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Old 05-28-11, 11:48 AM   #1
jonwvara 
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penetrating oil soak for fluted seatpost

I'm tying to get the stuck seatpost out of my Gran Sport frame. It's a fluted Sugino post. If it were smooth, I'd turn the frame upside down and pour some PB Blaster down the seat tube through the bottom bracket and let it soak like that, but if I do that with the fluted post the oil will all run out.
Is there some good way to seal up the gaps between the flutings and the seat tube to keep the oil from leaking out? Plumber's putty? Some kind of wax? PB Blaster seems to dissolve a lot of things, so I'm not sure what might work.
I'm not at all averse to experimenting on my own, but since the whole point of this forum is to prevent unnecessary and repeated re-invention of the wheel, I thought I'd see if anyone else already has an answer to this one.
I just hope this doesn't turn into a complete fecking nightmare. I'm probably due for one--have dealt with a bunch of somewhat-stuck posts in the past, but nothing that required heroic measures.
Well, okay, there WAS one that I required the combination of finesse and brute strength that is the hallmark of Frank the Welder. Maybe I will threaten this frame with him and see if that causes it to panic and loosen up.
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Old 05-28-11, 11:59 AM   #2
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Seat post flutes seldom (if ever) extend for the full length of the post. I don't have any examples of the Sugino post here to check, but the pictures I've found of various Sugino models suggest the fluting stops well above the end of the post:

http://www.velobase.com/ListComponen...4-4010b4f3cdb4

Go ahead and invert the bike and pour in some penetrating oil!
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Old 05-28-11, 12:05 PM   #3
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Quote:
Originally Posted by JohnDThompson View Post
Seat post flutes seldom (if ever) extend for the full length of the post. I don't have any examples of the Sugino post here to check, but the pictures I've found of various Sugino models suggest the fluting stops well above the end of the post:

http://www.velobase.com/ListComponen...4-4010b4f3cdb4

Go ahead and invert the bike and pour in some penetrating oil!
So you think these flutes don't extend to the bottom? If so, perhaps I could soak upside down and right side up in sequence, and soak the whole post that way?

Later edit: The simple expedient of shoving a partially straightened paper clip into the flutes seems to show that they extend about 1 1/2 inches below the top of the seat tube, or a little more than 3 inches from the top of the post.
So I guess I can squirt some PB blaster into the open tops of the flutes and let it soak like that for a few days--thus soaking the fluted area--then turn it upside down and pour some oil in from the bottom, soaking the unfluted bottom part of the post. I'll post back when I've given it a chance to work.
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Last edited by jonwvara; 05-28-11 at 12:15 PM. Reason: Uncharacteristic flash of insight
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Old 05-28-11, 12:14 PM   #4
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That should work in theory, but I would use 10% ammonia instead of PB Blaster. It doesn't work terribly well on fused aluminum. Of course, you might get lucky with it; and I hope you do.
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Old 05-28-11, 01:14 PM   #5
wrk101
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+1 Flutes do not go all the way.
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Old 05-28-11, 06:44 PM   #6
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I think the ammonia works best to release the bond between the aluminium and the steel although I had the same problem a few years back and I tried for about a year (off and on) to loosen the seatpost enough to extract it. I did save the post and the frame though.
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