2021 Grand Design Momentum 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.

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.

Frame cracked and suspension issues.

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.

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.

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.

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.

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.

This is an updated report with additional detail. Sorry for any confusion this may have caused. * Baggage door routinely open while travelling. A number of items may have been sucked out of the RV while moving down the road. We try to be hypervigilant and pull over as soon as we notice the door flapping open, and we secure loose items in drawers. * RV doors routinely open. The front door always opens, even though we use the 'deadbolt'. It's usually held in place by a hand rail that folds over the door, but this occassionally comes open, as well. This damages the door, and we're concerned that the metal stairs could fold out. The rear door has recently started openning on travel days. It's hard to tell when this happens, but we have had to pick things up off the ground after making a left turn at low speeds. * Brake eletrical issue. We had the RV in for repair at the manufacturer's service center. They reported that some of the brakes weren't receiving the proper voltage and were thus non-functional. * Front bedroom Schwintek slide mechanism came loose. Slide was partially inoperable, and would start to extend out of the unit during travel. When noticed, depending on how far out it had started to come, we would have to go back into the unit and pull it back in to complete travel day. This was repaired by the manufacturer. * Broken welds on frame. The manufacturer service center replaced the rear steps. They did not identify the broken welds that were causing the floor (immediately above the steps) to sag, and thus allow water intrusion. This lead to the rotting of the floor of the RV. The manufacturer provided an estimate of ~$20k to repair the floor, but didn't include repairing the broken welds. * RV is unlevel / lists to the passenger side. The RV has a lot of heavy items on one side, and nothing heavy on the other side to counter balance it: shower, refrigerator, oven, microwave, and side deck/patio. The tops of the tires are clearly visible when looking a

Bolts holding brake caliper assembly to the axle apparently loosen and fell out while on the highway. This caused the caliper to drop, resting on inner part of the tire rim, leaving approximately half to one quarter of the caliper on the disc. Caliper caused significant gouging on the rim. During braking, the caliper was prevented from spinning during brake application due to it hitting the axle u-bolt retention plate on top of the leaf spring. In the very limited backing, the hydraulic line held back the caliper. Safety issues are the complete lose of the hydraulic system, causing the complete lose of trailer brakes. The caliper gouging the tire rim could have caused the rim to break, with the result of the tire departing the trailer on the highway and hitting another vehicle. Issue was found when I noticed metal flakes (tire rim) in my driveway where I backed my trailer to park it. Following the flakes, I discovered the issue. Grand Design, and axle/brake manufacturer Dexter notified via email. No response as of yet. Hydraulic brakes were factory installed at the time of manufacture.

The contact owns a 2021 Grand Design Recreational Momentum. The contact stated that while having maintenance work completed on the RV, the dealer removed the nose cap and noticed that the insulation and the mylar tarp near the rear of the RV was burned. The contact was informed that the wiring on the nose cap had been overheating and causing the burn. The dealer had reconnected the wiring but had not repaired the RV. The manufacturer was made aware of the failure. The failure mileage was 40,000.

We are victims of frame failure. First sign was a creaky floor in the bedroom. Screws worked their way out of the wood flooring and pushed up underneath the linoleum. The movement of the nose cap pushed screws out of the trim and seal piece on the underside of the front cap. We reseated screws, upgraded screws, resealed this at least 5 times and now use gorilla tape to avoid water intrusion. The underbelly has fallen down while traveling so we had to reinforce this ourselves. Our driver side bay door will fly open when traveling. It locks but the locks will not hold it closed when the rig starts to flex. We now gorilla tape the door every time we travel to avoid objects flying out of our bay into traffic. The partition between the wet bay and the storage bay has bent. Our front driver side jack is not straight, it points outward. There is rubbing of the shelving and trim in the bedroom. The board that has the slide rollers under the main bed has failed. We have pinched decals on the exterior of the nose cap. The pin box sinks up into nose cap when hitched up. We have a toy hauler however we do not haul any vehicles or toys in our rig. We have had to replace both back leaf springs due to them failing. The main lighting panel has been damaged in transit so that the exterior accent lights will no longer turn off. This is an electrical hazard as well as an annoyance to anyone that camps near us. The roof seal that attaches the roof membrane to the front cap is elevated and not flush. When traveling from TX to Indiana for our frame failure appointment, the roof membrane completely shredded and fell back over the air conditioner. We had to gorilla tape the remaining roof to make it the rest of the way. Grand Design is not issuing a recall yet. Our rig is dangerous for us and anyone on the road with us. Our rig is in the shop right now and we have the highest hopes that it is properly fixed, and we do not have to return like so many others are.

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