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Quick D18 Question

Discussion in 'Early CJ5 and CJ6 Tech' started by FinoCJ, Feb 21, 2022.

  1. Feb 21, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

    Bozeman, MT
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    Is the PTO hole on the back of the D18 the same size no matter which size case it is?
    Also, is there any differences in the gears (assuming all are 1.25" intermediate shaft) based on case size? In other words, are the gears interchangeable, with the exception of the input/drive gear spline count?
     
  2. Feb 21, 2022
    wheelie

    wheelie beeg dummy 2021 Sponsor

    York, PA
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    PTO ports are all the same. Not all gears interchange. There are different intermediate gears with different bores for the shaft and I believe there are different sliding gears as well. The bull gear, on the back of the transmission, has several variants in inner spline count ( 6 spline and 10 spline)and outer tooth counts (26 tooth and 29 tooth). Maybe more. It's been a while since I've researched and worked on one. I'm sure others can provide better info.
     
  3. Feb 21, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

    Bozeman, MT
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    True, I recognize there are some additional variations with early cases, both military and smaller intermediate shaft sets....to simplify, this would be only for the 2.46 ratio, 1.25" intermediate shaft gears....in other words, essentially all the later civilian small case and subsequent large case gears.
     
  4. Feb 21, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

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  5. Feb 21, 2022
    Jw60

    Jw60 WRPD855 2022 Sponsor 2021 Sponsor 2020 Sponsor

    Sedalia MO.
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    The angle of the teeth are different on the d20 so they may seem to work but I've talked with guys that split a case with the wrong gear
     
  6. Feb 21, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    If staying strictly within the 2.46 ratio then all gears can be interchanged including the Ford Bronco or IH.
    It is the mix matching of other ratios (1.97 -2.43 or 2.03) that complicates the assembly.
    But the cases themselves, the rear output, the speedometer parts the front bearing caps and shift levers will frequently change for specific applications.

    The main shaft gear is technically a transmission part and the 2.46 ratio or 29 tooth gear only changes concerning the internal spline count. 10 spline for T-14 transmissions and 6 spline for all other BW transmissions.

    The rear PTO or bearing cap port bolt pattern remains the same on all case makes and models.
     
    Last edited: Feb 21, 2022
    Jw60 likes this.
  7. Feb 21, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Be aware the early Bronco has two different gear ratios (low range) and one gear set (T-shift) interchanges with the 2.46-1 low range. The later “J” shift is a different ratio and does not interchange. Also the Bronco “T” shift transfer case input gear is not machined with a recess and was retained with a snap ring, not a nut and washer. If you plan on using an overdrive or pto with this gear forget it. The nut is in the way.
    Not disagreeing but trying to understand how the transfer case input gear is a transmission part?
     
  8. Feb 21, 2022
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member 2021 Sponsor 2020 Sponsor

    Bozeman, MT
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    Thanks guys...I probably can simplify this more as I am only dealing with 2.46 jeep D18....sounds like the gears would be good for my storage bin, especially if they can be potential replacements for either my large case unit in the cj, or for the later small case unit in the 58wagon. Was even thinking I could get a spare gear set to machine and prep for a tapered bearing conversion without having to take one off the road.
     
  9. Feb 21, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    Well according to Jeep it is termed as a mainshaft gear. The mainshaft itself is technically a transmission part.
    Jeep never called it to be a bull gear nor an input gear not even called an output gear for that matter.
    Only ever called out as the mainshaft gear.
    That said I must admit it is only found in the section on transfer cases and never under the transmission section. So it looks like I am in error as Nick suggests.
    I recant as it appears to be a transfer case part according to the group index.
    The proper group index always precedes the nomenclature.
    Again I thank you Nick for that input.
     
    Last edited: Feb 21, 2022
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