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Secrets to Building a Race Winning Slot it Car.

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  • Secrets to Building a Race Winning Slot it Car.

    The car that I built for the 2009 Slot It shootout was made from a white kit and is completely stock except for the yellow motor, aluminum front wheels, and S1 tires.

    I chose the yellow motor because it is underrated by Slot it. The motor is rated at 11.25 watts, when fully broken-in it dyno tests at 13.5 watts, 4 watts more than an orange motor.

    The plastic wheels had a slight wobble so I replaced them with aluminum wheels.

    The S1 tires are made in Italy by the people who race them.

    The secrets to building a race winning car is in the assembly, and keeping the car as light as possible.

    All of the parts were inspected for straightness and any flash was removed.

    The chassis had 1/16” of material removed anywhere the chassis made contact with the body.

    The motor pod screw heads were made smaller and installed 1 turn loose. The screw thread ends were slot cut through the pad bosses and epoxied in place.

    The tires were glued to the wheels.

    All four wheels and crown gear were balanced.

    The crown gear had the slot widened 0.060” and Slick 7 washers were used between the axle tubes and the spherical axle bearings.

    The pick up boss was strengthened with epoxy and the chassis was assembled.

    The rear wheels are set for zero clearance and the gear is set at zero clearance.

    The rear tires were finish trued after mounting on the chassis. It took almost 2 hours of sanding on the sanding fixture and sanding skid pad to get the tires perfectly true. This also helped brake-in the motor and chassis.

    The body has two pieces of aluminum tubing added to the body posts for added strength. The assembled body was mounted with the screws ĺ turn loose.



    Three pieces of black electrical tape were placed on the bottom of the chassis over the pod screws. This acts like a shock absorber and removes the vibration between the pod and chassis.





    After tuning and testing I was satisfied with the car’s performance so I switched the chassis to a sidewinder for comparison.

    With the sidewinder it was 0.040 seconds slower on the skid pad, and 0.150 seconds slower on the track.

    I also tried the Lexan interior, it made no improvement to the cars performance.

    In the Shootout race on my track, the car was almost 0.300 seconds, and 2 mph faster than the cars with orange motors.

    Dave

  • #2
    How did you perform the balancing of the wheels and crown gear?

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    • #3
      Originally posted by davejr View Post
      The screw thread ends were slot cut through the pad bosses and epoxied in place.
      Sorry to be so dense, but I don't understand what you did here. Could you elaborate, please?

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      • #4
        A very wise racer from the coast once told me how to set up a Slot.It, Unless only genuine Slot.It parts are allowed, other brand parts can be EXTREMELY HELPFUL!

        Slot Car Corner bolts and lock nuts on the pod. The Slot Car Corner parts are a finer thread and makes getting the proper ammount of movement for the pod a SNAP. Also you can not strip out a bolt and nut like you can strip out a screw in a plastic pod.

        To take the dampening one step further try the Slot.It Magnetic Suspersion. It allows for more precice dampening of the pods movement, than what black electrical tape allows.

        My wet friend did not tell me this next part, but I discovered this when running 1/10 and 1/12 scale RC pan cars Adding one gram rotationg mass to the car is like adding 3 grams non rotating weight. That in mind, I like to keep the axels as light as possible. I like to stagger the set screws on the gear and rear wheels. I place them at 120 degree intervals. This displaces the weight of the set screws at equal points in the axel rotation and "balances" the axel.
        Last edited by DrDiff; 03-30-2009, 12:02 PM.

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        • #5
          So no added weight at all in that slot car, and using the yellow endbell motor. Doesn't it try to lift the nose out of the slot under hard acceleration Dave? Also, have you ever experimented with the magnetic suspension?

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          • #6
            Originally posted by kidvoltage View Post
            How did you perform the balancing of the wheels and crown gear?
            Go to your Local Hobby Shop and ask for a propeller balancing kit. Either the magnetic kind or the kind with two razor blades will work.

            Put the wheel or gear on the axel and spin it on the balancing kit. Note the position of the set screws when the spining stops. If the part is out of balance, the heaviest end [most likely the set screw] will always point down, . If the position of the set screws are random after each spin, then the parts are balanced.
            Last edited by DrDiff; 03-30-2009, 12:05 PM.

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            • #7
              Originally posted by davejr View Post
              With the sidewinder it was 0.040 seconds slower on the skid pad, and 0.150 seconds slower on the track.Dave
              Did you compensate for the side winder gear ratio? Or did you simply slap the existing parts into a side winder pod?

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              • #8
                kidvoltage

                To balance gears and wheels I use the same setup I use for balancing armatures.

                Two razor blades on a level table.

                Mount a gear or wheel and tire on an axle, roll it back and forth to find the heavy spot.

                Put a drop of epoxy opposite the heavy side, and keep testing until it rolls without stopping at a heavy spot.



                Zoom Beedo


                Once you have found the ideal chassis setting and you donít want it to change, cut a slot in the thread end and the boss in the pod and add a drop of epoxy.




                DrDiff

                I used an 3.11:1 inline gear ratio and a 3.09:1 sidewinder ratio.


                Dave

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                • #9
                  Wet

                  To keep the car in the slot without any added weight, I just set the braids flat and they act like a governor. In normal race conditions I never had a car come out of the slot.

                  To be honest, I donít know what the reason would be to use magnetic suspension on a smooth track. So I never tried one.

                  Dave

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                  • #10
                    Originally posted by davejr View Post
                    kidvoltage

                    To balance gears and wheels I use the same setup I use for balancing armatures.

                    Two razor blades on a level table.

                    Dave
                    Holy Moly! I'd hurt myself with that setup!

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                    • #11
                      Dave, youve outdone yourseld again. And i thought I had an eye for detail.

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                      • #12
                        Are Slick 7 washers legal in the Slot.It Shootout?

                        Nice article on the tuning and set up Gonna have to try a whole bunch of my cars without lead!!!

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                        • #13
                          From the Shoot-Out rules:
                          Non-Slot.it parts allowed for this series include: lead weight, body screws, pod screws, axle shims, guide spacers, machine screws/nuts/washers and grub screws.
                          Last edited by Robert Livingston; 03-30-2009, 02:38 PM.

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                          • #14
                            Originally posted by DrDiff View Post
                            Did you compensate for the side winder gear ratio? Or did you simply slap the existing parts into a side winder pod?
                            I don't think Dave ever "Slaps" something together?! Thanks, Dave, for another informative article!

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                            • #15
                              Normal is a setting on a washing machine...

                              Originally posted by davejr View Post
                              To keep the car in the slot without any added weight, I just set the braids flat and they act like a governor. In normal race conditions I never had a car come out of the slot.
                              Dave
                              I am curious how it will fare in Round 5 at Alan's. The 30 ft. main straight has a "Deer's Leap" in the middle of it and greater cars with less motor have found the floor due to an excess of traction and power... especially as he runs 13.8 volts.

                              Kerry

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