Transmision question/debate

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by catwrench55, Apr 14, 2018.

  1. catwrench55

    catwrench55 Light Load Member

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    I'd like to swap transmissions in in my pete with a 60 series. It's got a fro 10 speed currently, has always gotten the job done but have always wanted the ability to split gears in this truck. Truck is set up with 3.90 rears and tall 24.5s.
    I had a 16713 in another truck that lost a bearing and needs rebuilt with a few bad gears as well. Debating rebuilding and installing or possibly swapping to a 16718 speed " I can supposedly still use it for a core". I run frac sand in the oil field so the granny low in the 18 would be nice sometimes.
    Or...... I also have a good 12513 with a overdrive back box, my original plan was to find a good 9 speed over and mount this back box to it giving me a good empty highway gear ".62 overdrive" and still a decent low gear and reverse. This is appealing to me as I'm in a hurry dead Heading 50% of the time.
    My question is what is the best/newest 9 speed this old back box will work on? Who has done this?
    I realize that old back box isn't as reliable or nice shifting as a newer model but I've decided this truck is just for me to drive now I'll fix it like I want it.
     
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  3. BoxCarKidd

    BoxCarKidd Road Train Member

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    Probably nothing over a 12 series as they had ball not tapered counter shaft bearings like the higher torque transmissions I am familiar with.
    You are probably looking for something like a RTLO15210C? Transmission with the same OD but deep reduction also. Look at the Eaton Road Ranger web site for transmission ratios and models that work. Check with your local rebuilders.
     
  4. catwrench55

    catwrench55 Light Load Member

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    Ah so the back box on this 125 is different from a 14513 even. My local rebuilder mentioned the different style bearings and said he would have to look for a good core to match up.
     
  5. BoxCarKidd

    BoxCarKidd Road Train Member

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    My model numbers are incorrect but you gave none for yours. What is it?
     
  6. catwrench55

    catwrench55 Light Load Member

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    I've got a 12513 and a 16713
     
  7. BoxCarKidd

    BoxCarKidd Road Train Member

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  8. catwrench55

    catwrench55 Light Load Member

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  9. BoxCarKidd

    BoxCarKidd Road Train Member

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    Found that site under Roadranger Ratios. It lists all the transmissions, ratio in every gear, weight, length, and torque rating.
    The RTO12513 is way underrated for your truck. Plus it would slow you down 13 %.
    Some 16713's are very comparable to your FRO 1st, R and OD. I doubt anyone would take it in as a core on an 18.
    Some 18's are also very comparable and have a broader range.
    I usually look through the chart and do some shopping in cases like yours. Don't thank there are any higher torque transmissions with a get home gear.
    Good Luck. Let us know how it works out.
     
  10. catwrench55

    catwrench55 Light Load Member

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    Yeah I've poked through those charts quite a bit.
    To clarify I was contemplating using the OD back box off the 12513 and mating it to a 9 speed over transmision giving me that .62 ratio in 13th and keeping the decent low reverse of a 9 over. My biggest question is how much newer stronger 9 speed would still be comparable with that old back box.

    I'm going to likely end up rebuilding and using the 16713, unless shop tells me he can get within a few hundred dollars building me a 16718.
     
  11. wore out

    wore out Numbered Classic

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    What your actually looking for is an RTO14609B with an RTO14613 rear box. Keeps a pretty good low hole and fair reverse. Doesn't whine terrible in high gear direct but will sing pretty good in overdrive. There are some upgrades to make the front pretty stout. In the end those rear boxes make a lot of heat and are notorious for giving trouble.
     
    catwrench55 Thanks this.
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