Jim Smart
July 1, 2008

Step By Step

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Mump_0807_06_z How_to_fabricate_bend_hard_lines
Before flaring, the line tip must be cleaned to ensure uniform line flaring. This tool cleans the inside diameter and tip.
Mump_0807_07_z How_to_fabricate_bend_hard_lines
Use a file to perform final cleanup to get the tip square.
Mump_0807_08_z How_to_fabricate_bend_hard_lines
This is the flaring head that makes the bubble-that first stage in the flaring process. Expose just enough line to equal the width of the bubblehead die. We actually have too much line extended in this photo.
Mump_0807_09_z How_to_fabricate_bend_hard_lines
The bubblehead pilot is seated in the line end as shown. It's a good idea to lubricate the bubblehead and line for smooth operation.

There are two basic kinds of steel and stainless steel tubing-single-wall and double-wall. High-pressure function calls for double-wall. Low pressure, such as fuel or power steering return lines, needs single-wall tubing. There is also single-wall aluminum tubing, which would never be used for brake lines but is fine for fuel and cooling-system lines.

There are two basic kinds of tubing flares-single for low-pressure applications and double for high-pressure, such as brake and hydraulic systems. We'll explore the double-flare here because it's the most common type of high-strength line flare. It's also terrific for low-pressure applications.

It's easy to learn how to custom-fabricate brake and fuel lines for your Mustang project, and it can be done in your home garage. All you need is patience and the right tools for the job. When buying tube bending and flaring tools, don't do it on the cheap. Inexpensive tubing benders and flaring tools tend to fail more than they work correctly. It may surprise you to know that good line fabrication tools aren't all that expensive. Look to Classic Tube and The Eastwood Company for affordable solutions.

Whether you're using steel or aluminum fuel lines, the basic principles of routing, bending, and flaring are the same. We're in the process of building Project Reclaim by Mustangs Plus and The Restomod Shop. This month, we're plumbing Reclaim with brake and fuel lines. Because we don't care for the way Ford routed the fuel line from 1965 through early 1967, we're going to follow a safer path along the transmission tunnel and framerails.

Single-Wall Low-Carbon Steel Tubing
Bundy single-wall tubing is designed for low-pressure/no-pressure fluid applications such as fuel lines in carbureted applications. It meets or exceeds SAE J525, SAE J526, SAE 356A, ASTM A269, and ASTM A268 specifications-just about all automotive industry standards. Use single-wall tubing for fuel and vacuum lines, fuel rails, power steering, engine oil coolers, and other low-pressure applications. Sizes generally range from 0.187-inch to 0.625-inch outside diameter. Other sizes are available from a variety of manufacturers. Manufacturing technique generally includes welded, cold drawn, and annealed. These lines are typically available with a variety of different coatings depending on how you're going to use them.

Never use single-wall tubing for brake-system applications. It won't withstand high braking pressures.

Double-Wall Steel Tubing
Bundy double-wall steel tubing is designed for high-working pressures like those in brake systems. It's manufactured from low-carbon steel with tight tolerances for strength. Double-wall tubing meets and exceeds SAE J527 and ASTM A252 standards. Sizes range from 1/8-inch to 1/2-inch outside diameter, with wall thicknesses ranging from 0.028 inch to 0.060 inch depending on the outside diameter. As a rule, double-wall lines are copper coated for corrosion protection and strength, but not all are copper coated. Because double-wall lines must withstand high operating pressures, they also mandate a double-flare fitting in order to contain the pressures.

Double-wall tubing is available just about any way imaginable. You can buy it in cut-to-length coils or prebent assemblies. There's a variety of coatings available for double-wall tubing-Galfan (hot-dipped alloy layer of 95 percent zinc and 5 percent aluminum; Ford Specification ESA-M1A270-A), Algal (hot-dipped alloy layer of 95 percent zinc and 5 percent aluminum, lighter in color; Ford Specification WSA-M21P26-A), Nygal (hot-dipped alloy layer of 95 percent zinc and 5 percent aluminum, conductive and nonconductive, nylon coating; Ford Specification WS5-M21P30-A1), and PVF (hot-dipped alloy layer of 95 percent zinc and 5 percent aluminum, chromate primer, and paint coating; Ford Specification unknown).