Footpeg hole repairs

Discussion in 'Tech Area' started by darrel gunderson, Feb 13, 2020.

  1. darrel gunderson

    darrel gunderson Active Member

    Dec 13, 2008
    Likes Received:
    So I got and engine from a customer to rebuild, and after disassembling and cleaning, I find that the holes for the foot peg bracket have been opened up past a 10mm bolt ! Some one made a half ass attempt to use heli coils and they failed miserably.
    Normally I can use a standard 8mm timesert kit to repair them. Not this time. My choice was to either have the holes filled with weld, drill and then install 8mm standard timeserts or buy the oversized ones. I called the Manufacture in CA. and ordered the big sert kit . Came today and they worked great ! A little over $90 for that kit but was well worth it. I also put on some red lock tight. Here's a couple of pictures.

    Attached Files:

  3. allenp42

    allenp42 Well-Known Member

    Apr 1, 2014
    Likes Received:
    Wow, what a difference. Those oversize thread inserts look nice and saved the day and a few coins for the owner.
  4. Tripod

    Tripod Active Member

    Jun 23, 2013
    Likes Received:
    Great work. Im sure it made the owner happy!
  5. lukelaw1

    lukelaw1 Active Member

    Jan 28, 2013
    Likes Received:
    Heli coils are junk, love thread inserts
  6. racerx

    racerx Administrator
    Staff Member Administrator

    Jul 10, 2005
    Likes Received:
    With all four stripped this badly, thick-walled inserts are far and away the best repair method. The amount of heat produced by welding makes me a bit for what collateral damage may occur; and with the metal thinned this much, there's a good chance of blowing-through in one, or more, places. Afterward, all four bolt holes would have to be located from scratch. Footrest mountings are trickier to recreate, essentially from scratch, than seems possible. So, you end up with an outwardly invisible repair, piloted off of the original centerlines and those steel inserts are far stronger than the original threads.

    I don't completely agree with this. Helicoils can deliver the goods, provided they're installed correctly. There are differences between the two repair methods, which is better depends on the application. The only applications on these engines where I'd automatically consider Timesert as hands-down the best choice: sparkplug and drain plug holes.
  7. scooter

    scooter Well-Known Member

    Aug 28, 2009
    Likes Received:
    Standard practice for me to use helicoils as part of my design efforts in the aerospace industry. They’re not just used for repairs but are often used right off the bat in a design. Never had any issue. Once had an interesting failure where end-cap screws started shooting across the room during a pressure vessel high pressure proof test (used water instead of a gas such that things didn’t explode if something went wrong). Turned out the base aluminum wasn’t heat treated to spec which caused the Helicoils with the screws still inside to tear out and go ballistic. Happened way back early in my career. Still remember it like yesterday. Must have been like 25 screws that took flight. Left a nice ring of dents in the metal file cabinet down range.
    airblazer, cjpayne, racerx and 2 others like this.

Share This Page