Gearing advice for late model KW?

Discussion in 'Kenworth Forum' started by Simplespeed, Dec 28, 2019.

  1. Simplespeed

    Simplespeed Light Load Member

    103
    88
    Jun 12, 2013
    0
    I am looking at a truck to haul containers with. The company also does dry vans and flatbed but most of the work I do will be pulling containers locally in Houston as well as about 500 miles out with the occasional long haul as well as special projects that can happen anywhere in the 48 and last a couple weeks. But, I would say that 95% would be 100-500 mile trips on flat land in Texas and Louisiana. Much of the time will be grossed near 80k lbs.

    The truck is a 2016 T680 with a cummins rated at 450hp, 10spd eaton and 2.39 diff gears. My first thought is the the gearing is way to tall. But, I have been hearing that these new engines are making peak power in the low rpms and that is the reason they are coming out with these tall gear ratios. Any thoughts or advice would be greatly appreciated. Thanks.

    Also, any articles or information on this topic that you could share with me would be helpful.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

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

  3. tnevin225

    tnevin225 Road Train Member

    1,166
    1,601
    Jan 1, 2014
    0
    I have that setup but with 3.25 rears, that puts my RPM at 1325 at 65 mph which is great for fuel efficiency. That rear end sounds to low to work very well with a 10 speed.
     
    Bean Jr. Thanks this.
  4. Simplespeed

    Simplespeed Light Load Member

    103
    88
    Jun 12, 2013
    0
    Yea, it was a J&R Schugel fleet truck. They maintain their trucks well from what I hear. At this dealer that I have already been pre approved for, there are cascadias and pro stars with a cummins that i can also choose from in my price range. The cascadias have a DD15 with a dt12 and 2.53 or 3.23 gears. They are only 2x6 which i do not like and do not have a suspension dump. I believe the air dump is an easy fix. Locally i use my axle lock pretty often. After years of driving company cascadias I can hardly stand the thought of spending my own money on one.
     
  5. Simplespeed

    Simplespeed Light Load Member

    103
    88
    Jun 12, 2013
    0
    From what I can find online the x15 is rated for 450 makes its peak toque at 1000 rpms.

    I just realized that this truck would have an ISX15 which would make peak tq at 1100rpm, still pretty low. I have not seen the truck in person yet. I wanted to see if it makes sense before I travel to check it out.
     
    Last edited: Dec 28, 2019
  6. Roberts450

    Roberts450 Road Train Member

    2,237
    3,638
    Feb 6, 2016
    0
    With that kind of rear end gearing those will most likely be direct drive transmissions not over drive transmissions.
     
    Simplespeed Thanks this.
  7. spsauerland

    spsauerland Road Train Member

    4,296
    10,891
    May 31, 2010
    West Harrison, In
    0
    10 speed is probably a direct drive. That set up would be close to 3.36 with modern overdrive transmission. Just want to ease through torque when getting up to speed.
     
    Simplespeed Thanks this.
  8. Simplespeed

    Simplespeed Light Load Member

    103
    88
    Jun 12, 2013
    0
    Awesome, thanks for the help guys. I think this truck will work well for what I need.
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

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