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    The PF Bolt and Thread guru thread

    Ok you legends, here's one for you.





    The brass gear is meant to be a direct replacement for the shitty plastic one which cracked.

    The original one spins freely on the spindle, the brass one is tight and binds up after six or seven turns.

    So it seems the thread is close, maybe not cut correctly, maybe not the right thread at all.

    Got hold of a 1/2-10 ACME tap, it goes through both of them without any binding at all, they both rock a little on the biggest part of the tap.

    The ISO trapezoidal tap in the closest size is even looser.

    Measured the ID of the original, was 11.3mm, the new brass one was a bit smaller, drilled it out with an 11.3mm bit, followed up with an 11.4mm bit just to be sure. Still binds up on the spindle.

    The shop that supplied the brass gear is not really helpful, won't tell me the thread spec, says that the spindle must be damaged, which I don't agree with, since the original gear spins freely.

    They say use lapping paste and work the new gear back & forth to grind the thread. I don't think this will work...

    Any suggestions? Or am I fucked?
    Jaguar XJR, Freelander 2 HSE, Jaguar XKR, MINI Cooper S
    Originally posted by nutttr
    People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

    #2
    Different class (2g/3g/4g/5g) acme threads is causing the binding would be my guess.

    https://www.engineersedge.com/hardwa...read_13360.htm

    Don't mention the adBlocker !!

    Comment


      #3
      Lapping paste will be in the brass gear forever. Don't do that.

      Off the top of my head, M13x2.5 would be close - a little bigger. Not that i've ever seen an M13x2.5 thread or tap. Do you have any thread pitch gauges?
      Originally posted by Marlin
      Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

      Comment


        #4
        Originally posted by Fondles View Post
        Different class (2g/3g/4g/5g) acme threads is causing the binding would be my guess.

        https://www.engineersedge.com/hardwa...read_13360.htm
        That might be something to do with it, maybe?

        Originally posted by Faux Forg View Post
        Lapping paste will be in the brass gear forever. Don't do that.

        Off the top of my head, M13x2.5 would be close - a little bigger. Not that i've ever seen an M13x2.5 thread or tap. Do you have any thread pitch gauges?
        Yeah not going to even try the lapping paste...

        Nobody i've asked has even heard of an M13x2.5, does it even exist?

        Only thread gauges I have are for regular metric threads...

        So here's where it's at.

        I can't even confirm if the original thread is really an accurate ACME 1/2-10, it's not possible to remove the spindle from the car without a massive headfuck...

        I can't find anyone in Oz who has ACME nuts on the shelf, to try putting a regular nut on the spindle to see if it is really the thread we think it might supposedly be.

        The plan now is;

        Buy some ACME 1/2-10 hex nuts and threaded rod from the US, there's a seller on eBay who has them and will ship to here.

        - Try both the new and old gears on the threaded rod, for fitment.
        - Try the hex nuts on the spindle in the car, for fitment.

        In theory the gears should spin OK on the threaded rod, but the hex nuts bind up on the spindle in the car.
        If that turns out to be, then I found another US seller who has dies in 1/2-10 ACME, so can buy one of them and re-cut the thread on the spindle to suit the gears.
        http://www.toolsavings.com/templates...oupGuid=189588

        That's the plan anyhow...
        Jaguar XJR, Freelander 2 HSE, Jaguar XKR, MINI Cooper S
        Originally posted by nutttr
        People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

        Comment


          #5
          Before going to that much trouble give it all to a machine shop to sort out, you will be dollars and more importantly a lot of time ahead.

          Comment


            #6
            Originally posted by Mini View Post
            Before going to that much trouble give it all to a machine shop that knows what they are doing to sort out, you will be dollars and more importantly a lot of time ahead.
            Fixed.

            Not a cycle thread (same thread pitch no matter the size) or something English weird like that is it?

            Comment


              #7
              Ah should have mentioned that I've already been to two machine shops and gotten nowhere...

              The pedal assembly in these cars is via the Ford USA supply chain (similar units in the Crown Vic, Lincolns, etc) so it's not English.
              Jaguar XJR, Freelander 2 HSE, Jaguar XKR, MINI Cooper S
              Originally posted by nutttr
              People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

              Comment


                #8
                Originally posted by Jack Nicholson View Post
                Nobody i've asked has even heard of an M13x2.5, does it even exist?
                It'd be an odd one for sure, but without knowing what it is, it's possible.

                You could check the male thread with the three wire method - if you like trigonometry.
                If you've got a decent digital caliper you could also measure the pitch across 10 threads (like your photo) and check if it's an inch or not. Or, put some blue on it, screw it together, and check where it's jamming.

                But before any of that, does the gear mesh properly?
                Originally posted by Marlin
                Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

                Comment


                  #9
                  Pretty sure the ten thread measurement reads 25.4 on his calipers in the photo.

                  Apparently there are some modified ACME threads with different thread heights, though that wouldn't explain it binding up after a few threads. Either way, ASME standard for ACME threads is attached if you want to do some reading. Appendix A shows the modified thread forms, earlier in the document gives allowable tolerances for standard threads.
                  Attached Files

                  Comment


                    #10
                    Plastic caliper should go in the bin.
                    Originally posted by Marlin
                    Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

                    Comment


                      #11
                      Originally posted by ricardo View Post
                      Pretty sure the ten thread measurement reads 25.4 on his calipers in the photo.

                      Apparently there are some modified ACME threads with different thread heights, though that wouldn't explain it binding up after a few threads. Either way, ASME standard for ACME threads is attached if you want to do some reading. Appendix A shows the modified thread forms, earlier in the document gives allowable tolerances for standard threads.
                      Thanks very much for that, i'll have a look through it sober

                      Originally posted by Faux Forg View Post
                      Plastic caliper should go in the bin.
                      These are actually good ones https://www.wihatools.com/dial-caliper-dialmax-metric I checked them against the standards that came with my micrometers and it's as close as fuck.
                      Jaguar XJR, Freelander 2 HSE, Jaguar XKR, MINI Cooper S
                      Originally posted by nutttr
                      People must assume you are some sort of drug dealer with all these nice cars turning up to a fibro home

                      Comment


                        #12
                        Just ugga dooga it up with the rattle gun.
                        2017 Ford Ranger XLT (Jeep Wrangler recovery vehicle)
                        2007 KTM 250 SX

                        Originally posted by Monza
                        I've never considered myself the type of guy to eat arse but I am currently reviewing that policy

                        Comment


                          #13
                          If I can help with shipping anything to you please let me know.

                          Comment


                            #14
                            Originally posted by Jack Nicholsen
                            I can't find anyone in Oz who has ACME nuts on the shelf
                            There was a mob in Coburg Vic who specialized in making acme thread and nuts about 10 years back, a mate bought a 6ft length from them for a lathe - can't remember the name unfortunately. Failing that, hare and forbes might have something off a cross-slide or compound that would fit? I might try Graham McDonald Services out at Girraween to see if they can see a problem with your nuts first....given limited measuring equipment.

                            Originally posted by Mini
                            Before going to that much trouble give it all to a machine shop to sort out, you will be dollars and more importantly a lot of time ahead.
                            Problem no doubt, he's been turned away for a piddly job.

                            Comment


                              #15
                              You could use the taps that you have to check the thread pitch of the stud. If it is what I think it is, the thread could be stretched, which would cause the jamming you're experiencing.

                              Also, if you can force the tap with a (not running) lathe/drillpress/etc as you wind it through, you might gain enough clearance for it to work, assuming it's not binding on the crest. Obviously this is rough as guts though.
                              Originally posted by Marlin
                              Chickens will slip under water in the cover of darkness like a seal team and FUCK YOU UP.

                              Comment

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