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Thread: JBL 2447 broken threaded bolt

  1. #1
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    JBL 2447 broken threaded bolt

    One of my 2447 compression drivers have had one of it’s threaded bolts for fastening the horn taken a hit before my ownership. Unfortunately I could not resist the temptation to try to straighten it up and in the process snapping it right off. Do anybody know how these are attached to the driver? Are they just screwed in or is it possible to reach them from inside of the driver?
    I have searched for this bolt as spare part but without any success. Do you know if they are available from JBL?
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  2. #2
    Senior Member 1audiohack's Avatar
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    It is a stud threaded into the top plate. The magnet blocks the back side access.

    They are hard and often held with LocTite so drilling it out will be a difficult task.

    You could double nut one of the other studs to determine if yours are held with thread locker.

    In my world we fixture it in a vertical mill, flatten what’s left with an end mill, then you can make good center to use a reverse drill bit to see if it might just back out once the bit starts to cut. If not, a bolt extractor in the drilled hole next, if not, milling the minor diameter out and picking the threads clean after that. Dentistry.

    Or you could just use the remaining three.

    Barry
    If we knew what the hell we were doing, we wouldn't call it research would we.

  3. #3
    Administrator Mr. Widget's Avatar
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    “In my world we....”

    Oh, come on Barry.... in your world this never happens. 😉


    Widget

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    Senior Member rdgrimes's Avatar
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    A mechanic would use an "Easy-Out" of appropriate size.

  5. #5
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    “In my world we....”

    Oh, come on Barry.... in your world this never happens. 😉


    Widget
    Right. I wish! Haha.

    I have a brand new diff case assembly one of my guys stuck a pinion cassette retainer bolt in. Likely ran over a machine curl stuck in the female threads.

    At least my guys stop and leave the salvage operation to me.

    On topic I bought six new 2451’s that I wanted t use on some horns that other fasteners would have been more ideal but they are thread locked in permanently. Double nutted they don’t give a bit. I am pretty sure they will break before they let go and I am damn sure not going to go there.

    Just the way it goes, most times.

    Barry
    If we knew what the hell we were doing, we wouldn't call it research would we.

  6. #6
    Senior Member 1audiohack's Avatar
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    Quote Originally Posted by rdgrimes View Post
    A mechanic would use an "Easy-Out" of appropriate size.
    Right you are.

    And after they break the “easy out” off (that measures in the high 60’s Rockwell C scale) in the crooked hole they drilled, they will bring it to a machinist to save their ass!

    Don’t get me wrong, I know I am not the only guy that can remove broken fasteners but it sometimes feels like it.

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  7. #7
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    Thanks for info and ideas. If it is thread locked maybe find a 6mm nut and put it on top of the bolt and weld in the hole. Maybe the heat will loosen the thread locker. Or maybe if I'm able to screw one of the other bolts out with a flat screwdriver, then maybe I can cut a slot in it with a dremel.

  8. #8
    Senior Member DogBox's Avatar
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    Talent to good Use!

    Quote Originally Posted by 1audiohack View Post
    ....I know I am not the only guy that can remove broken fasteners but it sometimes feels like it. Barry.
    Yeah, but at least you get to be 'good' at it!

    [had quite a few in my time too. I hate Loctite!]

    DogBox

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