Usually payload goes before trailer weights. If you have 3500 payload, and the pin on a 19K trailer is 20%, you are 300 over payload.

 

Nobody's answering his question as to why there's a difference.

Pin weight is pin weight.

So why is one greater than the other one if all things are =

In other words, if I have a payload of 3,000 lb, why is one trailer greater than the other?

 

Because it Ford and they can rate it at what they want. Probably for reasons mentioned above.

And I personally wouldn’t surpass 17k with a 5th wheel on a SRW 350.

 

Let's leave personal decisions out of this, let's just talk about Ford and what if they've published. I've said many times in the past that they are suggested number and I get attacked for that. So let's work with the straight facts.

 

Ford knows 5th wheel means more truck payload, people etc and limits it. Thats what they say that truck can 5th wheel.

And yeah personally how much more than 17k can you go without going over GAWR? Assuming you have a few people in the cab as well.

 

Our work trailers dont exactly have anything not bolted down. So theyre designed to err towards extra nose weight, for stability.

Horse trailers arent exactly adjustable either. Cabin up front, cargo mid, horses on the rear. I guess they can walk aroumd a bit......

Typical 5'ers and TT's have a large forward compartment, for the same thing. And under bed storage. Beds should be up front.

Adjusting aft, to make it easier for the truck to tow, doesnt work well. Itll cause the trailer to lift the trucks rear axle over bumps. Rediucing grip and causing sway, and eventually a wreck. Tongue weight should be substantial. The usual 10% is a bit light.

So tongue weight is proportional to overall trailer weight. If 15% overloads the truck, moving that weight back, to reduce tongue weight to 8%, is a massively bad idea. Ive done it. Survived, but lesson learned. Its better to just get a truck thats bigger, doesnt sag, and has tires that dont get crushed by all of that weight.

Although we're wasting our breath. The average 5'er is a comedy of poor choices.

With our SRW trucks, it was pretty obvious that the tires were often the weak link. At 88psi, and still being clearly crushed by the weight.

We do have a few stubby trailers, where the tongue weight is so low, that the trailers dual or triple axles wont let the tounge drop, when the jack is raised. Thats right, jack off the ground, and the nose of the trailer just kinda hovers there. Technically the tongue is still over 10%, its just that the trailers front axle supports that 10% OK. Believe me, it's sketchy as heck. Only the heaviest crane trucks, 550-600, tow those.

 

My SRW F-350 is rated by the towing calculator for 3,566 for Gooseneck and 3,540 pounds for 5th wheel.

As someone who is NOT an expert do I know why? Heck no. But as best I can tell the connections I would have to make if/when a 5th-wheel or gooseneck is being installed actually is a bit different. I'm assuming the overall weight is distributed the same way for both types of hitches? I'm pretty sure the typical 5th wheel hitch is heavier than is the gooseneck but I think that should be viewed as payload rather than pin weight?

For me the difference in the ratings is really just 26 pounds and as I see it that probably means they have software set up which looks at how it calculates the stresses under load and it kicks out a fairly trivial difference so that's what I've got. Heck, the Ford engineers may not know exactly why the difference.

I'm just going to be sure that I stay below either number. Given that things can bounce and jerk around I figure it's probably wisest to keep the pin weight at 80% or less of the lowest of the two ratings. If I need to pull something heavier than that then I probably need to get a DRW and let someone else have my SRW.

Fortunately I don't need to push the limits. I won't.

 

Appreciate it all the feedback.

I'm still puzzled by this specific truck I'm looking at and what it spits out as the limits for 5th wheel vs gooseneck. I get all the "you don't want that much weight" debate....but out of the 20 or so trucks I've looked at: This is the only one that I've found that has this weird towing limit difference online. The PDF towing guide suggests it is wrong online....I guess ?

Oh well.

 

I suspect there is no one on Earth who can tell you why that difference exists for that particular truck. I'd bet that the numbers are spit out by a computer based on the various components in that truck.

The computer may have simply had bad input or there is a bug in the software. It might be interesting if you could get a Ford engineer to look at the VIN and the specs and try to figure out the "why" but I'm guessing they'd just shrug and go do something else rather than trying to figure out why the computer spit out those numbers.

 

I suspect you're correct; as an ex-Chrysler engineer and Ford supplier, I've run into similar situations, have known whom to ask and the answer has been some variant of "we probably ran out of X spring or Y axle, and installed Z". The manufacturing systems do indeed print out GVWR stickers based on build content so this is probably the best answer the OP is going to get, short of finding a Ford employee to pull up the assembly record for the truck and interpret it because there isn't going to be a plain-language rationale spelled out.

Just a note that I'm not a Ford employee, not pretending to be one but am a supplier and just providing my opinion.

 

Because a 5th wheel and a gooseneck are different things. Ford's ratings are calculated with the SAE J2807 method which is called out in the document. The limits are going to come from hitting the lower limit of either GAWR, GVWR, GCWR, tire load limit, or performance limits in the dynamic portions of the J2807 tests. You'll find in the subscript that different values are given for what is otherwise the same engine/axle/cab/bed configuration based on whether or not it has the Tremor package, and separately if it has the all season tires or all-terrain tires as those tires have different load limits.

Goosenecks and 5th wheels place the weight on the truck differently even if the pin weight is the same. The gooseneck is putting all the weight at a single point lower and slightly in front of the rear axle where the 5th wheel with its hitch is putting the weight higher up and farther back and also importantly with more leverage against the truck compared to the gooseneck. The ride height difference of the Tremor is also going to change the spread of how the weight sits on the axles as well. Then the J2807 method isn't just the truck sitting still on some scales, although that is part of it. It also includes dynamic tests that can be failed. You can get all the details here, but the short of it is if the tail isn't well short of wagging the dog it will fail. https://www.motortrend.com/how-to/15...s-the-standard

So since we know axles, tires, springs, etc. are the same yet the gooseneck is rated higher, the answer usually is goosenecks out perform 5th wheels in the dynamic portion of the J2708 tests allowing them to run more heavily loaded before failing because of sway or whatever. (My own conjecture on this, the 5th wheel hitch gives the trailer a 2-3 ft lever against the truck that the gooseneck doesn't have, so the tail will wag the dog more easily.) Sometimes it might be that you hit GAWR or tire load limits earlier with a 5th wheel because of how the weight is carried. On my truck 5th and gooseneck limits are identical because I run out of payload before the 5th vs gooseneck difference would matter.

 

As a mechanical engineer this is what I would have said too. In a nutshell, the moment (twisting) that is induced by the fifth wheel hitch being higher than the goose ball attachment point loads the truck a bit differently.

 

Thank you. I agree with you 100%,. You a much more elegant way of saying it than I would have. I don't agree with how they apply their standards to vehicles out of their weight class, but it is what it is.

I think part of the reason is also, is the braking portion of the test. With all things being equal, a. gooseneck at that weight will stop quicker, due to friction.

Continuing on with devil's advocate, how do you think this applies 5th wheels that have gooseneck attachments?

 

J2807

They follow the rules laid out and use specific equipment to base the ratings on. No two trailers are exactly alike, no two 5th wheels are exactly alike. Goosenecks travel different from 5th wheels, have different pivot points on the vertical plane, and have different axle bridges than each other. So they take the trailer specified by J2807 and use that for their tests.

In the end though, it still comes down to one thing, amount of available payload vs pin weight of trailer. That varies based on weight distribution, which on a 5th wheel cannot be changed but added to, and axle spacing, the further the axles are away from the drive axle the more pin weight there is.