Gear Ratio change for fuel savings.

Discussion in 'Car Hauler and Auto Carrier Trucking Forum' started by bmercer, Jul 13, 2017.

  1. shogun

    shogun Road Train Member

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    I think Cummings has an online calculator to find what puts you in the right rpm range with what gear, trans and tire size. If not I'm sure fuller Easton does.
     
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  2. diesel engine

    diesel engine Light Load Member

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    What are the savings in mpg you are looking for
     
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  3. bmercer

    bmercer Bobtail Member

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    I would like to see 8 mpg.
    I don"t think its going to happen with this truck.
    I ran 115 miles today bobtail an got 7.6 @ 1600 rpm and 65 mph.
    I going to do the same run tomorrow @ 1400 rpm.
    That will put me at 58 mph.
     
  4. sxdime

    sxdime Medium Load Member

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    A hard puller to the left or the right? Sorry Banker I had to do it lol. I didn't think there was any of their trucks that really pulled. ;)
     
  5. haycarter

    haycarter Road Train Member

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  6. uncleal13

    uncleal13 Road Train Member

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    I had a 2006 Century with a 450 Mercedes. It originally had 3.58 rears on 11R22.5 . It was a real dog. I switched jobs and went from 5 axle 80,000 lbs to 8 axle 140,000 lbs super-b and changed the rear ratios to 4.11 at a cost of $5,000.
    Later I went back to dry van and the truck picked up almost a full 1 mpg. I guess that Mercedes liked to spin faster then I was told. 1,500 rpm at 100 kph (62.5 mph). I could do 70 mph but it killed the fuel economy drastically. But it was still a bit of a dog.
     
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  7. Banker

    Banker Road Train Member

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    I did leave myself open for that! It didn't run like my Pete, but it was a fresh rebuild and surprisingly it really did run and pull good. I felt like it ran better after I polished the wheels and tanks. Just kidding!! It was better than my Allied truck that ran 75 but laid down on a slight grade empty.
     
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  8. KANSAS TRANSIT

    KANSAS TRANSIT Road Train Member

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    I really doubt you will ever see 8, we are at 8.5 with a setup that is 10,000 lighter, smaller motor, and a LOT less drag and rolling resistance, on only 3 axles. If I remember right the best we could do with that 7 car Pro star setup was around 5.5.

    Remember, that even 5 car is going to be no where near as aero as a box van.
     
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  9. bmercer

    bmercer Bobtail Member

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    I ran the same route today at 1400 rpm at a speed of 58 mph.
    It got 8.2. At this point I'm thinking only 6/10's mpg, it's probably not worth the effort to put any money in it especially not knowing the out come.
     
  10. Roberts450

    Roberts450 Road Train Member

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    Are you running tall or short 24.5's?
     
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