seized seat post

dboyne5

I have a seized seat post, left outside a few years. Tried WD40 . Any suggestions !!!!

piston

Steel post in a steel frame or alloy post in a steel frame?

You should read Sheldon Brown's methods and work from there - http://sheldonbrown.com/stuck-seatposts.html

If it's a steel post in a steel frame, I would plug the top of the seatpost if necessary, turn the bike upside down and pour diesel down the seat tube from inside the bottom bracket shell and allow to sit for a few days.

Incidentally, WD40 is only an average penetrating oil. Plus gas, GT85 or even diesel will work much better.

macnab

As said, diesel is much better than WD40 which is really only a water dispellant. You could also try heat treatment i.e. pour boiling water on the outer tube, or if its steel then a quick lick of a gas torch.

piston

Careful with a blowtorch as you could destroy the paint.

If it's an alloy post, it will expand/contract faster than the steel seat tube so heating it won't work but there would be a argument for putting it in the freezer for a few days as the seatpost ought to contract faster than the steel.

triggermortis

I'd go with the diesel or plus gas. If you're going to scrap the seat post you could try clamping it in a vice and turning the frame (after a soak in plus gas or diesel) to free it

macnab

piston wrote: »

If it's an alloy post, it will expand/contract faster than the steel seat tube so heating it won't work

Actually it would work quite well as the differential expansion would break the bond between the two components, but as you say caution is needed with a naked flame.
You could also do a combination of hot and cold, freeze it first then pour boiling water over it.

Diarmuid

Any suggestions for an AL seatpost in a carbon frame? Cool the seat post?

gav07

Diarmuid wrote: »

Any suggestions for an AL seatpost in a carbon frame? Cool the seat post?

I had one of these a few years ago. I tried everything from clamping the post in a bench-vice and using the frame as a turning-lever to pouring coke (a-cola) in through the bottle-cage holes and letting it steep overnight upside-down.

Eventually, I decided not to save the post. I sawed it off an inch above the top of the seat tube, cut it vertically from the inside all the way down using a hacksaw blade which took several hours, regularly hanging a mini-maglite down the inside to check progress and that I hadn't gone into the carbon tube. Then I just curled the post in on itself with a vice-grips around the inch-proud part and it pulled out easy enough.

A real pain - and all posts greased since.

DirkVoodoo

Diarmuid wrote: »

Any suggestions for an AL seatpost in a carbon frame? Cool the seat post?

Aluminum seatposts frequently become stuck by corrosion also, and penetrating oil is almost useless against aluminum oxide. Fortunately, aluminum oxide can be dissolved like magic by using ammonia. [Jobst Brandt doesn't think this works, because the ammonia won't penetrate -- see his comments on stuck handlebar stems. Drano drain cleaner in water also dissolves aluminum oxide. Leaving the frame upside down with the seatpost soaking in one of these liquids may possibly free the seatpost. With the frame upside down, you might also run liquid down from inside as described in additional suggestions.-- John Allen]
[Temperature-differential method, which is applicable to any seatpost material: Buy dry ice (solid carbon dioxide, which melts at -78.5° C (- 108° F). If you have access to laboratory supplies, you might also use liquid nitrogen, which is even colder, though its cooling effect is not as great because it boils, forming a shield of gas around itself. Ordinary water ice also might work. Remove the bottom-bracket parts, cork the top of the seatpost if it is open, and with the frame upside-down and a saddle attached to the seatpost, drop chips of (dry) ice or pour liquid nitrogen down the seat tube into the seatpost. Then hold the saddle down on the floor with your feet and twist the frame. You may also warm the seat tube by pouring hot water onto its outside. Wear winter gloves, boots and socks. Do not touch dry ice, the seatpost or other parts chilled by dry ice or liquid nitrogen. I thank John Newgard for this suggestion. Sheldon's original suggestion follows -- John Allen]

From here: http://sheldonbrown.com/stuck-seatposts.html