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This is a Firmstrong Urban Man 24" Single Speed:

bicycle on repair stand

I bought it used in a thrift store in the Salt Lake City, Utah, area.

As far as I know, the quill stem is not welded to the fork steerer tube, but I am unable to separate them:

quill stem inside fork steerer tube

I am working under the hypothesis that it is corrosively fused, since I have unscrewed everything that can be unscrewed, including the expander bolt. Here you can see there is a clean line of sight through the quill stem's bore:

quill stem hole

I tried applying some WD-40 Specialist Penetrant Fast-Acting to the edge of that steerer tube, hoping it would seep down into the crack, remove the corrosion, and allow the piece to come apart. That did not work, so I tried Blaster PB Penetrating Catalyst. That also has not worked:

blaster pb penetrant

rim of steering tube

I am looking for the proper way to just get this done.

Do I need a stronger chemical to eat through the corrosion? Do I need to be very careful in applying it right at the crack, repeatedly over and over, allowing it to keep eating through?

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    did you try whacking the expander bolt with a mallot? Commented 13 hours ago
  • I've been trying that, hasn't worked so far. Will explore applying heat with a heat gun next. Commented 12 hours ago

3 Answers 3

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I don't work with quill stems much but...would it work to do this? Get a long bolt that matches the threads of the quill stem bolt. The quill stem bolt might or might not work for this, depending on the length of the bolt and whether or not it has enough threaded length. Get a steel plate or something similar with a hole in it. Go to the underside of the fork, run the bolt up through the steel plate, and into the threads of the quill stem. The steel plate is a brace for the bolt, braced against the underside of the fork. You are now pulling the quill stem wedge DOWN and away from where it is stuck.

The only problem with this idea is that I don't know if a fork like this has access from below.

The problem with whacking is that you don't know where the primary "sieze" is. If it is between the stem and the steerer tube, whacking on the whole handle bar might help, but it will be driving the quill stem tighter. If the sieze is between the quill stem pieces, whacking on the bolt seems to make sense, but I think there will be too much buckling in the bolt to transfer the force to where it needs to go.

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    But if whacking the extended wedge bolt doesn't free the wedge, you know the wedge must be stuck, too. Commented 6 hours ago
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Reinsert the long quill stem bolt and thread into the wedge, but leave it loose. Tap the top gently with a rubber hammer, then less-gently, with increasing levels of force till it moves. If no luck then use a steel hammer for the shock/impulse.

You can also remove the front wheel and flip the bike over, then add penetrating oils under the wedge. IE, from "below" and let them soak upward. Heat might help, but getting heat on the steerer tube and not on the wedge might be a challenge. It might be possible to get the quill bolt or some matching threaded-rod into the wedge from below, and then into a slide hammer

Your other option is to not remove the stem and ride it at the current height, which makes bearing replacement extra hard.

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    You can also remove the front wheel and flip the bike over, then add penetrating oils under the wedge. We know the wedge is corroded into place, so putting penetrating oil at the top won't do anything to loosen the wedge until it can soak all the way down. I'd say turning the bike over and getting penetrating oil on the wedge is probably the first thing to try. Also there are better penetrating oils than PB Blaster. Kroil, for one. Or one part acetone, one part kerosene, one part automatic transmission fluid, and one part mineral spirits or turpentine - AKA "Ed's Red". Commented 6 hours ago
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Go to thermal shocking. The cold direction is safer; hot cooks finishes and can be more easily overdone. Finish Line Chill Zone is what I use. It can free most things near-deterministically. You have to use a lot of it all at once, moreso than is intuitive, which people struggle with and keeps it under the radar. Buy the 17oz can and use at least half of it, using the spray nozzle to hit it from the both top and bottom (putting the spray nozzle up through the underside of the crown), let it sit overnight for the penetrating oil component to do its thing, then reef some more. In these situations, unless you can rig a slide hammer just right to act with enormous force but also not break things, the initial breaking-free almost always comes with rotational force because of leverage, not from in-line force like a hammer strike to the expander from the underside. How you get that rotational force depends on what you're working with and what elements you're trying to save.

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