DPF System causing vibration during accelertion?

Discussion in 'Freightliner Forum' started by Wickedchicken, Oct 22, 2021.

  1. Wickedchicken

    Wickedchicken Bobtail Member

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    Nov 6, 2020
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    Hello guys,

    I got a 2020 cascadia dd15. I have a vibration or a shudder throughout the entire truck in what seems to be
    a transmission or related components issue.

    Repairs done: Tri-axle wheel alignment, New tires all around. motor/tranny mounts replaced. U-joints replaced. Drive shaft balanced. both front end king-pins replaced. Front leaf springs replaced. These repairs have failed to solve the problem.

    The problem: Only when accelerating between 25-45mph does the shudder occur and this shudder is intermittent. I'm trying to find out what is causing it so I observe.

    Observation: I observe that when i'm local and in short traffic stop and go, the vibration starts to occur between these speeds. It's almost like the truck doesn't have enough airflow to breathe. (i notice the soot bar elevated on the dash readouts). However when i'm on the highway for 2 hours or more the truck seems to do regen and the shudder goes away right after the regen.


    Any thoughts or ideas on what this problem might be related to?
     
    fcfightermma Thanks this.
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  3. msh

    msh Light Load Member

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    Jul 18, 2021
    Los Angeles, CA
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    is this your truck or you are company driver?
     
  4. Wickedchicken

    Wickedchicken Bobtail Member

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    Nov 6, 2020
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    what difference would that make?
     
  5. msh

    msh Light Load Member

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    Jul 18, 2021
    Los Angeles, CA
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    big difference, sir. if its not your truck there is nothing to worry about it. Otherwise.... )))
    monitor inlet and outlet pressures in one box... you may have dpfs full of ash or partially plugged doc face. that noise with little vibration is coming from one box.
     
    Last edited: Oct 23, 2021
    Ross_Tech and AModelCat Thank this.
  6. Wickedchicken

    Wickedchicken Bobtail Member

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    why would i post a mechanical concern if it isn't my truck? obviously if the truck i am driving is a company truck then the concern regarding maintenance responsibility would fall on the owner and not me. But if i am asking a question on a forum about a mechanical issue about the truck then it would be safe to assume that is my own truck.
     
  7. msh

    msh Light Load Member

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    Los Angeles, CA
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    i have seen small fleet drivers here asking questions about truck issues...
     
  8. msh

    msh Light Load Member

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    Jul 18, 2021
    Los Angeles, CA
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    who suggested you to replace motor/tranny mounts, U-joints, front end king-pins, front leaf springs on 2020 truck? :)
     
  9. Wickedchicken

    Wickedchicken Bobtail Member

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    Nov 6, 2020
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    Why do you ask?
     
  10. supersnackbar

    supersnackbar Road Train Member

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    Because, if a repair shop suggested it (other than a Freightliner dealer doing warranty work), someone is possibly doing unnecessary work...on a 2020, even if it was a team truck, those parts shouldn't need replaced unless there has been a serious lack of preventative maintenance or you have a lot of defective parts. Front springs and king pins shouldn't need done for a minimum 500-600k(unless you do a lot of off road work like oil wells, or gravel hauling)...u-joints too, unless the driveline has been abused. I had a 2019 that supposedly needed a center support (a.k.a. carrier) bearing at 215k...which I questioned. Every DD15 I've driven from 2019-2021's vibrate like I am driving on a huge orbital sander, it's just something about these new emission Detroits I guess..
     
    Last edited: Oct 27, 2021
    msh Thanks this.
  11. jason6541

    jason6541 Road Train Member

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    Omaha, NE
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    My 2020 western star was doing this vibration thing as described above. greased every 10k miles checked everything. Nothing loose or worn.
    Narrowed it down to front end a cyclical vibration would come and go. Like a rotating assembly getting in and out of phase. Pulled wheels and drums and used a magnetic base and dial indicator and found my from hubs were not machined true. Mounting pads for wheel were off , They had A variance of about .03 to .06 on the high side, both hubs were machined off. While it doesn’t sound like much when they got in phase oh hell it was rough.
     
    Wickedchicken Thanks this.
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