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  1. #1
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    Broken Brake Caliper Bolt Extraction

    I have a rigid fork that has a broken off caliper bolt in the brake mount post. I tried drilling it out, the plan was to attempt to re-thread after extracting, but I quickly realized that Shimano brake bolts are hardened and the drill bit wasn't doing a damn thing.

    Any chance I can get this thing out? Not sure what options I have or if I really want to try to helicoil if this thing gets hogged out.

  2. #2
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    Might be able to weld a nut to it. I have done that before with success.

  3. #3
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    Picture?

  4. #4
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    get a hardened drill bit and try again.
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  5. #5
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    Quote Originally Posted by SingleSpeedSteven View Post
    I have a rigid fork that has a broken off caliper bolt in the brake mount post. I tried drilling it out, the plan was to attempt to re-thread after extracting, but I quickly realized that Shimano brake bolts are hardened and the drill bit wasn't doing a damn thing.

    Any chance I can get this thing out? Not sure what options I have or if I really want to try to helicoil if this thing gets hogged out.
    You can successfully drill this out......start with a small drill bit and go up in size until you can get an EZ Out into the hole. Key is to use sharp quality drill bits.

  6. #6
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    The problem with drilling is that the bolt is much harder than the surrounding aluminium. It'll be very hard to drill the bolt out without it deflecting and doing damage to the fork.

  7. #7
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    I'd start with a small dremel bit to make a small bowl shape to keep the drill bit from wandering so easily. Goes without saying...carefully.

    Something like this, but others may have a better idea.

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  8. #8
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    Without seeing this it's hard to say but I've found that very often, you can just turn the bolt out.

    The bolt is held in by the pressure of the bolt-head against the face of the mounting post. Once the head snaps off, there is nothing holding the threaded part of the bolt in! If you can find any way to get a bit of purchase on the end of the bolt you can often turn it. I've seen me using a small flat-blade screwdriver just digging and pushing at the bolt, turning it a tiny bit at a time, until enough is out to get a grip on it and unscrew it.

  9. #9
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    Quote Originally Posted by Mr Pig View Post
    Without seeing this it's hard to say but I've found that very often, you can just turn the bolt out.

    The bolt is held in by the pressure of the bolt-head against the face of the mounting post. Once the head snaps off, there is nothing holding the threaded part of the bolt in! If you can find any way to get a bit of purchase on the end of the bolt you can often turn it. I've seen me using a small flat-blade screwdriver just digging and pushing at the bolt, turning it a tiny bit at a time, until enough is out to get a grip on it and unscrew it.
    Although quite often there's a reason it broke in the first place, like a cross-threading, heavy corrosion, etc. so in those cases it won't turn very easy.

  10. #10
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    Quote Originally Posted by Sparkman999 View Post
    Although quite often there's a reason it broke in the first place, like a cross-threading, heavy corrosion, etc. so it may not turn very easy.
    Quite. The OP will know if that's the case hopefully and if he's tried to drill it then it might be too late to turn it. Just mentioning it as much for future reference as anything. Turning the bolt is always the first thing I try.

  11. #11
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    Quote Originally Posted by Mr Pig View Post
    Quite. The OP will know if that's the case hopefully and if he's tried to drill it then it might be too late to turn it. Just mentioning it as much for future reference as anything. Turning the bolt is always the first thing I try.
    Good point. Would be quite frustrating to finally get a hole drilled, an ez-out in and then find out it turns relatively easily :-)

  12. #12
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    I would try the screw driver thing first. There is plenty of times where the snap was when trying to remove (or during installation too) and putting to much torque on it. In which case it may back right out.

    As for drilling, no dremel. Use a fine point center punch to create the indent in the center of the bolt and use quality bits. Starting tiny and work up. Be very careful not to snap the small bits off and that your going in straight.

    Cobalt bits are best when dealing with hardened bolts but regular steel bits work too. DO NOT just run max speed on the drill, keep the speed down as low as you can manage, use wd40 or cutting oil (not bike oil or motor oil, they lubricate too well and hinder the ability for the drill bit to cut) and slowly drill it out.

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  13. #13
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    how did u manage to snap the bolt

  14. #14
    BOOM goes the dynamite!
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    Quote Originally Posted by RAKC Ind View Post
    I would try the screw driver thing first. There is plenty of times where the snap was when trying to remove (or during installation too) and putting to much torque on it. In which case it may back right out.

    As for drilling, no dremel. Use a fine point center punch to create the indent in the center of the bolt and use quality bits. Starting tiny and work up. Be very careful not to snap the small bits off and that your going in straight.

    Cobalt bits are best when dealing with hardened bolts but regular steel bits work too. DO NOT just run max speed on the drill, keep the speed down as low as you can manage, use wd40 or cutting oil (not bike oil or motor oil, they lubricate too well and hinder the ability for the drill bit to cut) and slowly drill it out.
    See, I knew there would be someone with a better idea...OK, no dremel! Center punches were already on my ever-growing "tools to buy" list.

  15. #15
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    Also use a counterclockwise drill bit. Using a counterclockwise drill bit will many times extract the bolt during the process of drilling.
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  16. #16
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    Quote Originally Posted by Mr Pig View Post
    The problem with drilling is that the bolt is much harder than the surrounding aluminium. It'll be very hard to drill the bolt out without it deflecting and doing damage to the fork.
    OP might be able to find a steel insert (like shock mounting hardware) to protect the threads and still allow a small hardened bit through to the bolt.

  17. #17
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    Can you remove the brake post and replace it or access the back side of the brake post?

  18. #18
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    Start with a center punch, then a center drill then a LEFT hand twist drill bit, preferably a stubby one so it will flex less. Often times the left hand bit will back the bolt out on it's own. This is infinitely easier to do in a drill press than with a hand drill. If you get to the bottom of the bolt and it's still in there, go with an easy out. You will likely need to re-form some of the threads.

  19. #19
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    the suspense is killing me! is the bolt out?!!

  20. #20
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    The OP has departed the scene or decided to ignore the thread.
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  21. #21
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    Would be the latter, just saw a post by him a bit ago

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  22. #22
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    I am still here! Been busy and haven't had time to mess with it... I don't know if the screw driver trick will work as it's broken off below the neck of the bolt hole. I think my best bet is going to be a left handed drill bit, which I completely forgot existed...

    As for how did I break it off, it's a brand new fork and got coating down into the threads. I was threading the bolt in a small bit at a time, backing it out, and repeat trying to clean the threads. Stupid, I twisted a little too hard and the bolt popped.

  23. #23
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    What's 'coating'?
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  24. #24
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    Quote Originally Posted by SingleSpeedSteven View Post
    it's a brand new fork and got coating down into the threads.
    What's 'coating'?
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  25. #25
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    I believe this fork is powder coat... not 100% sure though.

  26. #26
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    Broken Brake Caliper Bolt Extraction

    Quote Originally Posted by RAKC Ind View Post
    I would try the screw driver thing first. There is plenty of times where the snap was when trying to remove (or during installation too) and putting to much torque on it. In which case it may back right out.

    As for drilling, no dremel. Use a fine point center punch to create the indent in the center of the bolt and use quality bits. Starting tiny and work up. Be very careful not to snap the small bits off and that your going in straight.

    Cobalt bits are best when dealing with hardened bolts but regular steel bits work too. DO NOT just run max speed on the drill, keep the speed down as low as you can manage, use wd40 or cutting oil (not bike oil or motor oil, they lubricate too well and hinder the ability for the drill bit to cut) and slowly drill it out.

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    Exactly what RAKC said especially about drilling slow rpm with a sharp bit and using a cutting oil. Honing oil from a knife stone kit works well. Also I would add, use good firm pressure against the bit and make sure the bit is inline with the stud as youíre drilling. If youíre going to try a left spin drill bit and the stud doesnít start to back out, apply some liquid wrench and some heat to the boss using a blow dryer or heat gun, but do not overheat it beyond touch. This can expand the aluminum which expands more then the steel and also soften up any threadlocker that could be on the stud. If the left spin drill doesnít spin it out then use an ez out. Make sure to use a drill and ez out only about half the diameter of the stud. Otherwise if to big you stand the chance of expanded the stud even tighter into the boss threads with the ez out as youíre tightening it into the stud hole. Drill deep enough to allow the taper of ez out to grip the stud. Drill size for each size ez out is usually stamped on the side of it. Try using heat again if itís still not loosening. Let us know if you got it out.


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    Last edited by muddydc; 03-25-2018 at 11:20 AM.

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