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Tank Badge Screw Threaded Inserts

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  • Tank Badge Screw Threaded Inserts

    Has anyone had to replace a captive threaded insert in the tank which holds the tank badge screws? 2 of mine have fallen out. I have them, or what is left of them, but as they are they will not re-fit, as the flanges at the open end which prevents them falling through into the tank are no more.

    They are rather like rivet nuts, but with a closed end, in 1/8"BSW x 40tpi, approx 1/2" long.

    Any ideas?

  • #2
    Helicoil inserts, perhaps?


    • #3
      There is nothing to insert the insert into, John, if you see what I mean! The attached picture of the side of the tank, in primer, shows where the badge fixings are; or were. You will see the right-hand insert is in place, but where the left-hand one was, now there is just the hole. The other picture shows the inserts which I retrieved, one from each side. What they are missing is a thin flange, like a washer, around the open end, which drops into the slight recess in the tank surrounding each hole, into which it was then brazed. They are quite minute.

      I do have a set of taps, so inserts could be made from solid rod, max 1/4" diameter, but the tricky bit is how to create the flange. They could be turned up on a lathe, but I don't have one, and machinist's time is dear. I have an idea how to make them, but if there was something already available it would make life much easier!

      Attached Files


      • #4
        You dont need a lathe Ian, just put a piece of 1/4" steel (or maybe brass) in an electric drill (you will need to hold drill in a vice if you do not have a drill stand) and then with a small file reduce the diameter to fit the hole, you will need a needle file to form a square shoulder, then cut off the excess rod, turn it round in chuck and the reduce the head thickness again with a file. Whilst its still in chuck drill the tapping size hole using a drill held in another chuck. You will need to center punch the end so as to get the drill to run true, dont drill all the way through. Then tap the thread. You will then need to soft solder the insert in tank. Epoxy resin such as Araldite will be no good as petrol will soften it.


        • #5
          Hi John,
          I was under the belief that Epoxy was the correct thing to use with Fuel ????



          • #6
            My idea was to make it from brass, John, although I do have 1/4" steel rod, which should pass through the hole without needing to turn it down. To create the flange around the top I thought to make them over length, drill the pilot for the thread, then drill out at the end to a short depth, to a larger diameter than the thread requires, applying heat and swageing the thinner rim over to form the flange. Then tap the thread. The threads in the originals do not start until at least a 1/4" down inside the insert., so I believe that may be how they were made originally. Silver solder should seal it to the tank effectively.

            It requires a bit of faffing around which I could do without, hence asking if something suitable was readily available!

            I have added a pic which shows the inside, where you can just see the start of the thread..

            Attached Files
            Last edited by IanCordes; 14/08/2019, 10:38 AM. Reason: typo


            • #7
              Sounds the way to do it, but how are you going to hold the insert in place to swage over the end? surely it would be better to use a larger diameter and file it down in a drill as my first post to form a thin flange. I would agree brass better than steel and silver solder would be the better than solder.


              • #8
                I would swage over the end while holding it in a vice. Once done, and thread tapped, it is just a case of turning the tank on it's side, dropping the insert through the hole and soldering. I will give it a go. Your method is potentially stronger, but more work, and the silver solder will provide the strength anyway.

                Time will tell...........


                • #9
                  Donít forget to purge the tank, even silver soldering can ignite old tanks!


                  • #10
                    The tank has long since been purged, Dave, but fair play for thinking of it.


                    • #11
                      Any use?

                      Carbon Steel Flat Metric Threaded Rivet Nut Flange Rivnut Nutsert Fastener M3/M4/M5(M4-100pcs):
                      Last edited by sherpatensing; 15/08/2019, 09:31 AM.


                      • #12
                        Not really, but thanks for looking. The end needs to be closed off, and also they are metric. I have a dozen of the correct 1/8" BSW screws on their way. It is into the workshop for this one; not an insoluble situation.

                        More as it develops.


                        • #13
                          Screws available from here will need shortening though.
                          Last edited by John Wakefield; 25/07/2020, 06:01 PM.


                          • #14
                            Well spotted John. As fitted to AEC Matador window catches, unless I am very much mistaken?

                            I think the 1/4" ones should be ok. I have some 3/8" ones and they are too long. Fiddly to shorten though, as they are so small.

                            Ian C
                            Last edited by IanCordes; 27/07/2020, 04:05 PM.