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  1. #1
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    Broken Disc Brake Bolt

    So, I have a bit of a pickle...

    Working on my bike this past weekend, I noticed that the head of one of the 6 rotor bolts had broken off. The break is below the lip of the threads on the hub - so I can't grab any part of the remaining bolt.

    How do I get this out?

    It's a DT 240 rear hub - so I don't want to toss it.

    Can I run it with 5 of 6 bolts?

  2. #2
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    Running 5 bolts should be fine.......its happened to me and I was able to drill out the broken bolt, I just did it with normal drill bits....I'm sure its easier with the correct extraction bits.....

  3. #3
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    Should not be any tension on the bolt remaining in the hole so even a small screwdriver or pick could be used to back it out. Or out the other side if open. Push the screwdriver tip into the center of the bolt and turn while gently tapping with a small hammer.
    Left-hand drill bit or regular bit and an easy-out. Need a steady hand to not damage the hub.
    Take it to the LBS or a trusted auto repair/machine shop.

  4. #4
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    If you have access to a Dremel tool, use a cut-off wheel to cut a small slot on the top of the bolt and then back it out with a flat-head screwdriver.
    Go on ahead, I'm gonna take a breather.

  5. #5
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    Quote Originally Posted by LWright View Post
    Should not be any tension on the bolt remaining in the hole so even a small screwdriver or pick could be used to back it out. Or out the other side if open. Push the screwdriver tip into the center of the bolt and turn while gently tapping with a small hammer.
    Left-hand drill bit or regular bit and an easy-out. Need a steady hand to not damage the hub.
    Take it to the LBS or a trusted auto repair/machine shop.
    The bolt broke inside the threads the ragged edge of the break is gonna lock tha sucker in there tight.

  6. #6
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    Quote Originally Posted by venture View Post
    So, I have a bit of a pickle...

    Working on my bike this past weekend, I noticed that the head of one of the 6 rotor bolts had broken off. The break is below the lip of the threads on the hub - so I can't grab any part of the remaining bolt.

    How do I get this out?

    It's a DT 240 rear hub - so I don't want to toss it.

    Can I run it with 5 of 6 bolts?
    You can run 5 bolts instead of six......

    But the thing broke with six so don't be to surprised if another one breaks....

    On the other hand the broken bolt could have been installed improperly...(cross threaded, sitting high over-torqued....or it could have been subjected to some type of corrosion....

    Get it out if you can...maybe the hub is also damaged.

  7. #7
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    I wouldn't run (5) bolts on a dt 240 hub. I mean, I would never risk damaging my hub when I could simply take the rotor off and take the wheel to my local machine shop and have them extract the broken bolt for $10.00 or $20.00 because spending that little bit and having it done right is so much better than you doing something you have never done before. Yeah, I could see if it was a cheap $40.00 or $50.00 hub, then have at it, but dt 240's aren't cheap so I wouldn't risk ruining the hub.

  8. #8
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    Thanks for the input - I will try some simple attempts (small screw driver, pic - but I suspect the LocTite might prevent such a simple solution) - and if that doesn't do it, then I'll take it to a machine shop....

    I don't want to risk damaging the hub.

  9. #9
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    The small size of the bolt makes it difficult but I've had good luck with this method.
    You can take a normal drill bit and regrind the cutting edges backwards. It's easy to do, have another drill bit beside you to look at while you do it. Doesn't have to be a great job, it's only for one use.
    Set your drill to run backwards and start drilling the bolt. Since there shouldn't be any tension on the bolt and the heat of drilling will soften the locktite, I've had the friction of the drilling wind the bolt out every time I've done this.
    Much easier than it sounds.

  10. #10
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    Before you mess it up, I'd just take it to a machine shop, they will likely do it for under 20.
    Riding.....

  11. #11
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    Put some heat on it, torch, lighter, whatever to help break the bond from the loctite

    Don't go overboard. Aluminum will expand faster than steel with the heat so you get that working for you too. Other then that I'd second the slot, or pick / screw driver methods that people have mentioned.

  12. #12
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    Snapped off Torx rotor bolt head, how do I get it out?

    An extractor and some patience worked for me!

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