Transmission cooling line fitting size help

Transmission and Drivetrain Tech

  1. cudajames

    cudajames Well-Known Member

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    Hello, finishing the plumbing on a transmission cooler line. I am stuck - I can not find the fitting size/type for the hard line that runs from the transmission to the radiator

    My goal is to put the 3/8' hose barb on the hard line and run it to the cooler. Should have been simple

    So far -6an (-4 fits into the radiator and does a -5 exist?) and 1/4" npt do not work-to large

    I attached a picture of the fittings - I am looking to replace the brass

    IMG_1150.JPG

    IMG_1151.JPG

    IMG_1153.JPG
     
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    • RustyRatRod

      RustyRatRod 30 Degrees Outta Whack

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      It's 3/8 flare. Are you saying you're going to run rubber hose? I would advise against it.
       
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      • Donnie514

        Donnie514 FABO Gold Member FABO Gold Member

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        1/8" pipe into the radiator.
        5/16 flare on original tranny line.
        In the photo the brass fitting looks to be correct.
        Are you running braided steel lines to a trans cooler or OEM lines to the tranny?
         
      • cudajames

        cudajames Well-Known Member

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        OEM replacement lines from the tranny (right stuff) and had planned to run rubber hose between the tranny cooler/radiator/tranny line.

        Some of the tranny cooler kits that I looked out - shipped with straight rubber hose. Now, I am reading that RRR isn't a fan of that option. Should it be braided?

        The brass fitting is out of the radiator - which I would like to replace with a different fitting. So one side is 1/8" pipe and the other 5/16 or 3/8s flare

        Thanks, still learning
         
      • kursplat

        kursplat FABO Gold Member FABO Gold Member

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        the cooler kits all seem to come with those fittings. if you want i'll see if i have any and send them to you. i never use them. i've done steel braided rubber hose w/ barbed fittings to fill the gap between the stock lines and rad. sucks, almost always seeps. steel braided rubber from the trans to rad w/ AN fittings on both sides. works well, watch the routing. PTFE w/ AN fittings from the trans to the rad. better than rubber hose. and hard lined the whole thing using the stock lines. cut the ends near the rad and use the proper hard line compression fittings and bend up what you need. looks the best but your going to make some bad bends when you're learning. all of these were for installing a cooler.
         
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        • cudajames

          cudajames Well-Known Member

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          Thanks, I am close to having the plumbing completed with rubber hose. Just need the one fitting and this part will be completed. Is the fitting 5/16th flare (which seems right) or 3/8s flare which seems to big

          I did plan to upgrade to braided later - since I would know the lengths. And bending line would be really hard for cooler location - and probably beyond my skill and patiences

          I decided to mount the cooler on brackets in front of the radiator and route the 3/8s hose through existing holes - the routing has nice gradual bends and I think is pretty nice.

          I am so close to getting the car back on the road

          IMG_1064.JPG

          IMG_1111.JPG

          IMG_1112.JPG
           
        • famous bob

          famous bob mopar misfit FABO Gold Member

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          They do make a rubber re inforced hyd type hose for that application. Just go overboard w/ keeping it insulated and away from any heat or sharp abrasive edges. Double hose clamp if using hose clamps ----------------done a turbo 350, turbo 400 and 2 727`s that way , no problems . All had higher than stock line pressure .
           
        • kursplat

          kursplat FABO Gold Member FABO Gold Member

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          car looks good :thumbsup: here's what i did on the 74'
          DSC00567.JPG DSC00569.JPG

          and the 68'
          4.JPG
           
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          • cudajames

            cudajames Well-Known Member

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            Very nice, especially the 68. What fittings did you use - the cooler with be 1/2" npt to what? And I assume you made the braided line to length

            Maybe it is better to redo everything now - since there is no fluid or anthing so a lot easier and cleaner to take apart now
             
          • kursplat

            kursplat FABO Gold Member FABO Gold Member

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            the cooler has -6 fittings built in. i knew what i wanted so just ordered it that way. the trans end is what, 1/8 NPT? i had those to -6 already. i ordered the hose and other fitting off summit. easy to put together. if you haven't.
             
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            • Donnie514

              Donnie514 FABO Gold Member FABO Gold Member

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              WHOOO....The trans end is not 1/8 NP"T"
              It is 1/8 NP"S"
              Fragola # 481671BC at Summit
              1/8 NPS to 6 AN
              NPT and NPS are different, May be able to inter mix but it is not correct.
               
            • RustyRatRod

              RustyRatRod 30 Degrees Outta Whack

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              On is it 5/16 flare? I'm sorry. I was thinking 3/8. Forgive me.
               
            • kursplat

              kursplat FABO Gold Member FABO Gold Member

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              that's why i "?". couldn't remember, i figured someone here would know for sure, thanks

              "Both NPT and NPS have the same thread angle, shape, and pitch (threads per inch). However, NPT threads are tapered and NPS threads are straight (parallel). Both threads have a 60° included angle and have flat peaks and valleys."
               
            • Mike69cuda

              Mike69cuda 64 is the new 17 FABO Gold Member

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              I have put transmission coolers on about every car I have owned for the past 30-40 years. I always use the hose and fittings that come with them. It has worked great. Just like anything you do, got to do a good job. Make sure hoses are on deep on the tubes and fittings and clamps are tight. Probably not the most professional looking job if you are a 99% type guy, but functional.

              Back in my youth when I was a poor boy in the hood, I used fuel line. Didn’t know there was such a thing a transmission line. Wouldn’t have bought it anyway if I had free fuel line lying around. Poor people have poor ways. Come to think of it, never saw a piece of gas welding rod till I was in my 20s. Thought everybody used coat hangers.

              Moral of my story: If you want a top quality job, it costs time and money. If you just need functional, that is cheaper and easier, but if you are a cheapskate hillbilly, you can make about anything work......
               
            • Donnie514

              Donnie514 FABO Gold Member FABO Gold Member

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              Mike, Old is old, real is real, right is right, and hillbilly just may be incorrect. The older we get the more correct we want to be.
              SORRY
               
            • Mike69cuda

              Mike69cuda 64 is the new 17 FABO Gold Member

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              I don’t disagree with you at all. My point is that there are a lot of guys out there that are just struggling along trying to get their car going. A lot of the advice here, while good, tends to be gold plated. Not everyone wants to spend a lot of time and money getting some detail perfect when the whole rest of the car needs attention. Sometimes the best way isn’t really necessary. “Better” is the enemy of “good enough”.

              I find some subjects presented as right and wrong when it is more likely good (enough), better, and best.
               
            • kursplat

              kursplat FABO Gold Member FABO Gold Member

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              which is why i offered to send him the fittings.
              do it as right as you can afford
               
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              • CudaFactHackJob

                CudaFactHackJob FABO Gold Member FABO Gold Member

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                When there isn't enough time to do it right; there's always enough time to do it twice..but us pofolks got poways..
                 
              • Donnie514

                Donnie514 FABO Gold Member FABO Gold Member

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                That's crazy...…..Why even say it?
                 
              • CudaFactHackJob

                CudaFactHackJob FABO Gold Member FABO Gold Member

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                Because perception is reality?
                 
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