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Secrets to Building a Race Winning Slot it Car.

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  • #46
    Could also possibly be a non-perfect racing surface.

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    • #47
      But didn't your earlier tests / video show that a in line setup when suspended on the axial centerline would torque / gyroscope.


      If it would do that in mid air then it also has to be doing it when put in a car and running on the track.
      And if one were to use a skid pad to sand the tires, This could be the reason why tires do not sand
      equally when being sanded on a car with in line configruation being run in opposite directions on the
      skid / sanding pad.

      I also remember some of your earlier tests / videos of sidewinders that showed lifting the guide completely
      out of the slot.


      I believe your own photo and video evidence destroys your statement about no torque / gyroscopic load
      having an effect on the handling of a 1/32 scale car.

      Physics is Physics. Being a scale car does not exempt one from laws of physics.
      Maybe I just don't have enough understanding of physics...

      Originally posted by davejr View Post

      With 1/32 scale cars there is no torque load or gyroscopic load that effects the
      handling of a road racing slot car.

      One thing that will make an inline car handle better in one direction is the lateral
      vibration created by the gears.

      Setting up an inline car with axle spacers normally eliminates this problem.

      The major cause of any chassis design handling better in one direction is the grip
      of each tire.

      If both tires are perfectly true while running on the car, any type of chassis should
      handle the same in either direction.

      Dave
      Last edited by DrDiff; 04-01-2009, 08:52 PM.

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      • #48
        But didn't your earlier tests / video show that a in line setup when suspended on the axial centerline would torque / gyroscope. If it would do that in mid air then it also has to be doing it when put in a car and running on the track.
        No doubt Dave will answer this better than I can, but there's a big difference between suddenly applied power (which creates an action/reaction around the axis of the pinion shaft, and a similar action/reaction between the tires and the track, causing nose lift).

        After all, a dragster will lift its nose as it leaves the gate, still travelling at a relatively low speed. But a car driven in a straight line at constant throttle, even at a hundred miles an hour, will have no tendency to lift. Even if a car does lift as a result of high speed, this is caused by aerodyamic forces rather than acceleration.

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        • #49
          chalk on tires

          Funny how my RC cars suspension settings started changing when I started doing this. I prefered white or yellow chalk and 5-7
          lines drawln accross the contact patch radially. 4-5 hot laps around the track and come back in to read the tire wear.
          Make changes and go back out untill all the chalk was off the tires.
          Last edited by DrDiff; 04-01-2009, 08:51 PM.

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          • #50
            Race winning not skid pad winning...

            Point taken wet... But then again we are talking skid pad at constant throttle and all. There are no skid pads used for racing. Drivers are constantly in and out of the throttle when racing on a track. Thus the car is constantly experiencing changes in load on the tires contrary to Dave's statement. I think that Dave's work has value and that there is some evidence that a car that does well on a skid pad should do well on a track. But it is not a direct correlation.

            Quite frankly Dave's work has given him some level of athority here in the SCI forums. And quite frankly to not put something to test due to weight... well... kinda coping out if you ask me. Especially when he has presented both photo and video evidence in the past.

            Originally posted by Wet Coast Racer View Post
            No doubt Dave will answer this better than I can, but there's a big difference between suddenly applied power (which creates an action/reaction around the axis of the pinion shaft, and a similar action/reaction between the tires and the track, causing nose lift).

            After all, a dragster will lift its nose as it leaves the gate, still travelling at a relatively low speed. But a car driven in a straight line at constant throttle, even at a hundred miles an hour, will have no tendency to lift. Even if a car does lift as a result of high speed, this is caused by aerodyamic forces rather than acceleration.
            Last edited by DrDiff; 04-01-2009, 08:51 PM.

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            • #51
              The 'chassis in suspension' is also a good way to check balance. Add BB's to the light side until it balances and then do it front to back. Then let the chassis pod flex take care of the rest of the adjustments.

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              • #52
                DrDiff

                This article about; FACT OR FICTION

                http://slotcarillustrated.com/portal/forums/showthread.php?t=27555

                Is a demonstration to disprove the idea that motor torque adds weight to one wheel and removes weight from the opposite wheel.

                What the photos and video demonstrate is the momentum created by the acceleration of the armature applies less than 7 grams of weight on the left rear tire the instant 14 volts is applied.

                This force dissipates immediately and is only present when power is applied instantaneously.

                The 450 grams of motor torque never applies any additional weight to the wheels.

                The photo of the 312 is demonstrating weight transfer created by the pinion climbing up the spur gear.

                These forces are demonstrated in this article;

                http://slotcarillustrated.com/portal/forums/showthread.php?t=28606

                Dave

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                • #53
                  The same force that causes a drag car to wheel stand if it has the right guide arm.

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                  • #54
                    Dave,

                    Thanks for clarifying that. Like I said earlier, Maybe I don't have enough knowlege of physics to participate here. Ironically the only way to learn is to ask questions and have things explained by those who understand. Passing of knowlege...

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                    • #55
                      That is understood. We have varying experiences and backgrounds. R/C guys try to use that experience and model builders can make their contribution as well. We all understand that there are new people as well. Patience will make it easier to 'pass the knowledge.'

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                      • #56
                        While skid pads and other tests can isolate certain phenomena, the results of lots and lots of actual racing shows that, in general, Slot.It sidewinder pods out-handle Slot.It inline pods. You can tune an inline to be fast, but my experience shows that the sidewinders with the same motors, tires, gear ratios, etc. tend to be easier to drive. Not necessarily faster, but more consistent, and more likely to win races. Look at race results from proxy races and you will see this trend. There are exceptions, but the general rule is that the SW's are the winners.

                        My understanding of the underlying physics is that torque reaction from the inline upsets the cars rather more than sidewinders, as the IL car is forced to twist (roll) along its longitudinal axis. When the car is at the ragged edge of adhesion, transitioning in and out of corners in fractional seconds, a mere, few grams of force suddenly applied to one side of the car can really screw up the handling.

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                        • #57
                          I was going to go on and on about proxy racing being a compromise and all.... but then again I look at the subject...

                          "Building a Race Winning Slot.It Car" Not "Proxy Series Winning..."

                          If you think of it this way. Dave has given us a tremendous wealth of knowlege on how to build a car for his track and his type of racing.

                          Yes what is fast on one track should be fast on all kinds of tracks... And what is fast in a 2 hour sprint race may not work for a 12-24 hour endurance race... And most of all we don't ship, say Elsecondo, to every race in the series either... Though I doubt he would complain!

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                          • #58
                            To capsulize the thread, balance is important, the chassis needs to be stiffened front to back but the chassis should still be allowed to twist just slightly, not much. The pod adjustment is the primary tuning item. Tires are another key to handling. Specific tires for specific surfaces. Gears will use the motor to its best advantage depending on the length of the track. A bunch of wheels with different tires may be necessary if you race on a variety of track surfaces.

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