Community Forums

buck58 · 05-25-2023, 07:00 PM

I have a 2020 GD momentum 397th & underneath belly/insulation is sagging. At first I thought water

but put a hole in it ( & repaired) no water insulation dry. It hangs LOW… any ideas??

Arch Hoagland · 05-25-2023, 07:05 PM

Belly sagging is normally caused by too much beer......

buck58 · 05-25-2023, 07:14 PM

2000 comedians are out of work right now 🤷🏻

Skip426 · 05-25-2023, 07:20 PM

Air flow can stretch the fabric ; if it's fabric .

Many " High end " RV manufacturers use , coroplast plastic panels to prevent this situation ; and even then there will be some sag as the panels are only secured at the edges.

Dark Sky · 05-26-2023, 07:35 AM

If your belly cover is coroplast, I would cut open an access flap about 12"x 12". Then see if you can find any sort of cross beams. If you find something solid you can drill some small holes and use self tapping screws with wide washers to improve the attachment of the cover. I would not drill into something that feels solid without looking. A tank leak would really suck.
You can easily seal up the access flap with gorilla tape. Get the 'permanent' stuff and clean the area with brake or carb cleaner first.

buck58 · 05-26-2023, 07:38 AM

I’m not sure what “Coroplast” looks like, but I’ll find out, it’s a 2020 grand design momentum 397 th so whatever they put under them is what it is….

RVnAggie · 05-26-2023, 08:15 AM

Coroplast is a corrugated plastic sheeting. If you can see the edge, it looks like ribbed cardboard that most packing boxes are made of only it’s plastic….pretty common underbelly material. Some sag is normal/necessary depending on how low your holding tanks are.

I had issues as well; wasn’t sagging, but thanks to cheap brads shot into the flange of the frame to attach it and a few trips through Shreveport on I-20, several brads came out; so mine was hanging rather than sagging.

Replaced the missing brads with screws where possible, and to prevent future occurrences of the same, I built several crossmember supports out of 3/4 x 3/4 x 3/16 angle to run from frame to frame. Painted them black and attached to outside flange of frame with stainless screws, washers and ny-lock nuts. Only trick is you may have to bend/contour some to the supports to match the necessary sag for the tanks, but has worked well and passed the Shreveport test many times since.

Safe travels,

buck58 · 05-26-2023, 02:46 PM

That sounds great, pictures??

RVnAggie · 05-27-2023, 06:45 AM

Certainly; I’m out of town now w/o trailer, but will be glad to take a couple pics and share when I get back next week.

**hamm2018** · 05-27-2023, 08:06 AM

Quote:

Originally Posted by buck58

I’m not sure what “Coroplast” looks like, but I’ll find out, it’s a 2020 grand design momentum 397 th so whatever they put under them is what it is….

Coroplast is the material used in some yard signs, you see with the metal stands.

tuffr2 · 05-27-2023, 08:54 AM

Colorplast is a good material to use to seal the bottom. My though if you get under there a brace is missing. Look at how they did it, it might be obvious like too long of a span between braces.

Good luck.

Yosemite77 · 05-27-2023, 09:29 AM

The best way to describe Coroplast is that it looks like cardboard made of plastic. One option for adding support would be to screw some pieces of angle iron to the frame.

MandK · 05-28-2023, 08:40 AM

I added x-factors to strengthen my suspension and an added benefit was coroplast support. X-factors are money well spent imo and the belly lift was a bonus. Or just use the angle iron mentioned above.