup or so, so most of it evaporated out. After taking it off the stand I hammered it against the concrete; holding the frame hitting the seat post on the ground. I got a little movement. I marked it with a sharpie when I started and the post definitely moved about 2 mm. I hammered and hammered trying to move it out, but had no success. In only. I decided to try coke now and it's sitting with coke. I did notice that coke is slowly dripping through now. Never saw any ammonia come through so it's a promising sign. unfortunately I also have coke coming around the top of the steering tube. I guess those bearings are next on the list.

I'll check again in a couple hours.
 
Jetboy said:
Today I took it down and drained the Ammonia. It's been sitting for about three weeks. I didn't realize how fast it evaporated. There wasn't a whole lot left in it. Probably about a cup or so, so most of it evaporated out. After taking it off the stand I hammered it against the concrete; holding the frame hitting the seat post on the ground. I got a little movement. I marked it with a sharpie when I started and the post definitely moved about 2 mm. I hammered and hammered trying to move it out, but had no success. In only. I decided to try coke now and it's sitting with coke. I did notice that coke is slowly dripping through now. Never saw any ammonia come through so it's a promising sign. unfortunately I also have coke coming around the top of the steering tube. I guess those bearings are next on the list.

I'll check again in a couple hours.
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That's a progress! As long as there is movement, you have successfully unstucked the post. Now I would not hammer the post down any further, imagine how rusted the bottom of the seat tube is! You can put the frame on its side (put some cardboards underneath as a paint protection ), use a pipe wrench (the biggest you can find) to move the seatpost - assuming at this point you are willing to sacrifice the seatpost. You might need to put one foot against the head tube for leverage. You only need move it slightly, and then try the other direction. Going back and forth until you can move it completely. (PB blast may be used as lubricant at this point.)
 
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well, I did let my post soak in Liquid Wrench for a couple of days.

Put the seat post in a vise and twisted the frame hard. The seat mount let loose. That part was press fitted in the seat post. Post still firmly stuck. Dang...

Hacksawing the post while inside the tube is hopeless I think. There is 13" of post stuck in there.

So either I continue with chemical warfare (I read that caustic soda works too) or I turn an adapter on the lathe that I can fit inside the stuck post. Latter sounds like more fun.

Coke results?
 
e9999 said:
well, I did let my post soak in Liquid Wrench for a couple of days.

Put the seat post in a vise and twisted the frame hard. The seat mount let loose. That part was press fitted in the seat post. Post still firmly stuck. Dang...

Hacksawing the post while inside the tube is hopeless I think. There is 13" of post stuck in there.

So either I continue with chemical warfare (I read that caustic soda works too) or I turn an adapter on the lathe that I can fit inside the stuck post. Latter sounds like more fun.

Coke results?
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Eric, The liquid wrench is useless for aluminum oxide. Try soak it in household ammonia. I've never tried coke, but was able to twist mine after soaking the post in ammonia for less than a week.
 
Butt Ugly Chuck said:
Get yourself some dry ice and leather gloves. Heat the steel seat tube up with a hair dryer. When it's good and warm apply dry ice (handle with gloves!) to the aluminum seat post. The thermal conductivity of aluminum is so much higher than steel, the post will get VERY cold even inside the warm seat tube (which will cool much more slowly). Simultaneous temperature expansion of the seat tube and contraction of the post might be just enough to pop it out.
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Butt Ugly Chuck said:
Jetboy said:
Then I might buy a little dry ice, and cool it way down, then try some heat on the steel and see if I can get it to break free.
Click to expand...
Give it a go, but in reverse order. Heat the steel first. The aluminum will cool so much faster. Get the steel hot, then put dry ice on the post. Aluminum conducts heat MUCH faster than steel. The post will get COLD and contract well before the steel has a chance to cool and contract.
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Jetboy, you've been fighting your stuck post for more than two months, and now e9999 is joining the fray with his own battle. How many weeks are you guys going to let your frames soak in how many solutions of caustic crap before you attempt my brilliantly simple (and quick) approach?:D Am I going to have to find my own bike with a stuck post to prove my genius?:p

Butt
 
wxm said:
Eric, The liquid wrench is useless for aluminum oxide. Try soak it in household ammonia. I've never tried coke, but was able to twist mine after soaking the post in ammonia for less than a week.
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well, I didn't hope that the LW would dissolve the corrosion (if that's what that is), just would penetrate and facilitate motion of the parts.

But I may try ammonia, though. How hard did you have to twist? Did it kinda fall off or was it still necessary to ruin the post?
 
Butt Ugly Chuck said:
Jetboy, you've been fighting your stuck post for more than two months, and now e9999 is joining the fray with his own battle. How many weeks are you guys going to let your frames soak in how many solutions of caustic crap before you attempt my brilliantly simple (and quick) approach?:D Am I going to have to find my own bike with a stuck post to prove my genius?:p

Butt
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yea, yea. Been meaning to do something like that for a while now, but I'm aiming for liquid N2, that should be better. Logistics a bit of an issue, though.
 
e9999 said:
well, I didn't hope that the LW would dissolve the corrosion (if that's what that is), just would penetrate and facilitate motion of the parts.

But I may try ammonia, though. How hard did you have to twist? Did it kinda fall off or was it still necessary to ruin the post?
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It was hard. I had to grab by my biggest pipe wrench, and put a foot against the head tube to make the first twist. (I would definitely give your hitch idea a try if it came around again! :clap: ) Anyway, this was the bike carrying the "death sentence" by my local bike shop, it was a 1985 Miyata, who knows how long the post had been stuck there. I did not have to think about saving the post as I had first tried the LW and pipe wrench with no luck, sent it to local bike shop, they had no success. At that point the post was already ruined...
 
wxm said:
It was hard. I had to grab by my biggest pipe wrench, and put a foot against the head tube to make the first twist. (I would definitely give your hitch idea a try if it came around again! :clap: ) Anyway, this was the bike carrying the "death sentence" by my local bike shop, it was a 1985 Miyata, who knows how long the post had been stuck there. I did not have to think about saving the post as I had first tried the LW and pipe wrench with no luck, sent it to local bike shop, they had no success. At that point the post was already ruined...
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OK, good to know. So ammonia is not a miracle cure either then. But may be a step in the right direction.


FWIW, I am now leaning towards the use of a reamer. Probably a 1" since those are likely most common, and it would remove very little material. I'd then use a skinnier 1" post in there and deal with the adjustments by having a number of holes in the post and using transverse pins. A bit clunky but would work for sure if I can find a longish reamer.
 
Update: To answer a few questions. My bike sat in Ammonia for about 3 weeks. And after that period I was able to get very minimal, but verified movement of the post. I was able to pound it in about 2mm. I have not been able to move it anywhere from that position. I have even used a bottle jack braced off the bottom bracket and pushing against the top of the post and was concerned about ruining the bike frame. It was creaking and groaning so I stopped. I'm not sure what would give first. I also have not gotten any twist out of it with a pipe wrench. Since then it has been sitting in Coke for about 3 weeks now. I've been super busy, but I want the garage space so I'm hoping to get to it this weekend. We'll see how it works. And as a recap I was able to find 100% Ammonia at big lots for cheap. Most floor cleaners and such probably have a dilute formula.

I'm kinda tired of fighting this thing. If I'm not able to remove it after 3 weeks in coke I may just go ahead and start cutting. I don't think I want to go back to Ammonia again.

As a side note, be aware that ammonia is a base and coke is acidic. it should be rinsed between use of the other and expect a chemical reaction when mixed... ie it will foam out and go all over the place. Ask me how I know...


Finally I don't know where they are available, but a ski shop owner I know who's big into biking said that he's heard of small diameter seat posts that just fit right inside the cut off post. You just cut the old one off at the top of the frame and cut a slit to match the slit in the frame tubing so it can be tightened, then put the new small diameter post inside. That actually sounded like a pretty reasonable solution, however there are likely lots of seat post ID's and it may be difficult to get an exact fit, further I have not even looked into where they are available and what the cost would be.
 
I had sort of concluded that if I didn't hear of a great chemical solution, I was going to try and ream mine and just use a skinnier post. Seemed to me like the smallest size that would be realistic is a 1" post. Some of those around, less reaming to do, and likely more reamers around too.

can't wait to hear that your post just fell out after the Coke bit, though...
 
Good news!!

I had a few minutes to play with it when I got home today. It twisted with a pipe wrench. I twisted it around about 3 times all the way. I didn't have time to work it all the way out, but it moved relatively easily. I had a 3' pipe on the wrench, but it wasn't super tight. As I twisted it started to move up and out. I had to go to diner, but I'll get it the rest of the way out tomorrow for sure. I'm not sure if it was the coke or the Ammonia or a combination of both. I know I couldn't twist it with just the ammonia, but it did move a bit when I pounded on it before the coke.

It's still really tight though. After twisting it around it the tube got nice and warm from the friction.

I'm fairly sure the post is ruined. It's still round, and I might be able to sand down the damage from the teeth if the pipe wrench. Either way I'm stoked it's coming out. I was surprised how easy it turned after sitting in coke for a while. I'm a believer in the coke. I'd give it a try. This bike was sitting for close to 20 years and it came out.
 
excellent!

I almost have to try it now, eh?

mmm.... just when I got some reamers to play with....

I imagine you have coke everywhere inside your tubes now. Do you think it got into the headset and need to relube?
 
e9999 said:
excellent!

I almost have to try it now, eh?

mmm.... just when I got some reamers to play with....

I imagine you have coke everywhere inside your tubes now. Do you think it got into the headset and need to relube?
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Yeah, I'm pretty excited. I was about to give up on it. It's an old junkyard bike, but it should make a nice commuter which is my plan. I might put a flat bar on it too. Not sure yet.

I got coke everywhere. I'm going to have to tear down the headset. It had coke pouring out of it. When the coke hit the ammonia it was like the mentos thing and it went everywhere. Fortunately I had a tarp under it and it kept most of it off the floor. But the bike is in rough shape so I'm planning to paint it once I get it all in good riding condition. I've already gone through the hubs and wheel bearings, brakes, and derailleur so most of the maintenance has already been done. I'll be tearing all down again for paint after a good shake down ride tomorrow and will have to do the headset.
 
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