F-450 maxed out payload

[dragonfly]

One thing that always confused me is that heavier axles and heavier brakes poundage wise, is not part of the sprung weight. Granted it is part of the "total" weight of the truck, but how do they affect the carrying capacity of the truck in reduced capacity?

I’m assuming this is all due to derating the GVWR to 14k to keep under the commercial rating system.
If anyone has any answers to this point I would like to hear your thoughts.

[A.Texas.Yankee]

You're thinking logically and real world capability. Logically you're correct in thinking and in real world it would increase capability.

But, this is a government regulation and very rarely (if every?) are those logical.

The GVWR of 14k lbs is based off total weight regardless of where weight is placed. You could put the axles on top of a locomotive and increase the unsprung capability to pull a freight line but obviously would exceed GVWR.

That's government for you.

Newly full timing in our 2021 Momentum 395MS-R with our tow pig being a 2021 F-450 KR

[Jerryr]

Bottom line, SAE J2807 tow ratings include default passenger weight, hitch and cargo weight. It may be complicated, but if someone thinks they are a few hundred pounds over their truck’s rated capacity, double counting cargo weight by not understanding the default cargo weight figure in their vehicle’s capacity ratings could very well matter…and they may not be over. I offer this insight as relevant information for consideration on the topic being discussed, assign it whatever “weight” you deem appropriate in your decision making process.

SAE J2807 is only one limiting factor to consider. It drives me crazy when a friend said his truck is certified to tow 8,000 lbs then looking at his payload sticker and Axle ratings he will exceed those significantly when towing his 3 horse trailer. He tows with a standard hitch rated at 500 lbs rating without a WD hitch. He has no idea what his trailer weighs loaded with horses.


Just today he asked me what my pin weight was on my 14000 lb Reflection. When I told him 2800-2900 lbs when loaded to travel he said can’t believe the manufacture can’t redistribute the weight or move the trailer axles more forward to lighten the pin weight.

In addition to SAE J2807 max towing weight you also need to make sure you don’t exceed
Payload
GVWR
GAWR
Max trailer tongue weigh or max pin weight listed on your hitch

Normally it’s easy to be WELL within Max towing weights listed using SAE J2807 but still exceeding either payload or GAWR found on the Safety Compliance Certification Label..

[Roll With The Changes]

One thing that always confused me is that heavier axles and heavier brakes poundage wise, is not part of the sprung weight. Granted it is part of the "total" weight of the truck, but how do they affect the carrying capacity of the truck in reduced capacity?

It is true that heavier axles, brakes, etc is "un sprung" weight. However, it still has mass and therefore inertia. That extra mass needs more energy to get it moving, more steering force to make it turn and the brakes need to dissipate more heat to get it to stop. Rotating mass makes an even bigger impact on the energy required.

[CWSWine]

Bottom line, SAE J2807 tow ratings include default passenger weight, hitch and cargo weight. It may be complicated, but if someone thinks they are a few hundred pounds over their truck’s rated capacity, double counting cargo weight by not understanding the default cargo weight figure in their vehicle’s capacity ratings could very well matter…and they may not be over. I offer this insight as relevant information for consideration on the topic being discussed, assign it whatever “weight” you deem appropriate in your decision making process.

The J2807 uses manufacture GVWR/GAWR as pass fail standards. The J2807 only deals with towing capacity and it uses the following.

"TVTW is base vehicle curb weight plus one 68.0 kg (150 lb) driver and one 68.0 kg (150 lb) front seat passenger plus 45.4 kg (100 lb) of optional equipment split evenly between front and rear axles plus the tow-vehicle manufacturer’s available trailering package and/or any required trailering content and representative aftermarket trailering equipment as specified in 5.2. "


The SAE (Society of Automotive Engineers) J2807 States the exceed in Manufacture GVWR/GAWR is reason to fail towing test. (Par 5.4)

http://fifthwheelst.com/documents/to...ds-2016-02.pdf

The J2807 also uses a 10% tongue weight and 15% gooseneck/5th wheel weight. So it set the towing capacity so high that you run out of GVWR/GAWR long before you run out of tow capacity in the real world with tongue/5th wheel weights in real-life running much higher than the testing weights.

Using 15% pin weight at 10,000 pounds would be 1500 pounds but say at 22% it would be 2200 pounds makes a big differance.

[grassmaster]

The J2807 is only a pass/fail test for manufactures' claims for load capicities. Its not a test to determine the failure load, hence it "certifies" the vehicle will handle at least as much weight as the manufacturer claims. It does not consider the factor of safety. Meeting the J2807 implies the vehicle meets the minimum load capacities claimed by the manufacture. It is not intended to provide you with the failure load or the ratio of failure load over design load (margin of safety) What you have is essentially a certified copy of the door sticker. The design factor alone used to be ~ 1.25-1.5 with the margin of safety even higher.
Moral of the story is you won't buy a truck that will break if its 10 lbs of the door sticker.

[Roll With The Changes]

The J2807 is only a pass/fail test for manufactures' claims for load capicities. Its not a test to determine the failure load, hence it "certifies" the vehicle will handle at least as much weight as the manufacturer claims. It does not consider the factor of safety. Meeting the J2807 implies the vehicle meets the minimum load capacities claimed by the manufacture. It is not intended to provide you with the failure load or the ratio of failure load over design load (margin of safety) What you have is essentially a certified copy of the door sticker. The design factor alone used to be ~ 1.25-1.5 with the margin of safety even higher.
Moral of the story is you won't buy a truck that will break if its 10 lbs of the door sticker.

Excellent point. I would also add that to my knowledge J2807 or any other SAE standard carries no regulatory authority. They are guidelines and comparisons only.

[grassmaster]

Excellent point. I would also add that to my knowledge J2807 or any other SAE standard carries no regulatory authority. They are guidelines and comparisons only.

Exactly. I remember back in the muscle car era when the 427 Fords, 426 Hemi's, 427 and 454 Chevy's were rated a =< 425 HP to get by governmental "street" standards and insurance company standards. Wasn't a one that didn't put out 450-500 hp right off the show room floor.