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Removing Sheared Mounting Bolt From Front Derailleur

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Removing Sheared Mounting Bolt From Front Derailleur

Old 07-20-13, 11:07 AM
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Removing Sheared Mounting Bolt From Front Derailleur

Hey Y'all,

I have a vintage Campy Chorus (I think) clamp-mounted front derailleur where the mounting bolt has sheared off in the clamp hole. There's about 1-2mm of bolt sticking out, which I could try to go at it with some pliers, but I'm guessing that wouldn't work and might make things worse (especially re: the bolt threads.) So I'm looking for the fastest/cheapest/best way to extract it. One thing: I don't have any power tools at my shoebox sized apartment, so I'd probably need to take it to a hardware store or some other shop for assistance.


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Old 07-20-13, 11:42 AM
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Vice grip pliers?
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Old 07-20-13, 11:48 AM
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Your luck in getting this out really depends on how and why it broke.

If it broke while the clamp was still loose, then it was probably cross threaded and the torque it's jammed in with is going to be very high (high enough the break the bolt in the first place) so getting it out without drilling it out is not likely. Also odds are the threads in the aluminum part are already buggered.

OTOH- if it broke when the clamp was tight and you simply over torqued it, then it should come out easily now that the load is off. Get a pair of pliers with good teeth DOA and you're not touching the internal threads in the FD body.

You know how it broke so you know the odds, but might as well give the pliers a go. But looking at the photo, I suspect that it might be cross threaded, so you may be SOL.
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Old 07-20-13, 12:26 PM
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Get some good penetrating oil (I prefer Kroil or PB Blaster), apply it and let it soak in for several hours. This will help to get the bolt unstuck whichever means you use to twist it.

If you can get a Dremel tool with a narrow cutoff wheel you might be able to cut a slot in the stub which will allow you to drive it out with a straight screwdriver.
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Old 07-20-13, 05:01 PM
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Thanks for the replies all. If anyone else has any other advice I'm all ears. I intend to pick a strategy in the next couple of days and give it a whirl.

By the way FB, I don't know how the bolt was sheared as I inherited the part. As far as I can tell it looks like a pretty clean break, but then again of course I can't see anything inside the threads so who knows what the story is in there.
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Old 07-20-13, 09:05 PM
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I have had luck with a method of using a small center punch tool and , small size hammer. At flat break off is make punch to make indentation , then use this point to angle tap center punch in ccw direction. to loosen bolt, when loose use plieres to remove. broken bolt
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