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  1. #1
    RC poster
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    Over/Under Drive

    Hey is the preference between the two? By that I mean is a underdrive better then a over or vise verse? Or are they the same at performance?

  2. #2
    RC Turnbuckle Jr. Greatscott's Avatar
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    Nope...

    Over/under drive is what the front axle is doing compared to the back axle.

    When overdriven, the front axle is spinning faster than the back axle. This gives a slight dig-effect, without actually having a dig installed. It helps when going up hill by allowing the front to pull faster than the back is pushing, which helps prevent the back axle from driving under the truck and flipping it over backwards. It also helps with turning, allowing the front to pull the truck around, instead of the back trying to push the truck in a straight line (locked diff). One down-side of this configuration is you can drag the back axle to places you don't want it, like over gates, or over a ledge.

    I am sure there is a use for underdriving the front, but I can't think of any...
    Submarine Qualified, Chief Inducted, Navy Retired

  3. #3
    RC Competitor
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    I totally agree with Greatscott, i see no reason either.

  4. #4
    RC Racer
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    Quote Originally Posted by Greatscott View Post

    I am sure there is a use for underdriving the front, but I can't think of any...
    Better for fishtailing and making figure 8s in the snow?

  5. #5
    RC poster
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    Thanks for your answer. I shouldn’t have been more clearer in my question. I know the purpose of it. What I was asking is there a benefit of a over-drive in front axle as opposed to a under drive in rear axle? Is one better or easier on parts. Thanks sorry for confusion

  6. #6
    RC Turnbuckle Jr. Greatscott's Avatar
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    Quote Originally Posted by puffymoose View Post
    Thanks for your answer. I shouldn’t have been more clearer in my question. I know the purpose of it. What I was asking is there a benefit of a over-drive in front axle as opposed to a under drive in rear axle? Is one better or easier on parts. Thanks sorry for confusion
    Sorry...

    It really doesn't matter which way you go as long as the ratio is right. If memory serves, the two common over/under drives is 6% and 11%. Just keep in mind that under driving the back axle will make you lose overall speed.
    Submarine Qualified, Chief Inducted, Navy Retired

  7. #7
    RC Competitor
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    As a rule of thumb I have always used overdrive in the front because you wont loose wheel speed but if the parts are unavailable for what ever reason then underdrive the rear is the next option in line.

    sometimes under driving the rear is hard because the larger ring gear can have fitment issues in the pumpkin on certain axles.

    a combo of both overdrive front and underdrive rear really get the effect going and for rock crawling it is nice but you do have to approch gates different once the axle ratios are not the same.

  8. #8
    RC poster
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    Feb 2018
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    11
    Ok perfect thanks for the help everyone

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