How It’s Made

Johnson’s Radiator Works Builds a Custom C10 Radiator

By Tommy Lee Byrd   –   Photography by the Author

Whether you build classic trucks as a hobby or operate a shop that cranks out several builds a year, you know the importance of the cooling system. As a well-known builder of hot rods and custom creations, Alan Johnson of Johnson’s Hot Rod Shop faithfully used Walker Radiator Works because of their durable construction and reliable performance. Vernon Walker revolutionized the street rod world with traditional brass and copper radiators that would cool even the most radical builds. When Walker Radiator Works closed its doors, Johnson stepped up to the plate to buy the operation. All of the machines, patterns, and notes came with the purchase, but the name was not available, so he renamed it Johnson’s Radiator Works and moved the operation near his hot rod shop in Gadsden, Alabama.

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Johnson’s Radiator Works builds every component of each radiator (aside from the drain petcock) inside its Gadsden, Alabama, facility. The machines, materials, and methods that Walker Radiator Works used have been carried on.

Johnson has since become a student of the process, learning every step necessary to transform flat stock on the shelf into a high-performance bolt-in replacement for your stock radiator. He and his staff have devoted countless hours to perfecting the build process and making it repeatable. Many of the systems and processes that Walker implemented are still in place but transferring it over to a new facility and new staff took some time.

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Johnson’s Radiator Works continues to manufacture its components with all the extensively engineered details that made Walker Radiator Works famous in the street rod world. The important parts of the formula are the louvered copper fins, which encouraged air direction changes.

Now, the crew at Johnson’s Radiator Works is building up an inventory of components like cores, tanks, tubes, fins, and brackets, and fulfilling orders as quickly as possible. Every piece of the radiator, with the exception of the drain petcock, is built under one roof by dedicated folks who are passionate about the finished product.

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The brass tubes are made in-house from flat sheet stock. The machine responsible for tube manufacturing folds the flat stock into 0.125×0.500-inch tubes with a Pittsburgh seam for strength. The tube is then coated in solder and cut to length.

During our time at Johnson’s Radiator Works, we learned about the advantages of a tried-and-true brass and copper radiator compared to aluminum construction. While an aluminum radiator is physically lighter, the brass and copper construction is more durable and conducts heat better if configured properly. That’s where the legacy of Walker Radiator Works comes into play, as the custom fin design provides more air direction changes inside the core, and four rows of 0.125×0.500-inch brass tubes allow excellent flow. These two features increase cooling performance dramatically, compared to stock brass and copper radiators and most aluminum radiators.

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These fixtures allow the core to be assembled to various heights, based on the radiator application. Here, Brittany Winningham assembles the core for this C10 radiator. Johnson’s Radiator Works has a fin height of 0.250 inch, allowing for more fins and tubes than a conventional core design.

With direct-fit applications from 1917 through the ’90s, Johnson’s Radiator Works offers a huge selection of radiators with standard hose placement as well as applications for LS engines. We had the opportunity to document a C10 radiator build, which is configured for an LS engine. The manufacturing process is extensive and great care is taken in every step of production. Follow along as Johnson’s Radiator Works starts with flat sheets of copper, brass, and galvanized steel and builds a direct-fit C10 radiator that’s ready for thousands of worry-free miles on the highway.

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Once the core is assembled with its fins and four rows of tubes it gives you an idea of how many tubes are used in a Johnson’s Radiator Works radiator. Extra cooling capacity and additional strength are benefits of this design.
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Special fixtures are used to hold the core before it is capped with the custom header panels, which are stamped in-house. Here, the cores are dipped in a heat-activated flux and lightly dried with an air nozzle.
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Several cores are ready to go into the oven. This melts the solder that is coated on the tubes and creates a strong bond with the fins.
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Brass header panels are stamped with a special die that creates a flange around each tube for additional strength. Glenn Jackson then carefully hammers the header panel into place. When this side is finished, he’ll flip the core over and hammer on the other header.
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The header is held in place with solder. In order to ensure proper adhesion, it is first dipped in flux and then dipped into the solder tank. Jackson measures the depth of the solder to make sure it only coats the header area.
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As soon as the solder coats the header and tubes, Jackson places it in a fixture and uses compressed air to blow the liquid solder out of the tubes before it hardens.
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The core is then rinsed in the wash bay and allowed to dry before moving onto the next step of assembly.
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As the core dries, we can see the strong bond created by the solder. This is part of what makes a brass and copper radiator so durable and reliable.
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Next, you’ll see Winningham and Jackson feeding flat brass stock into the shear. These pieces are measured and cut to length and provide a blank canvas for the one-piece tanks.
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The C10 radiator uses stamped tanks, and this machine makes quick work of it. Dies are changed based on the application of the radiator, but once it’s set up, Jackson can stamp dozens of tanks to have them on the shelf for future builds.
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Johnson’s Radiator Works even stamps out these filler necks in-house. This is a somewhat universal item, so they manufacture these in large quantities to have a steady supply.
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The blank tanks are taken over to the punching station where the holes are punched for the filler neck, hose outlets, and drain petcock. Since this C10 radiator is going in an LS-swapped truck, it will have two hose outlets on the passenger side and a 1/4-inch NPT bung for the steam vent.
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Johnson’s Radiator Works has files of information on each application, telling the workers exactly where to punch the holes. After the holes are punched, the “Johnson’s” logo and a serial number are stamped.
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Hose outlets are brazed onto the tanks for a strong bond. Other items, like the filler neck and bungs, will be soldered into place at the next build station.
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Johnson took great interest in learning the entire process of building a radiator and takes pride in each piece that leaves the facility. Here, Johnson is welding a divider in the tank, a piece that is only used for LS swaps.
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The core is placed in a fixture, which allows it to pivot and move for easy access to all areas. The final steps in the build process are tedious and involves soldering the tanks to the headers.
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Johnson is the first to admit that solder isn’t something that he had a lot of experience with at the hot rod shop. He has become a student of the process and learned how to make it flow and look nice, while also creating a strong bond.
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The bungs for the drain petcock and the steam port are soldered into place.
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Galvanized steel is used to build the brackets for each application. No radiator leaves Johnson’s Radiator Works without complete mounting brackets—so it’s ready to bolt into your vehicle.
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The galvanized steel mounting brackets are clamped into place on the radiator and fine-tuned for precise fitment. The two holes in the bracket ear allow the solder to flow under the bracket and then Johnson flows it around the perimeter for a strong bond.
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As evidenced by his hot rod builds, Johnson is a perfectionist and spends a great deal of time ensuring each radiator looks good and performs as advertised. He has a passion to carry on the Walker Radiator Works legacy.
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Each radiator is pressure tested before it’s painted and boxed up for shipment. It is designed to operate with a 15- to 18-pound radiator cap, so 20-plus pounds of pressure ensures proper sealing.
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The painting station at Johnson’s Radiator Works features custom attachments that allow for full paint coverage. Winningham handles painting duties and final assembly if an A/C condenser is being added.
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The finished product is ready to be boxed up and shipped off to the customer. This C10 radiator will bolt in using original mounts and works perfectly with a modern LS engine to provide worry-free cooling, no matter the conditions.

Johnson’s Radiator Works
(256) 399-9925

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