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  1. #1
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    Frame damage! Recommendation needed

    I took advantage of the cold weather to disassemble my Mach 4 and inspect all of the pivot bearings, etc. While reassembling the rear triangle to the front triangle, I somehow managed to strip an aluminum thread that is integral to the front triangle.

    Called Pivot this morning and they recommended I take it to a machine shop and have them install a heli-coil. Has anyone had this done locally? Where did you take it? Were you happy with the results? I'm not questioning the fix, I'm looking for recommendations on where to take my frame to have it repaired. I can't be the first person to have this happen. Thanks in advance.

  2. #2
    Now, THAT'S gonna hurt!
    Reputation: Oh My Sack!'s Avatar
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    Pretty much any machine shop that services automotive/motorcycle can easily do that work. It's a common repair across both disciplines. I've done it myself in my garage but if you're not so mechanically inclined or tool challenged, better have a shop handle it.

  3. #3
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    If your comfortable taking a frame apart then you will have no problem doing it yourself. Aaa metric will have everything you need to do it. You can do it in less than an hour

    Quote Originally Posted by golden boy View Post
    I took advantage of the cold weather to disassemble my Mach 4 and inspect all of the pivot bearings, etc. While reassembling the rear triangle to the front triangle, I somehow managed to strip an aluminum thread that is integral to the front triangle.

    Called Pivot this morning and they recommended I take it to a machine shop and have them install a heli-coil. Has anyone had this done locally? Where did you take it? Were you happy with the results? I'm not questioning the fix, I'm looking for recommendations on where to take my frame to have it repaired. I can't be the first person to have this happen. Thanks in advance.

  4. #4
    STRAVA!!!!!!
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    Quote Originally Posted by cbrock450 View Post
    If your comfortable taking a frame apart then you will have no problem doing it yourself. Aaa metric will have everything you need to do it. You can do it in less than an hour
    Make sure you get fine thread metric, the next size up from its original size, so long as the tap for the heli coil has enough meat to bite into. Locktight the crap out of it and it should work.
    NAPA has a good selection.

  5. #5
    Schipperkes are cool.
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    What size bolt? A lot of decent bike shops have a few Heli Coil kits.
    Quote Originally Posted by mikesee
    Better suited to non-aggressive 125# gals named Russell.

  6. #6
    650b me
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    Thanks for the input. There's a lot to consider here:

    1. Since I effed it up in the first place, do I trust myself to fix it? (Although, in my defense, I was using a CDI torque wrench at the time, and the other three bolts tightened to Pivot's torque recommendation without incident.)

    2. Do I trust a stranger at a machine shop to fix it? Maybe they're used to repairing threads on V-8 engine blocks, not a delicate aluminum bike frame.

    3. What is the cost of buying the tools I need a la carte vs. paying a machine shop to do it? If anyone has a guesstimate, I'm all ears.

    4. I can't think of a #4. But I already typed it, and I don't feel like back-spacing.

  7. #7
    Now, THAT'S gonna hurt!
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    Access to the thread repair site is going to be critical. Could the frame be jigged up on a drill press allowing straight access to the repair? The site will need to be drilled out over-size and either a Time-sert or Helicoil installed. I'd trust an old school machinist to this task far more than I would a bicycle mechanic unless the bike mechanic was an exception to what I've seen in shops.

    A Helicoil kit might cost around $35 plus or minus. A Timesert kit closer to a $100 dollar bill. I'd suggest you do some Googling on the 2 procedures to determine what would be best for your specific situation since you haven't really spelled that out.

  8. #8
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    Quote Originally Posted by golden boy View Post
    Thanks for the input. There's a lot to consider here:

    1. Since I effed it up in the first place, do I trust myself to fix it? (Although, in my defense, I was using a CDI torque wrench at the time, and the other three bolts tightened to Pivot's torque recommendation without incident.)

    2. Do I trust a stranger at a machine shop to fix it? Maybe they're used to repairing threads on V-8 engine blocks, not a delicate aluminum bike frame.

    3. What is the cost of buying the tools I need a la carte vs. paying a machine shop to do it? If anyone has a guesstimate, I'm all ears.

    4. I can't think of a #4. But I already typed it, and I don't feel like back-spacing.
    I have helicoil taps and it's not rocket science.
    But if you don't know what a helicoil is then maybe you shouldn't do your bike frame on your first attempt? Let a machinist do it.

    Also, not sure what your pivot bolt looks like but I would be worried about drilling it out and how much metal would be left.

    http://www.noblefix.com/PDF/Helicoil...sional-Kit.pdf

  9. #9
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    Quote Originally Posted by Oh My Sack! View Post
    Access to the thread repair site is going to be critical. Could the frame be jigged up on a drill press allowing straight access to the repair? The site will need to be drilled out over-size and either a Time-sert or Helicoil installed. I'd trust an old school machinist to this task far more than I would a bicycle mechanic unless the bike mechanic was an exception to what I've seen in shops.

    A Helicoil kit might cost around $35 plus or minus. A Timesert kit closer to a $100 dollar bill. I'd suggest you do some Googling on the 2 procedures to determine what would be best for your specific situation since you haven't really spelled that out.
    Talked to a mechanic friend who works at the LBS I used to work at and even he recommended taking it to a machine shop. Might be hard to jig up on a drill press...lots of asymmetry and hydroformed tubes. The only place I can clamp it into my repair stand is the seat post.

    I looked at the Timesert product - thanks for the tip. Looks more robust than heli-coil, but might not work for this application. Timesert has a flange on it and I need it flush-mounted. I think I'll go to the auto parts store and see if they can recommend a machine shop.

  10. #10
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    JBweld that sumb!tch!

  11. #11
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    Repaired!

    Thanks again to everyone for the suggestions. I decided to tackle the job myself. Made some phone calls and AAA Metric had the heli-coil kit I needed. They didn't have the drill bit I needed, so made a second stop at my fave ma & pa hardware store in Golden and I was set.

    Once I had what I needed, the repair took mere minutes, with one exception I'll detail later. Used my old 12-volt drill to drill out the hole. With the new bit in soft aluminum, this went quickly. In fact, I was glad I was using a 12-volt drill with a weak battery or I might have overdone it. Next it was time to use the kit:

    Frame damage! Recommendation needed-dscn7864.jpg

    Again, the special tap made quick work of the soft aluminum. Then I installed the insert with the special notched handle. It bottomed out and there was still almost a full revolution of the insert protruding from the hole. Nothing I could do about that but file it flush:

    Frame damage! Recommendation needed-insert-filed-flush.jpg

    Testing the bolt for fit:

    Frame damage! Recommendation needed-checking-bolt-fit.jpg

    Success! This really wasn't difficult at all. Hopefully it holds up well while riding. That will be the true test.

  12. #12
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    Great job!
    Blur LT & Highball

  13. #13
    Now, THAT'S gonna hurt!
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    Cool deal. Glad you were able to handle it on your own.

  14. #14
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    Thanks. You were right. Not a big deal if you are mechanically inclined.

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