Steel hose build guide

Hello everyone, thought I'd write this up since it's about the only thing I can contribute. Now I know there are already guides available online, but I haven't found any here, so I thought I'd write up a guide. I'm a U.S. Air Force aircraft hydraulics mechanic, and part of my job is creating hoses that are typically being used at 3,000 PSI, 3850 max. This is obviously overkill for anything you'd ever need for a car, but it beats the hell out of rubber hoses prone to rotting. According to our specs we follow in the air force, a Teflon hose with 2 layers of steel braiding has a burst rate (that is, will burst at approx.) 12,000 PSI. If it is requested, I'll see about getting burst limits for other hoses but chances are if it's steel you wont exceed it on a car.

As you become familiar with the process, this should only take approx. 15 minutes to build. I tried to make the steps comprehensive but in reality this is a very simple and quick task. You can save time during your pressure checks by connecting the hoses with a union and doing them all at once if your method of pressure/leak checking allows it.

Hose union

If you could, please provide some feedback (good or bad) on how you found this post. I'm looking to improve so let me know how to help make things more understandable!

Tools of the trade:

• Saw capable of cutting through steel, pick your blade accordingly.
  
• Masking tape
  
• Measuring tape
  
• Rubber mallet (not necessary, helps a ton)
  
• Wrench set
  
• Feeler gauges
  
• Equipment for pressure checks
  
• Shop vice (not necessary, helps a ton)
  

Hardware:

Hose with fitting assembly. I will be showing you a -4 sized hose with MS fittings on either end, the same principle translates to other sizes/fittings.

From left to right: Sleeve, fitting, nipple. It is worth noting that not all fittings look the same, but knowing how to build one type should gain you the understanding of how to assemble other types.

Step 1. Measure out your hose. The key to measurements is knowing how much to subtract from your cut. As an example, the fittings I will be using calls for 1.07in to be subtracted on both sides (2.14 total). A 13in hose needs to be cut at ~11in and the fittings make up the rest of the length. If you have a hose already and want to make a new one, measure from the middle of the B-nut to the middle of the adjacent B-nut (no pics of this, sorry.)

Step 2. Once you get your measurements, grab your masking tape and wrap it around where you will need to cut, this will allow you to mark the point on the tape with a pen for accuracy with the saw, and will prevent flair outs of the braiding. Cut the hose after making sure you have the correct size measured.

Step 3. Do not pull the masking tape off just yet. Put your two fittings "skirt to skirt" in the vice. Make sure you line them up pretty closely as you'll be pushing the hose through one and out the other. This can be done without a vice but it gets a lot more annoying. Push the hose through.

Step 4. Now remove the masking tape. Put one nipple in the vice grip and push the hose on to it, this will aid in separating the inner hose from the braiding. You can also wiggle the hose up/down/left/right if you still don't get enough separation. You're looking for enough distance to press your sleeve on to the hose without any of the braiding catching in between.

Step 5. Press the sleeve on to the inner hose. This is a pain in the ass. The sleeve gets pressed on from the narrowest first, and needs to bottom out at the lip. Once you press it on, beat the shit out of it until it bottoms out at the lip.

Step 6. The nipple should still be in the vice, if not put it back on. Now that you have the sleeve installed, we want to make sure it's not going anywhere. Push the hose back on the nipple, and then pull it off firmly to make sure the sleeve does not move and the inner hose is still flush with the lip.

Step 7. Take the nipple off the vice, and put the fitting on. What we need to do is expose some of the threading of the fitting so we can thread it on to the nipple. You might get away with just pulling with your body weight on the hose, but if you still don't have enough threads to start the threading, take your nipple and push it in to the hose and lightly hit it with a rubber mallet while simultaneously pulling the hose.

Step 8. Start threading the fitting to the nipple by hand. If you cant get it, try step 7 again until you have enough threads to start you off. Once you have it started, finish it off with a wrench but do not bottom it out. Make sure you go slow to avoid cross threading.

Step 9. Grab your feeler gauge and measure the distance between the fitting and nipple. The distance should be between .023 to .043"

Step 10. Moment of truth. You will need to pressure check the hose for leaks. Now hopefully someone can chime in on this and I'll edit accordingly. We use a bigass frankenstein-looking mofo to pressure check our hoses at 6,000psi. This is going on your car, make sure it works perfectly. Don't settle with "good enough". Like I said, we check these at 6,000PSI and use them at 3,000.

Step 11. Take your Supra on some nice twisties and let your friends know that you built these hoses to aircraft grade specifications. Buy me some sake if you're ever in Japan

This is my first guide on anything ever, it is probably incomplete. Please let me know if you have questions! I build these all the time so if more pics are requested of a specific step please ask and I'll gladly help. Hope you guys found this useful!

Nice write up

Nice write up

Thanks! I'm not great with cars but I know hoses pretty well after dealing with C-130s regularly. I'm just glad I can contribute some of my knowledge to the forum.

I miss flying on C130's

Always got a good kip on them

I miss flying on C130's

Always got a good kip on them

Having never flown on one, I can't say I'd ever miss them, all I can say is I've used every word I know while working up in the cargo door repairing the rudder and elevator boost packs. That, and stripping the plane of its insulation mid-July getting a dust shower, that does not a very happy week make.

Nice write up

Nice pressure tester too! Bear in mind some of the fittings people will use on braided PTFE hose will look quite different but that was an excellent write up and should be moved to the technical section IMHO. Thanks for taking the trouble to post this!! What's your name BTW?

Nice pressure tester too! Bear in mind some of the fittings people will use on braided PTFE hose will look quite different but that was an excellent write up and should be moved to the technical section IMHO. Thanks for taking the trouble to post this!! What's your name BTW?

That is an excellent point! I'll add that to the write up shortly. In my experience, knowing how to do one type has led to an understanding of how to do other types of fittings, that is to say I can always figure out pretty quickly the method of assembly, I'm confident that it shouldn't be any issue for anyone else either. Names Hayden Leitzke.

Hayden, great post, thank you!

Hayden, great post, thank you!

Glad I can help.

If anyone builds one I'd love to see results!