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  • Float

    Physics of float. I can kinda understand why float might help load the outside corner tires with mass to help in the corners but it also might have adverse affects on COG shift and vibrations in corners. So is float a proven science for plastic chassis 132 cars? Does improving float help 4 post cars or only two post cars?
    David

  • #2
    Float will help any car the secret is to find out how much float for a particular car is best
    Dave
    Peterborough Ont
    CANADA

    Comment


    • #3
      this is a good topic that i would like to clear up
      hope I'm not hijacking the op's thread

      up to now , i have always assumed that :-
      front / rear float is good
      side / side float is not so good , hence the tape to dampen side float

      is this correct ?
      Kev
      Burnley
      EnglandπŸ‡¬πŸ‡§

      Comment


      • #4
        I think more than anything a loosely mounted bodyshell allows the chassis to flex properly.
        Kevan - Isle of Man
        Life is like a box of Slot cars...πŸš“πŸš—πŸššπŸšœ

        Comment


        • Smokeio
          Smokeio commented
          Editing a comment
          Yes, more about the chassis flexing than the body moving. Also put the car on four scales as you tighten the body screws and watch the difference. It is significant!

        • Michael Squier
          Michael Squier commented
          Editing a comment
          That’s what I have assumed also, more by reading than by doing though. I’m still newish.

        • Fast Co.
          Fast Co. commented
          Editing a comment
          Yes. I think allowing chassis flex (and preventing chassis warp) are the keys.

      • #5
        In fact, you can destroy the handling by bad body mounting. You can have a beautifully handling chassis that drives like a wounded 3 legged animal once the body is fitted.

        The trick is to reduce the effect the body mounting has, if you can get it within a tenth of a second you've done an awesome job.

        That piece of plastic mounted above the centreline of the wheels will flap about when the car changes direction, I prefer to let it do so without affecting rear traction or lifting a front inside wheel.
        Kevan - Isle of Man
        Life is like a box of Slot cars...πŸš“πŸš—πŸššπŸšœ

        Comment


        • #6
          I don't claim to know as much as the experts. My results have been that 2-3-4 post mounting is not as important as the bodies ability to move in all directions and up and down slightly.
          I don't know the physics, but the movement of the body seems to use up some of the centrifical force generated on the whole car taking some force away from the chassis so it won't de-slot as easy. The weight transfer to the outside in a corner may also help to plant the outside tires a bit more. You can run some formulas and over think or just experiment with your cars. That is the best way to see what works. Use what you hear as a starting point and see where it takes you. You can't make a car corner better without testing and tuning.

          Every car is a little different and every track and tire combo is different.
          Matt B
          So. In
          Crashers

          Comment


          • #7
            Empirical tuning and personal preference πŸ’ͺ

            ...maximising the tyres traction is more important though.
            Kevan - Isle of Man
            Life is like a box of Slot cars...πŸš“πŸš—πŸššπŸšœ

            Comment


            • #8
              Kevan: I can certainly appreciate the body not being pulled tight to distort the body - that makes good sense. Kevan - are you saying you can get no-body vs. with-body times to within 0.1 sec? Speaking from a plastic chassis standpoint, I can get to 0.4-0.5 second differential with and without body on my 90-car fleet on an 8-second track. . If you can get 0.1sec differential with a body on, I need to get better obviously.

              Kev Burnley - no one replied to front-to-back vs. side-to-side. So I guess like MattB suggests, no-one knows the physics that are truly in play with FLOAT. I'm no expert either and I don't want to over think it, but if an expert can define the physics, experimentation can be reduced.

              Flexible chassis seems very important and we've all seen and heard the affect of a tight body distorting a chassis. Shifting weight to the outside tire sounds important - but a contrary postulation by a hobbyist suggests that the side-to-side shift of the body lags the chassis - allowing some mass to keep the inside tires from lifting. (https://blog.jadlamracingmodels.com/...-7-body-float/). He also indicates this lowers the Center-of-Gravity (CoG) - and I'd postulate that's because the inside wheels remain lower at the instant the the body is lagging the chassis. But it seems the body would then follow the chassis centrifugally to the outside with a detrimental thud when the body screw hits the the post hub. All the potential vibration resulting from a loose screw to post-hub fit might seem detrimental too.

              There are many other techniques discussed to improve float including half-threaded body screws, removing castle-like walls at the top of the posts that would prohibit
              the posts from sliding on each other, etc.. Float obviously improves performance as it is prescribed by all experts and pro-slotters. Preventing chassis flex seems the most likely physical attribute contributing to performance. But since the mass and centrifugal postulates differ - sometimes 180 deg - makes you wonder if these two aspects even play an improvement role?
              David

              Comment


              • #9
                perrotoro I've managed 0.1 sec with a brass chassis and the body (1/32 hard body) secured to the side floating pans but not with a plastic chassis, that's normally 2-3 tenths.

                You can have too much float where the body leans so much it's fouls the tyres or takes ages to settle down again out of a corner.

                My 3D printed chassis have two body posts, one just behind the front axle and one just behind the pod (I've tried all sorts, even sill mounted posts), some handle better with a snug front post and some loose.

                If you're using the original interior the whole bodyshell can be a significant chunk of weight that's best balanced with an equally significant chunk of lead in the chassis.
                Kevan - Isle of Man
                Life is like a box of Slot cars...πŸš“πŸš—πŸššπŸšœ

                Comment


                • #10
                  Most of our 1/24 brass frames have no flex at all, The loose body has nothing to do with letting the chassis flex for improved handling, as the chassis will not flex even with no body.
                  This is our experience with stiff brass chassis. Loosening the body just seems to take absorb of the centrifical force that wants to pull the car out of the slot. Maybe it also helps put some downforce on the outside tires.
                  Matt B
                  So. In
                  Crashers

                  Comment


                  • #11
                    Thanks Kevan and MattB, I'm primarily focused on float for plastic body/chassis cars for home racing.
                    David

                    Comment


                    • #12
                      Running only plastic chassis on plastic tracks mainly Carrera or recently Policar, over the years i run my cars with a solid pod ( but not overtighten ) , cut out any excessive up and down movement in the front axle, also make sure the rear axle is not floppy in bearings or to much movement between the motor spline and the gear hub ( inline ).
                      The next thing i do is decrease top weight , take out all extra plastic and if possible use a lexan driver platform, you will be suprised the differance this makes , and finally when i mount the chassis in the body i use body screws with a blank area by the screw top , this allows smooth movement in the chassis holes, another tip ream a little plastic out of the chassis mount holes not to much enough to let body screws move freely , and from there on you can just adjust for the amount of body you want.
                      Of course others may disagree but been doing this for years and it works for me.

                      Comment


                      • perrotoro
                        perrotoro commented
                        Editing a comment
                        Peter - I've done all tuning you discuss above, though I have not shaved plastic but from a few of my heavier Carrera cars. I had been running with magnets with snug but not tight screws. I've converted 5 of my 90 cars to non-magnet and may convert the entire fleet. That's why I'm focusing on Float in this topic. Some experts say float is more important for non-mag then for mag racing. I'm using the blank top screws as I mention above.

                        I have not reamed plastic from the mount holes - that's a great idea for float improvement. I'm just trying to find if there's someone that knows the science of improved performance via Float. Some say it shifts weigh to the outside wheels and others say the body lags the chassis' movement in the curve, keeping CoG on the inside for an instant. Obviously, many experts use float for improved what might be adverse affects of the body shifting to the outside, I'm just wondering if anyone knows the true science or whether it's just an observation that has been passed on through out the slotting years.

                      • PETER GUNN
                        PETER GUNN commented
                        Editing a comment
                        It all comes down to shedding top weight really c of g the body float dampens that out a bit, mostly with the body screws i tighten them then turn back say a 1/4 of a turn just to get a slight movement , all my modified Thunderslot and Policar Ferraris also have the chassis shaved all the way round to stop that rubbing on the body, you want to have nothing except the body screws connecting the body to the chassis .
                        Never have run with magnets , i like to have the ability to actually drive the car with my skill , over the years i have found there are a mirad of small things that increase performance .
                        I always strip a new car down and reasemble making sure all above is done and straight away the car always runs better, just take the guide and pick up,s just run a smooth round file down the guide post hole so the guide rotates easily , drop of lube in the post hole , splay the braids out to get maximum contact with the track that alone stops any guide jamming over and always returns to the centre , there are so many things like that which will give you a better car

                      • Kevan
                        Kevan commented
                        Editing a comment
                        There's no such thing as body float science so you'll have to go down the empirical route, take advice and DIY.

                    • #13
                      I like to put screws in a dremel and file the top 3mm or so of thread until it's smooth, as you say doesn't snag the chassis when the body moves.
                      Kevan - Isle of Man
                      Life is like a box of Slot cars...πŸš“πŸš—πŸššπŸšœ

                      Comment


                      • mattb
                        mattb commented
                        Editing a comment
                        This is a good tip.
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