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I didn't know a 13spd E/F could do this...

Discussion in 'Trucks [ Eighteen Wheelers ]' started by The_Flying_Dutchman, Jul 31, 2017.

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  1. Jul 31, 2017 #1
    The_Flying_Dutchman

    The_Flying_Dutchman Light Load Member

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    I recently switched trucks in my company and went back to a Mack Pinnacle sleeper with a 13spd after driving a 10spd 579 Pete daycab since early spring. When I run a 13, I always split the top end, even when empty, usually even bobtailing. Habit I guess.

    So, anyway, I was running a loaded tanker through Dubuque, IA, along the river bottoms, winding through an area where I switch from US20 to US151. I was in 5L coming around a corner, and instead of dropping into low range and downshifting to 4th, my brain went into 10spd mode for some reason. I flipped the splitter up and shifted into low, but still on high range. Then I split the low and dropped down my half gear.

    I didn't know a 13 could do this. Basically, its almost like driving a 15 when you down shift in the high range. It could be kind of handy, because it seems like low in the high range is about equal to 4, so you still have one gear left after 5 if you want to keep down splitting gears instead of dropping a full gear into low range.

    Has anybody else ever drove a 13 like this? Are you even supposed to? Could you cause any damage to the transmission? I notice the Eaton Fuller trans sticker doesn't even mention running low on the high side or splitting low in high range, so I wonder.
     
    The_Flying_Dutchman, Jul 31, 2017
    The_Flying_Dutchman, Jul 31, 2017
    #1
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  3. Jul 31, 2017 #2
    Hulld

    Hulld Road Train Member

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    I have know about this since I started back in the early eightys.
    I never really did it a lot of times on my old rto12513, it just felt awkward to me.
    As far as damage I don't think so but I will let others weigh in.
     
    Hulld, Jul 31, 2017
    Hulld, Jul 31, 2017
    #2
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  4. Jul 31, 2017 #3
    x1Heavy

    x1Heavy Road Train Member

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    You should have a temperature gauge for that transmission on your dash somwhere. as long it's in a happy spot at operating temp within a good range you should be ok. If you load it and it starts to get hotter... remove the load.
     
    x1Heavy, Jul 31, 2017
    x1Heavy, Jul 31, 2017
    #3
  5. Jul 31, 2017 #4
    swaan

    swaan Road Train Member

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    It's not recommend to use the bow low gear in high range.. having said that , lots people do.

    My personal opinion is it will prob be fine if your empty or bobtail, but I would never use that gear pulling heavy in high range. Something about the oil circuit for that gear or it's a bushing and not a bearing. Don't quote me on that thou.

    Either way it's frowned upon or not recommended.
     
    swaan, Jul 31, 2017
    swaan, Jul 31, 2017
    #4
    snowman_w900, AModelCat, OLDSKOOLERnWV and 2 others Thank this.
  7. Jul 31, 2017 #5
    BoxCarKidd

    BoxCarKidd Road Train Member

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    There have been some other type posts on this forum with different transmissions.
    I had to thank about this a lot as I was taught to do this. A little easier just adjust your RPM and speed. No split or clutch as some worked better clutching with range splits.
    These transmissions have fairly equal size gears on the mainshaft and countershaft in all gears except first and reverse. That puts about three teeth in mesh at all times. With a twin countershaft that equals six.
    First and reverse have a very large mainshaft gears and small countershaft gear. They are made for just getting going with large gear reductions and low torque. Not very many teeth are in contact with these. When you drop into 1 or Lo in high range it is possible apply a large amount torque on a small mesh area.
    So like Swann said.
     
    BoxCarKidd, Jul 31, 2017
    BoxCarKidd, Jul 31, 2017
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  8. Jul 31, 2017 #6
    lovesthedrive

    lovesthedrive R.I.P.

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    On a 13 to go into lo in high range you wont do anything as your only spinning transmission oil.
    A garage explained it to me a long time ago as the "goosey gear" You can put it there, you just wont get torque from it.
     
    lovesthedrive, Jul 31, 2017
    lovesthedrive, Jul 31, 2017
    #6
  9. Jul 31, 2017 #7
    Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    Transmission guy told me many years ago, don't ever do that. That low gear will be spinning faster than you think. Expect failure if you keep it up.
     
    Diesel Dave, Jul 31, 2017
    Diesel Dave, Jul 31, 2017
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  10. Jul 31, 2017 #8
    swaan

    swaan Road Train Member

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    Yes. Common knowledge the trans was not designed to be used like that. Ask any good gear shop.
     
    swaan, Jul 31, 2017
    swaan, Jul 31, 2017
    #8
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  11. Jul 31, 2017 #9
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Rear countershaft bearings are also small. Not designed for high torque.
     
    BoxCarKidd, Jul 31, 2017
    BoxCarKidd, Jul 31, 2017
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    uncleal13 and Diesel Dave Thank this.
  12. Aug 1, 2017 #10
    DDlighttruck

    DDlighttruck Road Train Member

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    I don't understand. You mean to tell me you shouldn't drive in the low half of the tranny? On the attic in the top 4?

    Why not?
     
    DDlighttruck, Aug 1, 2017
    DDlighttruck, Aug 1, 2017
    #10
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