Lock washer/fastener questions

Discussion in 'Discussion Forum' started by Rodger, Oct 10, 2015.

  1. Rodger

    Rodger True Classic

    Olympia, WA
    I am in the process of replating or replacing most of the fasteners on my K20 restomod. In disassembling the car, I have come across three basic different ways that things are bolted together.
    1. Hex head bolt or nut with a split type lock washer and a flat washer under that.
    2. Hex head bolt or nut with a serrated tooth type lock washer (some internal, some external) and a flat or fender washer under that.
    3. Flange type hex nut with built in serrations in the flange. Sometimes there is a fender washer under these but not always.

    On my K20A2 engine, Honda seems to use almost exclusively hex head bolts with an integral flange that is flat underneath. No lock or other washers. Since this engine is only about 13 years old, I would venture to say that it is more up to date with the current state of the art in fastener technology.

    I have seen a couple of threads where Bernice has made a convincing case for the poor performance of split lock washers. How do tooth washers compare to split washer performance? Why are there internal and external tooth washers and is one more indicated than the other in certain applications? Are lock washers even needed? :confuse2: I am a dentist (prosthodontist) by day and I do a lot of dental implant restorations. They are all clamped together by small screws at specified torque values (yes, we use little tiny torque wrenches) and there is nary a lock or other washer to be seen.

    I have looked at websites for purchasing new fasteners and have noted the availability of all these types of washers as well as flange nuts and bolts, with and without serrations. What would be the optimum choice for new fasteners for the X? Should I follow Honda's lead and use hex head flange bolts? If so, with or without serrations? :confused:

    I just want to use the best, current technology as I put the X back together. Thanks in advance for educating me as there are a lot of really smart folks on this forum that I have already learned a ton from.:worship:
  2. Rupunzell

    Rupunzell Bernice Loui

    Proper joint design is quite a complex subject is very deponent on many many factors.

    Honda and the majority of manufactures have almost completely given up on split washers (flat refuse to term them "split lock washers" as they do not lock what so ever). This is why they are almost never found in modern vehicles, industry and specially aero space industry where they have given them up many decades ago.

    Follow the OEM Honda standards for flange screws. These have a built in washer that allows starting the fastener using a socket, provides load spreading due to the build in washer and they often have a polymer friction patch on the lower area of the threads to aid in retention.

    Notice critical threaded fastener joints in engines have no "lock device" yet they rarely if ever come loose if they are OEM installed. There were many, many engineering and testing and production engines in service proving what was done works with no added "locking device".

    There are threaded joints that can greatly benefit from a locking device like Nord Locks and such. These have been tested on the industry Junkers machine for vibration resistance with good results. Understand how these work and why threaded fasteners can come un-done under high vibrational loads.



    Threaded fasteners are intended to produce joint clamping force. pins are intended to locate the assemblies to be jointed. If the two plate in the videos above where pinned, the two flat plate will have great difficulty shifting due to vibration as the threaded fastener clamps them together making secure joint between two plates.

    If you're curious, this is the discussion that was not pleasant as a result of "split split lock washer."

    Last edited by a moderator: Dec 4, 2016
    darwoodious likes this.
  3. Rodger

    Rodger True Classic

    Olympia, WA
    Fascinating stuff

    Thanks for the video links. So it looks like lock washers in general do not contribute to joint stability and are not needed, especially if using flanged bolts/nuts. In critical areas, Nord-lock washers seem to be the way to go.
  4. htfx19

    htfx19 Herzel Frenkel

    Gan-Yavne, Israel
    And now Bernice

    I'll have to redesign all my projects,
    but thanks anyhow...

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