Need more pin weight!

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timelinex

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I have a 2021 Grand Design Momentum 381m 5th 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:
  1. 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!
  2. Water tanks would be a good idea, but my research has shown they are over the axle's and won't help
  3. 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.
  4. 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

weights.jpg
 
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I have experienced the same thing to a lesser extent than you when I have the RZR in in the XLR 321. Mine is not really a problem or worrisome, but I can tell the pin weight is considerably lighter. When I have the RZR out the rear end sits on the overloads a little. When the RZR is loaded the overloads do not make complete contact with the stops.
 
Your pin weight target should be more like 3800 lbs (20%) but I don't see any realistic way to add 1000+ lbs. The optimal solution is to move the trailer axles rearward to change the balance point, but that's a major mod (assuming the axle mounts are welded).

Is this a triple axle trailer? I think it must be, but want to be sure.
 
Gary RV_Wizard said:
Your pin weight target should be more like 3800 lbs (20%) but I don't see any realistic way to add 1000+ lbs. The optimal solution is to move the trailer axles rearward to change the balance point, but that's a major mod (assuming the axle mounts are welded).

Is this a triple axle trailer? I think it must be, but want to be sure.
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No one's 381m pin weight is 3,800#. The rule of thumb is just a rule of thumb for a general 5th wheel. You can do a search and you will find no ones pin weights on these things get past 3300# or so even when fully loaded.

Anyways, it would be great to get it up to 3200# or so. So advice towards that would be appreciated!

Seems like consensus seems to be dead weight in the front.
 
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I’m not familiar with your Grand Design, but most 5th wheels have a lot of storage up front….use it! Put any and everything that you “may” need when traveling into your storage.

In our case, 2 Honda 2000 generators, 2 sets of tire cables, lots of tools, hydraulic bottle jack, folding tables, folding chairs, ect., ect.! You can’t go wrong with having everything you may want/need, and the weight adds up pretty quickly! memtb
 
Memtb said:
I’m not familiar with your Grand Design, but most 5th wheels have a lot of storage up front….use it! Put any and everything that you “may” need when traveling into your storage.

In our case, 2 Honda 2000 generators, 2 sets of tire cables, lots of tools, hydraulic bottle jack, folding tables, folding chairs, ect., ect.! You can’t go wrong with having everything you may want/need, and the weight adds up pretty quickly! memtb
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The very front is full with generator and batteries. The compartment behind is full too! But there is enough room for dead weight if that's what I need to do (bags of lead?)
 
You might review how you are loading the toys. Get as much weight forward as possible. You might even go as far as figuring out which axle on the SS is carrying more of the vehicle weight and load it accordingly. Is the SS fully fueled when loaded? It doesn't sound like you are going to fond a silver bullet for this, but rather a bunch of seemingly small changes.
 
timelinex said:
No one's 381m pin weight is 3,800#. The rule of thumb is just a rule of thumb for a general 5th wheel. You can do a search and you will find no ones pin weights on these things get past 3300# or so even when fully loaded.
Click to expand...
Yes, a rule of thumb, but that "rule" represents best practice. . 3300 is a lot better than 2600, but still short of where you should be for comfortable towing. Most 5W RVs are in fact closer to 25% pin weight, contributing to their excellent road manners
 
tlmgcamp said:
You might review how you are loading the toys. Get as much weight forward as possible. You might even go as far as figuring out which axle on the SS is carrying more of the vehicle weight and load it accordingly. Is the SS fully fueled when loaded? It doesn't sound like you are going to fond a silver bullet for this, but rather a bunch of seemingly small changes.
Click to expand...

Did all that. My 2100# SxS is 1175# in the rear and 920# in the front. So that's why I back it in as far as it will go.

My gas tank in the SxS was mostly full but we are talking about 10 gallons. It's not really feasible for me to constantly drain or use out the rest of my tank on there.
Gary RV_Wizard said:
Yes, a rule of thumb, but that "rule" represents best practice. . 3300 is a lot better than 2600, but still short of where you should be for comfortable towing. Most 5W RVs are in fact closer to 25% pin weight, contributing to their excellent road manners
Click to expand...
Please find me one example of someone with a 381m that has a 20%+ pin weight. The highest I have found someone say they were able to get up to is 3120#. I have done alot of research on this, so I'm not just making these things up.

Also, I am willing to be corrected, but my understanding of "best practices" is ACTUALLY 15-20% and it came from the trucking industry thats been doing it forever. Then people RV'ers were finding that as more and more people full timed, the realistic outcome was 20-25% so that is why the rule of thumb was changed to expect having a pin weight of up to 25%. This is to make sure people weren't overloading their trucks. Not because 25% is somehow a best practice. I Would love to be proven wrong on this, so if you have a link to an authoritative source (not just an article from a random person) that shows 20-25% is a best practice, rather than 15-20%.... I would love to see it.
 
I guess my takeaway from this is that when buying and researching a toy hauler, weight and balance is as important as MGVWR.

I think it's crazy that OP is trying to figure out how to get 1000# of pin weight over the 5W.

There is no "easy solution" to this. Even adding or subtracting gas from the SxS is worthless as the entire weight of the vehicle is behind the axles.

The simplest answer is 1000 pounds of lead in the overhead bunk which, of course is pretty impractical. Anywhere else forward of the axle you need more than 1000# to achieve the moment arm.

What a crazy situation. The only thing I can think of is that the maker was thinking a couple of 300# dirt bikes not a 2100# quad which arguably is a pretty heavy "toy"
 
tlmgcamp said:
Does the manufacturer set a max toy weight?
Click to expand...
I am going off the top of my head, but I believe it is 3,000#
Ex-Calif said:
I guess my takeaway from this is that when buying and researching a toy hauler, weight and balance is as important as MGVWR.

I think it's crazy that OP is trying to figure out how to get 1000# of pin weight over the 5W.

There is no "easy solution" to this. Even adding or subtracting gas from the SxS is worthless as the entire weight of the vehicle is behind the axles.

The simplest answer is 1000 pounds of lead in the overhead bunk which, of course is pretty impractical. Anywhere else forward of the axle you need more than 1000# to achieve the moment arm.

What a crazy situation. The only thing I can think of is that the maker was thinking a couple of 300# dirt bikes not a 2100# quad which arguably is a pretty heavy "toy"
Click to expand...
The people with more reasonable pin weights are generally putting in bikes and ATV's that weight <1k total.

If I had to guess, I think GD realized that they may be making it too light up front as I think the 381M has been replaced by the 381ms in 2020. That comes with a stock pin weight of 3440 instead of ~2850. All else being equal, that would put me at 3,300# or so which is my goal.
 
timelinex said:
I am going off the top of my head, but I believe it is 3,000#

The people with more reasonable pin weights are generally putting in bikes and ATV's that weight <1k total.

If I had to guess, I think GD realized that they may be making it too light up front as I think the 381M has been replaced by the 381ms in 2020. That comes with a stock pin weight of 3440 instead of ~2850. All else being equal, that would put me at 3,300# or so which is my goal.
Click to expand...
This should have said that they replaced the 381m with the 381ms in 2022. NOT 2020
 
Just thinking about where is the washer/dryer location and if you don't have them this would be an easy several hundred pounds that would actually have a benifit besides clean cloths.
 
Hvactech said:
Just thinking about where is the washer/dryer location and if you don't have them this would be an easy several hundred pounds that would actually have a benifit besides clean cloths.
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Our w/d hookup is in the garage, so even if we added it, it would actually exacerbate the problem!
 
I used to carry a couple " collapsible " water jugs in the cargo bay of my old airplane as it was nose heavy if I was flying by myself. I could pour out the water if I was takeing passengers in the rear seat.
You could store several 5 gal water jugs in the front room. Water is about 8 lbs a gal so that's 40 lbs a jug.
 
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