Spec it.....

Discussion in 'Ask An Owner Operator' started by Lee76, Jan 2, 2011.

  1. Lee76

    Lee76 Light Load Member

    59
    24
    Dec 8, 2010
    Delaware
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    To make a long story short, I will soon operate my own truck.... again.

    Here is the deal. The last time I owned it was a k100 cab-over hauling grain, and fuel then was cheaper, considering. This time it is a 2006 Century Class Fruitshaker, with Thero King A.P.U., sitting right now as a glider chassis. S-60 Detroit engine (500hp), and a fuller 13-speed, both rebuilt top to bottom and put back into the rig, all the other parts-Turbo, radiator, etc. replaced with new. NOW! these days I'm all too aware of fuel mileage, and I run a dedicated route, but I try to hit as few tolls as possible, running east PA to Chicago mostly, sometimes to southern Wisconsin. (I-70, I-68, I-79, I-70, I-74, I-65, sometimes rt.30 across Indiana) Right now, the guy I'm buying the truck from, plans to put the truck back together how I want it before taking it away from him. The rear end gearing is what hangs me up, and I already realize with the thirteen speed, I might have to join the Double Nickle club, but I'm never really pressed for time anyway. My westbound loads are usually under 25,000lb., return loads are usually 40,000lb.

    The Ponder: Right now he has many different gear ratios he can put in the rears for me. The old gearing was 3.42, and not sure with all the hills I take, if 3.55 might be more ideal, or stick to the stock set? See what I mean?:biggrin_2556: What do you all have to say here?
     
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  3. Ruthless

    Ruthless Road Train Member

    9,101
    90,263
    Aug 28, 2010
    The City.
    0
    13 OD? detroit runs good on 370s. i have a 10 OD on 3:70; i get it just right at 63-65 on flat land. gonna move to a 13/15/18 next as when im hitting hills heavy that 10 is too high to stay at 65, and 9 is just a touch too low. if i run at 75 hills don't phase me unless I'm over 85k. a buddy of mine has the same truck as me with 3:55s; ends up down shifting a lot sooner at the same hill face at the same speed. but gets better mpg at 71.
    my .02
     
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  4. WMGUY

    WMGUY Road Train Member

    1,684
    800
    Jan 1, 2011
    Nine Mile Falls, WA
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    i run I90 from north idaho to seattle and im runnin 105,500 with a detroit 500HP and an 18 speed with 3.70's in a PETE 379 getting 5.2-5.4 running 65 mph and i pull 5 6% grades going one way... so i think 3.55 would suit you well but if your worried about the hills go to the 3.70's the detroits handle the higher rpms better then the other engines do, in my set up i can hold 35-40 on the hills so you would be good either way good luck, let us know what you go with
     
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  5. Lee76

    Lee76 Light Load Member

    59
    24
    Dec 8, 2010
    Delaware
    0
    I guess it will be a trial and error thing week to week or month to month then. From what the owner told me, with the 3.42's he used to get 7.5-8.0 at 60mph, he never got into how it pulled hills though, he ran nothing but Texas and Oka with it. I keep digging around, hate to consult Kevin Rutherford on this, but beggars can't be choosers either huh?. I'll start a new thread and document the whole circus once I have the title. Thanks for the input guys.
     
  6. mastllc

    mastllc Medium Load Member

    379
    150
    Aug 28, 2008
    somewhere in ga
    0
    i know most freightliners with Detroit's and 13sp come from the factory with 3.58 or 3.73, my friend has 3.58's in his truck,(2007 coronado 515 detroit, 13sp, 3.58 rear ends) and usually gets about 6.5-7.3 MPG haulin an average mix loads.
     
  7. Les2

    Les2 Road Train Member

    5,150
    2,288
    Jul 25, 2008
    kicked back in my lazyboy...
    0
    What tire size are you running? It will make a difference!
     
  8. Krooser

    Krooser Road Train Member

    2,493
    1,066
    Jul 25, 2010
    Wisconsin
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    Sounds like the truck has Meritor rears... my FLD had 3.58's with a S-60/9 speed... got 7.4 steady up to about 68 mph.
     
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