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Regear for more MPG

Discussion in '2nd Gen. Tacomas' started by MaineTaco, Sep 20, 2009.

  1. MaineTaco

    MaineTaco [OP] The NUTS

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    Ok I think that this is a new one... I have a 2006 AC 4x4 4.0 V6 6 speed w/ 265/75/16 Genaral Grabber AT2. Now I know that the Auto's get better MPG's on the highway because they turn fewer RPM's. What if I could re gear to turn lets say 800 RPM less at 75MPH, would it be worth it in the long run "200,000 miles" to save some gas?

    Will
     
  2. DanGer

    DanGer Avatar approved by 98tacomav6

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    I would say no, only because it is a truck. You would get better returns getting a second set or rims with smaller, less agressive tires for street, then swam them out with your ats for offroading
     
  3. chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    4.10 gears, sliders, lots of buttons, and yellow flashing lights on the dash.
    You would use more fuel. It would put more load on the engine, and your economl would suffer.
     
  4. MaineTaco

    MaineTaco [OP] The NUTS

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    How? The Auto's turn less RPM'S and get better MPG's
     
  5. DanGer

    DanGer Avatar approved by 98tacomav6

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    you will lose a good amount of power is what chris is saying. Your engine will have to compensate for that by burning more fuel
     
  6. chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    4.10 gears, sliders, lots of buttons, and yellow flashing lights on the dash.
    There is a narrow RPM window for economy. Too little of a gear, hurts mpg, and too much gear hurts it. If the lower the gearing, the better the mpg, all OD gears would be as low as possible. Generally, best economy is had around 2/3's of the way to the peak torque out put of the engine. Being as the 1GR has a peak around 3800 rpm, best economy gear would put the truck near 2000 rpm at 65 mph. Which is about what it is stock.
     
  7. TL697

    TL697 Well-Known Member

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    ^ This...
     
  8. MaineTaco

    MaineTaco [OP] The NUTS

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    Chris again you have upstaged yourself!!! You my friend, are a wealth knowledge.

    Will
     
  9. MaineTaco

    MaineTaco [OP] The NUTS

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    But wait would the same be true if you had a supercharger? I know a S/C and MPG don’t really go together but you can see my "what if".

    Will
     
  10. Demoncleaner

    Demoncleaner Well-Known Member

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    Try 70 instead of 75. Saves a mpg or two, and no speeding tickets. Probably only hit those speeds on I-95 anyway, for typical two lane state/county hwy (65 and under) 6th about perfect to pull low 20's mpg.
     
  11. NAAC3TACO

    NAAC3TACO Well-Known Member

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    You will never recoup the money you spend on a gear change in fuel savings. Rear end gear ratios do not effect highway gas mileage very much unless there is a big spread in ratios. Say you went from a 4.10 to a 3.73, you would hardly notice much diff in fuel economy. In fact, like Chris pointed out, you will have to compensate with more gas pedal in the city. JMO.
     
  12. b168

    b168 Well-Known Member

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    :confused::confused::confused: I just had mine regeared... but it still feels like theres not much diff well infact there should be a diff esp when u press the gas from a full stop. I had mine regeared to 4.56"s???????

    My question is, is there a way to find out, aside from diamantling the whole diff, if what they installed was really a 4.56 and NOT a 4.10's.

    Please help Thanks!:confused::confused::confused:
     
  13. Carson

    Carson Well-Known Member

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    Maybe compare what your top speed is in 1st, 2nd, 3rd, etc gears with somebody else? Then maybe you can do some math somehow to figure it out idk...
     
  14. jay_shy

    jay_shy Active Member

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    jack up both rear wheels and rotate rear tire one full revolution and count how many times the drive shaft turns. Would give you a pretty good idea.

    Jason
     
  15. Tacoyota

    Tacoyota senile member

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    4.56 gears, rear trutrac,DT header, 235/85r16 Duratracs, 2nd filter pulled, inter.wipers, Cruise control, Factory alum. whls/winter tires(2nd set), Afe pro Dry-S , Dumbo eared flaps cut down.
    This will get you close:get a gps and go 60 mph. that is 63360 inches per minute
    265 (tread width appx) divided by 25.4 is the inch width.=10.43"
    10.43x.75 (.75 is aspect ratio)=7.82"
    7.82"x2=15.64" +16=31.6"
    31.6"x 3.14=99.3" or inches round the tire(best to just roll 1 turn and mark!)
    now divide 63360/99.3(or a better 1 roll #)=638 ...thats your tire rpm
    now find the gear you are in and multiply. This will be close to finding say 4.1 from 3.9 axle ratio, but it has some room for uncertainty

    (edit) a true mathemetician could simplify that set of data im sure.
     
  16. chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    4.10 gears, sliders, lots of buttons, and yellow flashing lights on the dash.

    Fwiw....the "265" is actually the Section width.....not the tread width. ;)
     
  17. Tacoyota

    Tacoyota senile member

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    good point. wont effect that number assualt luckily:D
     
  18. chris4x4

    chris4x4 With sufficient thrust, pigs fly just fine. Thor

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    LOL! true.
     
  19. SSrUs

    SSrUs Member

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    You don't need to dismantle the differential to find out. It can be checked somehow by blocking the front tires and jacking up one rear wheel. Then have a buddy rotate the wheel by hand one revolution while you count the revs of the driveshaft. I believe if you have a 4.56, one rev of the wheel equals 4.56 revs at the driveshaft.
     
  20. Tacoyota

    Tacoyota senile member

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    when I was 20 the math might be easier. Now that I'm 40 I like your idea with the jack!
     
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