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  1. #1
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    Upset Stripped Thread - Need help

    Man, totally like WTF, had to remove my pedals for the first time in 2 years and found that the left pedal must have been cross-threadded by the LBS. Then to get it to seat correctly a gallon of some goop like lock-tight was used. It was a real btch to remove.
    Anyway I am now left with a crankarm that has the thread totally stripped and wont take at all on the pedal thread.
    What do I do, has anyone got any ideas?
    Will loading the thread with somthing like a cold-weld formula be strong enough to hold, or am I looking at some kinda machining job? Or worse still new crankset?
    Any ideas apreciated...
    For me; Want and Need are much the same thing...

  2. #2
    Nightriding rules SuperModerator
    Reputation: crisillo's Avatar
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    I think a helicoil is the safest bet.

  3. #3
    Who is John Galt?
    Reputation: Big Jim Mac's Avatar
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    I used to work at a motorcycle shop and one of our common tasks was to helicoil stripped oil drain bolts. They seemed to hold well. But on a crank? I'm thinking you need a new one. Can you confront the LBS and ask for at least their cost on a replacement?
    What, me hurry?

  4. #4
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    shop eBay for a left crank. surprisingly, people sell individual crank arms (and you can probably special order individual crank arms from QBP). Using JB Weld will just ruin the crank arm AND pedal.

  5. #5
    Nightriding rules SuperModerator
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    Quote Originally Posted by Big Jim Mac
    I used to work at a motorcycle shop and one of our common tasks was to helicoil stripped oil drain bolts. They seemed to hold well. But on a crank? I'm thinking you need a new one. Can you confront the LBS and ask for at least their cost on a replacement?
    I have seen it done and working over a decent period of time (couple of years).. of course a new crank is the best solution.. I was just suggesting a cheaper alternative...


    the ebay suggestion is also quite good... single crankarms are usually quite cheap

  6. #6
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    are you sure it's totally cross threaded? I've seen cranks where the lead thread was damaged so the pedal wouldn't go in, but once that was cleaned up things where fine. Even if it is cross threaded the whole way, it might be possible to run a tap through and clean it up enough to work (though you might have a limited number of times you could install/remove the pedal).

    If a new crank, or arm is out of the question I'd find a t-nut or thread insert and drill out the hole. I wouldn't think this is a task to do at home though (unless you have a really good way to make sure you are drilling straight).

    I'd also think helicoil would work.


    what crank is this?

  7. #7
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    Quote Originally Posted by crisillo
    I have seen it done and working over a decent period of time (couple of years)..

    Given that threading a steel spindle directly into an Al hole is acceptable... If done properly a helicoil would be at least as strong.

  8. #8
    Nightriding rules SuperModerator
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    Quote Originally Posted by Joules
    Given that threading a steel spindle directly into an Al hole is acceptable... If done properly a helicoil would be at least as strong.
    yep.. totally agree...

  9. #9
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    Although a helicoil insert may be strong enough to work, I'd have a serious lack of confidence while riding my bike that way. The reason why is that if it does fail it's most likely at the worst possible time like when you land a drop or are weighting the pedal with force. That will most likely end in injury. I am by no means an expert in this so if aything, take it to a machine shop, ask their advice and have them do it.

    The first thing I'd do is bring it to the LBS and show them what happened because of what they did. Maybe they will offer some assistance. It's just a tough one to prove.

    Good luck, my friend.

  10. #10
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    I'd also reccomend the heli coil route. The only trouble will be finding a shop with the right size. You might try an automotive machine shop. If nobody has one, then it's a new crank arm. You would spend less money on the new arm than you would buying the heli coil and tool to put it in. On the other subject of your bike shop x-threading it. Don't be so sure. If you have steel pedal spindles threaded into an aluminum crank arm, and you don't take your pedals off once in awhile, they will sieze.

  11. #11
    mtbr member
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    Dosnt sound good

    Thanks for all the advice guys. Sorta sounds like I am looking at a new crank arm. Its a Truvative Stylo with the external bearings and the pedal was a Crank Candy. The problem was it was cross threaded all the way thru, as I was winding the pedal out it was cutting out a full on strip of aluminium all the way. The pedal actuall sits loose in the thread and can almost be pulled out by hand without relvolving.
    Oh well I'll take it into the LBS and see what they have got to say. **** happens I guess...
    For me; Want and Need are much the same thing...

  12. #12
    mtbr member
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    ... and if we just ... All Fixed - good as new.

    Ended up asking our company motor mechanic his advice, and being the helpful guy that he is just said to leave it with him. Anyway he dropped it back to me this morning. He had drilled it out 4mm larger, tapped a L/H thread, made a threaded aluminium plug, then drilled that and tapped the correct thread for the pedal. All this as a favour, what a guy.
    I'm just worried what the payback is gonna be now.
    Perfect repair and as strong as new.
    Thanks again for all your suggestions...
    For me; Want and Need are much the same thing...

  13. #13
    Nightriding rules SuperModerator
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    sounds sweet!

    post some pics of the fix... sounds like a very nice solution

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