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This topic contains 7 replies, has 4 voices, and was last updated by  Rob Kozakowski 11 months, 2 weeks ago.

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  • #15018

    Mark Lozon
    Participant

    I need help clearing this issue up….KT100 running WKA senior pipe (sprint kart). using the same final gear ratio(8.70)  what effect would running a t14 vs t11 on a triple disc. Some say the T14 will give and advantage off the corners some say the other way around……tell me your thoughts.

    #15024

    TJ Koyen
    Participant

    A ratio is a ratio. The difference in rolling resistance and friction is negligible.

    #15043

    Greg Wright
    Participant

    To get an 8.70 ratio with a 14T you would need a 121 tooth axle sprocket!!!!!!!

    #15055

    TJ Koyen
    Participant

    To get an 8.70 ratio with a 14T you would need a 121 tooth axle sprocket!!!!!!!

    Also a very good point to consider. Haha.

    #15074

    Rob Kozakowski
    Participant

    In sprint racing, I don’t know of anyone who disagrees with “a ratio is a ratio”.  It’s been tested by many of us, and I can’t find anyone who has found otherwise.

    Apparently, iIf you’re talking dirt-LTO stuff, there’s a lot of debate to be had.  Many experienced guys in that arena will tell you it DOES make a difference.  As strange as that seems to me, I’ve got no experience with it, so maybe it does make a difference in certain situations.  I certainly wouldn’t rule out that possibility completely.

    #15075

    Greg Wright
    Participant

    Rob, Man oh Man do the 4 cycle dirt guys get their undies in a bunch over that. What bothers me is that they insist that (example here) a 14-56 (4 to 1) ratio will out accelerate a 17-68 (4 to 1) ratio but the 17-68 will run faster on top.

      Let’s see here now, if it is a 4 to 1 ratio and the engine is turning say 6000 rpm the top speed has to be the same. I’m told I’m wrong, there could be some difference in acceleration curves due to changes in the friction developed in the drive train but 6000 rpm divided by a 4 to 1 ratio has to be going the same speed no matter how you achieve it. Again I’m told I’m wrong. Ain’t buying it.

     

    I will add that with some experimentation I have found that using the bigger combination of gears will reduce some friction in the drive train due to not turning the chain around as tight a corner (drive sprocket) and there is an almost imeasurable gain that does show up on a dyno run. The gain is within the standard range of deviation but consistently showed up on the + side.

    This is impossible to test with sprint type gear ratios.

    #15082

    Rob Kozakowski
    Participant

    Yep, the 4-cycle dirt guys definitely get upset when they’re challenged on that one.

    Rotating mass and friction in the driveline are the 2 things they seem to throw out a lot of the time.  Hard to believe there’d be any measurable gains or losses from going bigger or smaller, but then again sometimes in life, there are things that you just can’t really explain.

    Fortunately over in the sprint world, we seem to be at a consensus that a ratio is a ratio.  We also normally go as big as we can reasonably get away with without risking chewing the teeth off the axle sprocket.

    #15085

    Rob Kozakowski
    Participant
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