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  • Traction problem I don't understand

    I have been tuning a Scale Racing Product chassis for use with a Mustang GT body. The chassis is all metal, so it's fairly heavy. It is running an NSR EVO King anglewinder with 13/31 gears. This is exactly the same motor and gearing NSR uses in their angle winder models. The problem I am running into is I am having considerable difficulty with traction under acceleration. Weight doesn't seem to help. I have tried two different CB Design 11x17 wheels, one with Quick Slicks and one with Super tires, both silicone. Wheels and tires are true and there is no chatter; just lousy traction. I have a number of NSR anglewinders and have never had this kind of problem. Remember, same motors and gearing. So just for grins, I swapped NSR wheels and Quick Slicks from one of my anglewinders onto my Scale Racing Product chassis... No more traction problem! These are NSR air gap wheels and matching Quick Slicks. I don't understand how this could make such a difference.

  • #2
    If you are running a car without traction magnets there is a limit to how much power you can put down. Long can motors have a lot of torque, even the ones with lower RPM ratings. You did not say what your track voltage was, most clubs that run without magnets use 10 volts. I have a RevoSlot Toyota GT-One, that has a heavy metal chassis and is an anglewinder. The motor is an FC-130 type however, it is rated at 21K and 200g-cm, at 10 volts the car is perfectly manageable. If changing motors or lowering the track voltage is not an option you could put some diodes wired in series between your controller's white wire and the track white connection, each diode will drop 0.7 volts.

    Comment


    • Bal r 14
      Bal r 14 commented
      Editing a comment
      You are missing the point. There are no traction problems with NSR airgap wheels and Quick Slicks when there is with CG design wheels and Quick Slicks or Super Tires, same car, same voltage.. which is set to 8.5v. Is there some advantage to NSR air gap wheels? I see negative comments about them, never anything positive, which is what causes my confusion.
      Last edited by Bal r 14; February 10, 2022, 02:00 PM.

    • docdoom
      docdoom commented
      Editing a comment
      I have always been able to get better lap times with air gab wheels vs sold rib rims...I can take same car and rubber tire and the air gab tires are faster and more consistent over the run than a sold ribbed wheel. maybe the air gab tire allows the tire to move around and conform to the track surface better that a solid wheel. another thing is Thay do not overheat/ loose grip over the run either

  • #3
    Here's an update.... after a number of attempts to verify my results I found that I appear to have a number of sets of Quick Slicks that stick like glue and the cars that have them require little or no weights. I swapped those tires with other Quick Slick tires (all CB57 firm) and traction loss occurred. No other changes... same NSR air gap wheels, gears, weight, everything. I am sure I can correct the problem with some weight, but that wasn't the point of this experiment.

    Comment


    • #4
      how true are those tires that have less traction? almost sounds like a contact patch issue. be interesting to see the wear pattern on the tires.
      THE other Vancouver aka Vancouver Washington across the river from keep Portland weird....
      Member NASTE (Northwest Association of Slot Track Enthusiasts)

      Comment


      • Bal r 14
        Bal r 14 commented
        Editing a comment
        It's really hard to tell if these tires are true. I have attempted to true them, but who knows? I set the car on my track on a sheet of very fine sandpaper and hold it while I apply power. If the tires are not true, there is some vibration I can feel. If they are true there is virtually no vibration.

        Thanks for confirming my feelings about air gap wheels. I retested that with different combos of Quick Slicks and Super tires on air gap and standard wheels and air gaps definitely grip better.

    • #5
      What about the contact patch? When I true tires not only am I going for perfectly round tire I'm also looking for a full contract patch with the track. No cupping You can tell by running a few laps and looking at the wear pattern on the tires. Any shiny area would mean that part of the tire not touching the track.
      THE other Vancouver aka Vancouver Washington across the river from keep Portland weird....
      Member NASTE (Northwest Association of Slot Track Enthusiasts)

      Comment


      • #6
        Contact patch is excellent.. Just out of curiosity, I checked the contact patch of all of my cars with silicone tires and observed the center of some tires with airgap wheels is shiny. Traction on these cars is excellent with little or no weights. Just an FYI, I have only had to true 6 silicone tires out of about 100.

        Comment


        • Mikeinclover
          Mikeinclover commented
          Editing a comment
          Did you try the Quick Slicks DF157 tires? They were designed to fill in the air gap on NSR wheels so they are flat across the whole patch. What type of track are you racing on? Maybe you should try the Extra Firm compound. Another thing the CB58 or DF158 will give you a little more sidewall it seems to work a little better in most applications.

        • Bal r 14
          Bal r 14 commented
          Editing a comment
          Track is routed MDF with 3 coats of semi-gloss latex, very smooth and clean. I have tried CB57 extra firm and they do not perform as well. The air gap definitely improves traction. Same CB57 tires on same test car with CB design wheels yields worse traction than with NSR airgap wheels. I have some CB58 tires and have more coming. It definitely works better from what I have seen. If nothing else, they provides a little more needed ground clearance.

        • Mikeinclover
          Mikeinclover commented
          Editing a comment
          We have found that firm start out a little better than Extra firm but the Extra firm just keeps getting better and better as the firm hit a plateau. In the NSR nationals I believe everyone ran Extra firm this year. Last year it was about 50/50. Firm seem to have an advantage on Carrera track but on wood and Scalextric it is Extra firm. Just my 2 cents.
          Last edited by Mikeinclover; March 2, 2022, 08:27 AM.

      • #7
        One problem I have found with "truing" silicone tires is, if the tires were not kept cool enough during the grinding and truing, the tires had "lost" some of their grip. Put a different set on and the grip was back.

        Comment


        • Bal r 14
          Bal r 14 commented
          Editing a comment
          The only silicone tires I have had to true were not Quick Slicks or Super Tires... I can't recall what brand they were. But, they turned out very well on, plastic wheels.

      • #8
        Silicone tires get very hot when you true them, you either have to limit the truing time and allow things to cool down before the next pass or you have to squirt a little soap solution on the tires as you are truing.
        The sticky goop from the tires will quickly render your sanding media ineffective, if you continue truing nothing more will be removed, but the tire will continue to heat up and may be damaged. If the tires have been glued with cyanoacrylate that adhesive does not tolerate much heat and you would risk the tire coming unstuck.

        Comment


        • Bal r 14
          Bal r 14 commented
          Editing a comment
          I have observed the sand paper doesn't last very long because of the goop. I use a very fine sand paper, low rpms and only minimal contact, so the tires don't heat up. I change the sand paper frequently. Consequently, progress is painfully slow. If I need to glue tires, I use Permatex Ultra Black gasket maker. It's a lot easier to remove and is heat tolerant.

      • #9
        Traction isn't just all about tire grip, there's also how often the entire contact patch is touching the surface, and that involves the suspension. In this case the suspension is the tire itself, air gapped rim or not, its likely the difference between firm and soft suspension settings on a race car.
        Is your track completely flat with no bumps?

        Comment


        • Bal r 14
          Bal r 14 commented
          Editing a comment
          There are no bumps, but there are many elevation changes and track is as smooth as ice. I try to keep the surface of silicone tires very smooth. It's very difficult to tell if there are issues with the contact patch as the surface of the tires doesn't show much change. As best as I can tell with 8x magnification is the contact patch is good.

      • #10
        You haven't mixed up o grip front tires by mistake have you?
        Cheers,
        John.

        Comment


        • Bal r 14
          Bal r 14 commented
          Editing a comment
          It's hard to mistake tires with nail polish on them.

        • Rastas
          Rastas commented
          Editing a comment
          The way you wrote the intro , tuning I expected the tires to be out of the package new! So you are using old tires?
          John.

        • Bal r 14
          Bal r 14 commented
          Editing a comment
          The ones that had excellent traction were older (4 - 5 months with minimal use... about 1/2 hour). The other tires were new. I am not aware that age was a factor with silicone tires.

      • #11
        I'm seeing all kinds of things that potentially affect traction, including track design. But, I keep going back to one simple fact... if I swap the tires to one of those I know has great traction, the problem goes away. Lap times drop by .7 seconds immediately. These are CB57 tires, just like the ones being replaced. Nothing else changes. There is no visible difference in these better tires. They may feel a tiny bit different to the touch, but it's hard to be sure. It seems like Quick Slicks made a batch of incredibly good tires. I sure wish I had more of them.
        Last edited by Bal r 14; March 1, 2022, 09:32 AM.

        Comment


        • #12
          Are some of the Quick Slicks of the Firm compound, and the others X-Firm?
          Dickie Pearson
          Canterbury, NH

          HOST - Home Operated Slot Tracks
          MSR - Main Street Racing

          Comment


          • Bal r 14
            Bal r 14 commented
            Editing a comment
            I have never used extra firm. I ordered a couple pair to try, recently. I was not impressed but I am willing to give them a longer try out.
            Last edited by Bal r 14; March 1, 2022, 07:12 PM.

        • #13
          Bal r 14,

          Lots of stuff to intake. But I will add my 2 cents.

          Wheels: Definitely the air gap wheels get you better grip around the corners. At the NSR Nationals, all podium finishers had air gap wheels. Your observation of the center of the tire being shiny is correct. When you glue you tires to the wheels the only contact patch you have to glue your tires is the outside shoulder of the wheel. So when you start to hit higher rpm's , the center of the tire "grows, expands" which is what it was designed to do. This will make the tire a larger diameter and thus faster top end speed. So why does the center still stay shiny? My thought is the center is not traveling fast enough to expand, and thus does not contact the track. If the tire is really tight on the wheel, then it will need higher speeds to expand. Also the podium finishers at the NSR Nats user 58XF, not the DF series. But many other racers did use the DF series. On the market are these donuts designed to be placed in between the spikes . This helps keep the center from concaving, dipping in so they may contact the track at lower speeds.

          Silicone tires. First you need to take a look at the web site for the Great Lakes Slot Car Club. It has a lengthy article on silicone tires. But in a nut shell there are 3 steps: 1. Glue tire to wheel. 2 True tire. 3. Polish tire.
          If you are not doing this, you are losing all kinds of grip from your silicones tires, or urethane or rubber for that matter. It is a lengthy process. Silicone tires can be out of round NEW. So even if your wheel is perfectly round, but the silicone tire is out of round, it will vibrate out of the corner and down the straight like a car tire out of balance. And the silicone used can come from different batches, so there may be a difference in grip even with the same part number. Regarding silicone tire age, the jury seems to still be out on this one. I can understand the silicone losing some chemicals thru evaporation over time which might result in less grip.
          Regarding heat through the truing process, if the tire gets hot and you get those droplets on the sand paper, it is not a total loss. You just need to keep polishing with the finer grits with soapy water and all will be ok. This will make more sense when you read the article.

          Truing tires is a time consuming process ( 4-6 hours per set )If you are slipping on your tires and letting them ride on a piece of sand paper on the track, this is not very effective. You may have hit the high spots on the tire, but over time the tire will spin on the wheel and you will have new high spots at that time.

          1. Wash the wheel and the inside of the tire with soapy water to get the release agents and manufacturing oils off.
          2. Glue the tire to the wheel ( Slot Car Corner has a great tool to assist with this ) using a good automotive weather-strip adhesive. Immediately, when you slip on the tire, spin it on the wheel. Wheel stays stationary and the tire spins on it. This will help to level the glue and tire and make it more true, thus reducing truing and polishing time. Dry for at least 1 hour, preferably 24 hours.
          3. On your Tire Razor, spin the tires on about 10 volts and round off the edges,, that is where the sidewall meets the tire tread, round off at about a 1/8 inch radius. In the beginning you can experiment with this radius. This radius will help you get better grip when cornering.
          Then reduce to 8.5 volts for the rest.
          4. Then "true " the tires using 120 grit sand paper. Dry. no lubricant's on sandpaper. True so all tread surface is dull , not shiny.
          5. Then polish the tire with 220 grit with soapy water. Touch up the edges with 220 so the radius is the same as the tread.
          6. Then polish the tire with 320 grit with Soapy water. Touch up the edges with 320 so the radius is the same as the tread.
          7. Then polish the tire with 400 grit with soapy water. Touch up the edges with 400 so the radius is the same as the tread.

          There is some conversation with going to 600 grit, but current thinking is by the time you have broken in your tires, they are at about 400 grit anyway so why spend the time.

          You do not want any part of the tire wider then the wheel, as if the tire protrudes outside of the wheel, there is no support ( wheel ) for the tire, thus not grip. If it protrudes outside the wheel, cut if off when spinning, inside and out. You want the tire profile to be the same on the outside and inside of the wheel.

          I have done tires where the sidewall is slightly slanted in.

          So for the problem you are having, it is hard to tell if the tire is bad if you are not following these glue/true/polishing steps. If the tire is not glued to the wheel, it will peel away from the tire going around corners and your car will exhibit vibration and hopping in corner and at exit of corner.
          The XF do last longer, but current thinking is they have slightly less grip. But at the NSR Nats, XF were the tire to have and it was not a long race. ( routed track ) So now when I tune a car, I make up 2 sets of wheels, Firm and XFirm and try them both. Also Super Tire may have a very slight edge on plastic tracks, but I know Quick Slicks are working hard to close this gap, and may be there now.

          Hopefully this helps.

          Disco

          PS: I have done this tire truing process on wheels where there is not air gap wheel available, and with great results.



          Last edited by Disco Denny; March 6, 2022, 09:27 PM.

          Comment


          • Bal r 14
            Bal r 14 commented
            Editing a comment
            Thank you. I am not spending that much effort on trueing the tires. I will have to do more. I let my tires ride on a very fine piece of sandpaper to tell me if the tires are true, not to true them. With my hearing aids cranked to max, true tires make a slight but steady sound on the sandpaper, almost like static. If they aren't true the sound oscillates. I think you can feel it, too. But that may be less reliable.

        • #14
          Actually feeling the vibration is how I tell how close I'm getting to the tire being true. I will use a small screw driver and as the tire is spinning on the Tire Razor, I rest the screw driver on the spinning tread lightly. You can feel the vibration indicating there is still out of roundness with the tire. When the tire is true, it feels like the screw driver is resting on glass, no detectable vibration at all. Then I go to the next step ( sand paper ) in the truing process. Some racers will use their finger nail to detect any vibration.

          Another video you may want to see is from Cinncy Slot. They show a tire being trued and have set up a motorized device that oscillates the sanding plate left to right to left. etc. So much better than moving it by hand. I have built the same thing but instead of truing 1 tire at a time like Cinncy Slot, I do both tires at the same time. I use it to true my front tires also.

          Really Bar, it all depends how much time you want to put into it. I am a very serious racer and will devote what it takes to get the job done , with in the parameters of the rules . But after 2 years of my buddy Ken and I struggling/aggravating with trying to get our cars to work, it all fell into place when I was taught by Rob Hall from the Detroit area how to true tires. He spent 2 hours with me on Facetime one sunny summer afternoon on how to true tires, and I haven't looked back since. When your tires are true the car will need less weight, and it will track around the corners faster and with more grip which will make for a faster car. Did I mention I do non magnet only? Sorry if I missed that.

          There are other items that will lead to the rear tires or rear of the car chattering. If their is space between the axle and the axle bushing, the back of the car will chatter. There can be no discernable evidence of space at all. There is a super glue trick that fixes this issue. If the motor is not absolutely secure, whether with screws or glued into place, the back of the car will chatter. Dont rely on the snap of the motor mount to secure the motor. And I'm talking about your non motor pod chassis.
          And if the "back Porch" of the chassis is too flexible, the back of the car will chatter. Ninco is famous for this. By back porch I mean the rear part of the chassis that holds the axle bushings. It is more narrow than the chassis to allow the rear tires room. But where that narrow ness meets the chassis , there can be flex, and will lead to the rear chattering. Again I'm talking about non motor pod chassis. I use metal strips made from banding material. It is used to band product together when on a pallet board. I cut it into narrow strips and glue it to the bottom of the chassis so half is on the porch and the other half is on the chassis. This usually stops the flexing and stops the chattering.

          When you stop the chattering, the car will accelerate and exit the corner very smoothly. And of course a bit of lead weight is usually needed. Some times you get so much bite you will need a bit of lead weight on the front of the chassis by the guide flag as the front of the car will lift and maybe deslot on acceleration.

          Disco

          Comment


          • Bal r 14
            Bal r 14 commented
            Editing a comment
            All but two of my current cars have pods and none have chatter. I don't like cars without pods... too many issues to deal with. I stick to higher end stuff with pods, aluminum wheels, gears and adjustable front wheel height and conventional guides. Traction is primarily an issue on my track because of lots of camber and elevation changes and some tight turns. It is not a problem on other tracks in our group who have more conventional designs. So, I will do some more work on my tires than I currently do. But, I'm not that serious about it, yet.

          • dinglebery
            dinglebery commented
            Editing a comment
            Can you show us some pics of these car chassis you're referring to, with the pallet straps glued into place?
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