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1/4 tungsten cubes vs 2.1 or 2.3 oz tungsten bar

Discussion in 'Pinewood Derby Tools' started by blkhunter01, Apr 13, 2020.

  1. blkhunter01

    blkhunter01 Pinewood Ninja

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    Help I am in the design phase of my first ladder car? What is the best weight type to use 1/4 tungsten cubes or 2.1 or 2.3 oz tungsten bars for behind the rear axle? And bars or cubes in front of the rear axle?? Please help?
     
  2. T-Bone Racing

    T-Bone Racing District Champion

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    I haven’t seen a speed increase or decrease from the 2.1 or 2.3 oz bar. I would definitely use one of the bars for behind the rear axle though. I would then use the 1/4 tungsten cubes for in front of the rear axle.
     
  3. Jimmy & his 2 Kids

    Jimmy & his 2 Kids National Contender

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    Agree with T-Bone about neither having speed advantage. IMHO it’s not a matter of speed advantage but a matter of personal building preference. And also accomplishing the same weight placement behind the axle but with less hassle.
     
  4. blkhunter01

    blkhunter01 Pinewood Ninja

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    Ok so next question I see some of the rear weights centered on the axles and some favoring the dfw side of the car. So much so, that the dfw side rail has been completely cut out on the dfw side. Is this of any benefit?
     
  5. Craigs Cruzer

    Craigs Cruzer Pinewood Ninja

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    If you are running on 3 wheels, the car wants to pull that elevated wheel down. There tends to be a consensus that rear weight distribution should be evened out between the rear wheels as best as possible. In order to balance the car between the rear wheels, weight has to be shifted to the side that has both front and rear wheels touching. Cutting the rear weight pocket so it is shifted toward that side helps in trying to achieve that balance from the onset. That's the intended reasoning for offsetting that rear pocket.
     
  6. blkhunter01

    blkhunter01 Pinewood Ninja

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    How do you achieve balence between the rear wheels with the rear weights behind the axle offset to the dfw? I am guess I got with the cubes in the pocket in front of the rear axle.
     
  7. Gso125 Racing

    Gso125 Racing Workshop Leader Pro Race Winner Pro Racer

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    Do you have 3 scales it helps to understand how the weight balances
     
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  8. blkhunter01

    blkhunter01 Pinewood Ninja

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    Not yet the three scales are on the list.
     
  9. T-Bone Racing

    T-Bone Racing District Champion

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    Before I had three scales, I just used one, and had a piece of wood that was level to the scales. If I was doing a rear wheel, I’d put the wheel on the scale, the other on the wood, and the DFW would rest on another piece of wood that is the same height as the scale and the other piece of wood. Then I’d just move the wood and scales around until I knew what needed adjustments. The three scales is the easy way to do it, but this is a good way if you don’t have them.
     
  10. Jimmy & his 2 Kids

    Jimmy & his 2 Kids National Contender

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    Do a search for Chuy’s 3 scale set up. MIND BLOWING!
     
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  11. txchemist

    txchemist National Contender

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    Here is my present inventory of bars for behind the axle- Some builders even order a specific weight in grams which I will attempt to do for everyone and I will let you know if that inventory is gone and what the closest might be.
    SH is super heavy.
    GP is ground and polished.
    upload_2020-4-14_15-38-46.png
     
  12. Jimmy & his 2 Kids

    Jimmy & his 2 Kids National Contender

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    There ya go BH01. TX is your last stop for tungsten.
     
  13. DerbyBoyz

    DerbyBoyz Rail Runner Pro Racer

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    Best place to get weights... is from TX.
     
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  14. DerbyDad4Hire

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

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    Evening the weight out on each rear wheel is SLOWER. Centering your weight in a triangular manner is what is fastest for me.
     
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  15. txchemist

    txchemist National Contender

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    Well- we might be still looking at the same thing. After you fine tune where you put the cubes in front of the axle, and you now have max speed, if you measure the weight on each back wheel, I might suggest 3 possible ranges.
    A Balanced ( 0 to 5 grams difference between back wheels)
    B slightly heavier on NDFW side (5 to 10 grams difference)
    C. No attempt to fine tune for speed ( over 10 grams difference)
    Now the actual center of gravity location between A and B is about a fat line from a sharpie in distance.
    So below is an example of the weights behind the axle NOT shifted, but after tuning for max speed and shifting some weights in front of the axle, this car ends up pretty well balanced.
    [​IMG]
    And here is the same car where no fine tuning with weights takes place. So which distribution more close resembles your preferred stacking?
    [​IMG]
     
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  16. Chris Stevenson

    Chris Stevenson Pinewood Ninja

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    Maybe a dumb question, but wouldn't the three scale method reflect more weight on the rear wheel on the non-dominant side because there is no weight being put on the front, raised wheel?
     
  17. Loud2ns

    Loud2ns District Champion

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    You are correct. The picture above shows the right rear as 71.58 verses 56.95 on the left. Left front is the dfw.
     
    Last edited: Feb 8, 2021
  18. txchemist

    txchemist National Contender

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    But the cure is NOT to put weight on the raised wheel side but to shift cubes over to the DFW side- what happens is the DFW and the back NDW almost balance all the weight on them so you move weight away from the back NDW to put a more equal load on the back two wheels.
     
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  19. Prozach2

    Prozach2 Workshop Leader

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    I also did my first ladder body this year. I did cubes last year and these tungsten bars in the picture from TX Chemist this year. I thought the big bar behind the axle and the long bar directly in front of the rear axle worked really well. They were cleaner and easier to work with than the little cubes. I also used the little cubes and tungsten putty to get the weight just right.

    I also want to give props to TX Chemist. I emailed him some questions that I had about building a ladder body, steer, weight distribution, etc. He gave me some great advice and got back to me right away.


    797052F4-AEB3-465E-9F8A-D7B21D7690F0.jpeg
     

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