Threads on hoses? - Cant figure this out

Discussion in 'Brakes for your Classic Mopar' started by purplehazenils, Feb 13, 2018.

  1. purplehazenils

    purplehazenils Well-Known Member

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    Hey guys I have been sitting for about an hour trying to figure out what threads the rubber hoses on my dart has. Im planning (trying) to upgrade to braided brake lines and just cant seem to find what threads I have, Im used to the metric system, so Im totally lost..

    The car:
    -1969 Dart original Kasley Hayes disc brakes up front and original drums in the back.

    The threads:
    -Front female-female hose ... 0.32 in. inner diameter, 0.362 in. major diameter, pitch 0.0374 in.

    -Rear female-male hose ... female end same as above, male end has 0.362 in. inner diameter, 0.433 in. major diamater, pitch 0.051 in.


    Im measuring in mm and converting to in, I dont even know how you measure to get fractions in inches hopefully I will learn something from this.

    28081648_1717756074947407_437129895_o.jpg
     
  2. Dusterdenovo

    Dusterdenovo Contentedly Old School FABO Gold Member

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    Have you got the hard line that the hose was connected to?

    Measure the threads on the fitting at the end of the hard brake line.
     
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    • purplehazenils

      purplehazenils Well-Known Member

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      Yup I have them, thats what I measured off of. That said Im using a mm vernier calipers so its not 100% precise..
       
    • AJ/FormS

      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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      SAE are measured in threads per inch. And the difference between the sides is far enough apart that you don't need to be ridiculously accurate. If you have a quarter inch of thread available, you just count the number of turns,in that 1/4 inch, and multiply by 4. This works for bolts.
      Tubing is measured a little differently.
      They only put one type of thread on each size of braketube, so in reality you only need to know the size of the tube that you are working with, and you will automatically get the right fitting by specifying the tube size.

      Metric is a different deal,(see below) and I can't imagine you will encounter that on a KH system.

      as also implied below, 1 inch = 25.4mm
      And 3/16 tubing is 4.77mm, but in your case; 4.77mm is 3/16 tubing,lol..
       
      Last edited: Feb 13, 2018
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      • jos51700

        jos51700 Well-Known Member

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        Set your caliper to 25.4, and count the threads per inch. If you only have 6.35 mm of available thread to measure, count the threads in that, and multiply by four.
        English threads are thread per inch, metric measured the width of the thread.
        the thread counts don't typically overlap.
         
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        • purplehazenils

          purplehazenils Well-Known Member

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          Cool, thanks, forgot about that when writing this. I multiplied it out it so now it is roughly:

          The threads:
          -Front female-female hose ... 0.32 in. inner diameter, 0.362 in. major diameter, 25 threads per inch.

          -Rear female-male hose ... female end same as above, male end has 0.362 in. inner diameter, 0.433 in. major diamater, 16 threads per inch
           
        • purplehazenils

          purplehazenils Well-Known Member

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          Ok, just to get it straight the threads on the rubber hoses are determined by the size of the copper tubing of the brake system? I dont have access to the car right now but say the copper tubing is 3/16 that means I want braided hoses that are -3 AN which is 3/16...?

          Looking at summits catalog the braided hoses all seem to be -3 AN, so its a standard?
           
        • brian6pac

          brian6pac Well-Known Member

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          Brake lines are standard 3/16" flare, 1/4" flare 45 degree,
          -3AN are 37 degree flare, don't mix them up
           
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          • 65-440

            65-440 Well-Known Member

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            Just take it to an auto parts store and match it up with the small 12" sections of tubing they have. Pretty sure it'll be 3/16
             
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            • Big_John

              Big_John In my defense, I was left unsupervised.

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              Your front is a 3/8-24 UNF and the rear is 7/16-20 UNF.

              Those are standard sizes for brake line fittings.

              FYI, your thread pitch was .051 for the rear. Since we do "threads per inch" instead of pitch on our thread sizes, that is 1 divided by .051 and that rounds up to 20.

              Our thread sizes go like this... 3/8-24 UNF 3/8 is the major diameter, 24 is the threads per inch (1 divided by pitch) and UNF means it's a fine thread. UNC means it's a coarse thread and you might see UNS for special threads every once in a great while.
               
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              • 67Dart273

                67Dart273 Well-Known Member

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                Sorry buddy your post makes no sense....at least not to me, and I KNOW what these fittings are. YOU WILL NEVER FIND a 37 degree flare "factory" on one of these girls

                1......CAVEAT.....not all flare nuts are "standard." Examples might be into the prop valve and master cylinder. These are likely ALL 3/16 U.S. inverted flare tube, but the thread on the nuts is special into the master / etc to keep the assembly folks from mixing them up

                2.....Otherwise, "standard" fittings such as the hose you showed or into the rear axle distro block, and the wheel cylinders, are almost certainly "standard" 3/16 U.S. inverted flare.

                Google "inverted flare fittings specifications" or similar, and you will find "old school" catalogs which show what the threads are.............

                Here is just one, "Parker"

                https://www.parker.com/literature/F...ectors Group Static Files/G-BrassFittings.pdf

                3....MALE THREAD on your hose........These are NOT inverted flare "standard" and vary.....some of them have an inverted flare seat, some are a straight thread with a copper gasket. You have to be wary and think them out. If the cylinder has a "seat" at the bottom of the thread, and the hose end has a taper, then that's the seal.
                 
              • brian6pac

                brian6pac Well-Known Member

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                Sorry you don't understand
                His is looking for braided -3 AN, and all AN are 37 degrees, Just to be clear AN stands for Army Navy, And 37 degree is standard.
                 
              • scott657

                scott657 Well-Known Member

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                • RustyRatRod

                  RustyRatRod Just another dumbass. FABO Gold Member Technical Editor

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                  OH MY GOD!!!!!!
                   
                • jos51700

                  jos51700 Well-Known Member

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                  The guy is working in Sweden on American stuff. Parts stores are out, and he has to deal with English. This is going to take patience lol
                   
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                  • BillGrissom

                    BillGrissom Well-Known Member

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                    Google "tube nut", which is what the part on the tubing which screws into the brake hose is termed. You can buy individually on ebay. They come in several thread sizes (and thread lengths), to mix up tubes at the master cylinder and such. Most tube nuts are for 3/16" brake tubing, regardless of thread size. But, early Mopars (~1966-) had a 1/4" tubing and nut from MC (single pot) to distribution block, so be careful when re-plumbing that for a modern MC (must install 1/4 M inv to 3/16 F inv adapter in port).

                    Around 2000, U.S. cars changed to metric tubing, nuts, and "bubble-flare" ends. Those don't interchange. But, I found the metric tubing is close enough (6 mm I recall) to double-flare and use as 3/16". Also, others found you don't need a special bubble-flare tool since you can use an old dbl-flare tool to make bubble-flares (youtube's).
                     
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                    • purplehazenils

                      purplehazenils Well-Known Member

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                      Thank you guys .. Alot!!
                      It felt like mission impossible makes sense now and I know whats what.

                      I will be ordering two of these for the front
                      Summit Racing® Stainless Steel Braided Brake Line Assemblies SUM-220302

                      And one each of these for the rear
                      Earl's Performance Brake Adapters 501902ERL
                      Summit Racing® Stainless Steel Braided Brake Line Assemblies SUM-220303

                      The thing is we dont really have part stores like you guys do. Or local ..anything haha. For example you cant drop by your local exhaust shop, dont think they exist and the local alignment is hours away in the populated south of Sweden lol.
                       
                    • brian6pac

                      brian6pac Well-Known Member

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                      You still need to reflare your lines to 37 degrees to use a braided line
                       
                    • AJ/FormS

                      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                      There was a company in the early 2000s that sold braided front brake lines for my 68 Barracuda with KH 4-piston brakes, with the correct ends on the lines; They are still on my car today. Great product.They had other stuff too.
                      I bought them from an ad in a car magazine,(Possibly Mopar Action) not from a supply house like Summit or Jegs.
                      I thought the price was very fair.
                       
                    • purplehazenils

                      purplehazenils Well-Known Member

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                      Ok got ahead of myself I will measure and take some pics of the flares tomorrow and have a look around for a flaring tool or if other places have the correct threads and flares for their braided line.
                       
                    • purplehazenils

                      purplehazenils Well-Known Member

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                      Just realized there are adapters (which one of you already posted) so that's obviously easiest to go with. I'm really starting to feel dumb, I'm pretty bad at threads and also stuff that's non metric, so put them together and its a disaster.

                      So with the stuff below (for the front female-female 3/8-24 rubber hose) I can go from 3/8 in.x 24 @45 deg on the copper brake line, to the adapter which makes it -3AN @37 deg for the braided brake line and then back again. ..right?

                      Female-female braided -3AN line
                      Summit Racing® Stainless Steel Braided Brake Line Assemblies SUM-220302

                      Male -3 AN to Female 3/8 in.x 24
                      Russell Brake Adapter Fittings 641291
                       
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