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  1. #1
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    Stripped Crank Extractor removal technique

    Wanted to share idea
    just successfully removed crank with stripped extraction threads
    took some hard thinking, worked well

    the situation :
    DS crank stripped
    square taper
    loose ball

    method :
    remove crank securing bolt from DS
    remove nds crank with normal extraction process
    remove nds cup
    remove nds bearings
    thread nds cup halfway into shell (no bearings , spindle is floating)
    stack spacers around protruding nds taper (socket wrench for ex. used a bbt-22 myself)
    thread long bolt into nds taper, head of bolt must bottom against your spacers before running out threads
    tighten the bolt into spindle
    DS crank bottoms against DS cup, as spindle pulls thru to nds side
    stripped DS crank successfully removed

  2. #2
    Senior member Dan Burkhart's Avatar
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    Quote Originally Posted by xenologer View Post
    Wanted to share idea
    just successfully removed crank with stripped extraction threads
    took some hard thinking, worked well

    the situation :
    DS crank stripped
    square taper
    loose ball

    method :
    remove crank securing bolt from DS
    remove nds crank with normal extraction process
    remove nds cup
    remove nds bearings
    thread nds cup halfway into shell (no bearings , spindle is floating)
    stack spacers around protruding nds taper (socket wrench for ex. used a bbt-22 myself)
    thread long bolt into nds taper, head of bolt must bottom against your spacers before running out threads
    tighten the bolt into spindle
    DS crank bottoms against DS cup, as spindle pulls thru to nds side
    stripped DS crank successfully removed
    Now that's usin the ole' noodle. And no stress on the bearings. Well done.
    Gearhubs demystified and other cool stuff.


    The greatest mistake you can make in life is to be continually fearing you will make one. Elbert Hubbard.

  3. #3
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    Got a picture? Post it with a bit more detailed write up in the hints and tips sticky thread...

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    I rank an individual’s resourcefulness high on their list of qualities, so way to go xenologer!

  5. #5
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    A very clever technique for non-destructive crank removal. If I may I'd like to offer a couple of comments:

    The 8 mm bolt you use to thread into the NDS spindle end has to be an M8x1.0 mm. This is a finer thread than the more common M8x1.25 so you will have to find an appropriate bolt.

    Pulling the drive-side crank arm against the DS cup to extract the spindle might cause the chainrings to hit the DS chainstay if there is insufficient clearance. Check it first and you might have to remove the chainrings to avoid damaging the frame and/or chainrings.

  6. #6
    coprolite fietsbob's Avatar
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    OK with loose ball Cup and cone BB ... But ..

    N/A with a cartridge UN type BB, though.

  7. #7
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    Nice off the cuff solution, but it requires BB disassembly and much more problematic if it's the NDS crank. Jabob's chuck wedges are a better, quicker solution.
    There's no such thing as a routine repair.

    Don't tell me what "should" be - either it is, it isn't, or do something about it.

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  8. #8
    Senior member Dan Burkhart's Avatar
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    Quote Originally Posted by cny-bikeman View Post
    Nice off the cuff solution, but it requires BB disassembly and much more problematic if it's the NDS crank. Jabob's chuck wedges are a better, quicker solution.
    The problem I see with that method, or using a pickle fork, is that the spindle bearing race is pulled hard against the bearing balls with the force being transferred to the cup. Possibility for bearing damage.
    Gearhubs demystified and other cool stuff.


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  9. #9
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    Wouldn't a faucet handle puller work on the DS side?
    Robert

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  10. #10
    mechanically sound frankenmike's Avatar
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    Grand idea. Sheldon had a method for cartridge bbs- remove bolts, ride around the block carefully until it comes loose, walk back

  11. #11
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    Quote Originally Posted by frankenmike View Post
    Grand idea. Sheldon had a method for cartridge bbs- remove bolts, ride around the block carefully until it comes loose, walk back
    Final step: Discard removed crank with rounded out tapers.

  12. #12
    mechanically sound frankenmike's Avatar
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    Quote Originally Posted by HillRider View Post
    Final step: Discard removed crank with rounded out tapers.
    I knew someone would say that, hence the insertion of the word "carefully"

  13. #13
    Senior Member bmontgomery87's Avatar
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    Quote Originally Posted by frankenmike View Post
    Grand idea. Sheldon had a method for cartridge bbs- remove bolts, ride around the block carefully until it comes loose, walk back
    tried this for about 20 minutes with no luck.

  14. #14
    coprolite fietsbob's Avatar
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    go for another 120 minutes..


    a Self extractor stripped out, the ring is only engaging half the thread, still some left .. using a real tool worked ..

  15. #15
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    Quote Originally Posted by frankenmike View Post
    Grand idea. Sheldon had a method for cartridge bbs- remove bolts, ride around the block carefully until it comes loose, walk back
    Warning: people here do NOT like to use the easy way.

  16. #16
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    Quote Originally Posted by bmontgomery87 View Post
    tried this for about 20 minutes with no luck.
    You did it wrong. You probably rode around the block a few times so you wouldn't have a long walk after the crank came loose. That was the mistake. You have to drive the bike to a fairly remote area with good cycling. Then you ride away from the car headed into an area with little traffic and no amenities (a lack of cell phone coverage also helps). Doing this at high noon on a broiling humid day also helps. The key is that the crank will not come loose un til you're assured of a long, miserable trek back.
    FB
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  17. #17
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    I commend the OP on his resourcefulness, a skill I rate above all others. OTOH, a pair of Jacobs chuck removal wedges makes this job so easy you'll wonder why we ever bothered with threaded extractors. Cost is less than most crank extractors, and they last forever.
    FB
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    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  18. #18
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    Quote Originally Posted by FBinNY View Post
    You did it wrong. You probably rode around the block a few times so you wouldn't have a long walk after the crank came loose. That was the mistake. You have to drive the bike to a fairly remote area with good cycling. Then you ride away from the car headed into an area with little traffic and no amenities (a lack of cell phone coverage also helps). Doing this at high noon on a broiling humid day also helps. The key is that the crank will not come loose un til you're assured of a long, miserable trek back.
    Experience is the best teacher?
    If you don't know the way, you shouldn't be going there.

  19. #19
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    Quote Originally Posted by leob1 View Post
    Experience is the best teacher?
    Sort of. Decades ago two friends and I went to the Poconos for a 3-day weekend tour. To give you a frame of reference, we took the train round trip from NYC. Anyway as we're doing our two minute bike check, I notice that my buddy's right crank bolt is missing. "No problem, I worked half the night trying to get the dam crank off, and it's there for life". Famous last words, good for about 3 miles. Long story short, we improvised a tow system, and spent three days climbing and descending in the hills rotating riding solo, towing, and being towed. An excellent learning experience both in engineering a tow system that works, and bike handling, especially on descents.

    BTW- I'm still partly convinced, that if I hadn't noticed, and he hadn't said anything, the crank wouldn't have come off.

    OTOH- I've successfully used the "back off the bolt, and sprint a hill" method of crank removal a number of times.
    Last edited by FBinNY; 07-18-14 at 11:44 AM.
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  20. #20
    Senior Member bmontgomery87's Avatar
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    I ended up just taking a chisel and a hammer. knocked it pretty hard 4-5 times while having someone brace the bike. popped right off.

  21. #21
    Senior member Dan Burkhart's Avatar
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    Quote Originally Posted by FBinNY View Post
    I commend the OP on his resourcefulness, a skill I rate above all others. OTOH, a pair of Jacobs chuck removal wedges makes this job so easy you'll wonder why we ever bothered with threaded extractors. Cost is less than most crank extractors, and they last forever.
    I know this is an effective technique, but do you have any concerns about the effect of the axial impact on the bearings against the cup in the course of driving the crank off this way, or am I concerned over nothing?
    Gearhubs demystified and other cool stuff.


    The greatest mistake you can make in life is to be continually fearing you will make one. Elbert Hubbard.

  22. #22
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    Quote Originally Posted by Dan Burkhart View Post
    I know this is an effective technique, but do you have any concerns about the effect of the axial impact on the bearings against the cup in the course of driving the crank off this way, or am I concerned over nothing?
    IMO, unless you pound them in with a steel hammer, there's no concern. If you're super concerned you can use a brass or other soft face hammer.

    There's all sorts of concern about brinnelling a bearing with a hammer, but it's actually very hard to do. It might be a legitimate concern for precision or high speed bearings where it might be enough to cause vibration, but not (IMO) in the bike world, where low speeds and normal wear would render it a non-issue. The vast majority (all?) of "brinnelled" bearings we see on bikes are the result of false brinnelling or fretting, not impact damage of any kind.

    When I consider questions like this, I make my decision based on a 3-step test. Theory, practice & materiality. Can you brinnel a bearing this way? - possibly. Will you do so? -- not likely. Might you do so to an extent that was material to the life or function of the bearing? --- extremely unlikely.

    BTW- I might add that these are intend for use on fairly expensive machinery, whose spindles run at high speed on ball bearings. Many of these machines use hammers and wedges to remove taper fit tooling, including the workhorse Bridgeports we see everywhere
    Last edited by FBinNY; 07-18-14 at 01:34 PM.
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