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I am hoping for some advice to remove a crank bolt from my Campy Chorus cranks. I was trying to loosen them and on the drive side I smoothed out the opening of the 8mm Allen bolt so that I can't get a good grip. What can I do to get a secure enough grip in order to loosen it? Thanks
 

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If that doesn't work, use a screw extractor. You'll need to drill a hole so you'll want to be careful, but they are very effective. You can pick a set of them (multiple sizes) up at any home improvement store.
 

· "Cypress Gardens" Fl.
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Good Idea............

wim said:
Unless you rounded the opening out completely, see if you can get a 3/8" SAE hex in there. It's about 9.5 mm metric.
but if that dont work try to file the flats of the allen head until the 3/8" hex does fit. Try to restore the rounded hex of the bolt, and if the 3/8 hex wrench still does'nt quite fit, but is close, then hammer it into the bolt.

Try all that before using a screw extractor.
 

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All good ideas,

but one more bit of prep work might be advisable. Before you mess with the wrenches again, lay the bike down on its side, spray a lot of penetrating oil around the bolt head, and let it soak a few hours. I'm assuming it's seized or at least vey tight, and that contributed to your original problem.
 

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croswell1 said:
but if that dont work try to file the flats of the allen head until the 3/8" hex does fit. Try to restore the rounded hex of the bolt, and if the 3/8 hex wrench still does'nt quite fit, but is close, then hammer it into the bolt.

Try all that before using a screw extractor.
Umm, allen bolts have the flats on the INSIDE surface of the head. Can't file the flats. Also, if it were a conventional bolt, I'd think filing would be out anyway, since it's down in the crank.

OP: Make sure you've stripped the hole all the way to the bottom. Sometimes you can strip the bolt because you didn't have the tool engaged well enough, and this can leave some good flats farther down in.

My progression is:

1. Valve grinding compound along with the correct-sized allen wrench (sometimes the extra friction will get you there if the hole isn't too stripped).

2. Hammer in a slightly-oversized allen wrench.

3. Screw extractor.

Notes: Use an old/cheaper wrench for 1 and 2--both methods can really fark up your tools. For number 2, be very careful not to break off part of the tool in the bolt, or you're done. Drilling out the bolt isn't even an option when there's a hunk of allen key in the hole. Don't use ball-end allens for this purpose because of the risk of breakage.
 

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I think he meant

bikeboy389 said:
Umm, allen bolts have the flats on the INSIDE surface of the head. Can't file the flats.
file the flats of the WRENCH.
 

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JCavilia said:
file the flats of the WRENCH.
OK, I get it. Didn't read it that way, but I can see it. Perhaps the idea of filing down an allen key sounds so crazy to me the idea wouldn't fit in my head. Whatever. Thanks for the clarification.
 

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Couple comments...
"filing" an allen key means "grinding". If the tool is soft enough to file, it ain't worth using.

At the very least, you'd want to use a tap-handle on a screw-extractor for symmetrical torque application - extractors are quite brittle, actually, and any side-force can shatter 'em.
And if the bolt is part of a self-extractor, I would be surprised if a screw extractor is gonna allow enough torque for succesful removal without itself breaking off in the bolt. Can the self-extractor "ring" be removed from the crank so you're just working with the bolt? (then use a traditional crank-puller)
 

· Chili hed & old bike fixr
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I have been working with allen wrenches for over 40 years and have used the best brands available and have modified many as required. They are all filable and all can be hack-sawed to alter the length. If you cannot do this, look in the mirror, It ain't because the wrench is too hard, but what's between your ears is way too blunt, er, dull!
 

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The left-hand-threaded type crew extractors are very hard. That makes them extremely brittle. When you snap off the end of a screw extractor in a screw, you are really screwed! You need to use a torch or a grinding tool.

If it were me, I'd find a tight fitting allen wrench ("8mm" can vary), grind/file off the end so it has sharp edges, and put it in an impact driver. Then lay the bike down and put a block of wood under the bottom side to support the end of the BB, get an assistant to hold the crank, and hammer on the impact driver. Impact drivers are about $15.
 

· Chili hed & old bike fixr
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Since the hex is boogered anyway, you can drill the head off of the screw. Start in the center of the allen recess. There is usually a depression in the center, drill with a small drill, 1/8 or smaller down about a 1/4 inch into the screw. Gradually increase the drill size until you get to 5/16, and the head should pop off onto your drill bit. Now there will be no torque on the screw and you can grab it with needle nose pliers and unscrew it. Buy a new on, you are good to go. I have done this oodles of times in years of machine repair.
 

· "Cypress Gardens" Fl.
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"bikeboy..bikeboy..bikeboy..............

bikeboy389 said:
Umm, allen bolts have the flats on the INSIDE surface of the head. Can't file the flats. Also, if it were a conventional bolt, I'd think filing would be out anyway, since it's down in the crank.QUOTE]

What are we going to do with you? :D
For clarification;........You Can file the flats on the inside hex of the allen bolt, and "no" we're not talking about a conventional eight-sided bolt. The point of my post was to try and restore the sharp consentric angles of the allen head. After all, it is rounded, correct??
No matter what size allen key you stick into it, you're still faced with a rounded allen head, right?

Not trying to be mean or anything, but the allen bolt has to be restored as best as you can get it, or you will have to drill it and back it out with a screw extractor. Use a small file with a squared end, and file the flats square. It does'nt make any difference what size it turns out to be, just get it square. You can always file the next size up allen key to fit, and then you'll be good to go.
 

· 100% torqued
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You won't be able to file or improve the interface between an allen and the wrench. Just drill that sucker out. Get a 1/4" or so bit and just simply drill right into the center of the bolt. the edge will pop free and you can remove the center with a needle nose as mentioned above. I ain't rocket surgery.
 

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curlybike said:
... If you cannot do this, look in the mirror, It ain't because the wrench is too hard, but what's between your ears is way too blunt, er, dull!
Offering an idea from experience and in good faith - $0.02

Having bullcrap called on your idea - part of human discourse

Gratuitous personal attack - PRICELESS display of character.



Thanks, curlychild, for making it so easy to ignore you from here on.
 

· "Cypress Gardens" Fl.
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Feel ya Dude...........

austex said:
Offering an idea from experience and in good faith - $0.02

Having bullcrap called on your idea - part of human discourse

Gratuitous personal attack - PRICELESS display of character.



Thanks, curlychild, for making it so easy to ignore you from here on.

Dont you just love it when someone rudely "steps on you" without a polite "excuse me", sending the message that you dont know what you're talking about?

Personally, I dont deal with that. It's an attempt to cheapen my integrity, and I wont stand for it.
 

· "Cypress Gardens" Fl.
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Oh yes you can..........

Howzitbroke said:
You won't be able to file or improve the interface between an allen and the wrench. Just drill that sucker out. Get a 1/4" or so bit and just simply drill right into the center of the bolt. the edge will pop free and you can remove the center with a needle nose as mentioned above. I ain't rocket surgery.
and I'm not going to be called on this again. THINK ABOUT IT ! Dont you think 'Peltz's' original problem at least merits a try at restoring the allen head before taking the drastic measure of drilling it and risk ruining a perfectly good bottom bracket if his drill line is off??

That, my friend "is not rocket surgery" :mad2: :mad2:

On your line of thought, if he drilled it enough for the head to "pop off", like you say, he would be drilling into the threads of the spindle - ruining his bottom bracket.

you're not going to "cheapen" my integrity, hoss
 

· Chili hed & old bike fixr
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croswell1 said:
and I'm not going to be called on this again. THINK ABOUT IT ! Dont you think 'Peltz's' original problem at least merits a try at restoring the allen head before taking the drastic measure of drilling it and risk ruining a perfectly good bottom bracket if his drill line is off??

That, my friend "is not rocket surgery" :mad2: :mad2:

On your line of thought, if he drilled it enough for the head to "pop off", like you say, he would be drilling into the threads of the spindle - ruining his bottom bracket.

you're not going to "cheapen" my integrity, hoss
Sorry, but if you only drill deep enough to pop the head off you are a fair distance from the spindle threads. this leaves enough threaded shank to grab and remove the threaded piece that now has no load on it.
I really don't care if you like me or not, but I am trying to help you all by getting the facts out there. You can persist in doing it the hard way if you want, I got no dog in this fight. I do Know that there are a lot of folks that give advice that shows lack of knowledge. If I call them on that, that makes me a bad guy, I think not. Better for all to use their heads and pick up hard learned knowledge the easy way.
 

· Chili hed & old bike fixr
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austex said:
Offering an idea from experience and in good faith - $0.02

Having bullcrap called on your idea - part of human discourse

Gratuitous personal attack - PRICELESS display of character.



Thanks, curlychild, for making it so easy to ignore you from here on.
Please do, I certainly wouldn't want to hurt your delicate little feelings again.
 

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Before doing anything else, try using a brand new 8mm allen wrench. That'll work more often than you'd imagine. If that works, throw away your old wrench before it can round off anymore bolts.

If that doesn't work, go to a tool store and buy a screw extractor AND THE RIGHT SIZE DRILL BIT TO GO WITH IT. Drill a hole as close to the exact center of the bolt as you can and twist the screw extractor counterclockwise down the hole.
 
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