Seized seat post

boater · Post by **boater** » 2 Jun 2007, 12:56am

How do you free a seized seat post? I've come across the same before with a previous bike. THat was a Muddy Fox too. I ended up cutting off the post, then slicing the stump vertically inside the tube with a padsaw before clamping and extracting with mole-grips. That took hours!

The original aluminium post is a close fit and has jammed in the steel tube with corrosion. I've tried WD40, ice-packs on the seat post and boiling water on the frame, whilst attempting to turn the post with mole-grips.

I don't fancy going through the same exercise as last time. Any tips?

reohn2 · Post by **reohn2** » 2 Jun 2007, 9:24am

This topic has come up before and all the methods you mentioned were mentioned on it,so it sounds as if you've had good try.I'm afraid its time to get out the padsaw and settle in.unless some one has a magic formula.

robgul · Post by **robgul** » 2 Jun 2007, 9:54am

Two possibilities :

1 Remove the BB and turn the frame upside down so that the seat tube is vertical (hold it in a workstand or vice) - squirt WD40 through the (usual) hole in the BB shell and let it run down inside the tube wall - you will need to lave for several days, repeating the WD40 application every half-day or so.

2 I understand that application of ammonia by the same process works ... but have no experience (do this one outside!)

... and I assume you have tried gripping the protruding seat post in an engineer's vice and trying to turn the frame (i.e. using the vice/bench as a massive mole wrench in reverse)

Rob

JohnW · Post by **JohnW** » 2 Jun 2007, 11:50am

A nasty problem and a common one.

I can't add to the above advice, but if it's happened to you before, have you learned the lesson of history?

For the future, as you are assembling the bike and before you insert the seat-pin, try liberally coating the seatpin and as far down the seat tube as you can get with Millers Black-Moly D180. Don't leave any bare metal for steel to alloy contact. Any grease will help of course, but this is one that our local fire brigade use on threads in their pumps : it's formulated for under water use. It works!

If your seatpin is fluted and the flutes extend below the top of the seat tube, make sure they're well filled with the grease.

If you buy ready-built bikes, this is one of the matters to address before you ride it.

JohnW

PW · Post by PW » 2 Jun 2007, 10:19pm

The ammonia one worked for me, though I don't know of a source for it these days. Our Transatlantic cousins use Cola or Root Beer, don't know how good it is but if it works let us know!

meic · Post by **meic** » 2 Jun 2007, 10:58pm

How about knocking it IN a bit. This may help to break the bond. You will be able to give it a hefty blow from above with a hammer and you had already decided to destroy the seat post so you havent much to lose.
Then retry all the other methods to see if it has helped.

Colin Stanley · Post by **Colin Stanley** » 3 Jun 2007, 6:10pm

Have just keyhole sawn an aluminium alloy seatpin which was securely stuck in an old steel frame.
It took a little time using a hacksaw blade the wrong way round so that the cut was on the pull out stroke. I didn't remove the necked down part of the seatpin (old type) and when sawn through used a pipe wrench to grip this end. It came out eventually. I set the blade length to be just the same as the seatpin length so I knew I would only cut the aluminium. Take your time when sawing. It took me about an hour with stops to check and rest etc, as I didn't want to cut into the steel seat tube.

glueman · Post by **glueman** » 3 Jun 2007, 6:46pm

If you don't mind wasting the seat post, you could get the largest pair of molegrips available and start twisting, or drill the pin and put a large bar through it and heave. I once had a seatpin that was so rusted neither of these worked, the latter succeeding only in starting to twist the frame. I like the coke suggestion.

pigman · Post by **pigman** » 4 Jun 2007, 10:01am

try penetrating fluid sold at any diy store. Although cheap and universally available, I've found its a lot more effective than say WD40 et al... and I've learnt over the years to be patient - you have to wait days and use repeated applications for it to work. Being fairly impatient, this for me is the hardest bit - I want an instant result.
I wouldn't try to force the existing (dry) pin out simply by twisting - there's a liklihood that the pin will twist and shear, leaving you to "enjoy" the internal hacksaw blade method again.

ianr1950 · Post by **ianr1950** » 4 Jun 2007, 11:35am

PlusGas is far better than WD40 as it is specifically a penetrating and dismantling fluid fluid.

pigman · Post by **pigman** » 4 Jun 2007, 1:09pm

ianr1950 wrote:PlusGas

yeah - that's the name, just couldn't remember it. - if that fails, then you're in sh#t!

ransos · Post by **ransos** » 4 Jun 2007, 1:26pm

I had a similar situation - penetrating oil, lump hammers & vice (plus 2 big blokes) all failed. The LBS then applied heat to the seat tube, and hey presto! They even managed to avoid damaging the paint.

CJ · Post by CJ » 4 Jun 2007, 2:01pm

The final solution - in both senses literally - is cuastic soda, administered to the inverted frame via its bottom bracket. It will dissolve the aluminium seatpost but leave the steel frame unharmed. It will also dissolve skin, floorboards, concrete ... so don't forget to put a plastic bucket underneath to catch the remains.

Caustic soda is sold for cleaning drains.

montmorency · Post by **montmorency** » 4 Jun 2007, 5:59pm

CJ wrote:The final solution - in both senses literally - is cuastic soda, administered to the inverted frame via its bottom bracket. It will dissolve the aluminium seatpost but leave the steel frame unharmed. It will also dissolve skin, floorboards, concrete ... so don't forget to put a plastic bucket underneath to catch the remains.

Caustic soda is sold for cleaning drains.

Have used that in the distant past for a stuck stem.

In that case I was planning to have the frame and forks powder-coated afterwards anyway. Can't now remember the exact effect of the caustic soda on the old paintwork, but I don't think it was pretty.
(I think I immersed the entire head-tube in the caustic-soda).

In more recent years, my engineer son has suggested that Isopropyl alcohol might break the steel-alloy bond, but I have not had the opportunity to test this out.

Regards,
M.

JohnW · Post by **JohnW** » 5 Jun 2007, 10:49pm

montmorency -

All of the above are well tried solutions to a problem, and offered in the light of experience.

Prevention is much better than cure, and a well greased seatpin, greased heavily enough to prevent alloy to steel contact, will help prevent the problem. If you're cycling habits are such that your bike gets wet a lot, or if it's stored in a place that condensation inside the tubes is likely, then take the seatpin out from time to time, clean it and re-grease it.

Prevention is better than cure : a stitch in time saves nine and all that.

JohnW