There’s something very satisfying about precisely routed custom hard lines. They convey a high degree of detail, especially when executed in stainless steel.
Such precision has always been a hallmark of Sled Alley, the Pro Touring specialist shop northeast of Detroit. They’ve been working on Mark Stielow’s latest Camaro project—one we’ve highlighted with recent stories on its floorpan installation, frame connectors, and more. At this stage in the build, a retro-dressed-yet-modern LS7 is sitting in the Detroit Speed front subframe and the suspension and steering systems have been installed.
We’ve been following Mark Stielow’s latest build at Sled Alley for the past year. It’s a former drag car undergoing a Pro Touring makeover. Chassis work involved swapping the original subframe for one of Detroit Speed’s hydroformed subframe assemblies.
It’s time for the brakes. As with his previous few cars, Stielow is adapting a production-based GM antilock braking system to complement the big discs at each corner. It uses a C6 Corvette master cylinder and booster (from Detroit Speed), along with a GM ABS control unit mounted on the subframe. The Detroit Speed front suspension uses C6 spindles and there are C6 hubs on the Detroit Speed Floater rear axle, all of which accept the necessary ABS sensors.
As work progressed, the coilover front suspension and rack-and-pinion steering system were installed, along with the modern LS7 engine, which was dressed to emulate the look of a vintage COPO 427.
The brake system also requires hard lines from the master cylinder to the ABS module and another set from the module to each of the four brakes. While there is added complexity in incorporating antilock brakes to the car, the basics of fabricating custom hard lines for the system are the same as bending them for a conventional brake system, a fuel system, or other components.
Attention turns next to the brake system, which incorporates an adapted GM ABS module for a C6 Corvette, along with the corresponding sensors, master cylinder, and booster. The 1/4-inch hard lines from the master cylinder to the ABS module and the 3/16-inch lines from the module to the brakes require custom fabrication and that’s why we’re here.
The mechanics of the project also aren’t particularly difficult, even when it comes to flaring the ends, but the key is patience and a keen eye for detail. Tangible measurements are required, but so is the intangible measure of eyeballing the lines to check the accuracy of the bends. It takes a bit a practice but it’s a project that can be accomplished at home with the right tools.
The mounted booster/master and ABS module, along with the front-wheel spindles and rear-wheel hubs, are the anchor points between the ends of the respective hard lines and the starting points for measurements. A length of easily bendable household aluminum conduit is used to make those first few bends to use as a pattern.
They include tubing benders, tubing cutters, and flaring tools, which range from simple and affordable flaring tools from Harbor Freight or your local auto parts store to more specialized versions that cost hundreds of dollars. As we’ll see in the photos, Sled Alley uses a variety of benders for wider- and tighter-radius bends, as well as different flaring tools.
The conduit is easy to reshape, too, allowing more flexibility to work around the contours of chassis and engine-compartment components.
When it comes to the brake line material, there are four options: steel, soft steel, stainless steel, and a nickel-copper alloy (known by the trade name NiCopp). The basic galvanized steel is the least expensive and easy to work with, but it will develop surface corrosion pretty quickly and, as anyone from the Rust Belt will attest, they can rust out over time. Soft steel is a low-carbon material that’s easy to bend and is coated with a thin plastic wrap to stave off corrosion. It’s a good, affordable option for an everyday driver.
With the conduit serving as the template, it’s time to flare and bend a length of stainless steel tubing, which Sled Alley obtains from restoration parts supplier Inline Tube. It’s purchased in 10-foot lengths, but coiled hard line is also available—although it takes more time and a specific tool to straighten it. Here, a tubing cutter is used to trim the stock to the approximate length.
NiCopp lines are composed of 90 percent copper and 10 percent nickel. It’s a very easy-to-bend material and corrosion-proof, but stainless steel is the ultimate for strength, durability, and appearance. It’s also the most expensive option, although it really doesn’t cost that much more. It also won’t rust and aesthetically it looks the part—just the thing for a high-tolerance, high-performance, and exacting-detail Pro Touring build. Not surprisingly, that’s what Sled Alley went with on Stielow’s car.
Flaring one of the ends is the next step, but before diving into it, a quick primer on flaring tools. For most of the stainless steel lines, Sled Alley uses a hydraulic hand tool from Mastercool, which offers greater pressure control that helps reduce the chance for cracking. A kit similar to this can cost $600 or more.
Stainless steel is the hardest material of the four, but while it’s not difficult to bend, it is very susceptible to cracking during the two-stage flaring process. Each end must be checked carefully or the brake system itself will confirm the crack later, when brake fluid starts to drip onto the shop floor.
There are also times when a simple and inexpensive tool does the trick and Sled Alley also keeps one handy. A similar kit from Harbor Freight goes for about $30 and gets the job done, especially with softer brake like materials.
Whether tackled at home or left to the professionals, the attention to detail required for bending hard lines takes time. Lots of time—and in the case of Stielow’s car and its ABS system, it involved building two sets of lines: a set of 1/4-inch lines from the master cylinder to the ABS module and 3/16-inch lines from the module to the brakes. In fact, Sled Alley has gotten in the habit of also splitting the lines to the rear wheels at a junction at the rear of the engine compartment. It’s for the sake of serviceability.
Before bending the line, first slip the fitting over the end of the line and push it out of the way. After that, the line’s end is slipped into a die in preparation for the first of two flaring steps required for the 45-degree flare tip used with brake line fittings. Here, the line is positioned so that its end is parallel with the end of the die.
“These Pro Touring cars are built to be driven and things happen on the road or track,” Sled Alley’s Matt Gurjack says. “The junction makes removal much easier, splitting the lines into two sections. Otherwise, it would be virtually impossible to remove the lines as single pieces.”
Next, the appropriately sized flaring adapter is placed in the tool and, with this hydraulic tool, a handle is squeezed to force the adapter into the line and roll back its wall.
Such time and attention to detail from Sled Alley paid off in a very satisfying-appearing layout, with the lines running along the subframe and tightly around other chassis elements with aerospace precision. Of course, every car’s lines will be routed differently, depending on its powertrain and other equipment, but the tips and procedures outlined in the photos here offer a great overview of what it takes to give a project car the bends.
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Here’s a look at the initial bubble flare. It’s the first of two flaring steps.A second adapter is inserted in the tool to complete the full flare.And here’s the finished, 45-degree rollback of the tube will, completing the double-flare process.Stainless steel hard line is notorious for cracking, as seen in this example, making it imperative to inspect each flare carefully after it’s formed. Cracks like this will mean leaks after brake fluid is added.With the flare completed, it’s clear why the fitting is slipped over the end before it’s flared. It won’t slip on over the flare.As with the flaring tools, there are multiple options when it comes to bending tools — some more elaborate and expensive than others. For wider bends, a tool such as this one makes easier work of it.For tighter bends, Sled Alley use a handheld tool like this.For the line templated with the conduit seen earlier, which was measured and templated from its connection at the ABS module, an initial 180-degree bend is made.Next, measurement marks made on the conduit are matched on the hard line, indicating where to start the bend.That measurement mark is lined up with the 0-degree mark on the bender and line is simply bent by hand to the approximate angle. The process continues for each necessary bend in the line.On longer lines, the angles can splay outward toward the end, and in this case the line is checked against the angles of another line that was already bent and test-fitted in the car. The new line needs adjustment to make it straighter.There’s no exact science to tweaking the line. Sometimes it’s just a twist by hand, while other times a little extra pressure while it’s held in a vise will do the trick.With a little manipulation, the line is in the right shape and at the correct angle.After that, it’s time to check the fit with a trial installation. So far so good here.The line runs to one of the front brakes and its placement looks good there, too.At the front, the brake lines connect to a fitting for the flexible lines, which is secured to the frame by weld-on tabs supplied by Inline Tube. Prior to welding the overall fitment is double-checked and the tab’s permanent position is marked on the frame.Here’s an unobstructed view of the hard brake line, the flexline fitting, and the mounting tab. Note how tightly the hard line wraps over the subframe. Exquisite work, here.Clamps also from Inline Tube hold the lines in place along the front crossmember and other areas of the chassis and engine compartment, adding to the overall precision of the lines’ appearance.A look under the hood of most new vehicles reveals the brake lines are coiled, typically near the master cylinder. The design offers motion-absorbing flex in the system and Sled Alley has started incorporating the feature into their brake lines.Finally, the brake lines are tightened to complete the project. It took more than a week on this project, as separate lines had to be created between the master cylinder and ABS module and the module and the brakes themselves.The results of the painstaking work speak for themselves. The precise layout of the brake lines reflects the high level of detail built into the car—but all of it will have to be removed, along with the LS7 engine, when it’s time to paint the engine compartment and powdercoat the chassis.
