Need advice on gear ratio

Discussion in 'Experienced Truckers' Advice' started by MikeinTennessee, Mar 28, 2020.

  1. MikeinTennessee

    MikeinTennessee Bobtail Member

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    So can someone tell me the best way to gain a little more road speed. DD15 with 10 speed OD and 342 rears low pro 22.5 tires.To get 75 MPH I am turning 2100 RPM
     
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  3. x1Heavy

    x1Heavy Road Train Member

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    Take the Nanny off. Redline is 2150. Those low pros are not saving you much anyway.
     
  4. MikeinTennessee

    MikeinTennessee Bobtail Member

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    Not to sound stupid but, will swapping to 11r 22.5 help much? And what do you mean take the Nanny off?
     
  5. x1Heavy

    x1Heavy Road Train Member

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    Many trucks are governed to a set speed. If you have taller tires that will help.

    Most trucks like to run close to 1600 RPM and that usually comes out to around the legal speed limit. I understand why low pros are on, however prefer the 24's I would not be surprised to see the situation improve if 24's are back on there.
     
  6. MikeinTennessee

    MikeinTennessee Bobtail Member

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    Ok. The truck isnt governed to a certain speed. I just want to get the RPMs down and be able to run 75 or so and not be that high of an RPM. This was an old ATS truck so I am guessing it was probably geared to run at the 63 or so mark. That is right around the 1600 RPM range
     
  7. TripleSix

    TripleSix God of Roads

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    That’s impossible to do in the big hole with 3.42s and an 10 speed overdrive. I run a lower gear than you and don’t run anywhere near that high an rpm even past 85.

    @Superhauler, mind giving a 2nd opinion?
     
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  8. larry2903

    larry2903 Medium Load Member

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    That’s a direct drive tranny, only way to get rpm’s down is swap tranny or gears.
     
  9. MikeinTennessee

    MikeinTennessee Bobtail Member

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    Thats why I was wondering about swapping rears or tranny out. Not looking for 100 mile an hour truck. Just don't like that high RPM.
     
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  10. x1Heavy

    x1Heavy Road Train Member

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    The ratio you gave is pretty powerful for pulling and I suspect that you want to keep that ratio.

    That leaves the transmission. However I don't know if it is possible to put in a transmission that will give you what you need at 75. It would be nice if you had a set of taller tires around to try it on and see if the speed situation improves versus your engine. 63 to 75 isnt that large.

    I don't have any more ideas anything else I would say would not mean much. And that comes from a thought that the truck is useful to you and you want to keep using it.

    Edit just read your response. No one is looking for 100 either. 75-80 is plenty. And you will have enough RPM's on hand to take on the smaller hills or deal with headwinds etc.
     
  11. Mid-May Trucker

    Mid-May Trucker Road Train Member

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    I think you bought a truck that was made for 60 miles an hour
    Crete?
     
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