2021 Grand Design Momentum Body & structure Problems

We own a 2021 Grand Design Momentum 393g toy hauler that has severe frame flex and bolts in slide have started backing out. We noticed this when driving and the extreme pushing/chucking when accelerating or braking and also the visible failure on the unit. We have contacted Gran Design, the manufacturer, for warranty repair and was able to go see the unit when they torn down to look at frame. The side walls were both broken and wall frame fell out when opened up. The unit is now at the manufacturer in Indiana for repair, my husband did not feel it was safe to tow so we requested manufacturer transport the unit. We were told by a Lippert Frame Tech the unit is not safe to use.

NHTSA ID

11750219

Incident

Apr 28, 2026

I am reporting a serious, progressive structural defect involving excessive frame flex and structural failure on a 2021 Grand Design Momentum 395MS fifth-wheel RV. This complaint directly aligns with the ongoing NHTSA investigation PE24-0209. The unit exhibits clear and worsening structural integrity failure, including: Slideouts and doors open during transport. Upper deck walls moving under load Lag bolts missing or backing out and pushing through flooring At least one critical structural bolt missing from factory installation Floor deformation and slope changes in the upper deck Slide-out malfunction due to frame distortion Loud popping and snapping noises while towing consistent with frame flex or structural separation These conditions reflect loss of structural integrity under normal use and represent a serious safety hazard, including risk of catastrophic failure while towing. On June 24, 2026, Lippert (frame/component supplier) assigned Case #6876203 and scheduled a mobile service inspection. This Grand Design Momentum 395ms is not safe to tow. It is a danger on the roads and they need to be recalled at the least for inspections of the frame for damage.

NHTSA ID

11749089

Incident

Jun 17, 2026

Frame cracked and suspension issues.

NHTSA ID

11740465

Incident

May 18, 2023

Regarding 2021 Grand Design Momentum 376THS: Compartment doors popping open during transport; Grand Design Customer Satisfaction Campaign TSB-24-001 dated 11/1/2025 regarding frame flex and wall securement. Returned to dealer on 12/1/2025 for inspection. Dealer found the following: All doors except p/s compartment door warped or bowed; P/S cracking in sidewall paneling on slides Front cap mollding broken screws Deformation or cracks at expansion joint located under upper deck slide out Gapping between exterior wall and floor Screw cover separation around front bulkhead Loose or shifted wall panel trim; trim pulled away from floor Crinkling wallpaper and cabinet paneling loos in upper cabinets

NHTSA ID

11739799

Incident

Dec 1, 2025

Scheduled appointment with dealer for the Grand Design Frame Flex recall today, 22 May 2026. Approximately 4 hours after dropping the trailer off the dealer called and said that the technician found significant frame flex and that the unit was unsafe to be towed. No other information was provided. I did ask for the measurements that the TSB 24-001 requires to be filled out ans submitted to Grand Design. The lady that called was completely unaware of what I was asking for.

NHTSA ID

11739591

Incident

May 22, 2026

My Grand Design Momentum fifth wheel trailer is experiencing frame flex and structural integrity failure. The unit has developed spider cracking in the exterior fiberglass, interior wall separation, and plumbing issues believed to be caused by frame flex. The dealership has acknowledged structural concerns and installed lag bolts, but the underlying structural defect remains. Grand Design has denied that the frame flex caused the structural damage. This creates a serious safety risk while towing, including potential structural failure. I believe this is a manufacturing defect affecting the structural frame integrity.

NHTSA ID

11720529

Incident

Feb 25, 2026

The contact owns a 2021 Grand Design Momentum RV. The contact stated that while inspecting the RV, the contact became aware that the outrigger brackets were bent and fractured. The contact stated that the failure was visible over the axles. In addition, the welding on the cross-member beams was fractured, causing the floor to crack, and the exterior fiberglass was cracked by the bedroom slide-out. Additionally, there was a four-inch-long crack on the frame of the upper deck. Most recently, the contact found movement of the cabinets in the upper deck, and a portion of the fiberglass on the front cap had separated from the roof. The RV was taken to a welding shop to be diagnosed, and it was determined that the metal used to support the walls in the unit was not strong enough. The contact was informed that the weight on top caused it to bend and crack. The outrigger brackets were replaced, the cross members were replaced, and the other cracks were repaired. The manufacturer was notified of the failure and denied the warranty claim. However, the manufacturer failed to acknowledge the failure and advised the contact to call the insurance company since the manufacturer believed that the RV had been involved in an accident. The contact denied that the RV had been in an accident. The contact noticed the issues since the RV was purchased. The failure mileage was unknown.

NHTSA ID

11699857

Incident

Jul 17, 2022

The contact owns a 2021 Grand Design Recreational Momentum RV. The contact stated while driving 55 MPH, the RV frame flexed. The contact stated that when the RV was loaded, the failure persisted. The contact stated that the screws to the bedroom slide out were detaching. Neither an RV dealer nor an independent mechanic was contacted. The vehicle was not taken to a dealer or an independent mechanic to be diagnosed. The vehicle was not repaired. The manufacturer was notified of the failure and informed the contact to bring the RV to a technician to be inspected. The failure mileage was 15,000.

NHTSA ID

11696350

Incident

Mar 15, 2023

Mileage

15,000 mi

excessive frame flex/failure, Interior cabinetry coming cracked and apart. Floor separating from side walls. Main door coming open during transit.

NHTSA ID

11695772

Incident

Aug 1, 2024

The contact owns a 2021 Grand Design Momentum RV. The contact stated while the RV was parked and occupied, or while driving the RV, there was an abnormal popping and creaking sound coming from the frame of the RV while depressing accelerator pedal or depressing the brake pedal. Neither a dealer nor an independent mechanic was contacted. The contact stated that while driving the RV at an undisclosed speed, the doors opened independently. Additionally, while walking inside the RV, there was an abnormal sound coming from the floorboards. The contact also stated that the frame of the RV was full of rust. The vehicle was not taken to a dealer or independent mechanic to be diagnosed or repaired. The manufacturer was not notified of the failures. The failure mileage was 6,000.

NHTSA ID

11684821

Incident

Aug 15, 2025

Mileage

6,000 mi

The contact owns a 2021 Grand Design Momentum RV. The contact stated that the RV had experienced a failure with the frame, causing the RV to become unstable while being hauled. Additionally, the frame was positioned on the pin box inside the unit, and the lag bolts and screws loosened, causing damage to the interior cabinets and trim. The RV was taken to the local dealer, who replaced the bolts and screws, but later, while using the RV, the failures reoccurred. The RV was not yet repaired. The manufacturer was notified of the failure. The failure mileage was unknown.

NHTSA ID

11681767

Incident

Jun 1, 2025

The contact owns a 2021 Grand Design Momentum. The contact stated that while the trailer was parked, the contact became aware that the axle on the trailer had become inoperable. The contact stated that the axle springs had detached, and the I-beam frame of the trailer was bent. The trailer was taken to an independent mechanic, where it was diagnosed and determined that the axle springs and the frame had failed and needed to be replaced. The trailer was not repaired. The dealer was contacted; however, the trailer was not diagnosed or repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 8,000.

NHTSA ID

11681297

Incident

Aug 18, 2025

Mileage

8,000 mi

I am experiencing symptoms, consistent with excessive frame movement and structural failure in my 42 foot fifth wheel toy hauler RV. We have been monitoring this for the time we have owned it just over six weeks and have noticed an increase and symptoms that research shows indicate there is a problem.. we are seeking professional inspection and guidance to establish the scope of it and hopefully catching it at the earlier side in order to hopefully deal with the issue easier than after a total failure. The symptoms include 1- the interior upper section horizontal lag bolts that hold the camper walls to the frame all had come loose completely. There were four on one side and five on the other. 2- the underside curved fillon panel by the pin box is ripple and curved, and shows movement 3- the left and right sides of the camper towards the front are becoming out of square with the rest of the camper and the seals around the doors are showing larger gaps and looking more out of square 4- interior doors and exterior doors of the camper are all experiencing difficulty latching and are becoming out of square to the original structure 5- there is a changing of the distance, measurements both in height, and in relation to the lower frame members from the pin box where the camper tows from. And what appears to be some twisting out of square. 6- front panel door is buckling in the center and will no longer close geometry of the opening has been compromised It is clear that we are experiencing frame structural failure between the area where the camper toast from in relation to the main frame of the camper

NHTSA ID

11680513

Incident

Jul 30, 2025

Frame failure 2 inches of deflection Doors popped open on hwy walls cracked lag bolts falling out water leaks and floor rotting out from flex

NHTSA ID

11671713

Incident

Jul 7, 2024

We purchased our 2021 Grand Design 395M Momentum new in early 2021. Over the past year we noticed cabinets on the passenger side bedroom separating from there wood frames. We initially repaired the cabinets ourselves thinking it was just poor workmanship. This last trip from Houston to Myrtle Beach the cabinets again separated. Someone in the campground at Myrtle Beach informed us about the issue with Grand Design's frames. Upon closer inspection I noticed that the bottom of the cap had separated approximately 1" and when you lower the unit onto the 5th wheel hitch the pin box sinks an additional 1.5". It appeared sever enough that we were uncomfortable towing the unit back to Houston. We secured an enclosed trailer (at our expense) for our items and left the unit in storage (at our expense) until we could contact Grand Design. We contacted Grand Design and are scheduling our unit to be towed to a local Myrtle Beach dealer for repair. In my opinion if we would have attempted to tow the trailer it could have broken loose and collapsed on to our truck or broke free entirely. At a minimum I do believe a letter notifying owners of the issues is warranted and what repairs/changes are being made. It is only a matter of time before there is a catastrophic event with sever injury or death.

NHTSA ID

11664720

Incident

May 30, 2025

FRAME FAILURE AND STRUCTURE. CARGO DOOR OPENED WHILE TRAVELING. (SAFETY ISSUE) FURNITURE SEPARATING FROM STRUCTURE. BROKEN OVERHEAD CABINETS OVER BED (SAFETY ISSUE) WALL SEPARATING FROM FLOOR IN CARGO AREA WOOD DUSTING FROM CEILING IN BEDROOM AND GARAGE AREA.

NHTSA ID

11664700

Incident

May 9, 2025

We took possession of our new 2021 Grand Design 381M fifth-wheel travel trailer in April 2021. During 2021 and 2022, the trailer saw minimal road use. However, during our travels, we observed significant movement within the trailer, and on several occasions, the cargo bay doors opened while in transit. In August, we contacted Grand Design due to visible interior damage and abnormal movement. They arranged to pick up the trailer and transport it to their facility for inspection and repair. Grand Design confirmed that the trailer had suffered a frame failure. They reportedly completed the necessary repairs and returned the trailer to us. Unfortunately, not all issues were resolved. In May 2023, the trailer was returned to the facility for additional repairs. Afterward, it was returned to us once again. In August 2024, signs of frame failure reappeared. We contacted Grand Design, and a mobile technician was dispatched to inspect the trailer. The technician confirmed another instance of frame failure. Due to seasonal considerations, we arranged for the trailer to be transported back to Grand Design in March 2025. Repairs were made, and the trailer was returned later that month. We remain deeply concerned about the adequacy and durability of the repairs, and whether the trailer is truly roadworthy and safe. Despite multiple requests, Grand Design has not provided any photos of the frame damage or documentation of the repairs performed. This lack of transparency is especially troubling given the recurring nature of the issue and the broader concerns surrounding frame integrity across multiple Grand Design models. We are left with the impression that the structural integrity of our trailer—and potentially others—has been compromised. We believe this poses a serious safety risk for anyone traveling on U.S. roadways.

NHTSA ID

11659949

Incident

Feb 26, 2021

We started noticing issues on our RV and reported it to Grand Design. Those issues included bolts holding front philon breaking and loosening, wallpaper at base near floor shifting, excessive new noises on slide movement, lippert legs stopping due to being off balance on level ground, stress cracks in front cap, sawdust in pantry cabinet, loose lag bolts upon further inspection and dresser panel repeatedly popping off on travel days. Based on the issues, we took it to a a GD dealer (La Mesa in Sanford FL) for inspection. After measurements I was told by Grand Design that it was excessive frame flex. The philon was removed by the dealer and in that small section no obvious cracks were noted. They replaced lag bolts from the inside. We asked if they would remeasure and they said that Grand Design didn't require that, but they would. We were told that the measurements did not change after the lag bolts were replaced. They did not fill out the official form since Grand Design didn't require it. They repaired the stress cracks in the paint, but the dealer told me that the wallpaper shifting and sawdust was normal. We took the vehicle and then the caulking all cracked where the philon attached (the same places that bolts broke and were loose prior to. I am concerned that there was not further inspection, so I called Grand Design. They said the measurements are in spec and always have been, so he's not sure why anything was done. From my research and from looking at the forms, 1/2 inch is out of spec and nothing has changed on my rv.

NHTSA ID

11641738

Incident

Jan 1, 2024

After a trip we noticed that when we had the rv connected to the truck, the front closet would not close. There was also cracking on the nose cover of the rv. We (my wife and I) had a problem with the cargo doors and entry doors coming open on other trips and lost stuff on the highway so we talked to the rv dealer to get a frame inspection. what was found was that the frame was broke in a few places and the door side wall of the camper was not attached. We have also had the rear spring hanger break the year before while driving almost pulling me out of the lane I was traveling in. The camper is sitting at the dealers now because it cannot be towed, and the dealer will not weld the frame due to liability. missing and broken bolts in the frame and body were also discovered.

NHTSA ID

11641264

Incident

Oct 16, 2024

Our 5th wheel had broken welds on the drivers side of frame in early 2023 that were repaired at the factory. There is now a service bulletin for a lag bolt inspection, we brought it to a dealership for inspection and it was determined many lag bolts are either missing or broken which means our side walls have been probably attached to the frame. It was also discovered the the frame is flexing outside of the acceptable parameters and there are cracked welds now in the passenger side. We were told it is unsafe to move the 5th wheel at this time. We are awaiting feedback from manufacturer.

NHTSA ID

11637724

Incident

Jan 17, 2025

Excessive frame flex in pin box area of fifth wheel. Forward left cargo door unlatching while towing. Vehicle is currently at Lazydays dealer in TN for inspection and TSB for excessive frame flex. Inspection has revealed major structural cracks and structural failure in upper deck steel frame structure. Vehicle has been deemed unsafe to transport and must be repaired in place or partially repaired for transport to factory. We noticed excessive deformation of the pin box and substantial rubbing of internal cabinets, etc upon return from a recent trip. Based of the damage, it would have been possible for the RV structure to separate from our tow vehicle putting us and others on the road at significant risk of injury or death. We saw indications of interior movement of cabinets and rubbing on walls for several thousand miles, but no indication of significant pinbox deflection until recently. Manufacturer has provided no guidelines or communication to owners to be aware of potential problems or to indicate things to look for that may indicate the vehicle poses a serious risk/hazard. Initial signs of rubbing inside the vehicle, and a loose latch and flapping of cargo door were observed in January 2024. We have video of substantial gap opening and movement of interior cabinets when taking vehicle off of stabilizer jacks and loading onto fifth wheel hitch of truck. Unable to get additional pictures currently as the RV is at the dealer for repairs. Will attempt to get photos of internal frame damage early next week if possible.

NHTSA ID

11636284

Incident

Nov 24, 2024

Side compartments opening while towing unit on highway…items in compartment flying out …hatches won’t closed properly to much gap…big gap also on top cap where it connects to wall in front..unit taken to lazdays Tampa for frame flex recall…inspection revealed major cracks in frame everywhere as a result causing major frame flex…lots of welding is being done…by grand design mechanic ..slide system also damaged as a result of frame flex …unit is currently still at lazdays Tampa being welded together…they keep finding more and more damage …. You guys should send an inspector to inspect it to see major frame damage from poor frame build I believe unit is unsafe to be roadworthy with the amount of welding and repairs to frame the keep doing

NHTSA ID

11636185

Incident

Dec 14, 2024

I am experiencing major frame failure. My propane doors on both sides have opened while towing. Gotten so bad i had to duct tape them shut. Not safe pulling over to do this. The main cause of this happening is Frame Flexing which i can confirm with a video i took. I can also see my frame flexing while hitching and unhitching trailer. My top floors are squeaking badly which is indicative to my frame bending and breaking welds. Doing research I have seen pictures of other trailers the same year with broken and cracked frames. This poses a safety issue while towing as i feel the trailer can break away from the tow rig and cause some serious damage.

NHTSA ID

11633267

Incident

Jun 13, 2024

I own a 2021 Grand Design Momentum 381m. In august of this year we found broken welds and bolts in our RV frame. The dealer we took it to told us grand design has known about the issue for several years but refuses to issue a recall, instead they issued a service bulletin. GD told us on the phone, there have been no catastrophic failures yet, so there is no need for a recall. Blue Compass RV in Prescott, AZ, at the direction of GD, welded the frame and told us it was good to drive back home to Florida. Once back in FL, we took the RV to the dealer we purchased it from to have the cabinets repaired, the frame flexing caused damage to the cabinets in the front of the RV. The dealer told us the frame was not fixed and needed to go to the factory in Indiana for repair. We have been unable to use our RV for 3 months now. We are currently waiting for our RV to be transported to the GD factory on 8 Jan 2025.

NHTSA ID

11632960

Incident

Aug 22, 2024

I had noticed the Pin Box flexing, especially over bumps or any rough road or bridge approach. As it got worse I could tell we a lot of flex in the frame area where the Pin Box is located. I contacted the dealer and they examined our RV and determined the frame was flexing due to the bolts connecting the chassis to the actual frame of the RV body being to small and working loose/broke. The dealer replaced the bolts with larger bolts and advised the flex is now within specifications. It is better but it's not great by any means. I'm concerned as the RV gets older the condition will get worse and could even become hazardous. This condition has already affected the value of the RV and when it's out of warranty I'll have no recourse other than to fix it myself.

NHTSA ID

11623904

Incident

May 6, 2024