2021 Grand Design Momentum

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 flex 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.

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

The contact owns a 2021 Grand Design Recreational Momentum. The contact stated that while hauling the RV and driving at undisclosed speeds, the rear side door unexpectedly opened and the slide-out extended outward. No warning light was illuminated. The trailer was taken to a local dealer and remained with the dealer for additional inspections. The RV was not repaired. The manufacturer was made aware of the failure. The failure mileage was unavailable.

NHTSA ID

11727885

Incident

Apr 15, 2022

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

Grand Design is addressing concerns of excessive frame flex or wall securement in the front upper deck area of a limited number of fifth-wheel units. This condition could potentially occur over time due to a combination of manufacturing variations, an overload condition, or hitch modifications. Wall securement or excessive frame flex does not compromise vehicle safety or structural integrity of the coach as verified by third-party experts. This service campaign covers 2020-2023 Grand Design Solitude and Momentum fifth wheel products that are 18,000lbs GVWR and over.

TSB 24-001 Issued in March on March 7th. Concern: Complaint of upper deck flex which results in cosmetic damages to the interior and excessive flex at the pin box. Remedy : The procedure outlined in attached summary to assess damages if any and direct customers to the next steps.