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  1. #1
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    Longer bol for damaged PM thread ok?

    I have Magura Julie HP disc brake installed on a Magura Durin Race fork.

    Last day i damaged the lower PM thread but now im using a longer bolt and its tight enough to recommend torque.

    I wonder if this is perfectly ok or its not a good subsitute for the original (shorter) bolt?

  2. #2
    dru
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    It's only Ok if you aren't bottoming out the bolt in the hole.

    Drew
    occasional cyclist

  3. #3
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    What do you mean bottoming out?

  4. #4
    dru
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    Bottoming out means that the bolt is threaded into the hole until it is touching the bottom. Your brake caliper could actually be loose on that mounting hole and you'd still get a good torque reading since the bolt is actually tightening itself against the bottom of teh hole and not against the parts it is supposed to be holding (your brake caliper).

    Just unbolt the caliper and measure the thickness of the mounting tab (eyeballing will probably work) and compare that to how much room you have on the new longer bolt when you thread it all the way into the post mount hole.

    Drew
    occasional cyclist

  5. #5
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    the end of post mount hole is open. I mean there is no botom. so the bolt goes all the way until it securely tightens the disc brake.. is this ok?

  6. #6
    Owl
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    Quote Originally Posted by Floriante View Post
    the end of post mount hole is open. I mean there is no botom. so the bolt goes all the way until it securely tightens the disc brake.. is this ok?
    Yes that sounds okay, but also check to make sure you have at least more than 3 or 4 turns of thread left past the stripped threads, or you'll just end up stripping the rest too.

    -Edit-, on second thought, I strongly suggest you attempt a repair on the stripped threads too, by using an epoxy injector or heli-coil. Combined with the longer bolt, you'll have a fail-proof part.

  7. #7
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    I have to drill the hole first and then insert helicoil right?

  8. #8
    Owl
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    Quote Originally Posted by Floriante View Post
    I have to drill the hole first and then insert helicoil right?
    yeah, the helicoil kit basically lets you tap in a larger thread, then insert the helicoil to squeeze it back to the original thread size

    You also have other options like Permatex 81668 Stripped Thread Repair Kit : Amazon.com : Automotive , which, if the ratings are as specified, is strong enough to hold down the calipers without having to drill and tap.
    Last edited by BluPenguin; 10-14-2012 at 04:32 PM.

  9. #9
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    A heli-coil would be the preferred fix for that. It might be OK the way it is but it's your front brake and I wouldn't want to take any chances with that.

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