Any suggestions for loosening a seat post? Alum inside Steel (1 Viewer)

[Jetboy]

I've been rehabing an older Widsor roadbike for a commuter. I ride my MTB 3 days a week to work. It's ~10 miles round trip, and all on pavement so I figured it's time for a commuter, plus I got the bike for free. It's been sitting for a while though. Anyway after new bearings, tires, tubes, and a thorough cleaning it rides pretty decent. I just need a new seat, and to adjust the seat height. The damn thing is stuck pretty bad. It's aluminum post inside a steel frame. I've tried rubber mallet, soaking in PB blaster and had no luck. I can't get any budge at all. I've also put a pipe wrench on it with a 3' cheater bar and I was concerned about twisting the frame. I'm not sure how to get the thing to loosen up.

I don't think I dare try heat. I've applied a little, maybe up to 200F, but I fear that I'll end up ruining the frame as it's brazed together.

Edit: After some quick research I realized how bad of an idea heat really is. Aluminum expands more than steel, so it would more than likely make it tighter.

I thought maybe cutting the seat post and trying to drill out the inside, but it's like 10" down in the frame so I don't see how I could really do a decent job of drilling it out.

Any ideas? I can't figure out anything that won't destroy the frame, which kinda defeats the purpose.




My other thought was to put the road bike wheels on my old mountain bike frame and make something more similar to modern commuters. The front tire fits fine and I think it'd be easy enough to set up the front brakes. The rear frame is too wide by about a full cm maybe more. Also the rear brakes should be easy enough. It's a steel frame so it could be modified if need be. My question there is what to do about the width of the frame drop outs. Should I lace up a wheel with a MTB hub or what?


Any advice is welcome.

Thanks,

Jetboy

 

[2mbb]

There are some ideas in this article. The ones I like are:

hold the seat post in a vice (bike upside down) and use the bike frame as the lever arm to twist it free

-or-

use ammonia (not penetrating oil) to dissolve the aluminum oxide corrosion.

-or-
cut the seat post off about 1/2" above frame. carefully using a hacksaw blade, make a kerf cuts on the inside of the tube, cutting through the aluminum, but not into the steel. You can then use vice grips to roll the seat tube inside itself to a small diameter.

15 Ways to Unstick a Seatpost

 

[Jetboy]

I think I might end up cutting it out. I've been putting amonia on it for a couple days and had no success. I guess a seat post is cheaper than a frame.

 

[wxm]

The amonia does work, it just that you really have to soak the post in for days. Here is what I did to successfully to release an aluminum post from an 20+ year old Miyata road bike.

(1) Remove the saddle, and block the center hole of the seat post. (I used the wine bottle cork.)
(2) Remove the cranks and bottom bracket
(3) Flip the bike up-side-down, and from the bottom bracket, fill up the seat tube with amonia. (You might want to put a catch pan down under to prevent over fill spill.) You want to fill enough amonia so that the join between seat post and seat tube will soak in.
(4) Let it sit for about 5 days to a week. (I only needed for 4 days).
(5) With catch pan in place and bike in up-side-down position, use a pipe wrench to see whether you can loose(twist) the seat post. Note the pipe wrench will likely making permanent mark on the seat post, you might want try something else if you want to save the post. With frame in one hand and pipe wrench in the other, it does give you a great leverage.
(6) If you still can't move the post, leave it and try again in a couple of days.

It worked for me, and hopefully will do for you too.

Good luck.

 

[IdahoDoug]

Don't count out a bike shop. They may charge you $10 but a pro can do wonders with the right tools, etc. Call around and some will demur, others will rise to the challenge. Cash talks if you bring it in to a small shop and simply ask if they can get it for 10 bucks or similar.

DougM

 

[wxm]

Don't count out a bike shop. They may charge you $10 but a pro can do wonders with the right tools, etc. Call around and some will demur, others will rise to the challenge. Cash talks if you bring it in to a small shop and simply ask if they can get it for 10 bucks or similar.

DougM

I did. Asking my local bike guys was the first thing I tried. (They were usually pretty good), and in my case they took my $10 (or $20 I don't remember exactly) and told me they were unsuccessful a week later. If you want anything done right, you have to do it yourself. - just kidding. But seriously, I don't think they had enough patience to have it setup and soaked in ammonia for a week.

 

[Jetboy]

I'm leaving on Tuesday for a month so my plan is to hang the frame upside down from an a-frame ladder on the back patio and fill it up with ammonia. Then I'm going to hang something like 50lbs of weights on it a couple inches above the ground and hope it's loose when I get back. The biggest issue for me is where to get Ammonia. I couldn't find any at walmart. Do they still sell it at local grocers?

 

[wxm]

I'm leaving on Tuesday for a month so my plan is to hang the frame upside down from an a-frame ladder on the back patio and fill it up with ammonia. Then I'm going to hang something like 50lbs of weights on it a couple inches above the ground and hope it's loose when I get back. The biggest issue for me is where to get Ammonia. I couldn't find any at walmart. Do they still sell it at local grocers?

Hmmm... I did not think about that. I assume you will find it in grocery stores. I stole it from the under the kitchen sink. PM me if you could not find it I will ask her.

Not sure you want to leave the ammonia in there for a month. It is not neutual, I am not sure it will do any harm to the metal for that long period.

[Edited] PS: Don't forget the pipe wrench.

 

[Jetboy]

I found some at big lots. It was cheap too. A 2 liter bottle for $1.

 

[KayakPanic]

another possibility might be to drill a hole through the seatpost (assuming that it will be junked or not needed) and then insert a heavy-duty screw driver into the hole and try to get it to twist one way or another (like how to unscrew a stuck oil filter w/o a filter wrench)

This would also give you a surface to hammer against and get the thing to budge...use something like a framing or a rock hammer, though, that rubber mallet is eating a bunch of your hammering power!

 

[Butt Ugly Chuck]

Don't know if this will work but it's worth a shot....

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.

Butt

 

[Jetboy]

another possibility might be to drill a hole through the seatpost (assuming that it will be junked or not needed) and then insert a heavy-duty screw driver into the hole and try to get it to twist one way or another (like how to unscrew a stuck oil filter w/o a filter wrench)

This would also give you a surface to hammer against and get the thing to budge...use something like a framing or a rock hammer, though, that rubber mallet is eating a bunch of your hammering power!

I can actually get a pretty good twist on it with a pipe wrench. The problem is that the frame is going to tweak if I twist too hard. I did try a 2.5lb sledge as much as I though I could without damaging the bike and didn't get a budge at all. After soaking I might try to hook up a slide hammer and try to hammer it out.

 

[Jetboy]

The dry ice might be a good option. Especially because aluminum expands and contracts more than steel. If nothing else it might open up enough gap to let the Ammonia get in there and do it's thing.

 

[KayakPanic]

"I can actually get a pretty good twist on it with a pipe wrench. The problem is that the frame is going to tweak if I twist too hard. I did try a 2.5lb sledge as much as I though I could without damaging the bike and didn't get a budge at all. After soaking I might try to hook up a slide hammer and try to hammer it out. "

more explanation needed...did you have the pipe wrence attached to the seatpost?

what are you afraid of "tweeking" on the frame?

what were you hitting with the baby sledge? the seat?



i still think that drilling a hole through the seatpost would apply the ammount of force to the right places to get it to budge...it would literally twist right out, assuming that you dont need the seatpost anymore.

yanking on a pipe wrench is a static force. having the screwdriver through the seatpost will apply relatively equal forces to both sides of the seatpost, most likely releasing whatever rust is down there, plus you can go one way and then try the other.

how much do you bench press? (just kidding)

 

[Jetboy]

"I can actually get a pretty good twist on it with a pipe wrench. The problem is that the frame is going to tweak if I twist too hard. I did try a 2.5lb sledge as much as I though I could without damaging the bike and didn't get a budge at all. After soaking I might try to hook up a slide hammer and try to hammer it out. "

more explanation needed...did you have the pipe wrence attached to the seatpost?

what are you afraid of "tweeking" on the frame?

what were you hitting with the baby sledge? the seat?



i still think that drilling a hole through the seatpost would apply the ammount of force to the right places to get it to budge...it would literally twist right out, assuming that you dont need the seatpost anymore.

yanking on a pipe wrench is a static force. having the screwdriver through the seatpost will apply relatively equal forces to both sides of the seatpost, most likely releasing whatever rust is down there, plus you can go one way and then try the other.

how much do you bench press? (just kidding)

I put a pipe wrench on the seat post. It's aluminum so the teeth bite into it pretty easily. I used a 3 foot or so cheater bar. It's a fairly thin steel tube frame. It's Tange tubing if that means anything. Anyway I could put enough force to twist the frame in half if I wanted. It's just not that strong. The tube wouldn't budge. It's very strongly rusted in there. I think if the frame was strong enough the post would be the next failure point.

As for the hammering. I started hitting the old seat till it broke off. Then I hammered right on the head of the tube.

From what I've read Ammonia seems to work best.

I've also got a backup frame if I have to I'll swap over the components.

 

[VanGo]

Try what WXM prescribed again method in #4, but use coke as alternative to ammonia. I worked as a tech for several years with custom bikes and this trick never ceased to amaze me. Hang in there.

 

[BRKLYN1]

time to bite the bulit annd do it the hard way, that allways works

things you need
1 six pack or a spliff your choice or both
2 Hack saw


cut the seat post off an inch above the top of the seat tube on the frame.
then remove the blade (large tooth 10 tpi. works best) from the hack saw and cut the seat post length wise.
it is a slow process but it works if you have access to a welder and a 3/8 or 1/2 piece of bar you can weld the blade to the bar and make a handle.

breath slow, I have saved many a frame this way

 

[Radd Cruisers]

I went through this quite a few years ago.

What worked for me was cutting the seat off at the top of the seat or just take off the seat, heating the seat post very hot then spraying some lubricant at the top of the seat tube kinda like souldering a pipe and it sucked into the tube.

Next day I sprayed mor on the tube base where the seat post goes in with some selifane wrapped around it with an rubber band holding it on to make a little catch and let it sit for another day.

Lastly I put the frame on a solid surface and hit the post with a dead blow hammer or lead hammer.

Then used vise grips and worked it out.

Goood luck.

Rob

 

[wxm]

Any progress?

 

[patpend2000]

Pull the bottom bracket, turn the frame upside down and fill the seattube with coke through the bottom bracket. This usually will remove any stuck post