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  1. #1
    mtbr member
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    External BB cup getting VERY tight when installing...

    I got a new external bottom bracket cup set. I went to install them and lubed up the threads as normal, etc. Drive side went in great, but the non-drive side began to hesitate. I gave it a little more torque and it was still tight. I was like, uh, am I cross threading? Naw, can't be - looks even... so I back the cup out and check everything out. Looks good... Installed it again, got tight again... What the...

    So I pulled the cup out, wiped off the grease, and noticed something interesting. I took a picture on my phone to show here. Being that the cup is black, it's kind of obvious to see. Somehow the threads on the frame must be cutting at the very top of these threads on the cup. The cup threads are not ruined, they look completely fine except for the pain skimmed off the top. I decided not to continue installing the crank, so I figured I'd post here. I checked over the threads thoroughly on the bike as well as the cups. I just don't see what could be causing this. Things look... perfect... as far as I can tell anyway.


  2. #2
    Former Bike Wrench
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    Might consider finding a LBS with a BB thread tap, get it faced at the same time. This should take care of any issues.

  3. #3
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    Quote Originally Posted by mtnbiker72
    Might consider finding a LBS with a BB thread tap, get it faced at the same time. This should take care of any issues.
    It is faced. In fact the frame is only about 3 months old. Got it faced/chased and had the BB put on, but I got a higher quality BB cup set so here I am trying to install it...

    I might run it by them though, just to see what they say. Can't hurt - right?

  4. #4
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    You probably don't need the shell faced but it wouldn't hurt to have the threads chased to be safe.

  5. #5
    Picture Unrelated
    Reputation: zebrahum's Avatar
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    Your BB cup may be deeper than your previous one, I would suspect if you chase the threads deeper then you will get rid of your issue.
    Don't you hate it when a sentence doesn't end the way you think it octopus?

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