15 KW T680 13 speed splitter grinding

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Vulpine93, Jul 31, 2020 at 9:02 PM.

  1. Vulpine93

    Vulpine93 Bobtail Member

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    Hi all,

    I've done my best to search Google and this forum for people who have similar symptoms and got conflicting information.

    The problem is this:
    I'm looking at purchasing a 2015 KW T680. The specific truck I've looked at has an MX-13 EPA13, an Eaton 13 speed, and 350k on the clock for a tidy sum of $50k. It has absolutely every interior and exterior option, a TriPac and inverter, and is reasonably well maintained (not a fan of the fact oil was done every 45k, I would do 25k). (And it's quite pretty, but that's besides the point.) The trans fluid has never been changed.

    When I was test driving the truck, bobtail, everything worked normally until I tried to split from high to low in a downshift. I'm fairly familiar with the Eaton 13's as I drove a WS 4900 with one for a while and can't recall this being an issue even with 600k on a rebuild. I recall that splitter shifting much slower as well, allowing more time to throttle up for the split.

    I would have my foot off of the accelerator, move the splitter to pre-select direct (13th to 12th), blip the throttle, and it would always go into low, but would also always grind while doing so. Does the splitter have it's own synchro, and could that be a problem even if it doesn't grind when up-shifting? Or is there something else I'm missing here?
     
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  3. Judge

    Judge Road Train Member

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    Synchronizer is going out.
    I’d ask the shop to fix it, before I signed anything.
     
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  4. Vulpine93

    Vulpine93 Bobtail Member

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    Why does it only grind on downshifts and not upshifts?

    Also does anyone have any experience with how much this type of repair costs? Does the trans need to come out?
     
  5. 401-Alex

    401-Alex Light Load Member

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    So its not just me with the whirling grinding noise in the down shift sound that drives me nuts
     
  6. AModelCat

    AModelCat Road Train Member

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    Splitter has no synchro. Only the range is synchronized.
     
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  7. Vulpine93

    Vulpine93 Bobtail Member

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    Jul 17, 2020
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    Whew. I had hoped as much.. maybe. What would cause this grinding? Doesn't seem to matter if I pre-select, or how quickly I get on the throttle, there is always a grinding noise. It happens immediately, even as I begin to apply throttle. The previous 13 speed I drove it seemed to split much slower, and gave me half a second to get the RPMs up.
     
  8. AModelCat

    AModelCat Road Train Member

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    Edmonton
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    The splitter shifts pretty much like the main box. No synchro as far as I know. Just an air piston pushing the shift collar back and forth. Wonder if the transmission air pressure regulator is too high? They're normally set for around 70ish PSI I think. If its getting full 120ish PSI from the reservoir its going to shift hella quick and hard.
     
  9. Vulpine93

    Vulpine93 Bobtail Member

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    Well, I'm having it inspected next Saturday, I'll let everyone know what they find there. Hopefully nothing too pricey, I'm dropping $300 to get it inspected and walking away would be annoying.. But I suppose that's why one gets it inspected.
     
  10. daf105paccar

    daf105paccar Road Train Member

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    Get a oilsample from the gearbox.
     
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