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timelinex · 04-30-2022, 09:36 PM

I have a 2021 Grand Design Momentum 381m fifth wheel. I knew based on others experience, the layout on these make the pin weight lighter than normal with a toy in the garage. I've got a 2100# SxS that I back into the garage.

We took a trip about an hour away and the drive wasn't great. Everything about the towing experience was good except one big thing. It felt really sensitive to sway. It just felt like it had a tendency to continue swaying until I intervene. I never had it get dangerously out of line or anything like that. So it wasn't terrible, but just didn't feel right. It's hard to explain. I Felt like it would not be a good time doing this for 7+ hours. I have towed with my last truck (tundra) at capacity (10k~) and it felt more stable as a bumper pull than this fifth wheel right (even though everything I read it should be opposite.). I was going 62ish in a 75 most the time ... But some of the time I had to go as slow as 53 or so just to feel stable.

Then I weighed myself and founds the problem. My pin weight is WAY too light. It was 2620# on a 19k trailer weight. I moved everything I could think of that had any weight to it up into the bedroom and the best I can get it to is 2660#. 14% is not good! This hopefully explains the driving experience.

Here are some things I have thought about:

I have airbags coming in as my back end is 2" lower than my front when loaded. So I imagine it's gonna get even worse as the front of the trailer is raised from raising the rear end!
Water tanks would be a good idea, but my research has shown they are over the axle's and won't help
I can lower my Pullrite 2600 hitch receiver one inch, and lowering the nose the trailer a little should transfer some weight. But as I said, this may not even even out the airbags. Also, right now I have 8" truck bed clearance, and this would eat up some of that, which isn't great.
Literally add some kind of dead weight in the Generator/Battery compartment. But it sucks to have to tow more weight.

Does anyone have any ideas how to remedy this? It would be nice to get to atleast 3k, but ideally maybe 3200.

Thanks guys

xc-mark · 05-01-2022, 05:00 AM

see where your weights are on the side by side maybe backing un puts more weight closer to the axle of the trailer.
What are you towing with a single wheel truck? I had a single wheel one ton crew cab 4x4, with , our 42' 17,400lb Redwood behind that truck it would pull the back of the truck around on twisty roads that required constant correction on the steering. I was at 3600~3800lbs pin weight depending on fresh water load. The single wheel truck was 500 to 700 LBS over the rear axle rating of 7050lbs. Fast forward same trailer and I got a 2020 duel wheel truck in front of it night and day better. No constant correcting ,hold the steering strait and it goes where the front tires are pointed.

The other thing is what tires are on your current truck, some tires have VERY soft side walls and they will add to the pucker factor alot. My buddy put a set of load range E nitto tires on because he likes the look and after 2hrs of towing he call up Nitto and asked them to buy them back and he went back to Michelins he had on the truck. He felt unsafe at 70mph and felt ok at 55 , Michelins felt the same regardless of the speed (very stable) He has a 9800lb bunk house that is 32' towing with a one ton.

CecilD · 05-01-2022, 06:31 AM

It seems like something is wrong that is more than just weight loading as that trailer has nearly 3,500# on the pin dry. It would be nice to be able to weigh each axle independently to ensure the MORryde 3000 equalization is working correctly. If more weight is being carried by the front axle, it would increase the length of the rear lever arm and unload the pin more. I really don't know the dynamics of triple axles, but this is a thought.

The way I look at it, lowering the front of your trailer would shift more weight to your front axle and would cause your percentage of weight distribution to get worse as you are moving your fulcrum forward. AS I see the physics, raising the front of the trailer would increase pin weight. Academic though, as you would want your axles to be equally loaded.

I see you had IS suspension on your previous trailer. Did you have it installed on this one? For some reason, Dexter does not recommend individually sprung Torflex axles on triple-axle installations. Maybe, because of the lack of equalization.

I see your fuel station holds 60 gallons or 360#. If the tank is rear mounted, towing empty would account for some weight shift. Not want you want to hear though.

Your trailer was designed to tow with stuff in the garage; maybe a call to Grand Design.

timelinex · 05-01-2022, 09:40 AM

Quote:

Originally Posted by xc-mark

see where your weights are on the side by side maybe backing un puts more weight closer to the axle of the trailer.
What are you towing with a single wheel truck? I had a single wheel one ton crew cab 4x4, with , our 42' 17,400lb Redwood behind that truck it would pull the back of the truck around on twisty roads that required constant correction on the steering. I was at 3600~3800lbs pin weight depending on fresh water load. The single wheel truck was 500 to 700 LBS over the rear axle rating of 7050lbs. Fast forward same trailer and I got a 2020 duel wheel truck in front of it night and day better. No constant correcting ,hold the steering strait and it goes where the front tires are pointed.

The other thing is what tires are on your current truck, some tires have VERY soft side walls and they will add to the pucker factor alot. My buddy put a set of load range E nitto tires on because he likes the look and after 2hrs of towing he call up Nitto and asked them to buy them back and he went back to Michelins he had on the truck. He felt unsafe at 70mph and felt ok at 55 , Michelins felt the same regardless of the speed (very stable) He has a 9800lb bunk house that is 32' towing with a one ton.

Believe me, i did the research on ratings and making sure i am well within my limita before buying. The tires are Nazama AT Open Ranges on 18" rims. I'm 1200# away from their load limit. Same as the axles...I am 1000# away from my rear gvwr (and based on research 4k away from the axle rating by manufacturer). I have 1100# of payload left on my truck with everything loaded minus people. My family is <400#. So I'm not over on anything.

No doubt dually would be more stable no matter what you are towing. If i turn out to tow this more than every few months, I will probably get a dually. Not because I need one to not be over on ratings (I'm not over), but because they increase stability no matter what!

timelinex · 05-01-2022, 09:50 AM

Quote:

Originally Posted by CecilD

It seems like something is wrong that is more than just weight loading as that trailer has nearly 3,500# on the pin dry. It would be nice to be able to weigh each axle independently to ensure the MORryde 3000 equalization is working correctly. If more weight is being carried by the front axle, it would increase the length of the rear lever arm and unload the pin more. I really don't know the dynamics of triple axles, but this is a thought.

The way I look at it, lowering the front of your trailer would shift more weight to your front axle and would cause your percentage of weight distribution to get worse as you are moving your fulcrum forward. AS I see the physics, raising the front of the trailer would increase pin weight. Academic though, as you would want your axles to be equally loaded.

I see you had IS suspension on your previous trailer. Did you have it installed on this one? For some reason, Dexter does not recommend individually sprung Torflex axles on triple-axle installations. Maybe, because of the lack of equalization.

I see your fuel station holds 60 gallons or 360#. If the tank is rear mounted, towing empty would account for some weight shift. Not want you want to hear though.

Your trailer was designed to tow with stuff in the garage; maybe a call to Grand Design.

Here's the issue. Seems like you are going off rule of thumbs and other things that don't account for the actual design of the trailer.... also not sure where you got 3,500# dry...unless your looking at the 381ms, which is NOT the 381m and is completely different front. Dry weight on mine was 15,242 with a pin weight of 2,848. I attached the sheet straight from the factory weighing. If you do a quick search, you will see that no one has reported a higher pin weight than like 3300# on a fully loaded 381m....doesnt happen. its obviously not designed for a lighter pin weight, which is part of the reason I bought it. But 2,660 is obviously TOO light!

Would appreciate advice for raising pin weight though!

jacknife · 05-02-2022, 08:27 PM

Moryde X factor between the axles and your suspension will stop most if not all of your sway . RoadMaster shock kits will also add to stopping sway and give your trailer a smoother ride .

xc-mark · 05-03-2022, 01:46 PM

Also any "AT" type tires add to your issues of sway . They build the side wall and tread area of the case soft so they are able to grab uneven ground. If you have a friend that has the same truck and he or she is willing to let you bolt on there wheels and tires for a hour it maybe the best idea for a cookout and beers.....

timelinex · 05-21-2022, 09:45 PM

Alright guys, so I added 350# of sand in the front, took out all my water other than about 30 gallons, took off the happijac queen bed up top, and loaded anything I needed as front as I could. My new trailer weight was 18,920 with a pin weight of 3120 (16.5%). I also added airbags to my truck.

It felt SOOOOOO much better. I didnt have that white knuckle feeling the whole time. Of course I still felt swaying every once in a while like if a semi passed. But it would self settle and that would be that (instead of oscillating worse and worse till I intervened).

thanks for alll the adivce guys. Hopefully ive solved the issue. Next is a 5 hr trip and the one after is a 2,000 miles yellowstone trip in July!