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Thread: Broken Bolt -- Front Strut/Frame

  1. #1
    Registered User roger 04 rt's Avatar
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    Broken Bolt -- Front Strut/Frame

    Yesterday I broke the bolt (M8x25) that holds the strut going from the forward frame, in the area of the oil cooler line and alternator, it broke flush with the frame.

    The bolt went in easily but when I went to torque it, it turned more than it should have. I took it out, examined it, put it in and proceeded to tighten it with a hand allen wrench (4"). It snapped then.

    Is there any reason I shouldn't drill a hole into the bolt and back it out--or is there a better way?

    Also, I haven't broken or stripped a bolt for about 40 years so I'm kind of surprised this happened. M8 is pretty big. Does it sound like a defective bolt, one that was over-torqued originally, or some thing that I did wrong?

    Can I use any old bolt that I find that fits or does it need to be the BMW part?

    Thanks for any help.
    RB

  2. #2
    maacova maacova's Avatar
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    Bolt

    If you broke it by hand you did nothing wrong. I do almost all the work on my 04 RT with a little 4" long ratchet that has 1/4" drive on one side and 3/8" drive on other. I don't want any chance of too much power. My wife calls me "Bull" because I break things and I need it to be things other than my RT.

    Ken Denton

  3. #3
    Registered User
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    try this first

    If you have enough room to work try a center punch and a hammer to back the bolt out. Place the punch near the edge of the broken bolt. Make a punch mark like normal. Then lean the punch over to push in a counter clockwise direction. Be sure you're not so close to the edge that you peen the threads together. If the bolt doesn't move fairly easily stop before you do too much damage. You still want the option to center punch the bolt for drilling. This doesn't work every time but, it works often enough to try first.

    If you don't want to use the factory bolt just be sure to get one the same grade as the original. If you had been using a grade 8 bolt in your current situation you might be looking at repairing threads with a helicoil instead of removing a bolt. Helicoils are much less fun to install by hand.

  4. #4
    Registered User mneblett's Avatar
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    If you have enough room to get a center punch in there, center punch it firmly and then use a left-handed drill bit with your drill in reverse.

    Often, just the left-hand torque will drive the stud out after a bit of being heated/hammered by the drill bit.

    At worse, you'll have created a good hole for an easy-out. Be careful to not go so deep that you penetrate the bolt and start going into the block.
    Mark Neblett
    Fairfax, VA
    #32806

  5. #5
    Registered User roger 04 rt's Avatar
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    Gents. Thanks. Drilled a small hole, forced an Allen wrench in and the bolt backed right out. Now realize that I had read the wrong torque spec. Most of the soft M8 bolts are speced for about 20 nM but I had seen strut to frame of 58--dumb. Swapped in a footplate bolt which will work until I get a replacement.

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