Jim Smart
July 1, 2008

Your Mustang's plumbing system manages functions important not only to driving, but also to driving safely. Brake lines, fittings, and valves must be able to withstand tremendous operating pressures. They must not fail even under the worst of circumstances.

Fuel lines, even in fuel-injected, late-model Mustangs, operate under much lower pressures. However, fuel must remain inside the line at all times, including extraordinary circumstances such as an accident. Because late-model fuel-injection fuel lines are primarily plastic quick connect/disconnect, we're not going to discuss them here.

Classic Tube takes the confusion out of brake- and fuel-line installation because the company makes every type of prebent line for classic Mustangs. However, if you have an application in which you would like to route the lines differently from the way they were routed at the factory, all you have to do is order rolls of line from Classic Tube and fabricate them yourself. If that doesn't work for you, send Classic Tube your exact dimensions and it will manufacture prebent lines at an additional cost. This means you can have brake and fuel lines made for just about anything out there.

When time prohibits ordering tubing from Classic Tube, your local automotive parts store should have double-wall/double-flare steel tubing in various lengths and diameters for brake and fuel applications.

How To Bend Lines
Bending brake lines has to be approached with the same kind of caution used during double-wall flaring. Get aggressive in your bending and you can kink the line, rendering it useless. Adopt a smooth approach to your bending, using a tubing bender or socket to round your radii.

Step By Step

View Photo Gallery
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).

Lines For Every Application
Classic Tube offers prebent lines for nearly every classic Mustang application. For the lines it doesn't offer, you can send the company your original prebent line for fabrication. Also available is high-quality 304 stainless steel prebent by the inch, up to 240 inches. Stainless steel provides a rich look that conventional galvanized steel lines don't. Be advised that, although attractive, it's more challenging to work with because it's a harder, more brittle steel. This means special attention to detail during installation. You'll need to loosen and tighten fittings until the flares seat and leaks stop. We suggest lubricating all fittings during installation, which improves sealing.

Steel tubing is available as 304 stainless, cold-rolled low-carbon, and Galfan, which is extremely corrosion resistant. Galfan can withstand a 4,000-hour salt spray, which makes it perfect for show car and daily driver alike. Tubing sizes range from 3/16-inch to 3/8-inch.

If You Mess Up...And Even If You Don't
If you've ever fabricated your own brake and fuel lines, you know bends sometimes happen in error. Rolls of tubing can also come out of the box with annoying bends that are hard to get rid of. The Tube Straightener from Classic Tube eliminates the annoyance for those working with 3/16- to 1/2-inch steel and aluminum tubing.