Was Stuck Seat Post, Now its Worse?

[wrk101]

OK, so I picked up a donor 1987 Tempo, with a broken and stuck seat post. I gave removal a try, lots of Kroil (much better than PB Blaster). It "sort of" worked. A section of the seat post came out, unfortunately, the seat post sheared off, inside the seat tube, about 2 1/2 inches down the tube.

So now what? I am thinking one option is to soak what remains in Kroil for a while, and then use a long replacement seat post, and drive that chunk further down the seat tube, maybe four inches.

Its close to being far enough for a minimum insert line. Given the terrible condition of the paint, this bike may be destined to the co-op anyway (land of the rattlecan). But I thought briefly of a PC, something simple, and rebuild.

I guess cutting it out is an option as well, but its pretty far down the seat tube.

Started like this (thomson seat post, or what is left of it):



Can't really tell a thing from the after picture, but here it is:

[raverson]

When faced with a similar situation, my solution was to drill a hole in the BB and run a length of 1/4" steel rod into the seat tube and tap out the stuck post. Assuming the stuck seat post was the proper size to begin with, you might be surprised what little force is necessary when applied in the right direction.

[Chris W.]

After trying all of Sheldons tricks for removal, I went the scary route...
I plugged the bottom hole of the seat tube via the bb, and filled the seat tube with a strong solution of lye, after a couple of days the seat post was gone (as was the paint around the seat lug cluster). Scary, but it worked. Eye protection, and long rubber gloves are a must!

Cheers,
Chris

[Campagnerdo]

If the seat tube is accessible from the BB, use a piece of all-thread to fabricate the equivalent of an automotive slide hammer.

[Fenway]

Easiest solution is to fabricate a pull press and yank that sucker out after adding some more oil:

If you have access through the BB drop in 1/4" threaded rod (from the top of the seat tube) and inside the bottom bracket screw on a nut and large washer of sufficient diameter to catch the lip of the seat tube from the bottom. At the top of the seat tube place another large washer of sufficient diameter to cover the top of the seat tube, preferably with a few rubber washers for padding and another nut. Start tightening the top nut and as the threaded rod, and washer from below, is pulled up upwards the seat post should come with it. If it doesn't either the rod will shear under the tension or your seatpost lug will fail. But in either case if the post was that stuck, the frame would have needed a torch or some serious caustic chemicals with a risk of ruining the frame anyway.

[wrk101]

Easiest solution is to fabricate a pull press and yank that sucker out after adding some more oil:

If you have access through the BB drop in 1/4" threaded rod (from the top of the seat tube) and inside the bottom bracket screw on a nut and large washer of sufficient diameter to catch the lip of the seat tube from the bottom. At the top of the seat tube place another large washer of sufficient diameter to cover the top of the seat tube, preferably with a few rubber washers for padding and another nut. Start tightening the top nut and as the threaded rod, and washer from below, is pulled up upwards the seat post should come with it. If it doesn't either the rod will shear under the tension or your seatpost lug will fail. But in either case if the post was that stuck, the frame would have needed a torch or some serious caustic chemicals with a risk of ruining the frame anyway.

Great idea! I want to try and save this frame, not for its value (in its current state, the value just isn't there), but for the challenge. The curved nature of the seat tube lug will make it a little more challenging. I can probably beat a large washer into a curved shape, back it up with rubber washers, a regular washer, and a nut, and start turning.

[cudak888]

The braze-ons on the downtube might prevent the use of this method, but if you can, try bolting a fender washer to the end of a threaded rod through the BB. It might work as a slide hammer.

EDIT: Fenway beat me to the punch. Nevertheless, be careful about clearing the water bottle braze-ons.

-Kurt

[wrk101]

Yeah, those bottle braze-ons could make this one more trouble.

[Michael Angelo]

I recently had to remove a seat post that resisted the washer and slide hammer trick. I used a hacksaw blade on a handle to cut a slot right down the inside of the seat post. Once cut the post slid out.

[wrk101]

The good news/bad news: none of the seat post is exposed, its all in the seat tube, at least two to three inches down. On the other hand, it was a Thomson alloy seat post, which appears pretty thin and very pliable. (One reason why it tore off). I might try to do a little precutting, to weaken it even more. Somewhat interesting, the portion that came out shows little/no sign of corrosion. I am thinking the prior owner jammed a too large seat post into the frame (what I have left is too distorted to take any meaningful measurements).

[Scooper]

I like the idea of the threaded 1/4" rod from the top and a large enough washer to catch the lip of the seatpost (and nut) from the BB shell end. Instead of just a washer and nut at the top, though, I think I'd use a short piece of 2x4 lumber with a quarter inch hole for the rod and a washer and nut on top of the 2x4. The soft 2x4 would hopefully prevent further damage to the top if the seat lug. Just bear in mind that seat tubes are usually single butted with the thicker wall at the BB end, so if the washer is small enough to get past the butted section from the bottom, it may be too small in diameter (Thomsons are pretty thin-walled) to get adequate purchase on the seatpost lip.

OTOH, the hacksaw blade trick might be easier since Al is pretty easy to cut.

[Aristotle80]

I recently wrote of my positive experience using lye to dissolve the post. Since you already have some rust spots and scratches the paint already needs restoration and a few lye stripped spots wouldn't change the appearance situation greatly.
http://www.bikeforums.net/showthread...bed?highlight=

[toosahn]

Try CRC Freeze-off. It works really well for aluminum stuck in steel.

[wrk101]

Thanks for the ideas. One challenge is that the post is sheared off 2 to 3 inches below the top of the seat tube. So there is nothing exposed to grab onto. Either I push it up from the bottom, dissolve it, or push it in further (once it is down 4 to 5 inches, it should not interfere with the replacement seatpost, unless it is super long.

[jyl]

I would be inclined to try cutting. Since there is no exposed post to pull on, you might have to make two cuts, then get a chisel tip or similar under the pieces of post to separate them from the seat tube. If they don't, then fall out, you can fabricate some sort of pulling tool, a hook or small washer on the end of a long rod. There are keyhole saws with long (12") blades and they might be a bit easier than a bare hacksaw blade.

The reason I'd go this route is, the post is stuck hard, hard enough that it tore in half instead of coming out. Without breaking the stuckedness, pushing from the bottom bracket, pulling from the seat lug, etc might just deform the seat post some more, leaving you with a wadded up mess.

[Michael Angelo]

When clamping down on the remianing portion of the seat tube. I put in an old socket inside the seat tube, so the tube would not crush and have better holding power when being clamped in a vise. Makes a big difference.

[wrk101]

OK, I got it out tonight. I ended up using 5/16 inch threaded rod, a few washers, and a block of wood at the top. Once I had the seat post up to the top of the seat tube, I used 2x4 blocks to raise up my top block. The rear was set on the seat post clamp area, the front on the seat tube lug. I really had nothing to lose.

I need to check the post with the caliper. No sign of any corrosion. I think the PO just used the wrong size post (too big) and jammed it in there.

Frame on bike stand:




Close up showing the blocking (note the seat post is part way out at this point):




The offending seat post:




Close up of the end that did the pulling (the first three smaller washers are for alignment (they slid into the seat post), and the last three did the work. The middle one of the last three is the largest, filed down to fit into the bottom of the seat tube. The other two washers are to stiffen this washer (I bent it a couple of times):





bill

[BluesDaddy]

Nice work! Frame is unaffected, I take it?

[wrk101]

Frame is OK. Needs a repaint, which I avoid like the plague. I need to find a reasonable cost PC in the Carolinas and this will be my first. Bought this bike to be a donor, so I don't have much into it.

[wrk101]

Extra credit bonus question: There are four bikes hanging behind the work stand. The closest bike is a so so Sanwa. Behind the Sanwa are two pretty good bikes. Then the last bike (furthest away) is a Giant MTB donor.

One of the two mystery bikes is made in USA. The other one is Japanese. Can you identify them?

[smontanaro]

Just attempted this with a Bianchi Brava. No go, as the opening between the bottom bracket and the seat tube is too small.

[Chris_in_Miami]

Extra credit bonus question: There are four bikes hanging behind the work stand. The closest bike is a so so Sanwa. Behind the Sanwa are two pretty good bikes. Then the last bike (furthest away) is a Giant MTB donor.

One of the two mystery bikes is made in USA. The other one is Japanese. Can you identify them?

Behind the Sanwa is a 1987 Schwinn Prologue (how many of those do you have now?) I can't tell what's behind the Prologue.