EcoDiesel GVWR Limiting Factor

[ryandoubleu]

Does anyone know the limiting factor the JTRD? The GVWR is 6450 and payload is 985. I scaled it with m the tank full and me in it and I was already at 6020. The front axle has a 3400# rating and the rear axle is 3750# so those are not the issue. With my family and camping gear loaded up I would probably end up at or a little above the gvwr.

Sponsored

 

[Mr._Bill]

The diesel engine is a 400 pound add over the gas model. The towing limits are a result of the cooling restrictions imposed by the vehicle design. The diesel performance has to be limited to a level that can be cooled by the airflow available.

 

[ShadowsPapa]

Ratings are based not just on axle specs - the truck is a whole system of things, capabilities of all of the parts. Cooling, transmission, clutch (if equipped), frame and mounting components, and more.

 

[ryandoubleu]

The diesel engine is a 400 pound add over the gas model. The towing limits are a result of the cooling restrictions imposed by the vehicle design. The diesel performance has to be limited to a level that can be cooled by the airflow available.

I’m not concerned about tow capacity, only payload. Payload is not dependent on tow capacity. I just don’t know how far beyond gvwr I can go without damaging the component which is the limiting factor.

 

[ShadowsPapa]

I’m not concerned about tow capacity, only payload. Payload is not dependent on tow capacity. I just don’t know how far beyond gvwr I can go without damaging the component which is the limiting factor.

Payload is still dependent on cooling. Load a truck up real heavy and you can over-heat things. I used to drive my grain trucks as full as I could get them - and on a warm day that extra load made them run hotter. Not too hot, but it takes power to pull the weight of the truck. The side effect of burning fuel to pull the weight of the truck is heat output. The cooling system must handle that heat.
More weight, you burn more fuel, you create more heat. Pulling a trailer isn't that much different than hauling more payload in a way.

 

[869 KPH]

I’m not concerned about tow capacity, only payload. Payload is not dependent on tow capacity. I just don’t know how far beyond gvwr I can go without damaging the component which is the limiting factor.

The answer I'm hearing is that you won't be damaging anything, just possibly overheating your engine. So just, uh, don't do that and you should be fine.

 

[ryandoubleu]

Payload is still dependent on cooling. Load a truck up real heavy and you can over-heat things. I used to drive my grain trucks as full as I could get them - and on a warm day that extra load made them run hotter. Not too hot, but it takes power to pull the weight of the truck. The side effect of burning fuel to pull the weight of the truck is heat output. The cooling system must handle that heat.
More weight, you burn more fuel, you create more heat. Pulling a trailer isn't that much different than hauling more payload in a way.

Agreed.

The part I question though is carrying an additional 550 lbs over gvwr would put me at 7k which should be less strain on the cooling system than towing a 2000lb trailer which would give a combined weight of 8k. So to me, for just carrying capacity, the cooling system is not the limiting factor to gvwr.

 

[ryandoubleu]

Payload is still dependent on cooling. Load a truck up real heavy and you can over-heat things. I used to drive my grain trucks as full as I could get them - and on a warm day that extra load made them run hotter. Not too hot, but it takes power to pull the weight of the truck. The side effect of burning fuel to pull the weight of the truck is heat output. The cooling system must handle that heat.
More weight, you burn more fuel, you create more heat. Pulling a trailer isn't that much different than hauling more payload in a way.

Is it possible that the payload is generated based on the vehicles combined weight rating?

 

[Mr._Bill]

Personally, I don't think the extra 500 pounds would be a big issue, at least not enough to lead to catastrophic component failure. If the weight is high enough on the vehicle to affect the center of gravity, that would be a different set of problems to worry about.

Exceeding the manufacturers listed payload capacity is never recommended. It happens frequently. It is usually not mentioned, unless the vehicle is in an accident or the State is one that monitors vehicle weights.

 

[ShadowsPapa]

The answer I'm hearing is that you won't be damaging anything, just possibly overheating your engine. So just, uh, don't do that and you should be fine.

No, that's not it - that's just ONE limiting factor. I laid out others - such as the frame, the mounting points of the cab and box to the frame, a whole list of factors. I was only describing how the cooling system factors in to payload and towing.

 

[MattK]

This is a video for Australia where they seem to monitor GVWR very closely but it's kinda fun:



It's super easy to overload a passenger vehicle. Especially when you don't account for the passengers! :D On my two week trips to nowhere Mexico I easily surpassed the weigh of my 2-door JK with all the water and fuel I needed, not to mention recovery and camping gear. Saggy rear end even on an AEV 3.5" suspension.

 

[ShadowsPapa]

Agreed.

The part I question though is carrying an additional 550 lbs over gvwr would put me at 7k which should be less strain on the cooling system than towing a 2000lb trailer which would give a combined weight of 8k. So to me, for just carrying capacity, the cooling system is not the limiting factor to gvwr.

It shouldn't be - trailers present wind resistance, a different sort of load on the engine cooling.
I'm with Mr_Bill on this, too - I don't recommend going over, especially not on a regular basis - but I don't think you are going to destroy anything. Sounds like it's for a vacation, not for a long-term or regular thing. Try to keep things light but I'd not sweat a bit over.

I had a friend get pulled over by Iowa "enforcement" for being over with his dually Ford truck - they said he was hauling dogs for hire. They were his dogs......... but they pulled him over and weighed his truck. He fought and won because he was not for hire but still.............

 

[ryandoubleu]

It shouldn't be - trailers present wind resistance, a different sort of load on the engine cooling.
I'm with Mr_Bill on this, too - I don't recommend going over, especially not on a regular basis - but I don't think you are going to destroy anything. Sounds like it's for a vacation, not for a long-term or regular thing. Try to keep things light but I'd not sweat a bit over.

I had a friend get pulled over by Iowa "enforcement" for being over with his dually Ford truck - they said he was hauling dogs for hire. They were his dogs......... but they pulled him over and weighed his truck. He fought and won because he was not for hire but still.............

Yes it would only be short term for family camping trips.

 

[LostWoods]

It's typically a safety factor on the axles and the suspension tuning but it can be the frame too. You can't add both GAWR values to come up with a GVWR number because someone will inevitably stick that entire capacity in the bed and exceed the rear axle. Most else can be ruled out on the basis the truck tows and would be expected to tow some without trailer brakes.

I have to disagree on the cooling comments though... from a powertrain perspective, the stresses are all the same if not worse. The powertrain sees no difference whether that weight is in the bed or out back other than the added strain on the wheel bearings. IMO if you aren't exceeding individual axle ratings, you'll be fine.

 

[cecaa850]

Let's not forget the load factor of the tires.

Sponsored