Dismiss Notice
Welcome to
Pinewood Derby Online, a forum for questions and discussions about everyone's favorite gravity powered racers!
CLICK HERE to register as a member today for full access to the forum, it's fast, simple, and absolutely free!

Understanding weight placement and center of gravity

Discussion in 'Building tips' started by firestone, Jul 5, 2019.

  1. firestone

    firestone Bent Axle

    Messages:
    13
    Likes Received:
    4
    Trophy Points:
    3
    Gender:
    Male
    Location:
    New Jersey
    IS there any consensus on the true ideal center of gravity? I've seen/heard/read about 1" in front of rear axle, but with how heavily weighted some cars look with cube weights all the way to the back, I can't imagine those cars have COG that far forward.

    Also I'm getting the feeling that cubes are the way to go. My son has been running cylinder tungsten above rear slot and just in front of it, and does ok at the Pack level, but we're looking to really step it up next year. His goal is to get back to the NYC event next year and be competitive.
     
  2. flockshot

    flockshot Pinewood Ninja

    Messages:
    69
    Likes Received:
    19
    Trophy Points:
    8
    Gender:
    Male
    Location:
    Michigan U.S.A.
    One of the variables in how far rearward you can place the center of gravity, is the type and condition of the track you will be running on.
    I am not the guy to define what is right, but I see many who use 3/4 inch, and I don't see many suggesting otherwise. However, those who say nothing on the subject, may know best of all.
    I am building a track for me and my grandsons to play with, and then I can do my own experimentation.
     
  3. Darkside

    Darkside District Champion

    Messages:
    112
    Likes Received:
    91
    Trophy Points:
    28
    Gender:
    Male
    Location:
    Maricopa, AZ
    I don't so much worry about the actual location of the COM. I go by how much weight is on each wheel. Sure you can calculate the location of the COM from that, but why bother. Six to one, half dozen to the other... A good safe starting point would be 15 grams on the DFW and the remainder evenly distributed between the rears. You can then experiment by adding or reducing weight on the front as well as from side to side on the rears from there to see what distribution works best for you.
     
  4. electric sheep

    electric sheep Hammering Axles

    Messages:
    7
    Likes Received:
    2
    Trophy Points:
    3
    Gender:
    Male
    I follow the same approach as Darkside and check the DFW weight. I noticed my kids cars had better speeds when I made this change. I haven’t had issues with this approach.
     
  5. Carl ODay

    Carl ODay Pack Champion

    Messages:
    18
    Likes Received:
    5
    Trophy Points:
    3
    Location:
    Highland, CA
    Did some googling and cant find a scale that will measure individual wheels... Does such a thing exist?
     
  6. Jimmy & his 2 Kids

    Jimmy & his 2 Kids National Contender

    Messages:
    520
    Likes Received:
    199
    Trophy Points:
    43
    Gender:
    Male
    Well yes and no... folks just use 3 very small scales for each corner. However Chuy over at NPWDRL is quite the engineer and has created a 3 point single scale for this very purpose. You can see it here:
    http://npwdrl.boards.net/thread/2577/3-wheel-scale
    Personally I have just always done the same... racing Awana with no axle location restrictions I have just enough room behind rear axle for 2 fulls rows of 6 cubes each, then the rest goes right in front of the axle with bias on the DFW. I do this with my Awana cars and league.
    Though the fastest league racers do pay closer attention to weights at each wheel I am sure when testing and tuning.
    Hope that helps some. Good luck!
    Jimmy
     
    Carl ODay likes this.
  7. Carl ODay

    Carl ODay Pack Champion

    Messages:
    18
    Likes Received:
    5
    Trophy Points:
    3
    Location:
    Highland, CA
    Chuy does like his Arduinos! Thanks for the info.
     
    Jimmy & his 2 Kids likes this.
  8. Jimmy & his 2 Kids

    Jimmy & his 2 Kids National Contender

    Messages:
    520
    Likes Received:
    199
    Trophy Points:
    43
    Gender:
    Male
    Sure thing! Yes he amazes me with what he does with them.
     

Share This Page