Hypothetical: limiting/weak point(s) in GVWR ratings for Solitude line

[Second Chance]

For TucsonJim , Cate&Rob , and any other engineers out there:

Given the overall design and build of the Solitude line, what would you consider the limiting or weak points in the design and construction which result in the assigned GVWR? 1) suspension system (including axles, springs, bolts, shackles, hangers, brakes, etc.), 2) the gooseneck portion of the fame and/or pin box (though the installed pin boxes appear to be rated several thousand pounds above any weight that would ever be put on the pin for a given model), or 3) the general chassis/frame (rail and cross-member sizes, design, welding, etc.)?

I'm going to get something cold to drink and something to munch on and sit back...

Rob

[TucsonJim]

Dang you. Time to go grab my slide rule.

I believe the correct answer is "it depends". There are so many components that can fail when they are overloaded. All of those you listed along with bearings and tires too. I saw a severely overloaded Solitude (4,000+ over weight) and their first failure mode was the tires.

I've seen several units that had cracks in the fiberglass along with frame failures. Most people assume it was a manufacturing defect, but I suspect it was overloaded.

Of course we've all seen bearing, axle, spring hangers, etc. that have failed. Was it weight driven?

We're not privy to the load calculations that are used to design the frame and equip the suspension and running gear. If I was in the RV business, and had the budget, I'd test the designs to the point of failure so I thoroughly understood the failure modes and effects. But when I worked in the rocket business, we had to do those things to meet government regulations.

Many of the failures we see may also not be due to an overall excessive weight problem, but how the weight is loaded on the RV.

So I guess my answer is still "it depends".

Jim

[bertschb]

I saw a severely overloaded Solitude (4,000+ over weight)...

How is that even possible??? That means they added 6,000lbs+ of stuff! We are full time now and we added 1,600lbs - and that includes a washing machine.

[Cate&Rob]

We're not privy to the load calculations that are used to design the frame and equip the suspension and running gear. If I was in the RV business, and had the budget, I'd test the designs to the point of failure so I thoroughly understood the failure modes and effects.

Jim captures the intent of "durability testing" with this statement. Every component is (or should be) designed to its theoretical load requirements and perhaps tested at a sub-system level, but it is only when you get everything assembled that you can test how everything works together and determine what is the weakest link. Every system has a weakest link and you want that part to fail in a relatively safe manner rather than something more important failing in a catastrophic manner. Owners upset that safe weakest link theory all the time by over strengthening the thing they are worried about. For example, if a spring breaks, it is very tempting to install stronger springs . . . not considering that you may have moved the weak link to the spring hangers or the frame.

The auto/truck manufacturers do extensive durability testing with the intent of finding and understanding the weak links. Those who worry about being a few pounds over payload might not worry so much if they had seen that truck overloaded and airborne time and time again trying to find what breaks first .

In the absence of extensive durability test information, the best predictor of what will break first is what has broken first on similar products in use. Tires were the first component to fail for many owners. Grand Design changed tire suppliers and upsized tires (a little bit). They are adding V braces to hangers on some models after several of us have had hangers break. Complaints about weak (1950s technology) electric brakes has led to the availability of hydraulic disc brakes on heavier models. Overloaded springs has been a fairly often discussed weakness. Across several years of forum discussions, there has been little or no mention of frame or pinbox problems.

My "2 cents worth" . . .
(another) Rob

[TucsonJim]

Across several years of forum discussions, there has been little or no mention of frame or pinbox problems.

Rob - I don't know if it was on one of the previous forums or FB pages I used to belong to. But I have seen broken welds on frames that led to shifting internal and external structures and fiberglass failure. I'm not sure if you can attribute that to a defective weld or over-stress.

Jim

[TucsonJim]

How is that even possible??? That means they added 6,000lbs+ of stuff! We are full time now and we added 1,600lbs - and that includes a washing machine.

When I talked to the guy, he had sold his house and I guess he needed a lot more stuff than he thought he had. Literally, every nook and cranny was jam packed with stuff, including tools. I wouldn't be surprised if he was a retired anvil salesman and took some to the products along with him.

Jim

[Second Chance]

... I wouldn't be surprised if he was a retired anvil salesman and took some to the products along with him.

Jim

Rob

[Cate&Rob]

I did see a Momentum owner remove thousands of pounds of the products he sells . . . before taking his Momentum in to the Factory Service Center for "failed springs" .

Rob

[Oregon Fun-Guy]

I am not an engineer, but find it interesting that on my trailer the GVWR = UVW + The weight of the liquid storage tanks full of water. This makes it difficult when camping for 5 or more days to not "overload" the trailer. Since discovering this calculation, I have been wondering how much work actually goes into the calculation of the GVWR.

Norm

[Cate&Rob]

Oregon Fun-Guy
Hi Norm,

Agreed that some models have GVWR too close to UVW. But, the liquid weight carried for dry camping should be limited to the capacity/weight of the fresh water tank. The waste tanks would start out empty and the fresh water would be transferred to the waste tanks.

Rob

[Oregon Fun-Guy]

Oregon Fun-Guy
Hi Norm,

Agreed that some models have GVWR too close to UVW. But, the liquid weight carried for dry camping should be limited to the capacity/weight of the fresh water tank. The waste tanks would start out empty and the fresh water would be transferred to the waste tanks.

Rob

Hi Rob, That's exactly what I do when I go dry camping. I fill up the fresh water tank and add gear that typically keep me under but close to the GVWR, but the grey and black water tanks fill up in about 5 or 6 days which puts me overweight until I can get to a dump facility. Of course I am using fresh water during this time and partially refilling this tank so the trailer becomes 700 - 800 pounds overweight. During this process the axles got bent. It was clearly stated to me that I was overweight so the axles bent. That is another story that I won't get into now.

[Beachcamper]

I assumed a full freshwater tank was not part of the UVW and any water in that tank would be added to the UVW? Our tank is 54 gallons which would add 432lbs to the axle area. After my conversations with Lippert, failed hanger incident and now dealing with slide box have been thinking best practice for me when dry camping is to buy one of those water tanks that you can fill up on your truck bed. When finally at campsite, fill freshwater tank with 30 gallons and have a blue boy I can dump out that water from the grey tanks before I leave.

[howson]

I assumed a full freshwater tank was not part of the UVW and any water in that tank would be added to the UVW? Our tank is 54 gallons which would add 432lbs to the axle area. After my conversations with Lippert, failed hanger incident and now dealing with slide box have been thinking best practice for me when dry camping is to buy one of those water tanks that you can fill up on your truck bed. When finally at campsite, fill freshwater tank with 30 gallons and have a blue boy I can dump out that water from the grey tanks before I leave.

Your assumption is correct. The rig's owners manual has quite a bit of info related to this exact topic.

I bought small, 5 gallon bags since my motorcycle takes up so much space in the truck bed (can't put a large tank back there--no room). The dumping part might be delayed for a period if at a Harvest Host site overnight. ("Navy" showers!) The DW and I have done much boondocking (yet) so it will be interesting to experience if reality meets expectations.

[315RLTSinPA]

That's the problem with most rv manufacturers. They don't put heavy enough components on the suspension. I think all parts of the suspension should be rated at or above the full GVWR of the trailer. None of this subtract the tongue/pin weight, then down size the suspension for the balance of the weight.

[Beachcamper]

Your assumption is correct. The rig's owners manual has quite a bit of info related to this exact topic.

I bought small, 5 gallon bags since my motorcycle takes up so much space in the truck bed (can't put a large tank back there--no room). The dumping part might be delayed for a period if at a Harvest Host site overnight. ("Navy" showers!) The DW and I have done much boondocking (yet) so it will be interesting to experience if reality meets expectations.

Howson, I was looking at these collapsible tanks. You can unload your motorcycle and head off to find a water source to fill the tank it collapse down to the size of a football when not in use.

https://www.amazon.com/AQUATANK2-Wat...2745256&sr=8-9