Incorrect shape of hexagonal flanged nuts

Discussion in 'Engineers' Talk' started by Marquitos, Jun 10, 2021.

  1. Marquitos

    Marquitos New Member

    IMG_20210609_231811.jpg IMG_20210609_231743.jpg IMG_20210609_231641.jpg Hi, I bought a towbar for my car which came with a kit of bolts and nuts and found the flanged nuts to be out of shape; is not a perfect hexagon but instead distance between opposite sides of hexagon are not the same. Is like when manufacturing the nuts these have been compressed making them oval alike; Has anybody found similar shape in nuts? Is this something normal?
  2. dray

    dray Active Member

    Do they go on the bolts ok, surely that's the only thing to worry about?
  3. Marquitos

    Marquitos New Member

    I inserted one by hand but couldn't pass it through; a spanner will probably do but thought it might damage bolt thread. I have asked the towbar manufacturer that supplied the bolts and nuts kit.
  4. Muzungu

    Muzungu Screwfix Select

    There are certain types of nut which have purposely distorted threads so they act as a lock nut. Certainly a possibility since it is a towbar. As above, can you start it on the bolt?

    Edit: What did the manufacturer say?
  5. Marquitos

    Marquitos New Member

    The nut just go inside by hand force without the bolt popping out.

    So this might be for the but to hold to the bolt and not to come loose with car vibration, that could made sense since there were also smaller nuts which have the same shape.
  6. Muzungu

    Muzungu Screwfix Select

    Yes. Since the nut starts on the bolt it will then lock when you have it fully home. If the distortion was over the whole length of the nut you would obviously have issues even starting it so I would say definitely this is what it is for.
  7. Marquitos

    Marquitos New Member

    Thank you Muzungu

    And for confirming this theory the fitting instructions of the towbar don't require a nut washer and other makers use instead nuts with nylon.
    Muzungu likes this.
  8. Marquitos

    Marquitos New Member

    This is the manufacturer response which confirms your theory;

    "Some of the nuts supplied will be oval, these are deformed lock nuts and are mainly used in any application where heat could possibly melt a nylon locking nut"
    Muzungu likes this.
  9. stevie22

    stevie22 Screwfix Select

    Learn something new every day! Seen nuts with slots at the top and compressed to alter the thread form to act as a lock but never this idea.

    One assumes it's cheaper, but I think I'll stick to Nylocs.
  10. spannerw

    spannerw Screwfix Select

    Not quite sure how a towbar can get so hot to melt a nyloc?
  11. Marquitos

    Marquitos New Member

    Maybe next to the exhaust?
    candoabitofmoststuff likes this.
  12. Abbadon2001

    Abbadon2001 Screwfix Select

    This is normal for a certain type of locknut - and they are far stronger than a nyloc.
  13. FlyByNight

    FlyByNight Screwfix Select

    Why did they not supply Loctite Threadlocker 272 - works up to 230c and there are others that are even higher rated.
  14. Tony Goddard

    Tony Goddard Screwfix Select

    These nuts are used in aviation, I have a few boxes of them, far better than Nylocs.
  15. Adamfya

    Adamfya Screwfix Select

    Nowt wrong with a nyloc..

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