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Poly-Flo T Fitting for Brakes

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  • Poly-Flo T Fitting for Brakes

    Anyone using the poly-flo fittings for brakes? They don't seem to have any bulkhead type fittings and I'm wondering how to secure the T that goes from the master cylinders to the reservoir. Also given that I'm using a polycarbonate reservoir I don't see a reason not to use nylaflow tube even on the firewall side, unless there's a greater risk I'm unaware of?
    Dave B.
    Edmonds, WA
    4 Place Quick Build

  • #2
    The nylon lines are good for the low pressure side, but from the master cyls to the brakes I have seen several problems.Very little if any exposed nylon line on the firewall side if the reservoir is attached to the firewall. Mark

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    • #3
      Thanks Mark. I looked at previous threads, here and elsewhere, on brake line materials and have a pretty good idea of the pros and cons of each. My thinking on nylaflow in the engine bay is that since my reservoir is polycarbonate, and would certainly give up the goods in a fire anyway, there's little additional risk using non metallic tubing. Even with a melted reservoir you'd still have brake authority, for a while anyway.
      Dave B.
      Edmonds, WA
      4 Place Quick Build

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      • #4
        It might be good to ask the DAR you are planning to use. Now is a good stage to start developing that relationship.

        One thing that comes to mind that you have probably already thought of is that the bulkhead fitting that goes through the firewall should be steel if at all possible. Otherwise in short order the hole in the stainless becomes a hole for the fire to pass through. Also, all plastics age, and some age less gracefully in elevated temps. Not sure how Nylaflow stacks up among its peers. I used aluminum lines forward of the firewall.

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        • Battson
          Battson commented
          Editing a comment
          If it's hot enough to liquefy large pieces of aluminium like a bulkhead fitting attached to a big heat sink, then you have much bigger problems than one 3/8" hole in the firewall...!

        • jaredyates
          jaredyates commented
          Editing a comment
          Fair enough, but let's make it metal and not plastic at least.

        • Archer39J
          Archer39J commented
          Editing a comment
          Heh, both good points

      • #5
        The brass Polyflow fittings from Aircraft Spruce are suitable for some applications where they are relatively protected. They can stand the pressure.

        I would absolutely not recommend the plastic Nylaflow fittings - they are total junk. It takes very little pressure to pull the Nylaflow fittings apart.

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        • #6
          You could put the reservoir on the inside of the firewall and not worry about any of those issues. The tradeoff is that its more difficult to add fluid, but once everything is set up right, you shouldn't have to add fluid often.
          Rollie VanDorn
          Zanesville, OH
          Patrol Quick Build

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          • #7
            Yeah I’ll look at having it cabin side, if I want to deal with trying to fill it, Jared makes a good point about the environment in the engine bay. Still have to figure out the T fitting issue, I can’t see just letting it flap around.

            I wouldn’t trust those plastic fittings for a static line, much less a brake line. In fact some folks recommend poly-flo fittings for pitot static too, they’re apparently more compact and easier to use than what comes with those kits, albeit heavier. Might go that route.
            Dave B.
            Edmonds, WA
            4 Place Quick Build

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            • jaredyates
              jaredyates commented
              Editing a comment
              Can you position the T near one of the 3/16 bolt and tab locations, and run the bolt through an adel clamp that goes around the tubing or the fitting? That saves you having to make another hole in the firewall. For what it's worth, I always fill mine from the brake caliper, so having access to the reservoir is only important for visually checking the quantity, and that would work just fine by poking one's head under the panel.

            • Archer39J
              Archer39J commented
              Editing a comment
              I’ll certainly look at that shockingly obvious and simple solution, thanks

          • #8
            Look at how American Champion does there install on the cabin side. Nylaflow with small overflow tube going to the belly. Very simple to service with no risk of spilling fluid inside the cabin. That is the way I am going to do it.

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            • JimParker256
              JimParker256 commented
              Editing a comment
              Thanks for this idea. So simple, and so easy. Combined with the "filling from below" concept (which I already was planning), it's just elegant!

          • #9
            If you are considering other options: I used ACS master cylinder mounted reservoirs. I'm in the process of filling my brakes for the first time and find it no trouble to fill the cylinders. Hard to beat no hoses or firewall penetrations.

            Thought I had a pic of them but I guess not. You can kinda see that I have one mounted in this pic.

            I'm a Tapatalk user so I can't see your "comment"

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            • #10
              Originally posted by Archer39J View Post
              Yeah I’ll look at having it cabin side.
              Hold up! Sorry, that may not be a good idea, from what I have found.

              In my experience the fluid is impossible to keep inside the reservoir, and even with a sealed plug it leaks habitually. This is a good quality Grove reservoir, and there is always a little pool of fluid on top. I have admitted defeat on that front, the stuff just finds it's way out.

              To make matters worse, it's a really nasty corrosive fluid, and it dries into a sticky treacle-like substance which does not clean up without strong chemicals. Cleaning it off the smooth firewall is hard enough, with easy access. Talk about the worst possible fluid to have inside the cabin all over your pedals and interior.

              Definitely put it on the engine side of the firewall, or put an overflow tube to the exhaust area.
              Last edited by Battson; 11-08-2018, 03:25 PM.

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              • #11
                Originally posted by Battson View Post

                Hold up! Sorry, that may not be a good idea, from what I have found.

                In my experience the fluid is impossible to keep inside the reservoir, and even with a sealed plug it leaks habitually. This is a good quality Grove reservoir, and there is always a little pool of fluid on top. I have admitted defeat on that front, the stuff just finds it's way out.

                To make matters worse, it's a really nasty corrosive fluid, and it dries into a sticky treacle-like substance which does not clean up without strong chemicals. Cleaning it off the smooth firewall is hard enough, with easy access. Talk about the worst possible fluid to have inside the cabin all over your pedals and interior.

                Definitely put it on the engine side of the firewall, or put an overflow tube to the exhaust area.
                Sure, wait till now to say something!

                Perhaps this is one reason to use ATF as a brake fluid. Too bad I filled my brakes with mill spec fluid yesterday.
                I'm a Tapatalk user so I can't see your "comment"

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                • #12
                  Originally posted by Battson View Post

                  Hold up! Sorry, that may not be a good idea, from what I have found.

                  In my experience the fluid is impossible to keep inside the reservoir, and even with a sealed plug it leaks habitually. This is a good quality Grove reservoir, and there is always a little pool of fluid on top. I have admitted defeat on that front, the stuff just finds it's way out.

                  To make matters worse, it's a really nasty corrosive fluid, and it dries into a sticky treacle-like substance which does not clean up without strong chemicals. Cleaning it off the smooth firewall is hard enough, with easy access. Talk about the worst possible fluid to have inside the cabin all over your pedals and interior.

                  Definitely put it on the engine side of the firewall, or put an overflow tube to the exhaust area.
                  I recall you mentioning that you had issues with the reservoir leaking. I certainly wouldn't want 5056 spraying in the cabin or engine bay. I'll be using ATF myself.

                  https://m.aircraftspruce.com/catalog...?clickkey=5672

                  Above is the matco reservoir I have. For now I'll start with it in the cabin and half full, see how it works. Overflow tube will be plan B, and relocating to the engine bay plan C.
                  Dave B.
                  Edmonds, WA
                  4 Place Quick Build

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                  • #13
                    I just haven’t had problems with it leaking on two Citabrias so not sure why you are seeing this. I asked my A&P and he really likes the American Champion installation.

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                    • #14
                      I mounted my reservoir high on the engine side with a feed into the cabin side to a manifold. I have used nylaflow tubing from the manifold to the brake cylinders. Since the lines to the cylinders are mounted high I have filled the system only partially up to the reservoir. I watch the fluid level in the lines and have never added fluid since building the plane. You can see the fluid level change slightly with extreme temperatures but the system seems to work well. There is no fluid in my reservoir.

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                      • #15
                        My reservoir has not leaked through the vent yet, but the two caveats are that I had to replace the top bolt and I believe the hole I made was 1/16 which may be smaller than the original, and that I don't use the airplane the say way Jonathan does, so it may get less disruption.

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