Fabricating Custom Hard Lines From Scratch
THERE ARE MANY WAYS TO FORM HARD LINE FOR THINGS LIKE BRAKES, NITROUS SYSTEMS, FUEL LINES AND ONBOARD
FIRE EXTINGUISHER SYSTEMS. Some are really good, and some aren't. Honestly, nothing beats the look of a carefully fabricated hard line, and in terms of quality and performance, nothing can compare. The big question is: How difficult is it to work with?
Carefully forming hard lines takes patience, and you have to be prepared to make mistakes (I have a drawer full of them). There's more too: Every application for hard line (brakes, fuel lines, etc.) is different and every car is different; floor pan shape is a good example, it can vary quite a bit between race cars and even more so on production cars. You can buy pre-bent
line for popular stock production cars— restoration shops sell it—but there's a catch. These pieces won't work if you've done things like swapped to a different master cylinder, added a line lock or switched to an adjustable proportioning valve. If the race car is back-halved with tubs, a narrowed rearend and a custom floor, then none of the reproduction lines will fit. For a racer, that means you're on your own.
That's the bad news. The good news is that with a bit of practice you can fabricate custom hard lines in your own shop. There are no tricks when it comes to building custom brake hard lines (or other lines); it simply takes time. In the process, you can also make them look great too. In order to get the job done you'll need a handful of plumbing supplies along with a few specialized tools. The truth is, you'll need a fair amount of patience as well. As mentioned earlier, you'll also find that mistakes can and do happen with regularity when forming hard line, which is something that goes hand in hand with the word “custom.”
Obviously, brake line can be fabricated from several different materials. There's no question that the very best is stainless steel. It's robust, good-looking and has a long service life. The con is the fact that it's more difficult to work with than conventional brake tubing. That doesn't mean it's impossible to work with, and the reality is with the right tools and materials, anyone can manipulate the stuff.
When fabricating brake lines, you should use 0.028-inch wall thickness, 3/16-inch OD seamless, annealed 304 tubing. At one time, this tubing wasn't always easy to find (aircraft supply houses were the best source), and I can assure you there are some really bad quality offshore-manufactured examples out there. Often the search for the line was more frustrating than actually building it. That's all changed now. Earl's Performance sells annealed 304 stainless tubing in multiple sizes and lengths. The Earl's part number for our 3/16-inch brake application (12-foot length) is 631696ERL. Plan on at least two lengths to build brakes for the average race car.
Earl's also has the appropriate fittings for the job too: tube nuts and sleeves. In most of the accompanying photos you'll see part number AT581803ERL used for the tube nuts and part number AT581903ERL used
The flare-lapping tools mentioned in the article are Koul Tools Surseat, which are available in three different kits. The P-51 (center) can lap tubing from 3/16- to ½-inch and it comes with 37-degree (AN) and 45-degree lapping heads. The Minis can do...
Tools needed: (1) A tubing cutter, (2) a dedicated 37-degree flaring tool and (3) a dedicated 3/16-inch tubing bender. All three tools must work with 3/16-inch stainless steel hard line. Tools designed for softer materials will be problematic. 3