The Backbone Of Your RV - know it before you buy it

Frame/Chassis Flex - A DOUBLE DEEP DIVE (Read or Listen)

The Analytical Traveler

Jun 19, 2025

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The above is the typical steel chassis. The supports are not very beefy.

The above is an all aluminum frame. The last photo is a riverstone legacy 5th wheel chassis upper deck. Note how much larger the beams and supports are that the box will sit on.

The last photo is a riverstone legacy 5th wheel chassis upper deck. Note how much larger the beams and supports are that the box will sit on.YOU SHOULD KNOW THAT THERE IS NO REGULATION IN THE RV INDUSTRY FOR THE CHASSIS. IT ISN’T LOGICAL BUT THERE IT IS.

Semi-trailer chassis are subject to regulations, particularly under the purview of the Federal Motor Carrier Safety Administration (FMCSA) and the Department of Transportation (DOT). These regulations cover aspects like structural integrity, weight limits, coupling mechanisms, and overall safety standards.

This should give you pause with regard to simply arriving at a dealer and trusting that things are already taken care of , SAFE, and looked after for you, while giving you more reason to research, research and research before handing over your hard earned $$$ for something you will depend on - AWAY FROM HOME, or as a home away from home.

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Be aware I use the term chassis flex rather than frame flex to discuss the part that your RV box sits on. Many call it a frame. The framework is the walls, flooring and roof of your RV. This is like your car that also has a chassis that the rest of the car is built on and around. The chassis is what your axles are mounted on and a part of.
Call me a stickler for details but…..that is a benefit for you so you can trust my content.

I am also addressing NEW 5th wheels specifically. If you are going to buy used, please please please, hire a Certified MASTER NRVIA (National Recreational Vehicle Inspectors Association) Inspector near you: click here to find one NRVIA LOCATOR

There is A LOT of chatter in RV Land. Everyone wants to share, and that’s great.
The problem is - often you get a limited view and that can create issues no one thinks about in ways, no one thinks about.
I often bring to light things left out of other publications, blogs, videos, and posts because I ask the right questions (often what others fail to ask) , read between the lines, and do my homework. The finished product is an all IN ONE PLACE detailed publication on one topic. You can see the time saving benefit not to mention the saved $$$ and frustration if it helps you avoid challenges you don’t need so you can enjoy your journey.

I am a fan of being level headed and keeping my personal opinion and biases and filters out of the picture to serve up a well rounded report, leaving you to decide for yourself. Though I will include my own views at times where needed.

I am a member of a ton of groups, forums, blogs. I see that most individuals are not stating their make and model and year RV, nor are they admitting when it could be a user error or the result of newbie ignorance which all of us are when we first begin., No shame in that. What I will say is that when information is vague and assumptions are made - a lot of folks get caught in that crossfire.
No matter what the issue or challenges or build errors RV’s may have, it’s important to be clear on all the details before jumping to a conclusion as to the actual cause of or reason for anything that goes wrong. Chassis failures are not always the RV Manufacturers error, nor is it always the consumers ignorance or misuse, the kind of roads they drive on and so forth.

Keep in mind, no matter how well engineered or beefy a chassis is - not finding out the weight distribution specs can still lead to issues. I recommend asking the builder for a weight distribution spec sheet. The engineers had to figure weight distribution when calculating the full weight after loading.

Sometimes THE FAULT DEFINITELY IS AN ENGINEERING & BUILD ISSUE due to a manufacturer design change in relation to a new floor plan. ANY change in an RV Engineering aspect of design will take TIME to determine its success or where it fails and how often it fails and the reason it failed. This is why the year of a certain model and floorpan are both important when looking at failures.

The video on “Enjoythejourney.Life You Tube Channel , is telling of just how dangerous a chassis failure can be even when not on the road. This mans wife was inside the RV when this happened.

I am aware that Grand Designs, manufactured by WINNABAGO ,for specifically their Momentum and Solitude larger 5th wheels had and can still have extremely poor chassis from 2014 and even up to 2024, so much so that they extended their chassis warranty to 5 years and even made it transferable to new owners. Apparently Insurance companies have ruled officially that the frame defects are a result of manufacturing and that the defective chassis are a major safety issue.
There was quite a bit of talk of Grand Design making deals with buyers and having them sign a Non-Disclosure Statement in return effectively muting any public disclosure of their experiences due to the chassis failures.
Here is another link if you want to read it or save later Titled:GRAND DECEPTION” — WINNEBAGO MUZZLES OUTCRY OVER MAJOR PROBLEM THAT OWNERS SAY MAKES RVS DANGEROUS, UNTOWABLE, WORTHLESS
LINK HERE
Here is an awesome YouTuber Video from “Enjoythejourney.Life” regarding Grand Design and their own confessions. He will go into the behind the scenes part of the story here its about 16 min long but may be worth your while.

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I want to add here just for your information that in January 2025, My Fiancee”, Jamie, and I were perusing RV shows here in Sacramento California. We were not looking for Grand Design 5th wheels, and when we got to the show, ALL THEY HAD for the most part were Grand Design RV’s. I already knew of the frame issues so we didn’t even bother really looking.
For Jamie, my Fiancee’ and myself - a costly mistake like that could devastate us financially since we are going all out for the next adventure in our lives.

I do want to say that this particular article is NOT about Grand Design specifically- it’s just the most readily available example due to so many people verbalizing their discontent, so please do research own your own, there is a ton of YouTube info and more on it. What I am stating here is not the entire story I am sure.

As I always say - because my forefathers said it - an ounce of prevention is worth a pound of gain.

To unsuspecting buyers, it is known that you can get a better deal at shows but no one tells you that SOMETIMES IT’S BECAUSE THERE IS A PUSH TO SELL COMPROMISED MODELS to people that haven’t done a shred of research and are instead - people caught up in the moment that are impulsive buyers. There really are more of those than you might think. DON’T BE ONE OF THEM.

ASSUMING AN ENTIRE BRAND IS A BAD BRAND is not an intelligent way to determine anything given the different makes/models and tiers. You could Cheat yourself out of an awesome Brand/Make/Model of RV if not careful. That’s where articles like this and careful research comes in handy, that not only prevents a potential nightmare buy, but also prevents you from overlooking a great one if they also have great service after the sale.

In fact there are PLENTY of RVERS that say they have no issues at all with a particular Brand/Model/Make, even though some people do.

Remember ALWAYS COMPARE APPLES TO APPLES. Never generalize and be sure to narrow it down in order see a pattern. If you don’t, it is impossible to know for sure.

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Your chassis, frame/walls, and roof when married together all work together to give each part greater strength. If any one are weak, the others are weak as well and a potential challenge or frustration later, if you use your RV frequently.

The suspension system of your RV really matters where it pertains to the ease of balancing weight distribution as many can raise, and lower up down, front back and side to side. If your’s cannot, then I suggest planning to get a suspension system like MORryde. They have been around the longest.

Remember - I am speaking in the context of 5th wheels in particular, but you may find many of the things listed here still apply to any RV of any size/weight.
Pop ups for example won’t apply, or teardrops, or those in truck beds. Light trailers designed for light use probably fair pretty well in comparison to fifth wheels 30 to 35+ in length.

MANY OF THE CAUSES OF FRAME FLEX

1. Excessive load weight
Pay attention to the Max. Load you can add to your RV’s existing weight and go to a weighing station to make sure you are well within those allowances.

2. Uneven distribution of your load front to back, side to side.
Learn how to distribute weight in your 5th wheel so that you utilize the pin weight of your tow vehicle too. Your manuals should tell you what that maximum is.
Fifth wheels can weigh anywhere from 8,000 all the way up to 18,000 DRY WEIGHT )before you put all your stuff in it), and up to 24,000 after you put all your stuff in it. There is a max weight after you load so take heed and pay attention because insurances have been known to deny claims if overloaded.

Things you will want to know about weight:
Weight components
Gross Vehicle Weight (GVWR): The maximum weight the manufacturer deems safe for the RV when fully loaded. This includes the weight of the RV, passengers, fluids, cargo, and optional equipment.
Tongue Weight: The weight that presses down on the hitch ball from the trailer. For fifth wheel trailers, the recommended tongue weight is 15–30% of the loaded trailer weight.
King Pin Weight or PIN Weight: The weight that presses down on the fifth wheel hitch from the trailer.
Use BUBBLE levelers to show you whether you are level side so side and front to back or not. (they even make small stick on ones you can put on and leave there to spot imbalances easily) If not - you will need to make adjustments with your load or suspension system.

3. A terrible suspension system (known as earthquaking) which gives your rig a shake rattle and potential roll due to excessive vibration that loosens screws, nuts and or bolts that once released can create excessive frame flex.

4. Slides that hold considerable weight
Slides that carry a refrigerator or exceptionally heavy area have supporting steal guides they extend out from. The welds can sometimes fail - and if not caught early, can be the cause of excessive frame flex causing chassis welds to fail if they have any weak areas.
NOTE: MANY TIMES RVers will change the refrigerator out for something larger and heavier than what came stock OR REMODEL and put more weight in areas not originally figured in the chassis engineering specks which can cause excessive chassis flex.

5. Towing when the 5th wheel is not level
This is self explanatory

6. Going too fast on rough uneven terrain (without a good independent suspension system) and even with one it can be an issue if going too fast. Respect your rig, your gear and the roads.

7. Hitting large DEEP pot holes.
Sometimes it can be unavoidable, but if you see them, slow way down so the transition from road to depth of the pothole can be navigated with the least amount of damage. A good Suspension system can allow each tire to be independent and move as much as 5” downward in order to keep all wheels in contact with the terrain at all times. Anything deeper and its obviously an issue - in either scenario - SLOW WAY DOWN.

8. Weak frame materials such as Aluminum vs. STEEL
Some chassis utilize both and others are all Steel or all aluminum

9. Delamination of outer walls can lead to other potential weak areas which can compromise wall strength causing excessive chassis AND ROOF flex.

10. Water damaged roof / walls
This can also cause delamitation, and wall materials to detach from screws causing a structure failure to occur that can then cause chassis flex and failures or weld separations.

11. Manufacturing flaws and weak welds

12. Poor engineering design of the chassis and or the upper build out or both
13. CUSTOMER UPGRADES to - solar panels/batteries
Your rigs compartment is in a certain spot and holds a certain amount of batteries, thus a certain figured weight. When you move everything to a different area and put in say 12 or 24 batteries and all the solar equipment and additional solar panels - GUESS WHAT?
yep you just added and redistributed weight without asking the manufacturing engineers whether that is wise or not.
Those things are a lot of weight difference and could cause chassis flex and twist.
14. Impacts
Impacts when backing up from the tops, side or bottom can cause issue
15. Corrosion and Rust
This is natural over time. Care should be taken to minimize this with undercoating where the chassis is exposed to the outside especially.
SOME FLEX IS NECESSARY to prevent issues like metal sheer that rigidity stress can cause if there were zero flex. When we talk about chassis flex, we are mostly addressing EXCESSIVE chassis flex, not the standard and expected flex based on the engineered design and weight distribution factored in.

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IS THE CHASSIS MANUFACTURER TO BLAME?

As just ONE example, Lippert is ONE of the MAJOR and LARGEST RV Chassis Manufacturers in America. Typically RV Manufacturers will deliver the specs to LIPPERT to build the frame according to the RV Manufacturing Engineers specs.
What that means is that YES Lippert CAN design and engineer a chassis for an RV Plant, but since they do not build the box that sits on top of that and the storage underneath that box - they really don’t want to decide anything and feel best honoring the chassis Engineering specs given the by the RV Manufacturer. Lippert themselves have state of the art Welders and engineers, and it’s possible some welds could be compromised, no one is 100% without error ratios, but suffice it to say, that what may seem an obvious cause is not always so clear as many consumers may think.

No one is without some responsibility in all of it and all are potential causes

Here is a 2 part You Tube video series interviewing Lippert:
Here is part 1:

HOW DO YOU KNOW YOU HAVE EXCESSIVE FRAME FLEX?

There are many tale tell signs like:

Bowing walls
Warping floors
loose cabinetry
leaks around windows or speakers
pin box shifting when you retract landing gear or if it moves independently from the RV (instead of with the RV upper deck it is attached to) as you move down the road as shown here:

Here is another video showing the pin box issue.

Loose outer or inner molding
Fiberglass outer walls cracking
Difficult to close doors
Slides popping out while on the road
Slides unable to close and seal evenly from the outside
Unusual rattling or loose components
Unstable ride

WILL INSURANCE PAY FOR THE CHASSIS REPAIR IF OUT OF WARRANTY

I wish I could say a definite OF COURSE! But - it’s complicated.

The short answer is that insurance will cover chassis damage IF it is the result of a sudden event like an accident, or natural disasters just as they would an automobile.

The long answer is that if the chassis damage occurs due to improper load weight, or distribution and or the result of standard wear and tear over the years it is definitely not covered. I can’t say all insurance companies are dishonest or do all they can to get out of paying a claim,

I’m almost positive there may be other restrictions that we don’t commonly hear about as an excuse not to honor a claim too for some but not all obviously..

IS THE RV MANUFACTURER & OR CHASSIS MANUFACTURER RESPONSIBLE FOR PREMATURE CHASSIS DAMAGE?

The warranty period varies between Manufacturers, makes and models.
Refer to your manual so you are aware of what NOT to do that could void that chassis warranty such as weight overload, uneven distribution, or changing anything on the original RV design like solar, battery weight and more because trust me - most will naturally will be looking to avoid or shift the responsibility and cost to repair., not necessarily because they are dishonest, but because they know just how common it is for RV owners to overload and not check weight distribution so do your due diligence.

In all fairness, the fact is though that the responsibility should be assigned to the causal factors involved whether that’s the RV owner, RV Manufacturer or the Chassis Manufacturer.

Document with photos, videos and any other supportive media for your particular make/model etc. If you have an issue you will need them later.

DO NOT enlist a third party chassis repair specialist without first getting authorization from the Manufacturer if you are within warranty but unable to travel to a designated dealer because it could post a safety issue.

IF NO WARRANTY AND NOT COVERED BY INSURANCE - WHAT CAN YOU DO?

THERE ARE SCAMMERS OUT THERE

First thing to do is to contact your manufacturer and have them give you a list of reputable or authorized companies to do the work for you.
If not, you could ask for the name of the company that made your chassis and call that manufacturer to get reputable service places or perhaps even go to them if you are able as they do repairs as well.

If you are unable to move the RV for safety reasons - ask for services that can come to you.

To ease your minds - please take the time to watch this next Video called DOES FRAME FLEX EQUAL DEATH FOR AN RV? An RV Repair Expert Speaks.
It’s 40 min long but all I can say is - if you don’t pay attention and do your due diligence by learning things like this - you could make a very expensive mistake you may not recover from.
Is that worth not taking the time?
So - the next issue is - does chassis flex and or failure mean your RV is TOTALED? Maybe, but it can be complicated.
Usually (not always) a total occurs only when the upper deck of a fifth wheel actually detaches from the lower deck

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LASTLY -
I’ll provide a Google Link as to what you can do if you are unfortunate enough to have already encountered issues that require further action due to manufacturer unwillingness to honor what is absolutely their responsibility to repair leaving you out in the cold with no RV and no way to repair it.

Of course if you are listening to this instead of reading it, you can go to the publication and go to the bottom to find the link for things like Legal options, small claims court, the Lemon Law, Consumer Protection Agencies and more.
LINK TO WHAT TO DO when left out in the cold. REMEMBER to click the MORE after the result pops up so you can get all the details.

You can find PLENTY of information on YouTube and other mediums. I encourage you to be selective for your own protection.

If you would like to visit our Facebook Group just click WOLF TREK RV STUFF
I think you may just be pleasantly surprised.

I wrote another publication called 6 critical RV zones you may want to check out if you are looking to buy an RV or Get a different one. It’s quite detailed.

Click the link in this publication to check it out.

Thanks for reading Wolf Trek RV Stuff! This post is public so feel free to share it.

Wolf Trek RV Stuff

The Backbone Of Your RV - know it before you buy it

Frame/Chassis Flex - A DOUBLE DEEP DIVE (Read or Listen)

MANY OF THE CAUSES OF FRAME FLEX

IS THE CHASSIS MANUFACTURER TO BLAME?

HOW DO YOU KNOW YOU HAVE EXCESSIVE FRAME FLEX?

WILL INSURANCE PAY FOR THE CHASSIS REPAIR IF OUT OF WARRANTY

IS THE RV MANUFACTURER & OR CHASSIS MANUFACTURER RESPONSIBLE FOR PREMATURE CHASSIS DAMAGE?

IF NO WARRANTY AND NOT COVERED BY INSURANCE - WHAT CAN YOU DO?

If you would like to visit our Facebook Group just click WOLF TREK RV STUFFI think you may just be pleasantly surprised. I wrote another publication called 6 critical RV zones you may want to check out if you are looking to buy an RV or Get a different one. It’s quite detailed.

Discussion about this post

If you would like to visit our Facebook Group just click WOLF TREK RV STUFF
I think you may just be pleasantly surprised.

I wrote another publication called 6 critical RV zones you may want to check out if you are looking to buy an RV or Get a different one. It’s quite detailed.