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Strain gauge or gear microswitch

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    Strain gauge or gear microswitch

    Hi guys,

    Anybody have any contacts or know of a way to make a decent switch for WOT shifting / IGN cut.

    I'm using with a H pattern dog box and would like the ECU to cut ign for a predefined time OR if possible, have the ECU sense a pressure on the shifter before cutting IGN then also sensing the position of the lever before reinstating IGNITION.

    Hopefully that makes sense!

    For use with an AUTRONIC SM4

    Thanks guys!

    A microswitch is likely to be more reliable, given that it's a digital device. With a strain measurement you'll need to monitor for a threshold constantly rather than a simple on/off, which is probably a more complicated solution than you need. Keep in mind there are plenty of ways to incorrectly wire up a strain bridge, especially if you want to isolate the measurement of strain to one particular plane, and there are a lot of really crap strain gauge installations out there. (Cliffs - if you've driven over any major bridge in Brisbane in the last couple of decades, my strain data has kept you out of the river. Ditto for 11ty-billion other applications).
    Go the switch - more reliable, cheaper, simpler. Presuming the ECU can do whatever it is you need to do with delays etc etc.


      I've currently got a clutch switch which cuts ign for a predefined time so it is easily doable.

      But I can also do this using an analogue input where the strain gauge would become useful because I can define a pressure based on a preload on the shifter before it activates and allows the shift.

      Does anybody know where to get these gearknob microswitches? I believe Hollinger do them but can't seem to find any info.


        Motorsport Systems do the strain guage boxes we use on the H patterns and sequentials. You set the boxes up and then they just output a 5V signal when they are activated and the ECU (MoTeC) deals with the amount of delay time.

        We now have the strain guages built into the gearknob and that works with H pattern or sequential, previousley we have had the guages on our H patterns bonded to the stick. Motorsport Systems do the bonding and they also suplly the knobs ($800 + GST).

        Hollinger do a microswitch knob that I think is around $800 as well, the microswitch setups are just a rocking gearknob with adjustable preload springs.

        I doubt you will be able to have a setup that senses the pressure and then waits for the stick to be in position before turning the ignition back on unless the gearbox has some kind of poition sensing built in (H6S does but its not finite). In any case in a dog box once you pull the stick out of gear and through neutral the moment the dogs touch your going into gear whether you like it or not.

        Pretty sure you going to be using an adjustable time delay. Performance Engine Building, Auto Electrical (Wiring Looms, ECU Installs, Diganoses and Repair), Custom Automotive Electronics, Car Preparation, Car Setup, Trackside Services,

        PM me for more info


          On H patterns - how does the setup determine whether it's a down shift or upshift? I can see its use on upshifts, but on downshifts, wouldn't one _want_ to have ignition function so as to be able to blip throttle on said downshifts?

          Actually, I've just thought about that during the time it took to type, and the answer would be simple enough, I think - by having another switch/signal in line, that only allows the ignition cut to happen at or near peak rpm/cutout. That way it'd know if the revs are really high, it's an upshift, but for a downshift, where the rpms will be lower just as the shift is initiated (and likely the throttle blip won't push it nearly as close to redline/fuel/ign cut rpm levels) it won't cut ignition...

          There was a bloke (well still is) on the jyturbo list who had a fairly off tap saab. It was rev limited at something like 9000rpm *(i forget exactly). He'd basically familiarised himself with the idiosynchrasies of the car, and that rpm limit was structurally mandated, it'd make good power up to the redline and beyond it (for a short time).

          So basically he just kept the right foot down, had the hand on the shifter and just as the rev limiter cut in, he'd jam in the next gear. Worked quite well
          John McKenzie

          Science flies people to the moon.
          Religion flies people into buildings.


            That is one method of shifting a dog box (hitting rev cut) but I'd prefer to somewhat control it.

            I'm thinking I should keep it natural instead of putting it in the shifter. I'm thinking a left foot activated switch on the foot rest so it'll be like hitting the clutch with without actually disengaging the clutch which will reduce wear on the discs / fork / crank thrust bearing etc. This way I could still preload the shifter, hit the switch with my left foot, finish the shift and drive as I would.

            Thanks for the input above fellas! All great ideas and that (only activate at HIGH RPM) idea is a good one (for upshifts only).

            I'll decide if I want to spend 800 bux - 1k for a switch on my knob or just keep it natural LOL

            Thanks again


              We are about to fit one of these for flat shifting a dogbox, Im looking at some systems from Europe, Group Buy anyone?


                Ignition cut in the motec at least has a selectable lower RPM threshold.
       Performance Engine Building, Auto Electrical (Wiring Looms, ECU Installs, Diganoses and Repair), Custom Automotive Electronics, Car Preparation, Car Setup, Trackside Services,

                PM me for more info


                  Originally posted by Supashake View Post
                  We are about to fit one of these for flat shifting a dogbox, Im looking at some systems from Europe, Group Buy anyone?
                  What price?
                  Might be worth the try if its cheap enough.


                    Will have more info early in the week.
                    GURU ENGINEERING PTY LTD



                      something like a bike quick shifter switch? guessing you could run a linkage to the clutch that would run it. not really designed for H pattern stuff...

                      would guess the sequential stuff would be way easier to deal with. Saw a dallara F3 a while back with a good system, you put pressure on the lever, and flip a paddle on the back of the wheel, which cut the ignition.
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                        I think in order to install those strain gauges (bike ones) you'd have to have a push and pull one installed on a linear position. Possibly the cables if you can find a spot.

                        You'd have to install them in series.
                        It'll take a bit of work setting them up with the ECU but could work quite well!


                          This is from the Vi-PEC forum.
                          The ONLY way to do it with true automation and success is to use the strain guage method, as Ray suggests.

                          There are a few sources for these and typically they were bonded to the gearstick, but can also be 'free-standing' and function as a part of the gear knob.

                          I use and recommend the Motorsport Systems units, which are made in NSW and are used by 99% of the V8 supercar teams.

                          They are a precision piece of electronics, not cheap, but the only way to go. Correct set-up will extend the life of the gearbox substantially over any other shift method.

                          With a H pattern box you will need varying cut times per gear, as cut times inline with the gates (1-2, 3-4, 5-6) vary to across the gate (2-3, 4-5), and cut logic will only work in a narrow band in terms of throttle position (WOT) and engine speed (just below limiter)

                          When working, it really becomes an automated process and is simply a case of flooring it and pulling the stick!


                            Thanks for the input.

                            I have called those guys already (recommended also by MOTEC).
                            They cost about 1k for a shift knob + $500 for the box. Super cars usually replace the shifter after each race so they made a shift knob version. This way the super car teams save on down time and also money that has already been invested into the shifter. They simply screw the knob onto the new shifter and voila!

                            Now the cheaper method is to send the shifter to Motorsport Systems and get them to bond it on the shifter itself. They modify and bake the shifter with the strain gauge on it. You also need to purchase a box which costs something like $500.00. The strain gauge mod is about $350.00 or so.

                            It is an expensive process but it would ideally be the best method.


                              bit of a bump, how did you go with this?
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