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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 01-26-06, 08:38 PM   #1
roccobike
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Trying to Separate Schwinn Fork from Stem

I picked up an old, 80's, Schwinn 10speed that has a heavily rusted frame. I'm trying to remove the fork and found, not suprizingly, it is frozen to the stem. I searched the forum and tried the following, I removed the center bolt and sprayed liquid wrench into the tube, then I inverted the bike and sprayed the tube from the bottom, then waited one day. I backed out the center bolt about 1/4 inch and hit it with a rubber mallet to break the quill loose. The threads promptly stripped so the center bolt has no purchase at all. I've loosened the nut at the top of the head so the fork and stem, together, are loose within the frame, but there is no separating the two. Short of taking a saw to the stem, is there anything else I can do to separate these two and salvage the fork?
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Old 01-27-06, 12:46 AM   #2
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Sorry to tell you that mr hacksaw is the best bet. Had a similar thing happen and after 2 weeks of trying every suggestion on this forum and doing the rounds of bike shops I ended up cutting the top off the stem. Then with a friend I put the remains of the stem in a vice, wrapped the steering tube/fork joint in a wet rag (it was bonded rather than brazed) and heated the steering tube while the forks were gradually twisted. In my case the stem was aluminium and the steering tube steel. Steel expands whereas aluminium has almost no expansion when heated. Came apart nicely. If you try this just remember to let the steering tube air cool (dont put it in water)
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Old 01-27-06, 11:49 PM   #3
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If you pull the quill bolt out and saw across the vertical section of the stem, you should be able to remove headset nuts and lightly tap the fork steerer right out the bottom of the head tube without using heat. If materials engineering has not changed since I was in school over 30 years ago, I seem to remember that aluminum expands more than steel when heated. That is a good reason not to use heat when the aluminum part is on the inside. Now getting that wedge out of the steerer could be a slight challenge but at least you have it where you can get to it. Replacement stems are pretty easy to come by and at bargain prices. Good Luck
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Old 01-29-06, 05:38 PM   #4
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Question: is the stem aluminum or steel? I'm assuming that it's aluminum. If so, then the aluminum is probably chemically bonded/fused to the steel fork's steerer tube.

First, you need to get the stem's wedge out, so you know that you're fighting only against the bonding between alumium quill and steel steerer tube. Since your quill bolt is stripped, use it as a punch - there are flat parts of the expander bolt next to the (formerly) threaded hole - get the bolt sitting on this flat part (you'll figure it out by feel) and then use the hammer.

Once you get this out, have someone hold the fork blades while you twist at the stem extension. If you can get the stem extension in a vice and twist the fork blades yourself, and hopefully loosen the connection. Initially, the hacksaw won't be of any use, because it won't get the quill out of the steerer tube, it'll just cut the top off which will leave you with zero leverage on the quill itself.

mentat6059's suggestion is good as a last resort, depending on whether steel or aluminum expands more. I can't answer that question, but Google probably can.

That all said, given what you've said about the bike, salvaging the fork probably isn't that big of a deal.
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Old 01-29-06, 06:00 PM   #5
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Thanks to mentat6059, robhunterx and timcupery. I was wrong about the quill. It appears that the quill is completely loose as I can see it moving around when viewed from the bottom of the fork. That said, Yes, it most certainly is a steel fork with an aluminum stem and the metals have reacted together. I think I'll try timcupery's approach first.
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Old 01-29-06, 07:22 PM   #6
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Also, if the stem isn't all the way down into the steerer tube (that is, some of the quill is showing above the headset), you could take the hammer to the top of the quill stem, try to pound it down into the steerer tube to dislodge it.
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Old 02-04-06, 01:53 AM   #7
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Use some Magic Mystery Oil (auto parts store) to soak the offending parts. It is an excellent penetrating oil. Loosen the bolt. Take a pine 2 x 4 and place it on the stem and wack it with a hammer. Should come loose. The wedge is probably rusted in place.
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