Braided-steel hose has been the choice for custom, high-quality lines and hoses on hot rods for decades. While I hope to revisit why and give a lot more information on various types of hose in a future article, I thought I’d provide a quick and easy guide to assembling a braided-steel line here.
To someone who has never assembled a hose end, this is a scary looking job. Especially for fuel line, or worse, high-pressure fuel line. It’s not hard to do, and the results are almost always a leak-free hose that looks great and will last for years.
There are a few variations in the way that people like to assemble braided-steel lines. I used Earl’s Perform-O-Flex hose and Earl’s Swivel-Seal hose ends for this line, so I’ll share with you their recommendations as well as my time-honored assembly method.
Perform-O-Flex is a higher-end racing hose with stainless-steel wire braided around a synthetic rubber hose. Swivel-Fit hose ends allow you to rotate the hose end once it is tightened onto the hose. This is extremely handy for maneuvering the hose one you have attached it to the gas tank or whatever it connects to. Earl’s also offers a slightly less expensive Auto-Fit hose ends that do not have the swivel feature.
The components of a braided-steel hose are the hose, the socket and the insert (or nipple). The two aluminum pieces clamp the hose end for a strong connection. These components are reusable, as long as the they aren’t damaged.
One of the keys to easy and leak-proof connects is a clean and straight cut. Wrap the hose tightly with duct tape where you’ll make the cut. This will keep the braided-steel from fraying. I really recommend using a 3-inch, high-speed cut-off wheel to cut the hose. Make the cut as straight as possible. Point the end of the hose toward the ground and tap it to get as much of the debris out after making the cut.
Remove the duct tape. If there are any strands of wire that are sticking out, remove them with side cutters. Push the socket over the hose end. Be careful that the braided-steel doesn’t snag on the socket and start working its way apart. If you made a clean cut, this usually won’t happen.
Keep pushing and twisting the socket down the hose until the end of the hose reaches the bottom of the threads inside the socket. Then back the socket off the end of the hose until there is approximately a 1/16-inch gap between the end of the hose and the bottom of the threads.
Use a dab of engine oil on the threads and the nipple part of the insert. Don’t use a silicone-based lube as these will usually cause the rubber to swell on contact, making the installation very difficult and compromising the assembly. There are specialty lubes available for this, but engine oil works well and you probably have some.
The hose may push out of the socket while you tighten the two pieces of the fitting together. Earl’s recommends marking the hose at the base of the socket. I have a different method I’ll show in photos number eight. An 1/8-inch of movement is okay, but any more than that, and you should take apart the hose assembly and try it again.
The final assembly is much easier if you use a vice. You can use two wrenches, but it is more difficult, and it is less likely that the hose end will install properly. We use a shop rag to cushion the aluminum hose end in the vice jaws. There are special inserts you can buy for a vice that further protect the hose ends (and special aluminum wrenches for that matter), but you’d have to assembly a lot of hose ends to make these worth purchasing. Earl’s recommends that you clamp the insert in a vice and rotate the hose and socket onto the insert threads.
I have a slight variation from Earl’s recommendations on the final assembly. I find it easy to cross-thread the fittings trying to rotate the hose and socket. And if the hose is long enough, this process just isn’t possible. Instead, I gently clamp the socket in the vice as shown. If the vice is too tight, it will make the socket out of round. I then thread the insert in place using a wrench. I also hold my thumb nail tightly against the hose at the base of the socket. Doing this, I can tell if the hose is pushing too far out of the socket as I tighten the assembly. I find this quicker than marking the hose, and I don’t have to clean permanent marker off the hose when I’m finished.
The biggest question is when do I stop tightening? The insert and the socket shouldn’t actually bottom out on each other. On smaller-diameter hoses (-6 and -8) the gap should be about 1/16-inch. With larger hoses (-10 and -12) the gap may be around 1/8-inch. I’ve assembled dozens of hoses in various sizes and never had a leak at one of the hose end. With both ends of the hose assembled, use compressed air to clean debris from the inside of the hose.