Why The Feds Are Investigating ‘Excessive Frame Flex’ In A Winnebago Brand’s RVs

An RV is one of the biggest purchases a person can make. Some people spend more on a camper than the value of some homes, and given that kind of cash being thrown around, it’s not unreasonable to expect decent quality. Some owners of Grand Design RVs, a subsidiary of Winnebago Industries, are finding that the quality of their rigs isn’t meeting their expectations. The National Highway Traffic Safety Administration (NHTSA) has received 23 complaints regarding Grand Design Momentum and Solitude fifth-wheel trailers that allegedly exhibited frame flexing conditions that have led to some reportedly dangerous events and at least one injury. Now the government has opened an investigation.

When a typical RV is built, the box containing the living environment is placed on top of a frame. You might think the finished product will be rigid, but there’s more to it. Both the RV’s frame and the living space are designed to flex a little to respond to outside forces such as potholes, speed bumps, unpaved roads, and the changing weather conditions around your RV. This flex — which is normal for body-on-frame vehicles — is considered to be healthy for a camper. The manufacturers believe that if the typical RV were as rigid as say, a Porsche 911, the frames would eventually suffer from metal fatigue and the RV’s walls might even take on irreparable damage. So some flexing is good.

However, the operative term there is “some.” RVs are supposed to be meticulously engineered to allow for just the right amount of flex. What happens if your unit flexes too much? In short, you might experience havoc. You might encounter doors you can’t open, doors that open themselves, seals that break, water leaks, frame damage, wall damage, slides that deploy on their own, and in a potential worst-case scenario, a total frame failure.

The topic of frame flex has been a hot one for the majority of 2024. Just punch in “RV frame flex” into a Google Search and you will fall down a rabbit hole that appears to have no bottom. Everyone from random people on internet forums to influencers on YouTube are talking about it. However, for most of the year, the issue of frame flex has been limited to anecdotes from owners and statements from the manufacturers. Now, as of October 10, NHTSA’s Office Of Defects Investigation is getting involved.

Sort Of A Misnomer

Before I continue, let’s really talk about what the heck people are talking about when they mention “frame flex” because honestly, the term is sort of vague and doesn’t really cover what appears to be happening in some of these cases. It’s also sort of misleading because, as we established earlier, some flex is perfectly normal.

When some consumers talk about frame flex, they’re talking about the structure on the front portion of their trailers, typically fifth wheels. The area of concern tends to be right around where the trailer’s landing gear meets the trailer’s lower frame plus the upper deck, as well as the pin box (the hitch). As I said earlier, the structure of an RV is supposed to be able to flex. However, a failure in the frame, such as metal fatigue or broken welds, can lead too much stress on the rest of the RV superstructure (it’s like a domino effect).

Calling it “frame flex” is also understating in some cases. Some people also call it frame failure. While a perfect term for this might not be out there, the end result is the same. If your RV suffers from this, it’s a big deal that’s expensive to fix and, allegedly  in one case thus far, has led to an injury. So, it’s not something you want to ignore.

For the purposes of this article, we’ll be saying “frame flex” from here on out because that’s now the common term even if it’s technically incorrect. Identifying the signs of frame flex can be difficult if you don’t know what you’re looking for, but Bish’s RV, a dealership with a popular YouTube channel, offers some insight from its experience.

Bish’s RV notes that you can check for the signs of frame flex when you hitch up your fifth wheel. If you’re hitching up or driving down the road and notice that the pin box moves somewhat independently from the rest of the trailer (shown in a gif above), that’s a problem. Remember, the pin box is connected to the trailer’s chassis. A minimal amount of flex from the pin box is expected, often 0.25″ to 0.50″. If it’s flexing more than this, it can be indicative of the signs of the so-called frame flex problem.

However, we are talking about movements in less than an inch here, so this isn’t something you’re going to easily measure with your eyeballs. If you can see that much movement easily with your eyes then you’re likely past looking for signs by that point.

Bish’s RV notes that there are other clear signs of frame flex. You might notice material separation at the riser, the vertical junction between the upper deck and the lower frame. You might also find stress cracks in the fiberglass outer walls of your unit, especially in high-stress areas such as next to a slide or near the pin box. Once your structure problem advances, you’ll likely begin to notice such issues as bowing walls, popped seals, trim falling off, and water leaks. In extreme cases, you might have issues closing or opening doors or experience the un-commanded opening of a slide while going down a highway.

Due to the spike in reporting on this issue this year, some people might believe that “frame flex” is new and impacts only Grand Design models.

A Concern For Years

While the focus of this investigation is on Grand Design and the topic of frame flex exploded in popularity in 2024, it’s actually not anything new. RV owners have been concerned about frame flex for years and across countless brands.

To give you an idea of what I mean, click here to read the tale of the owner of a Heartland Big Country Fifth Wheel owner. This person reported flex so severe that their RV’s walls started displaying two large cracks before the damage propagated into even larger cracks. It got to the point where the poster was worried about driving 2,000 miles home with the flexing fifth-wheel RV in tow. But here’s the twist, this post was all the way back in 2010.

Here’s another instance of alleged frame flex. This one involved a Forest River Wildcat 28RK that was purchased new in 2005 and allegedly suffered from a snapped front frame crossmember by 2011. In 2019, the owner of a Forest River Sabre fifth wheel reported multiple frame cracks and broken frame crossmembers, with users of the forum alleging that these issues were most likely caused by excessive flex.

The internet is littered with all kinds of stories like this, and it doesn’t seem to matter if the parent company of the RV builder is Forest River, Thor Industries, or Winnebago. What you can deduce is that the majority of these issues appear to happen to fifth wheels and as RV Travel reports, sometimes conventional travel trailers.

However, I did notice something that stood out, and it’s that Grand Design RV owners have been talking about frame flex a lot, especially this year when many YouTubers and RV publications have been publishing articles and videos about RV frame failures in general. For example, here’s just one video:

This NHTSA investigation focuses on Grand Design models, so let’s see what’s going on there. In 2021, the owner of a 2014 Grand Design Momentum fifth wheel discovered some pretty severe panel separation following a tire blowout. Later, the owner reported finding a hairline frame crack inside the propane tank’s compartment, which is believed to have caused the panel separation. That user, arhayes of My Grand RV, posted some grim results after than inspection:

Sure enough, the upper deck welds on both sides were broken. Additionally, the welded brackets that attach the curb side wall to the upper deck had some broken welds, though that did not impact this. He also found that the curb side I Beam that the landing gear attaches to has a bend and a broken weld. He measured deflection of the upper deck at 1 1/4″ on one side and 1 1/2″ on the other. Max allowable should be 1/4″. Deflection now is 1/8″.

It’s unfortunately not very hard to find complaints about Grand Design RVs suffering from alleged frame flex. But this leads to the question of what’s going on here and what do the manufacturers say about it?

Lippert Lead Engineer Offers Some Insight

There is a common denominator in most of these issues and it’s that the frames of these large fifth-wheel trailers are made by Lippert. While an RV manufacturer like Grand Design and Forest River may construct the body of your RV and fill it with the goodies you want, these manufacturers rely heavily on suppliers like Lippert. If you own an RV, your tongue jack, frame, and other major components were made by Lippert.

This has added an additional wrinkle in figuring out why the frames of these trailers are suffering from differing levels of failure. It’s not as easy as ringing up Grand Design because while Grand Design did make the specs of the frame, Lippert was the frame’s producer. So now you’re left dealing with multiple parties to deal with when trying to fix your potential problem. In an effort to get to the bottom of this, J.D., an engineer and host of the YouTube channel Big Truck Big RV, got exclusive interviews with Lippert lead engineer and VP of OE Engineering Tim Schultz.

Early in the interviews, Tim tells J.D. that Lippert designs frames in two main ways. In some instances, a manufacturer will demand that Lippert designs a frame to their exact specifications. In some other instances, a manufacturer will hand Lippert a floor plan and have Lippert’s own engineers create a frame for it. To give you an idea of the scale here, Lippert says it makes somewhere around 1,000 frames a day.

Tim explains how the chassis and the body work together. He explains that the RV body’s superstructure is secured to the chassis through lag bolts. Take a look at the example render below:

These are installed at the RV factory after Lippert builds the frame at its own factory. These lag bolts, as well as other bolts, secure the superstructure to the frame, creating one whole structure. Tim stresses that it’s critical that both the superstructure and Lippert’s frame work in unison.

Tim notes that this structure works as one right until a part of the system takes damage. It could be from a bolt loosening, an undetected water leak, or an impact that, to the RV’s owner, might have seemed to be minor. Or, it could even be from user error such as overloading or unapproved aftermarket pin box modifications. Unfortunately, every flex situation is different, so Lippert can’t point to any single cause.

One interesting point that Tim makes is the fact that some RV manufacturers will make some modifications to their RV designs after getting their frames from Lippert, but may not consult Lippert on what those changes might do to the overall structure.

Whatever the reason, once the structure is damaged, Tim notes, the RV wall is no longer supporting the weight it was designed to. As a result, Tim says, the load gets moved to a high-stress area, such as the joint where the upper deck area of the frame connects to the trailer’s lower frame.

In short, when you’re looking at a fifth-wheel camper, you might think that the front structure is just there for the ride because it’s bolted to a frame. However, as Tim says, the walls and the roof of that front structure are bearing a load. Tim says to look at it as the fifth wheel’s body is actually a part of the frame. That’s a great way to visualize this.

Tim also confirms what I mentioned earlier. The pin box is not supposed to move independently of the rest of the trailer. However, once the structure is compromised, a little bit of flex happens. Over time, that little bit of flex amplifies into a lot of flex as the metal fatigues and eventually fails, resulting in the signs reported by Bish’s RV.

Later in the video, J.D. asks Tim why doesn’t Lippert just make an overbuilt frame as you’d see on a gooseneck trailer. If the frame is spectacularly beefy, then it wouldn’t matter what’s going on with the RV’s superstructure. Attached below is a photo of a Big Tex gooseneck trailer, a heavy-duty trailer built for carrying large equipment:

Tim boils his answer down to weight. Sure, Lippert could make these frames absolute tanks, but now the hitch weight will rocket up to a level that might make the trailer too heavy for a consumer-level pickup truck to handle. Tim notes that sure, he could compensate for this by moving the axles, but now the rear overhang of the trailer is going to have a ton of weight, which also isn’t good. Tim also says the massive structure of gooseneck trailers will majorly cut into the living space, which buyers aren’t going to find attractive.

In short, Lippert makes fifth-wheel frames this way to maximize space, minimize weight, and still offer some strength. However, the frame needs the RV superstructure to be in good shape for the integration to work correctly.

As a final note for J.D.’s video, Lippert believes the frame flex issue is occurring largely in fifth wheels that weigh 17,000 pounds or more. Further, Lippert believes that these reported frame flex problems, while real, actually impact less than 1% of these 17,000-pound-plus fifth wheels. Since heavy fifth wheels are only a fraction of the RV market, Lippert believes we’re looking at a fraction of a fraction of the RV market. However, people can’t stop talking about this so it seems like a huge deal.

Unfortunately, there are no real hard numbers to say one way or the other. Some dealerships like Bish’s RV believe the issue is worse than you would expect it to be. At the very least, it’s comforting that Lippert is at least recognizing that some trailers are suffering from real problems.

The Investigation

The question you probably have from here is why? Why is this happening? How does your RV get to the point where its walls are separating from those lag bolts? How does your RV end up putting too much weight on an area of the frame that isn’t designed to support it?

A number of developments have occurred since the Internet lit up about this frame flex thing. First, we have the official response from Grand Design Recreational Vehicles:

Since our beginning in 2012, we have had the mission to build a better RV and a better RV company. Everything we do and every product we build revolves around our customers with the goal to create a superior RV experience. We back up this commitment to quality with first-class service and the industry’s most comprehensive and trusted warranties.

Simply put, we stand behind every RV we make.

In the spirit of our commitment to our customers, we would like to provide information around frame flex. Frame flex is a normal movement of the chassis in specific areas to absorb shock and stress. Our data indicates that a small number of larger Solitude and Momentum fifth wheels may have experienced excessive frame flex. If you think you are experiencing something irregular with your frame, please see the FAQ below, and reach out to our customer service department at customerservice@granddesignrv.com or (574) 825-9679.

Grand Design then provides some information to those concerned about frame flex:

What is frame flex and why does it occur?

As noted above, frame flex is a normal movement of the chassis in specific areas to absorb shock and stress. All steel frames have this flex. Similar to bridges, which are engineered to flex and bend to absorb the weight of vehicles and changing weather conditions, your RV chassis is engineered with the ability to flex as it is driven down the road. Without this flex, undue stress on the frame could damage the chassis or wall structures.

What causes excessive frame flex?

Numerous factors may contribute to excessive frame flex, including:

– Road Impacts
– Collisions
– Loading and weight distribution
– Use of unapproved hitches or pin boxes
– Competing suspension (chucking) between the tow vehicle and the fifth wheel
– Using a non-traditional tow vehicle
– Manufacturing variations
Please check your owner’s manual for weight limits and approved hitches and pin boxes for your unit.

What Grand Design didn’t say in its response was that in March 2024, it launched Technical Service Bulletin 24-001 for Momentum and Solitude fifth wheels. Technicians are to check for the signs of frame flex, including taking measurements of the deflection of the pin box. If the signs of flex are present, technicians are to install replacement lag bolts, which are larger and more numerous than originally installed. It’s noted that this TSB doesn’t appear to be public.

However, it seems like we’re finally going to get some hard answers here and it’s thanks to people who complained about their RV frame flex issues to NHTSA. According to NHTSA Action Number PE24029, the organization is now investigating these frame flex issues. As of publishing, the regulator has specifically targeted 2017 through 2023 Grand Design Momentum and Grand Design Solitude models. NHTSA believes the population of these RVs includes 55,887 units.

This investigation comes after 23 reports to NHTSA about frame flex issues, one of which led to an injury. I’ll note a couple of them here.

NHTSA ID Number: 11476895
Incident Date: 2022-08-01
Manufacturer’s Name: Grand Design RV
Vehicle/Equipment Make: GRAND DESIGN
Vehicle/Equipment Model: SOLITUDE
Model Year: 2020
Vehicle Mileage At Failure:
Vehicle Speed: 65
Number Of Occurrences:
Was Vehicle Towed: N
Consumer Location: Livingston, TX

The contact owns a 2020 Grand Design Solitude RV. The contact stated while driving 65 MPH, both the rear and the front entry doors of the trailer would unlatch. The contact also stated that the failure occurred while driving at lower speeds on bumpy road surfaces. The contact stated that the front entry door would unlatch but would not open all the way due to a safety bar that was designed to keep the door closed. However, the rear entry door would open gradually while driving. The contact stated that upon veering to the side of the road to manually close the rear door; while the contact was driving at a slower speed, the rear door flew open and struck the road sign on two different occasions causing damages the door. The contact purchased an RV handrail designed to close over the ends where the door would open. The contact installed the part herself. The contact stated that the rear door still unlatched but no longer flew open while driving. The dealer and the manufacturer were not notified of the failure. The RV was not diagnosed or repaired. The failure mileage was unknown.

Here’s another:

NHTSA ID Number: 11595267
Incident Date: 2024-06-19
Manufacturer’s Name: Grand Design RV
Vehicle/Equipment Make: GRAND DESIGN
Vehicle/Equipment Model: REFLECTION
Model Year: 2022
Vehicle Mileage At Failure:
Vehicle Speed: 70
Number Of Occurrences:
Was Vehicle Towed: N
Consumer Location: Longmont, CO

-Entry door of travel trailer opens during travel even with both deadbolt & handle locks in locked positions. -This could allow items inside travel trailer to be sucked out onto roadway. That could lead to property damage, injuries, & even death to myself, my passengers, & any other vehicle on the same roadway as me. Potentially making impact with road signs, other vehicles, bicyclists, or even pedestrians on side of roadway. This has also allowed diesel exhaust soot to be sucked inside the travel trailer, coating the ENTIRE interior. Created slip/fall hazard (I nearly fell) as it made the vinyl flooring incredibly slick. Harmful to health (covered the toilet seats, furniture, cookware, etc. I had to clean EVERY surface of the trailer interior to prevent harm to myself & my labradoodle (began to lick himself to remove soot picked up from interior surfaces). Multiple albuterol inhalations required during cleanup due to my asthma. -Multiple occurrences even after multiple dealership service visits. Issue first appeared within 100mi. of purchasing travel trailer brand new. -Adventure RV Cheyenne, WY (Blue Compass) verified issue & replaced under warranty entire entry door. -I contacted Grand Design to open a complaint ticket. I requested permission to have trailer inspected and issue resolved at Windish RV in Longmont, CO as the Cheyenne dealership was incompetent, dishonest, & failed to fix this. Windish RV was fantastic, but Grand Design refused to authorize further action for the issue. Windish RV suggested I should upgrade the door handle to a high quality replacement, as the factory handles are mostly plastic junk & same keys as every other trailer (not very secure). On my own dime I replaced the handle for $300+ labor with USA made RV Lock V4. -Appears door frame is separating from trailer wall, trailer currently at Windish RV for another repair attempt.

Those are just two of the complaints. It should also be noted that while NHTSA is looking at just Momentum and Solitude models, it also includes complaints of other Grand Design models that complain about frame flex. The one directly above was for the Reflection, another popular Grand Design model.

NHTSA also has an early summary:

The Office of Defects Investigation (ODI) has received twenty-three complaints alleging excessive frame flex on model year 2017-2023 Grand Design fifth wheel recreational trailers, models Momentum and Solitude. Twenty-two of the complaints allege that excessive frame flex resulted in a cargo or entry door opening while in transit, some with objects lost on roadways, while six complaints also state that slideouts extended out partially.

ODI has been in contact with both Grand Design and Lippert, the frame manufacturer. Grand Design believes that some frame flex, generally considered to be vertical movement in the upper deck area of the fifth wheel, is normal. However, Grand Design has developed a technical service bulletin (TSB), to evaluate concerns of excessive frame flex, defined as vertical movement greater than 3/8 inch. Per Grand Design, the frame ex is only occurring in the upper deck area of the fifth wheel and is resulting in cosmetic defects such as moving sidewalls, damage to cabinets, binding doors, etc.

However, Lippert believes that the effects of frame flex may also extend back to the front axle of the trailer. While Lippert provides frames for multiple trailer manufacturers, the majority of complaints are for these Grand Design products.

Cargo and entry doors that open and slideouts that extend while in transit increase the risk of injury or a crash. ODI is opening this Preliminary Evaluation (PE) to evaluate the severity of the potential problem and to determine whether an unreasonable risk to motor vehicle safety exists. To review the ODI reports cited in the Opening Resume ODI Report Identification Number document, go to NHTSA.gov.

What’s interesting here is that while Grand Design thinks frame flex is limited to just the front upper deck area, Lippert, in talking with NHTSA, thinks the issue could be substantially worse.

Unfortunately, this means we really don’t have a straight answer right now as to exactly why this is happening. Thankfully, concerned owners and prospective buyers can breathe a little easier now that NHTSA is investigating.

What You Can Do In The Meantime

Of course, that doesn’t help you right now. While we don’t exactly know the cause of frame flex just yet, there are some things you can do to protect yourself. For starters, if you’re concerned about frame flex, click here to get Lippert’s Upper Deck Measurement guide.

How this guide works is pretty easy. You take measurements with the trailer sitting by itself on the ground and then with it hitched up to your truck. If the difference between the measurements is greater than your unit’s spec, you might be suffering from structural damage. However, Grand Design’s TSB allegedly acknowledges that an RV can pass this test and still suffer from frame flex problems.

Dealers and manufacturers recommend refraining from changing to an aftermarket pin box that isn’t approved by the RV manufacturer. It’s also beneficial to have your rig weighed so you know exactly how much weight there is and where it is. Use this information to help you load your trailer properly and ensure it isn’t overloaded, which an RV specialist quoted by RV Travel says can also cause frame flex damage. If you’re handy, you might be able to remove the primary bedroom’s furniture or the fiberglass panel above the hitch to see if you’re missing lag bolts, such as this example Grand Design RV that was featured on Liz Amazing:

Bish’s also recommends getting the right tow vehicle for your fifth wheel. Of course, you don’t want to pair a half-ton truck with a massive fifth wheel, but the dealership and Grand Design both say that you might also want to refrain from buying that sweet semi-truck as a tow vehicle, too. Why? The explanation given is that fifth-wheel campers are designed to work with the suspension of a heavy-duty pickup truck, not with the harsher and rougher suspension of a semi-tractor.

Finally, the dealership warns that your fifth wheel is almost certainly not designed to live up to the marketing hype. It’s the dealership’s belief that fifth wheels are not meant to be lived in full-time, even though manufacturers do market them to full-timers.

This whole issue is incredibly messy and there are so many different things at work here. However, what is clear is that there is enough going on that it has warranted a NHTSA investigation. I have reached out to Lippert, Grand Design, and Winnebago. Winnebago was the first to respond to my questions with this statement:

Regarding your question on the pending NHTSA investigation, I can share that at Winnebago Industries, our commitment to our customers and safety is absolute. Recently, the National Highway Traffic Safety Administration (NHTSA) opened an inquiry with our Grand Design brand regarding excessive frame flex and its potential impact on large fifth wheel products. Inquiries such as this are normal work process for the NHTSA and do not indicate a decision related to the quality or safety of any of Grand Design’s products.  We have a strong history of collaboration and transparency with NHTSA and look forward to engaging with them on this inquiry.

Here’s where I turn things to you. If you’re an RV engineer or RV technician and you’re familiar with this frame flex issue, I want to talk. Message me at mercedes@theautopian.com.

Hat tip to reader BuiltWeak!