Truckers Report Jobs

Find Trucking Jobs

Company Driver Company Driver Dry Van Dry Van Flatbed Flatbed Refrigerated Refrigerated Specialized Specialized Owner Operator Owner Operator
More Trucking Job Searches ⌄ Fewer Trucking Job Searches
⌃

15 speed direct drive with 2.85 rears slow up hills and poor mileage

Discussion in 'Trucks [ Eighteen Wheelers ]' started by javelinjeff, Jun 21, 2015.

Page 1 of 4
  1. Jun 21, 2015 #1
    javelinjeff

    javelinjeff Medium Load Member

    621
    185
    Aug 30, 2007
    victorville,ca
    0
    14.6 3406E rated at 475 HP,,pulls good in lower gears but totally falls off on hills. I have to drop down to 6th to maintain 28 MPH on hills hauling @ 77-80k total truck weight. looking to do some gear and trans swapping to help climbing,,seems I'm spinning gears instead of spinning rears. Switched to 11R24.5 rubber helped my flat ground MPG but cost me 3MPH on hills,,considering switching to 18 speed and 3.42 rears,,any gearheads have any recomendations?
     
    javelinjeff, Jun 21, 2015
    javelinjeff, Jun 21, 2015
    #1
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. Jun 21, 2015 #2
    damutt

    damutt Road Train Member

    1,126
    370
    May 6, 2013
    0
    what do you have in the rears now? and is your 15 spd were you split hte top? or a deep reduction 15?
     
    damutt, Jun 21, 2015
    damutt, Jun 21, 2015
    #2
  4. Jun 21, 2015 #3
    javelinjeff

    javelinjeff Medium Load Member

    621
    185
    Aug 30, 2007
    victorville,ca
    0
    2.85 rears,,15 speed direct drive gearbox with 11R24.5 rubber,,had LP 22.5 rubber on it before,fuel mileage sucked at higher speeds,,better now with the 24.5s
     
    javelinjeff, Jun 21, 2015
    javelinjeff, Jun 21, 2015
    #3
  5. Jun 21, 2015 #4
    javelinjeff

    javelinjeff Medium Load Member

    621
    185
    Aug 30, 2007
    victorville,ca
    0
    deep reduction 15
     
    javelinjeff, Jun 21, 2015
    javelinjeff, Jun 21, 2015
    #4
  7. Jun 21, 2015 #5
    damutt

    damutt Road Train Member

    1,126
    370
    May 6, 2013
    0
    do you need a deep 15 for the work your truck does? if so i would do a reager to a 3.xx
     
    damutt, Jun 21, 2015
    damutt, Jun 21, 2015
    #5
  8. Jun 22, 2015 #6
    allan5oh

    allan5oh Road Train Member

    1,557
    556
    Jan 6, 2010
    Winnipeg, mb
    0
    You won't gain much switching gears/transmission. This sounds like a power issue. How fast do you run in what gear and rpm.
     
    allan5oh, Jun 22, 2015
    allan5oh, Jun 22, 2015
    #6
    dirthaller Thanks this.
  9. Jun 22, 2015 #7
    javelinjeff

    javelinjeff Medium Load Member

    621
    185
    Aug 30, 2007
    victorville,ca
    0
    run mostly I-5 north/south,,always heavy. 55 MPH at under 1300,,motor pulls down to 1200, doesn't help going over 1700 RPM for power,I try to keep it below that
     
    javelinjeff, Jun 22, 2015
    javelinjeff, Jun 22, 2015
    #7
  10. Jun 22, 2015 #8
    gokiddogo

    gokiddogo Road Train Member

    8,786
    14,768
    Mar 5, 2012
    Ontario Canada
    0
    I can't wrap my head around why you could achieve a higher mph or mpg based on changing the transmission ratio or read end ratio. How or why does it make a difference if the reduction happens in the transmission or in the rear end? All this provided the engine is operating in its normal rpm range.
     
    gokiddogo, Jun 22, 2015
    gokiddogo, Jun 22, 2015
    #8
  11. Jun 22, 2015 #9
    javelinjeff

    javelinjeff Medium Load Member

    621
    185
    Aug 30, 2007
    victorville,ca
    0
    Less resistance in the driveline to turn the rear end gears,I suppose
     
    javelinjeff, Jun 22, 2015
    javelinjeff, Jun 22, 2015
    #9
  12. Jun 22, 2015 #10
    swaan

    swaan Road Train Member

    2,942
    4,374
    Jul 12, 2009
    BC canada
    0
    A 15 direct with those gears should get fanomanal fuel milage.
    You just need more power.
    Your engine has something wrong with it or its a 310 economy. Lol

    Seriously thou, put your truck on a dyno and see what you got.i bet it's perty enimic

    What kind boost #s you getting ??
     
    swaan, Jun 22, 2015
    swaan, Jun 22, 2015
    #10
    Cetane+ Thanks this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

    • Page 1 of 4