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Open-C Versus Boxed

Open-C Versus Boxed

When you purchased Japanese trucks in the 1980s, one of the most significant selling points you could find was the difference in their boxed frame compared to the American Open-C concept.

The idea was straightforward. Although a boxed frame offered less stability with ongoing movement and road energy, the Open-C concept would eventually offset the bed line by an inch or more over the vehicle’s lifetime.

That flexibility would become a permanent change to the vehicle because of the frame flex. With the boxed concept, you could put the truck on a curb, have it stay in line with the cab and bed, and reduce the risk of broken mounts and cracked frames.

Today’s American trucks are now using a fully boxed frame because it is more rigid and has more torque capacity.

Open-C Versus Boxed

When shopping for trucks, you can find two primary frame options available. The Open-C style comes from American manufacturers, delivering more flex to the design. Japanese manufacturers use a boxed frame instead, providing more strength and durability to the driving experience.

Ford is the undisputed champion in the American market for building pickup trucks. Their F-150 has been the best-selling pickup for about four decades, and it’s even the top vehicle of all makes and models.

It took Ford until 2017 to relent with its hydro-formed box steel frame. Even then, the reason why this conversion happened was because of the flex levels it provides.

The modern boxed frame uses a steel sheet that gets placed on a one-sided die. It is then sealed before hydraulic fluid gets pumped into the die at high pressures. This action forces the metal to form into complex shapes.

That shaping work isn’t possible when using more traditional processes, such as die stamping or tooling.

Ford (and other automakers) can use these complex structures to produce high-pressure steel. The walls are thinner than ever, reducing the truck’s weight while adding rigidity to the frame. There’s enough flex to allow some of the road energy to get absorbed while keeping the overall ride comfortable and manageable.

With extreme rigidity comes lower spring tolerances to the frame, ultimately pushing the design past its limits to create cracking when it goes beyond the design limitations. That’s why Ford uses an Open-C channel with thicker, lower pressure steel that uses a soft harness temper.

The Open-C can flex millions of times without ever developing a stress fracture. Although that benefit is notable, it doesn’t change the offset problems that develop over the years when there’s extra flex within the frame.

That’s why the boxed frame is considered the industry standard today, even if American manufacturers had to come kicking and screaming to this design that Japanese automakers have used for decades.

Why Is Everyone Embracing the Boxed Truck Frame Today?

When you look at the advertising for the new F-150 frame that Ford uses for its best-selling truck, it delivers six key points as to why the fully boxed frame is better than the Open-C concept.

  • It delivers up to 60 pounds less weight to offer improved capabilities while on the road with the new formation techniques.
  • Ford uses staggered outboard rear shocks to improve the ride and overall handling of the vehicle.
  • The box-style cross-section rails increase torsional rigidity to ensure the problems with cabin flex don’t continue.
  • Higher stiffness levels are available because of eight through-welded cross members that are part of the overall frame.
  • It uses 12-corner crush boxes for improved impact protection at the front of the truck.
  • The automaker now uses 70,000-PSI high-strength steel for the boxed frame, improving the payload and towing ratings.

The result is an industry-first for pickups with the improved front impact protection. That doesn’t mean Ford is using new technology to design these pickups. Some of the items have been in passenger cars for years, while Japanese automakers have incorporated many of these design techniques since the 1980s.

You can go back to 2015 to compare how Chevy was showing how strong the fully boxed frame was compared to Ford’s Open-C concept at the time.

The Chevy Silverado only had a 0.26-inch displacement when placed on uneven ramps, while the F-250 Super Duty had a 0.94-inch measurement with the frame twist.

This conversion is unique because the Japanese automakers are making a similar transition to the Open-C design. With the 2016 Toyota Tacoma, the brand says that the second-generation vehicles no longer use a fully boxed layout.

Toyota trucks now use a boxed frame under the engine while maintaining an open C-channel to finalize the transition. They’re even using the same comparison points that Ford did when their roles were reversed.

With an Open-C frame, it is much easier to keep the wheels in contact with the ground while offering assistance with larger payloads.

◼️ Why Did American and Japanese Truck Producers Switch Manufacturing Spots?

Although Ford has never relinquished its role as a top-selling truck manufacturer in North America, they saw the writing on the wall with their Open-C concept. American drivers wanted more towing capacity, better payload support, and less frame flexibility, leading to potential damage issues with over-torquing.

That preference shift happened at the same time Toyota started struggling with its fully boxed frame. The first-generation trucks sold under the Tundra and Tacoma brands developed significant rust issues with the structure. It got so bad for some of those trucks that the Japanese automaker had to pay a considerable expense to replace them

Thousands of trucks had to have their frames repaired or replaced because of this problem. Although Toyota said the issue was due to sub-standard steel getting delivered to them from a vendor, the water levels that got trapped inside the frame rails would contribute to the problem.

It made sense to switch to an open-channel frame since it was cheaper. They could call it something fancy (TripleTech™), promote its benefits, and reduce the future risk of corrosion problems.

We also know that boxed frames are superior to open-channel ones in almost every way. It’s the same reason why tubes are used to build racing cars and trucks instead of Open-C choices. That’s because the suspension is the best place to create compliance with road energy issues, not the frame itself.

That’s why the Jeep Wrangler, Land Rover Defender, G-Wagen from Mercedes-Benz, and even the Chevy Colorado all use this design option.

Does an Open-Channel Frame Offer any Benefits?

When Ford used an Open-C frame in the 1980s and later, their marketing approach was to tell customers that a blend of rigidity and flexibility helped to support payloads and keep the truck on the road. It’s the same line that Toyota uses today.

The open-channel approach won’t sacrifice durability because it uses thicker steel in the frame’s construction. That means you have more weight to manage, although that design does support some payload benefits when the supports are in the right spot.

That means the only primary benefit to consider with an open-channel frame beyond the lower cost is that it is easier to bolt components to it. If you have a boxed design, there are two steel thicknesses to drill through to create attachments, which means you’ll need to use larger bolts for a successful experience.

The Open-C concept only uses a single sheet. Although hydraulic pressing can make it incredibly strong, the results for torsional rigidity are not quite the same.

That’s why it is often better to think outside of the box instead of sticking to your comfort zone.

What Are the Best Truck Accessories to Buy Today?

Whether you prefer a fully boxed frame or an open-channel design, it helps to have some truck accessories to maximize your investment. Since these vehicles are meant for hauling and towing, those items tend to be the first ones those new owners invest in so that they can take advantage of that versatility.

Here are the best accessories to consider purchasing today for your truck.

1. Husky Liners Floor Mats

If you own a Ford F-150, you have one of the most popular vehicles ever created. You’ll be getting in and out of the truck in different environments, which means it is relatively easy to track in unwanted debris. That’s why investing in some Husky Liners floor mats makes a lot of sense.

Husky Liners uses a FormFit design process to have their floor mats perfectly fit the contours of your truck. Cleats help the product to stay in place, while the material is simple and easy to clean. You’ll protect the carpet and upholstery and reduce the risk of having the mess start spreading.

Since these floor mats use laser-based measurements to create the perfect fitment, you’ll need to purchase the item or package designed for your truck’s make and model.

2. Tyger Auto T3 Soft Tri-fold Cover

When you don’t want moisture to get into your exposed truck bed, you could invest in a topper that attaches and seals to your sidewalls. If you don’t want to make a permanent change, another choice is to have a high-quality weather cover installed.

If you choose the Tyger Auto T3 Soft Tri-fold Cover for your F-150, you’ll be getting a product made from heavy-duty 24-ounce marine-grade vinyl.

It combines with aircraft-quality aluminum framing and stainless steel clamps for an easy installation process. Although small holes need to be cut in the liner if an over-the-bedrail option is equipped, you have no drilling to do.

3. Hunter Premium Truck Accessories Grille Guard

When you want to protect your truck bed, you might install a liner to create a safer surface to use. If you need more support in the cabin, you’ll look at floor mats and liners. What can you do when the issue involves offering more front-end collision support for your F-150?

If you find yourself in that circumstance, the Hunter Premium Truck Accessories Grille Guard is a suitable solution. It uses 304 stainless for the tubing and uprights to ensure you have a strong front end. Removable headlight guards give you some customization options, while trimming the air dam might be necessary if your truck doesn’t have tow hooks.

The installation kit is included. It requires zero drilling to finish the work, which means you can improve your truck in less than a couple of hours.

A Final Thought on Open-C vs. Boxed Frames

The open-channel frame might keep the wheels on the road better, but that benefit comes at the expense of frame torsion that could result in displacement with long-term exposure. A fully boxed frame is stiffer, but it delivers a stronger result for most truck-based applications.

I’ve enjoyed driving F-150s for several years. When I got my first job, it was helping out at a farm where the family had three of those trucks. The Open-C frame always felt uncomfortable driving through the fields because you could get a hefty twist in ruts, channels, and uneven ground.

That’s why I eventually bought a Tacoma when I was younger. Although the frame required more than one coat of sealant to prevent corrosion, it always made me feel secure.

With the automaker shift that happened, now I’ve got an F-150 in my driveway. We use it for hauling supplies, running errands, and the occasional road trip. When it is time to go camping, we can pack a lot in the back!

Our latest purchase has a 10,000-pound towing capacity, which means we’re thinking about a fifth wheel in the next year or two to have even more fun.

A truck is a personal purchase. It should make you feel safe and comfortable. That’s why there isn’t a “right” or “wrong” answer with the Open-C vs. Boxed frames debate. When you find the vehicle that meets your needs, it’s much easier to embrace life’s adventures.


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