Bottom bracket "conversion"

Discussion in 'HOW TO' started by ozzmonaut, Apr 27, 2012.

  1. ozzmonaut

    ozzmonaut

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    Ok, so I got an old 30's Iver Johnson motorbike frame. I had no idea that the two-piece cranksets were such a joy to try to locate. I see two options which I feel are within the scope of my abilities. I just want to see what experiences others may have had with these options: 1)cut out the crank hanger and replace it (i.e., weld in or splice) with a standard for one-piece cranks 2)harvest a hanger for a 3-piece crankset, which will fit inside the current hanger, tack weld it in, and run 3-piece cranks Obviosly the biggest factor in either of these options is that whatever hanger is placed in will have to be perfectly straight. With the second option, it has to be perfect the first time, because in order to avoid damage to the threads on the donor hanger, the welding will be done in an area where it would be difficult if not impossible to remove it to redo it if I screw it up. Either way it looks like I may be posting some project pics soon for this. I have a feeling I will go with the 2nd option, and I doubt that many people have done this one. Most people don't want to hack into a prewar frame too often.
     
  2. Bendix

    Bendix

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    years ago i had a framebuilder braze a threaded bottom bracket shell (not a used hacked piece) into an old iver johnson frame for me. it worked just fine with a square taper bb and 3 piece crank. :)
     
  3. ozzmonaut

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    Did he actually remove the original bb first or place the 3 piece shell inside the original one?
     
  4. spectratone

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  5. spectratone

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  6. ozzmonaut

    ozzmonaut

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    The second would work great, but $66 is more than I have in the frame itself. But it does get me thinking... could I somehow install the 3-piece bb I removed from a junk frame in a way that would keep it in place very tight, while still making it removable in case I ever find correct parts. I'm thinking: tack weld the 3-piece hanger in, then secure it inside straight to the inside of the original hanger with sheet metal screws. Where the screws stick out of the bb, grind the tips off, as well as the welds. Paint would cover the screw tips and the holes could be filled or welded if I ever remove them. We'll see.
     
  7. ozzmonaut

    ozzmonaut

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    I decided to first try grinding down the donor 3-piece hanger to fit inside the original. I managed instead to destroy the donor with my anger; but I cleared the path for the next donor to hopefully fit right in.
     
  8. Sinner4

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    With out pictures, Well..... Ummm I think I'd try to fit a Euro BB inside of the original for the tapered 3 piece. Shim it to get it straight and weld in. That way you wont have to mess with the removal of the old BB and the old Brazing.

    Don't get mad, Get Glad....

    http://harriscyclery.net/itemdetails.cfm?ID=1335
    ^^^^^^
    This same thing is $50 at the closest LBS to my house. I have used the cheap 3 piece BB Conversion that I have found in a few Huffy mtb's to install in a 1 piece BB Shell.
     
  9. Bendix

    Bendix

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    it was a fairly close fit, slipped right into the original. :wink:
     
  10. ozzmonaut

    ozzmonaut

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    I kept grinding the shell a little more and more, and it really seemed it should fit right in. I kept feeling around in the Iver Johnson bracket for anything that could stop it. So I tapped and tapped with a piece of wood and a hammer. Then the threaded part on the 3-piece shell got bent. There was no going back so I just hammered it on through. Oh well.
     
  11. gcrank1

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    So, maybe if you had threaded the ring in it would have held up?
     
  12. ozzmonaut

    ozzmonaut

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    Where were you two days ago? Actually due to the areas where I had to cut the frame away from the bracket and grind it down, I think it would have buckled there as well. I will have it installed on the next try though. I am not too familiar with three-pieces , and in fact I don't like them at all. But it seems to be the cheapest way to get this Iver Johnson up and riding.
     
  13. gcrank1

    gcrank1

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    Ya gotta watch that 'tap in' vs 'beat in'; all part of the learning curve..........Ive had years to practice and still do things 'poorly' on occasion. Hang in there, youre gettin' close.
     
  14. ozzmonaut

    ozzmonaut

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    You'd think after 17 years of working on these animals I'd have a little more patience. I had more patience as a 15 year old kid than I do now.
     
  15. gcrank1

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    Another thing that works well on stuff like this project is a piece of all-thread and 2 nuts (OK, 3 nuts, if you count the one doing it :D :wink: ). If you screw in the ring on the left side, slip the all-thread thru, a big 'washer' on the right and tighten the nuts down you will get a press action without any bashing.
     
  16. ozzmonaut

    ozzmonaut

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    That's what I'm gonna do. I'll get a short length of it from Lowes and a couple metal plates from my junk pile. Thanks
     

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