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Thread: Crank bolts

  1. #1
    Ubiquitous Fella That Guy's Avatar
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    Crank bolts

    I've been having a problems with the crank bolt backing out on my Tru-Vativ cranks. I don't have a torque wrench big enough to torque it to spec, but I'm giving it all I've got and its still backing out. Maybe I'm just a weenie. Anyway so I pulled it apart and took a look. There was a ridiculous amount of grease on the threads and I'm wondering if that would do it? I removed much of the grease, reassembled, and went for a quick ride. Okay so far. But any ideas on other stuff to check?

  2. #2
    cab horn
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    the torque
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    Senior Member MudPie's Avatar
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    Quote Originally Posted by That Guy View Post
    I've been having a problems with the crank bolt backing out on my Tru-Vativ cranks. I don't have a torque wrench big enough to torque it to spec, but I'm giving it all I've got and its still backing out. Maybe I'm just a weenie. Anyway so I pulled it apart and took a look. There was a ridiculous amount of grease on the threads and I'm wondering if that would do it? I removed much of the grease, reassembled, and went for a quick ride. Okay so far. But any ideas on other stuff to check?

    Typically, crank bolts are torqued to about 30 ft-lb. That's quite a bit of torque, and something that cannot be generated by a tool that fits in the palm of your hand. I use a 1/2" drive torque wrench with a 15" long handle, and that even takes quite a bit of muscle. What kind of tool/handle are you using to tighten that bolt.

    I always grease my threads and torque to spec and never had a problem in 10+ years of riding.

  4. #4
    Senior Member prschaa's Avatar
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    I checked the torque specs for Truvative Crank Bolts, not sure which set you have but they are listed anywhere from 42-47 N-m or 372-416 inch-lbs. Like mudpie said, a long handled Tq wrench is a good idea. autozone will rent you one if you don't want to buy one.

  5. #5
    Yes it is a paradox
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    Use blue Locktight on the threads if all parts in contact are metal. Auto part store like Autozone have Locktight.

  6. #6
    Sister Annie Sianelle's Avatar
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    If there's too much grease in the blind hole the bolt threads into you'll be trying to tighten the bolt down on a plug of grease and you'll never get it to stay tight.
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    have you checked to see if it has stripped the thread on the bottom bracket if it has then you will need a new bottom bracket for it but if it has not stripped the thread on the bottom bracket thn you should do what mudpie said and the operator said check the torque on the crank bolts

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