Bending Steel: Manufacturing Sway Bars and Helper Springs

There is a variation of the Hippocratic oath at work at Hellwig Suspension Products. When its people first look at a vehicle, they evaluate whether they can make it better. Sometimes the answer is no, and they move on to the next idea.

When the answer is yes, it sets in motion a chain of events that sooner or later ends with raw metal being bent into new shapes to help with sway and load control, among other processes, and then being offered for sale on the automotive aftermarket. And it happens over and over again in its Visalia, Calif., headquarters. Hellwig builds suspension bits for anything from a golf cart to modern and vintage muscle cars, light- and heavy-duty trucks to military applications. We wanted to see the process, how they’re built, so we toured the plant.

“That is absolutely our wheelhouse and our hit list that we go after,” said Hellwig CEO Melanie White. “From there, it’s what vehicles can we make improvements on, right? What can we make a better stabilized vehicle by putting our products on?”

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How the company decides which vehicles to build things for can vary. Through the company’s membership in the Specialty Equipment Market Association, Hellwig keeps track of market trends and the product pipeline from OEM’s. In fact, White was just elected as incoming chair to SEMA for 2023 and 2024 and was SEMA’s person of the year in 2018.

SEMA hosts what it calls “measuring sessions” for aftermarket companies in which SEMA will bring in new cars and trucks to the SEMA Garage in Diamond Bar, Calif. Member companies get blocks of time to come in and review new vehicles to see if updates are necessary to their existing product lines and to measure components on a vehicle to facilitate production of new parts.

“We take advantage of SEMA’s measuring sessions, for sure,” White said. “We get to look at the chassis. So, we measure, we see if there’s anything different. A lot of times, manufacturers are changing the outside of the vehicle and they don’t change the chassis, so there’s a lot of times where we can expand our application to cover that. What also happens, though, is sometimes they make a simple change, like run a brake line differently that gets in our way, so we test for everything.”

There is also good old-fashioned networking relationships with local dealers who might have vehicles that SEMA can’t get hold of in a given time frame. That arrangement once led to a dealer asking if they’d leave on the sway bar Hellwig developed for the vehicle because the improved handling would make the truck easier to sell. Hellwig also leaves notes on locals’ cars asking to use it for development of new product. Those relationships take time, but Hellwig has been at it for a while, manufacturing in Visalia for four generations. Hellwig management and employees also allow their own vehicles to be used for product development.

“They are really hard to establish for sure, and luckily we’re also known in the area. So, we have these little fliers that say, ‘Hey, we want to use your vehicle,’ but it has Hellwig branding on it,” White said. “The Tundra was really hard to come by in this area, the new Tundra. We knew for sure we could make some improvements on that one. And so we might have stalked some people.”

Once they determine the vehicles for which to create new products, the start the process in research and development. Hellwig’s Andrew Rivera has been with the company for 25 years. He started as a temporary worker in shipping, then moved to the furnace, then to final inspection, which we’ll talk about more later, to operating the CNC bending machine and then to R&D.

Rivera is self-taught in the use of CAD and CAM. He also takes dimensions using a Faro Arm machine, all of which goes into the data used to create sway bars using the CNC bending machine, one of two ways sway bars are formed at Hellwig.

One way is hot forming, which the raw bar stock is heated to the point that it glows orange. Workers stamp the ends flat and punch the holes then hot-form it to fit the application for which it’s intended.

The other way is using the CNC bender, which can bend a smaller bar and can create sharper bends and multiple radii that hot forming cannot. The CNC bender takes CAD data to make precise bends in the metal, pushes it out further, makes more bends, and so forth. What begins as a straight piece of bar stock is transformed into what will become a sway bar.

“It depends on a lot of different things like where do we have capacity, what application is it going on?” White said. “Some things like a truck sway bar, we like to do heat treated and hot formed, and then car applications are a little bit more flexible because there’s not as much weight to throw around.”

Depending on application and the kind of steel used, some bars are heat-treated after forming. Hot-formed bars go into the oil bath to cool them slowly. After heat treating, they go into the shot peening machine, where they are pummeled with steel shot. Shot-peening is performed to extend a component’s life by inducing a compressive stress layer to increase resistance to fatigue while also helping to resist formation of cracks.

After heat treating, the bars and springs go to final inspection, what Hellwig calls “arcing,” the station where dimensional and finish corrections are made to ensure the finished product matches up with the measurements and the CAD data.

“So maybe it doesn’t lay flat. We arc it back into shape,” White said. “Or if the arms are off at all, they have models that they go to, or they have tech sheets, so they measure all of that to make sure it meets all of our specifications.”

After arcing, they go to powder coating with Hellwig’s signature silver-and-black “hammer tone” finish, which is more than just a brand-specific detail like Eibach’s signature red springs and bars. The dimples in the hammer tone finish help retain the grease that lubricates the bushings.

In addition to building everything but the bushings in house, Hellwig also makes all its own tooling and jigs for the manufacturing processes. That includes products like the sway bars they build for military personnel carriers and Oshkosh airport firetrucks.

“It has three of our sway bars on it. It was really fun for me because I got to see them being installed on them and they don’t have like a huge demand for those vehicles,” White said. “I want to say they manufacture like one a month or something like that. But I just happened to be there at the right time to be able to see that getting installed.”

Of course, applications for light-duty trucks so many NASA members use to tow their racecars to and from the track are far more common. The process repeats itself every model year and as new ideas come to light.

“We have seasoned workers throughout the whole plant,” White said. “It’s important to make sure that we have experience out there on the floor. And we have some people that have worked for my grandfather on the floor, too. They have worked for three generations in our family.”