Complaints of trailer frame failures have been circulating online recently, and I wanted to take a moment to address frame failures and what you can do to minimize damage. I want to allay your fears; most frame failures are not the end of the world or your RV’s life, but they certainly can bring your travels to a halt.
Unfortunately, structural damage to the body can result from a frame failure, complicating the repair. Seldom does an RV completely break apart or disintegrate from a frame failure; signs of damage begin to show themselves over time before that happens.
In 2015, the dealership where I was the service manager received a travel trailer from Ohio off the Massachusetts Turnpike. One of the tires blew apart, wrapped around the rear door-side spring hangar, and ripped it and a chunk of the frame section off. The customer returned to Ohio, leaving the trailer in the care of the insurance company and us. In this case, we were able to source a new chassis from Indiana and we re-chassied the trailer. We also had a fifth wheel with frame flex issues that was replaced for the customer.
The RV PHD Newsletter is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.
Sadly, frame failures are nothing new. I experienced a saddle frame failure on a new Class A gas motorhome in 2001, which effectively destroyed the unit. The first signs of failure were generator fuel and hydraulic line damage. The cabinets started falling off the walls, and the basement compartments twisted. Upon closer examination, it was found that the saddle frame had not been welded or designed correctly and was missing structural members.
Frame issues on specialty vehicles are nothing new.
Fast-forward to 2023, and folks are experiencing cracks on travel trailers and fifth-wheel underpinnings. Why? Let’s look at some possible causes and solutions and what you should do if you have one.
Frame Failure Causes
First, almost all current model-year RV trailer frames are manufactured by Lippert and BAL, whereas motorhome subframes are built by motorhome manufacturers or companies like MorRyde. RV trailer frames are made to specification under contract. When an RV company designs an RV, they also design the frame and send the specs to the chassis manufacturer who builds it. Note that the frame manufacturer sources the steel and builds the product as stated in the contract, and often, the frame is laid out for a specific floor plan. These frame manufacturers deliver what is ordered and have no control over what happens to the frame or how the RV company uses it.
Further, a subassembly manufacturer or assembler always hopes the material they buy is of expected quality. Without getting into the engineering weeds (sorry, metallurgists), they order steel of sufficient strength to perform what they are building. In most cases, engineering calculations should provide some buffer for momentary external stresses.
So, we have at least two possible opportunities for errors. First, the RV manufacturer under-specs the frame (the lighter, the better), and the steel has issues from the steel supplier. It could be argued that under-designing the frame is just about money savings. While that may be a part of the overall equation, as I have said before, an RV is a system. RVers like more space and amenities, and the RVs must stay within certain weight limits for legal and safe towing. So, the more places that weight (mass) can be saved, the bigger RV they can build and have more stuff in it.
Second, steel is imperfect. The cheaper the steel, the higher the possibility of occlusions that cause failure.
I spoke to RV owner and former metallurgical engineer Tom Dougherty about his thoughts on these issues. Tom follows several RV-related blogs and has also seen posts and comments regarding various frame failures. I shared some images with him for discussion, and the cracked frame from the Nomad RV Detailer (above) generated some interesting conversation. He noted that, although this did not appear to be a weld fracture, “the nature of the welding process can sometimes change the physical properties of the metal adjacent to the weld. Depending on the conditions and type of material being welded, this could conceivably soften the metal and locally reduce its strength. It could also potentially embrittle the metal which could also adversely affect the performance of the joint. To determine if either was a factor would require micrographic analysis. But, just from a visual perspective, you’ve got two structural members coming together in an area where there will be a stress concentration from the weight moments it is subjected to. If that repeated loading/unloading cycle is sufficient to instigate a crack, that crack is likely to spread.”
Dougherty noted in passing that many automotive industry manufacturers use high-strength, low-alloy (HSLA) steels in structural applications. These steels allow light-weighting of components while still maintaining strength requirements. HSLA steels also have corrosion resistance advantages, he says.
Of course, there are quality issues. Mistakes happen, and that is unavoidable. Quality control is about inspecting products at each stage of the manufacturing process. I know that the RV manufacturers are working on improving that as they can, but there are holes in that, too, with workforce issues that every industry has to deal with. The frames, however, are naked when they leave their respective plant, so there should be no issues with welds, etc. when they ship. That’s easy to inspect.
Another cause, to be fair, is that RVers overload their RVs. It is a known fact, and the RV Safety and Education Foundation has studied this for years. They have weighed thousands of units and found all kinds of issues. While weight and balance in an RV may not be as critical as with a Boeing 737, I still think RVers, like commercial drivers, need to account for weight and balance. While this can be the subject of an entire book, RVers should at least weigh the RV and tow vehicle (or towed vehicle) when loaded at a three-platform scale (CAT Scale or similar) to get an idea of where they are. It is better to weigh by wheel position, but not every RVer can do that. It is better to have some data than no data. Much of what RVSEF saw on their data was that RVs might not have been entirely overloaded but were overloaded on one side or even one wheel position. A catastrophic RV wreck on I-81 in Pennsylvania in 2023 was caused by a blown front driver’s side tire. While many things can cause tire failures, overloading and underinflation are ones that we can control.
Whatever the causal human factor, other factors certainly play a part. Most notable are road conditions. The conditions on some interstate highways shake any vehicle to death, especially RVs. Potholes and other undulations can create tremendous stress on structural members. These bending moments can lead to fatigue, stress cracks, and tears over time. There doesn’t need to be a manufacturing defect for this to happen, but failures are more understandable when some or all of the above factors are combined.
Signs and Symptoms
Trailer frame failures can manifest themselves in many ways, some subtle, some not. Many frame failures are discovered while techs maintain suspension and brakes/bearings. An annual inspection of the running gear is an RVers right of passage and essential given the failures we’re seeing. But there are some things you can be looking for as you do your RV walk-around inspections.
- Tire wear- Tires wearing very unevenly may be an alignment, balance, or inflation issue, but a frame issue can also cause it. Checking the spring hangars, frame webbing, and tire spacing can lead to a diagnosis.
- Tire spacing between tandem axles is uneven.
- The trailer or motorhome tracks crookedly down the road
- Filon (fiberglass) cracks in the sidewalls. Sometimes, it is because of a weakness in the wall structure, especially around slide-out rooms. It can also be because of frame flex.
- Shifted basement compartment doors on motorhomes. Similarly, the interior linings of basement compartments buckle and fail.
- Loud creaks or bangs from the frame when walking in the unit or extending or retracting slide rooms. This is common with a separation of the trusses from the I beams or the welds for a through-frame slide mechanism.
- Visibly bent or cracked steel structure. Some cracks are more evident than others, like horizontal cracks in frame webbing, etc.
- 5th wheel pin movement. Often, this also results in the movement of body side moldings, broken interior cabinets, wall/floor separation, etc.
What to do?
If you suspect a frame issue, do not drive the RV if possible. Common sense plays into this, but if you have any questions about the drivability of the unit, contact a professional for guidance. The manufacturer is often the best point of contact. A certified RV technician is also a good option. You need to have you and the RV in a safe place.
Frame flex and broken or cracked frames are two different things. Flex may indicate a broken frame, but it can also be from overloading or weakness that could lead to fracture. A broken frame is, as it sounds, where a crack or other fracture is confirmed.
If frame flex is a concern, stress measurements are taken to determine whether the flex is beyond spec or not. Remember that every structure, including RVs, needs to have *some* flex. Ever stand on a bridge with traffic going by or on the upper deck of a shopping mall when it’s busy? There’s movement. RVs will move and flex to a point. The key is that they don’t flex so much that the system begins to destroy itself.
Lippert’s guide for measuring frame flex on fifth wheels can be found on Redwood Owner’s site HERE. Note that this may be an old form, but it does provide at least a guide on measuring frame flex. If you think you have an issue, please contact your RV and/or frame manufacturer.
Mobile welders nationwide can do heavy structural welding and at least get the RV safe to transport for more permanent repairs. Often, it is best to disassemble the unit on-site to do the proper repair and get it on the road again.
A broken frame is not necessarily a death sentence for the RV. Much of it depends on how much structural damage is done because of the flex. The steel of the trailer frame can be repaired and strengthened in most cases.
The difference with motorhomes
Class A motorhomes are a bit more complicated. The heavy truck chassis underneath the coach is seldom, if ever, a problem. Ford, Freightliner, and Spartan Motors do a standup job with their chassis rails. The issues I have seen are more tied to the saddle frame.
A motorhome manufacturer welds together a floor frame structure that sits over the chassis rails like a saddle. On many basement units, these frames hold the holding tanks, wiring, ducts, and basement compartments, among other components.
If the coach gets into a wreck, the saddle frame has to be scrutinized and, if shifted, may lead to the coach being totaled. It is lighter gauge steel welded together to form the structure, so some spots are weaker than others.
Signs of damage to this frame are similar to the trailer but seldom related to chassis frame issues. Instead, if the saddle starts to come apart, the body and floor will begin to show collapse and shifting damage. Doors may jam, cabinetry may fail, and floors may buckle.
Prevention
The key to a good outcome is prevention. If there is a hidden flaw, there is nothing anyone can do until it surfaces. But maintenance and watching your weight and balance are huge in preventing a frame problem.
- Weigh your RV when loaded for a trip, and reweigh when the loads have changed.
- Do not exceed any of the weight and towing ratings of your vehicles.
- Maintain your tires, wheels, brakes, and suspension. Tire inflation is vital for safety. Remember, a blown tire is capable of causing severe frame damage. Have the chassis professionally inspected and serviced at least annually or as the manufacturer prescribes.
- Keep the frame clean and painted. Severe rust weakens the frame. Also, cleaning and touching up the paint on the frame will reveal small cracks or issues before they become major. Consider grinding or sandblasting a badly rusted frame and then treating and painting with a product line like POR-15.
- Be alert. Look at your vehicle before every trip during a walk around. Do it at truck stops or rest stops, too. Just quick ones, but look for things that may have changed.
Unfortunately, as Tom Dougherty points out, there’s not much an RV owner can do to prevent the hidden failures. “I never really looked at my 5th wheel’s leaf springs, and it wasn’t until the broken leaf springs were pointed out to me during a brake and suspension service that I even said, oh, yeah, I can see that. So I think the consumer is sort of a victim in all of this unless you’ve got a good inspection process where you take it in periodically and have somebody go over it and see if anything is starting to happen.”
The RV PHD Newsletter is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.
