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Wheel gap - hope this isn’t a dumb question

Discussion in 'Ask The Pros' started by cosmo9370, Jan 16, 2023.

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  1. cosmo9370

    cosmo9370 Hammering Axles

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    First, thank you to everyone for all of their advice and willingness to share your expertise. Very much appreciated!

    So I have read so much great advice here but it has my heading spinning to the point I think I am confusing myself and probably missing the obvious!

    I have seen most experts say get the wheel gap as close as possible, some saying as close as .015 mm. However, it is also suggested to remove 1/16 inch from DFW for rail rider. So doesn’t that mean the gap on the DFW needs to be at least 1/16 in order to clear the 1 3/4 inch center rail? Or does that gap just refer to back wheels and front wheel has an obviously bigger gap?

    Our rules say the minimum space between wheels is 1 3/4 inch to clear center guide strip.

    Also, for removing the 1/16 from DFW does that mean from front all the way down past the axle hole or to sand out just enough in the ‘wheel well’ area?

    thanks again so much for all the advice out here, you all rock!
     
  2. DerbyDad4Hire

    DerbyDad4Hire Administrator Staff Member 25+ Pro Race Wins! National Champion

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    Shave it enough for the wheel to clear it. I would go .01 on the gap.

    PRO TIP- if you get to the race and they say there isn't enough room between your front wheels then pull your raised wheel out until it passes.
     
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  3. cosmo9370

    cosmo9370 Hammering Axles

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    Thank you DD4H! I really appreciate it!

    one more dumb question. Is the gap from the center hub or the top of the wheel. With the 3 degrees angle/cant in the rear, wouldn’t the top of the wheel might rub the body if I use the hub for the gap.

    sorry, I’m an obvious newbie just trying to make sure my Cub Scout does well enough to not be embarrassed! Of course winning will do that! lol

    maybe I need to clear my mind and come back with a fresh head. I’m starting to forget my physics classes!
     
  4. flockshot

    flockshot District Champion

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    It is easy to get overwhelmed, but don't worry about it. I was trying to consolidate all my notes last night and found that I had made the same note 4 times.

    The gap between the hub and the body is about the thickness of a credit card.
    Everybody here builds very thin cars. Like perhaps 3/8 inch, so no amount of angle in the wheel will ever come close to rubbing on anything. If your body is at or above the height of the wheel, I would suggest a thinner, more aerodynamic car, and that weight you cut off the top of the body can go in the rear, pushing the car in the form of tungsten.
    The DFW cut out can be only in wheel well section, or from rear of wheel all the way forward. I see them both ways. The purpose of the cutout is to move the DFW more to the center of the car so that the two rear wheels will be equal distance from the rail.

    Fear not. Ask all the questions you want. Everybody has been where you are right now.
     
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  5. cosmo9370

    cosmo9370 Hammering Axles

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    Thanks Flockshot, I appreciate the feedback and encouragement!

    so I think I just figured out something else that I had wrong. The .01 gap is .01 inches, not millimeters. When I thought it was millimeters, I got out my spark plug gapping tool and was like ‘there’s no way’!!! LOL!
     
  6. T-Bone Racing

    T-Bone Racing Workshop Leader

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    Yes, about a credit card between the body and hub of the wheel, it don’t go crazy with it. In a scout race, whether your gaps are a touch tighter or looser will only change 0.001-0.002. Not much.

    Focus more on polishing your wheels and axles, getting your car to be a quarter inch, and make sure your weight is in the back. Those 3 things alone should be enough to win every time. Hope that helps
     
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  7. Jupiter 2.9

    Jupiter 2.9 Council Champion Pro Racer

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    A credit card is .032, I think that’s to much.
    A paper business card is .010. Cut a thin v then push the wheel in “snug” not tight. When you remove the card you should still see a whisper of axle.
    But like T-Bone said, thin car, wheel & axle prep are a bigger bang. You should polish & wax the contact are on the body as well.
     
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