Ira B

Greetings fellow bike nuts.

I have an old Diamondback Sorrento frame that I want to build up into a short haul (1.5 mile with some hills) bullet proof commute beast for a friend. It's nothing fancy by a long shot but it is a very sturdy CroMo frame that is just what my friend, we shall call him "Tubby" needs.

Problem is that it came with a dumb shock absorbing POS seat post that is stuck, and I mean STUCK in the frame and needs to be removed because the funkey hardware on the top end is trashed. I suspect part of the problem is that to accommodate it's internal spring this pig is at least a foot deep into the frame.
I have pulled a lot of stuck seat posts but never had this much trouble. Have tried all the usual tricks like soaking it in ATF from both ends, installing an old steel seat clamp and beating the slobbering wizz out of it, heat gun on the seat tube and ice cubes down the post. No joy.
Only trick I have left is to drill a hole in the BB and use a long steel rod to try punching it out from the bottom but I would like to avoid drilling holes in the frame.

Any bright ideas other than toss it in the recycle bin at the dump?

wrk101

Search is your friend. Google works best. Its been discussed at least 500 times already. Use search and you will get hundreds of ideas, success stories, and failures.

FBinNY 

Since you've tried all the standard methods, here's my absolute last resort method.

Instead of trying to pull it up, push is down.

For this I use a 5#x16" sledge hammer (the type used by stone masons). Set the Bottom bracket on an anvil, or other high mass support (a log splitting stump works). Keep the bottom bracket in for support to keep the shell from ovalizing.

Cut the post so there's only 2-4 inches showing. Make a reference mark 1/4" or so above the frame. Have a friend hold the frame, and deliver a solid blow to the post. The object is to move it in one shot, otherwise it'll just mushroom. If you can just get to budge by as little as 1mm you're halfway home.

Use a pipe wrench to twist the post while pulling up. Be patient, and keep adding cutting oil thinned with mineral spirits, or a "liquid wrench" like product so it doesn't re-seize in the frame. Be sure to rest it to cool as you work.

If you have a vise on a bench securely bolted to the wall you can also hold the post and twist the frame off. (I've pulled benches off the wall this way).

This method has a decent success rate, but I save it as a last resort especially with light steel frames, because it's possible to upset (buckle) the seat tube this way.

BTW- even if you don't wear safety glasses for most things, this definitely calls for them, and also a decent apron. Chips can fly off the top of the post with high energy.

gyozadude

Before you try FBinNY's last resort, two things I'd check.

1. It may be hard to tell, but did the previous seatpost installers look like they wedged the seat post in? That is, they pounded the seat post in? If the seat post clamp looks a bit stretched or wider than is necessary and you've already tightened the seat post, then that might be a problem. The folks wedged a seat post that was too wide. Pounding it down will only further wedge it. I don't have a really good solution for this.

2. My 2nd to last resort would be to remove the BB spindle and cups. Turn the frame upside down. Try to pour Coke and let it sit. If the coke is dripping out the end, you will need to seal the end (maybe a cork or rubber stopper, and rubber band with some plastic to help retain the cola in place. Let it sit 24 hours. Then take a pipe wrench to the seat post and see if it comes out.

Good luck.

Ira B

Thanks for the advice guys. I've never tried pounding one further in but have found the the initial breaking loose is the key and that may just work.
Most cheapo seat posts are hollow tubes and I have used a slide hammer/puller with success but this one is a dead end tube with a spring in it so that is no dice.
Never tried Coke before. I have acquired a can in my fridge somehow and rarely drink the crap so maybe I'll put it to good use and give that a whirl.
My last ditch method has usually been to drill a 3/8 hole through the protruding top part of the post clean through both sides of the tube and insert a steel rod or large philips screw driver through it, then use that as something to whale on with a hammer and to try turning the post side to side. I save that for last.

reptilezs

slide hammer idea is neat, how do you attach it to the post?

FBinNY 

I use this as a before last resort, using a long shaft threaded to a toggle bolt (the largest that fits). It's OK when a post is willing, but can't concentrate the energy as effectively as hammering downward does. Once in a while, once I've broken the bond by moving the post 1-2mm down, I can use the toggle device to work it up while turning it with a pipe wrench.

Ira B

If it is the Laprade type you rig up a way to attach it to the adjustment bolt hole. If it is the cheapo pipe type you use a hook type dent puller attachment, insert it through the post and hook the bottom edge. It has to be pretty rusty crusty for this to not work.

reptilezs

have you tried taking the suspension post apart? from what i remember. unthread the collar and the whole top part comes out. then the spring can be pulled. bottom plug is a threaded preload plug and can be dropped in the frame. takes a 6mm i think(use your socket bits and some long extensions). had a few fall apart in the stand while working so i believe the top part does come out.

Ira B

I removed the remains of the top/inner piston part and the internal spring but have to admit I never looked down the hole.
Will check that out. If it is as you suspect that may offer some other possibilities.

Ira B

Well I did the coke thing by squirting some in the water bottle bolt holes on the seat tube and leaving the bike upside down in the stand overnight and this morning....well Ill be horn swaggled! A slight twist with a pipe wrench and the thing almost fell out.
I am not a true believer that soda pop may actually work for this but it may have also been the AFT I used earlier having time to work or some combo of the two.

gyozadude

Glad it worked for you, whether or not it was the Coke or oil. But early in my poor-college kid days, I was trying to replace a stripped lug bolt that would not come out of the hub behind the brake rotor on my cheap Toyota. I tried spray lube and letting it sit. No workie. The old staff machinist down in the Mechanical Engineering lab (same guy who taught me to weld), suggested the coke trick. Just let it sit and it'll do wonders, he said. I found a small plastic tub and bought 2 big 2 litre bottles of coke, and poured them in and immersed hub and rotor and lug bolts. Next morning, a solid tap, and each bolt, including the stripped one, came out.

Not a believer? Maybe. I've never really bothered to investigate if Phosphoric Acid, the only active ingredient I can think of in Coke, is responsible for dissolving rust and other things to unseize metal parts. But purer phosphoric acid is sometimes used in anti-seize cleansers and engine flush solutions.