Making brake lines

[captain_john]

Lacking a "Plumbing" forum, I thought that I would post up my progress here in the "Workshop & Tools" forum.

I ordered my brake line components from Pegasus Racing and they arrived here yesterday. I am easing into the production of these hoses, as I know nothing about their assembly. They are the Aeroquip hose ends with PTFE (teflon) hose. It is all new to me!

After opening the box, It seems that the stuff is fairly high quality. The fittings are reusable, but I didn't order any additional sleeves... so I best not screw up!

I found this very detailed page (http://www.hydratechbraking.com/Hydratech/hosetech.html) and will be following it's instructions to a tee.

Pics to follow.

Has anyone here assembled these hose ends before? Do you have any tips for me?

CJ

[Spike]

Ooooh, looking forward to watching this!

PS. I'll move this to the general construction questions since this is a topic that will relate to all of the airframes.

-- Spike

[Wicked Stick]

John,

That's a nice link with great pictures of how to do it.
I'm sure you'll get er done just fine, but if you want any help, just let me know. Also, they mention a screw driver and tapered punch to help with the intsall. I have the specific tool for it if you want to try it out. I think the tool is for the -3 hose though, not sure it will work with -4.

[captain_john]

Lemme start off by saying a few things...

First of all, thank you to Wicked Stick and Mitch (the A&P IA friend of mine from the FBO) who came over tonight to help me past this hurdle.

Secondly, making your own lines will not save you any money but you will learn ALOT in the process. It isn't easy and it is very meticulous. You need to pay much attention to detail!

Third, It is time consuming. We spent 15-30 minutes on each line!

All that being said, I am glad I made them myself.

PICS TO FOLLOW!

One thing that stumped me was pressure testing these puppies. Mitch has a nitrogen tank at the FBO and will help me bring the lines up to pressure (without contaminating them). I think that nitrogen is a good method of testing, as the tank is about 1,000 psi and I doubt that the brakes will surpass 500 psi.

I have two more lines to make. I will post those pics soon!

Stay tuned!

CJ

[4kilo]

CJ,

There is one issue you need to be concerned with if using pressurized gas for testing. The compressed gas stores a tremendous amount of energy, and if the tested component fails, that energy could propell parts at tremendous velocity. I know there is a 99.9% chance you will pressurize the part, it passes and you let the pressure out, but please plan for the worst case.

If you use a liquid of some kind, the stored energy is not so dangerous. That's why pressurized parts are normally hydro-tested.

Pat

[TomNativeNewYorker]

The hydraulic systems I work on are pressurized to 3000
PSI. Any hoses or tubing we need are usually local manufactured on base at the hydraulic shop. If I recall correctly after the lines are made they flush them clean with PD-680. They are put on a hydraulic test stand and pressure tested to 5000 PSI. Afterwards they are drip drained and caps and plugs are put on all fittings to prevent contamamation. Any other components such as actuators are filled with a preservative hydraulic fluid to prevent internal corrosion. We are supposed to drip drain this fluid before installation of the component but the fluid is compatible we generally leave it in to prevent introducing too much air into the system.

[captain_john]

Thanks for the input guys!

I had been wondering exactly how I was going to do that safely.

I have witnessed hydraulic systems exploding A-Frame conduit benders recently and have tremendous respect for pent up energy.

I will test these safely, I assure you.

Thanks! I will keep you posted!

CJ

[captain_john]

OK, here is the long awaited update! With help from Wicked Stick and Mitch (Friend, local alcoholic, A&P, IA) I am done with my first plumbing job!

Making one's own stainless steel PTFE brake lines is no more difficult than using the plastic lines provided by Van. I also chose to install a parking brake (line lock) so that complicated the install a bit.

Installing the fittings on a 45 degree angle eased the installation of the hard line between the brake valve and the bulkhead fittings.



Here are the hard lines:



You start by cutting the lines to length. I chose to use an abrasive wheel in my die grinder. A nice parallel cut through the line with electrical tape around the desired location works well. The electrical tape keeps the strands from expanding. The ss braid is kinda like one of those chinese finger toys.



Having the tool that is available from Pegasus is really helpful in getting all those strands back and out of the way so they don't get stuck in your connector.



You can then use the tool to push the sleeve onto the inner PTFE line.



Once the sleeve is in place, you insert the nipple/connector into the line. Hit the threads with a drop of lube and snug it up. The line will rotate around the fitting so having another person present to flip the line around while you tighten the joint is handy.



It is most important that you not forget the female part of the connector before completing the other side of the line!!! Tightening the connector is best done using the vice and a wide wrench.



Tighten the fitting down until the male/female gap is about .020" - .030 apart.



VIOLA!!!



It is as easy as that!

Now for the testing procedure. Hmmmm, I will letcha know how that goes. Each of the fittings seemed to go together very well. I would really be surprised if they all didn't pass inspection.



You will need only one 90 degree fitting to complete this installation.

Hope this helps you!!!

CJ

[captain_john]

Also, thanks to Dave G. for the return springs!!!



I finally installed them, Dave! It was nice to meet you in person over TWO YEARS ago when you first gave them to me!!!

That was "pre-divorce" for me! I was on my cross country bike trip then. Oh, the memories that are made when you build one of these things...

CJ

P.S. In this pic I am sizing the ss line to the same length as the Van's 118 line. They made theirs out of Aeroquip 303 fabric covered stuff. In hindsight, I probably could have gotten away with that stuff instead of stainless steel. I suppose looking down at the SS is prettier! hahaha

[TomNativeNewYorker]

Looks good. Do you have an adel clamp on the lines to prevnt chafing where they pass through the support lightning hole?

[TomNativeNewYorker]

Looks good. Do you have an adel clamp on the lines to prevnt chafing where they pass through the support lightning hole?L

[captain_john]

Tom, that is one detail I left out of the write up.

Being an electrician, I have a nice nylon snap in 1 1/4" cable clamp for that task.

I will punch a standard hole with my Greenlee punch sets and just pop it in!

Sooooo slick!

Thanks for the compliment!

CJ

[dons]

Looks very nice CJ, let us know how you decide to do the pressure testing, and how it turns out. I like the look of the SS covered hoses, something tells me that they can take a bit more abuse too.

[captain_john]

The test part has me wondering how "companies" test theirs.

Take Bonaco for example. Do you think they test theirs? I dunno? Machine Man tells me that his were bone dry inside and didn't have any evidence of being ever torqued onto anything prior to his acceptance of them.

Which makes me wonder, if I have faith in my assemblies (I am totally naive' to the possibility of failure and these assemblies) do I really NEED to test them?

I am sure that I will have lots of time to observe them before actually taking flight. Some of that observation will include stepping on the pedals and observing the compression of the caliper(s), no?

Soooo then, do I NEED to test them?

What is your take on this?

CJ

[Cherokee Driver]

If we are voting on the question...I say test them.

Do you want to find a problem now when a leak can be cleaned up easily or after you have nice carpet and upholtery in there?

My 2 cents.

By the way...it looks very, very nice.

CD

[TomNativeNewYorker]

Which makes me wonder, if I have faith in my assemblies (I am totally naive' to the possibility of failure and these assemblies) do I really NEED to test them?

I am sure that I will have lots of time to observe them before actually taking flight. Some of that observation will include stepping on the pedals and observing the compression of the caliper(s), no?

Soooo then, do I NEED to test them?

I do not know the working pressure of an RV brake system, but I would most certainly try to pressure test them prior to installation. I would MOST definitely op check them
after the system is built up.

It is SOP for any lines or fittings we replace to hook hydraulics up to the aircraft and leak check the system.

Anything involving safety of flight involves an op check of that system as well. Example, if we replace a hydraulic line for the landing gear we Jack the plane and woman operational drop check on the gear including the emergency blowndown system.

[dons]

I would certainly want to test them. Maybe a hand operated hydraulic pump and pressure gauge would work, around here those two would set you back about $100. You would also need some way to put it all together in a test jig so there might be a few adapters needed. Finding someone that already has that kind of test jig would be better though.

[dpansier]

A simple hydrostatic tester can be made from a grease gun and is capable of producing in excess of 8,000 psi.
Pre-fill the lines with water and minimize the air trapped in the system you are testing.
Remember air is compressible and water is not.
When finished, drain the water and apply a coat of oil to the pump piston to prevent rust.
Safety note:
This device can produce dangerous pressures, use caution and protect yourself.

http://img709.imageshack.us/img709/2540/dsc01662.jpg

dpansier
RV-7 Finishing up

[captain_john]

Don, That is very clever!

Hmmm, I will let ya know what I come up with.

CJ

[dons]

A grease gun is sure less expensive than a hydraulic hand pump, never thought of that.