2018 Grand Design Momentum Body and structure Problems

“I am writing to formally report a series of serious structural concerns we are experiencing with our Grand Design Momentum 349M fifth wheel/toy hauler, which appear to be related to excessive frame flex/failure or upper deck instability. These issues began toward the end of last year and have progressively worsened, raising significant safety concerns for our family. …”

“We have frame failure on our trailer, we have not taken it apart yet to give all the details on the welds broken but metal is starting to come out from the fiberglass, and our cabinets inside came part. We contacted Grand Design and they stated as second owners there is no warranty, we contacted Lippert they said to reach out to GD and our insurance said they do not repair manufacturing issues. We will be taking to a shop at the end of February and will have a better understanding of all the issues.”

“Structural Frame Failure. We found frame damage at a rest stop while traveling down the interstate. We observed side wall separations and multiple cracks in the welds around the pin box. The 5th wheel trailer was taken to a commercial truck frame repair shop in Florida and after opening up the panel underneath the pin box we discovered multiple breaks/cracks in the structural frame. We filed and insurance claim and an adjuster came out and photo documented all the frame damages along with documenting the overall build construction of the frame. …”

“I started noticing rub marks on the interior walls next to the night stands after the last few uses, and they appear to be getting worse after each use. I was made aware of the deck/frame flex issues the some GD fifth wheels are having and was referred to TSB 24-001. My RV is experiencing the exact concern described in the TSB. I opened a case number with GD, and took the RV to an authorized repair center. The repair center took measurements and confirmed my deck flex concern with GD and recommended a complete replacement/repair of the structural material and hardware. GD denied the claim! …”

“On the driver side of the 2018 Momentum Toy Hauler cracked in two locations above the center leaf spring holder. This issue occurred on May 1, 2025. While pulling out of a shop after having the leaf spring holders replaced the axle traveled through a small depression on the ground causing the frame to flex and make a loud enough sound to be heard in the truck pulling the camper. While investigating the situation it was discovered that the frame cracked at the weld points of the gusset bracket that was attached to the frame. …”