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How important is wheel gap?

Discussion in 'General Pinewood Derby Discussion' started by Scott Porter, May 5, 2019.

  1. Scott Porter

    Scott Porter Pinewood Ninja

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    I have been enjoying your site and want to say Thank You for great advice! I helped two Cub Scout boys from our church my wife and sponsor build 4 cars this season (I'm exhausted) . Thanks to you our two scout cars wonPack level first and second and our 7 oz outlaw cars did the same. Only bruises are younger brother won both first places. I imagine the info is somewhere in blogs but what wheel gaps should I be running? Right now I am at .035 on rears with 3 degree camber and .027 on fronts and stepping up the steering wheel angle. Only ran 1.5 degree but know many of you are WAY more aggressive. Again Thanks for helping me help two great boys have great big smiles! P.S. Thanks to DD4H for great components and advice!
     
  2. TRE

    TRE PWD Royalty Pro Racer Pro Race Winner

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    I run them as tight as i can get them...every car is a little different
     
  3. Reecedad

    Reecedad Council Champion

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    I run about .010 rears and .015-.020 front
     
  4. Scott Porter

    Scott Porter Pinewood Ninja

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    Thanks so much, I have never tried that tight but will.
     
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  5. Reecedad

    Reecedad Council Champion

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    I've found it helps with the wiggles
     
  6. Charles Studer

    Charles Studer Workshop Leader Pro Racer

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    The better you match up axles to bores the looser you can run....
     
  7. Scott Porter

    Scott Porter Pinewood Ninja

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    Sorry I missed your message. What does that match look like? With that do you run more gap? Gap ideas? Txs!
     
  8. Reecedad

    Reecedad Council Champion

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    Axles should measure about .005 smaller than the bore
     
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  9. Scott Porter

    Scott Porter Pinewood Ninja

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    Txs for that information. How do you do that? Calipers and pin gauges? Do you buy bulk wheels and sort till you find matches with your axles and then lathe or ?? Or ream bores some how? Thanks for allowing me to ask the process.
     
  10. Darkside

    Darkside District Champion

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    The first thing I do when I get a new batch of wheels is test them with pin gauges and classify them by wheel bore size.
     
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  11. Scott Porter

    Scott Porter Pinewood Ninja

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    Curious where you get bulk wheels? Do you also use a dial indicator to check roundness and match mold numbers? Txs!
     
  12. Reecedad

    Reecedad Council Champion

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    I check for runout first and put my best wheels aside for box stock
     
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  13. Darkside

    Darkside District Champion

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    You don't get bulk wheels. You buy them in packages of 4. I'll buy 25 of those at a time for 100 wheels.

    I think everyone starts out focused on the mold numbers for some reason. I know I did. Not sure where I heard that was a thing... I've never really found that the molds matter. Wheel quality seems pretty random to me.

    I start by classifying by bore size. Then I mount the wheels on the appropriate pin gauge and check for run out using a dial indicator. Anything with .001 or less gets set aside for box stock. ( just in case I ever get around to building a box stock car. :) )
     
  14. Scott Porter

    Scott Porter Pinewood Ninja

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    Thanks, that is very helpful!
    Thanks!
     
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  15. Charles Studer

    Charles Studer Workshop Leader Pro Racer

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    What they said +1
     
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  16. Scott Porter

    Scott Porter Pinewood Ninja

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    By that you mean .002 or less? What is an acceptable bore size? Or does it have more to do with the axle to bore gap like mentioned before? What size pin gauges should I have? Sorry for steering into the weeds but this is all very helpful to me. :)
     
  17. Darkside

    Darkside District Champion

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    Lol! When he said "+1" he meant he agreed. :D

    When it comes to bore size, smaller is better the way I understand it.

    The pin gauges I use are made by Vermont Gage and are sized .095+, .096-, .096+, .097-, .097+, and .098-... I have yet to find a bore below .095, but I'm sure they're out there. I would have pin gauges in .0005 increments if I could find them. The large sets on Ebay may have them, but not sure if i trust those sets.
     
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  18. Darkside

    Darkside District Champion

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    Ah man! Just got curious and searched for pin gauges in .0005 increments and found them in both + and - sizes from Vermont Gage.... looks like I'm buying more pin gauges.... The wife is gonna give me that look again.

    Just when I thought I had reached the bottom of the rabbit hole! Lol! :D
     
  19. Scott Porter

    Scott Porter Pinewood Ninja

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    Got that on the lol. I will try to remember the lingo! Txs and sorry Charles!, Very helpful info Darkside!
     
  20. Scott Porter

    Scott Porter Pinewood Ninja

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    Sorry if I made you spend money. Please send a link. :)
     

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