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I don't fear operating at GVWR, change my mind :)

 
Old 03-16-2019, 10:21 AM
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Default I don't fear operating at GVWR, change my mind :)

Hi,

I'd like to put forward why I don't fear operating at GVWR. My F150, unladen, has a measured FAW of 3100 and FAWR of 3375, which means that I'm operating at 92% of my FAWR ever single mile of its existence... by design straight from Ford. Now, since people's experience shows that the front axle is proven reliable to operate at >90%, I'll surmise that the much simpler (mechanically speaking) rear axle can do the same. Further, if each axle can do it seperately, I don't see they can't do simultaneously and therefore I would expect the vehicle operating near or at its GVWR could be very reliable. My suspicion is that replace rubber/suspension joints sooner could be induced by such an operation, but that's not all that poor of an outcome.

I am curious for some counter-discussion, you might even convince me that I'm wrong!

Edit: I had an interesting extra thought. With three additional adults (600 lbs) in my cab, I would like exceed my FAWR. Does that mean its unsafe to drive my F150 with four male adults in the cab?

Best,

-kehyler

Last edited by kehyler; 06-12-2019 at 07:41 AM.
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Old 03-16-2019, 11:01 AM
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I don't have a problem with driving a truck loaded to the GVWR occasionally. Even slightly over GVWR for short distances on rare occasions. There has probably never been anyone who didn't overload their trucks from time to time.

But I don't think it is a good idea to do so on a daily basis, especially in mountainous areas. The truck will pull its guts out and not last as long. You see people with 1/2 tons that buy trailers rated near the trucks limits, but by the time those trucks are 10 years old they are worn out. But you see a lot of 20-30 year old 3/4 ton trucks out there still chugging along that have been pulling the same weight. But it is only 75-80% of what they are rated for.
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Old 03-16-2019, 11:25 AM
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Originally Posted by marshallr View Post
I don't have a problem with driving a truck loaded to the GVWR occasionally. Even slightly over GVWR for short distances on rare occasions. There has probably never been anyone who didn't overload their trucks from time to time.

But I don't think it is a good idea to do so on a daily basis, especially in mountainous areas. The truck will pull its guts out and not last as long. You see people with 1/2 tons that buy trailers rated near the trucks limits, but by the time those trucks are 10 years old they are worn out. But you see a lot of 20-30 year old 3/4 ton trucks out there still chugging along that have been pulling the same weight. But it is only 75-80% of what they are rated for.
Agreed, nothing wrong with loaded to the max, but wear and tear on everything is increased, so parts will wear more. Going OVER though, that is a different story. Sure the truck can handle it, but not for long, and it puts the driver into a liability situation that were something to happen, injuries happen, etc. then they are 100% liable regardless of fault. Not talking Law or such, but civil liability. Frankly, if one needs to load the truck beyond it's rated capacity all the time, get a bigger truck. If towing a heavy trailer down the street once in a while though, I see nothing wrong with that.
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Old 03-16-2019, 11:45 AM
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Default Estimation Effort

I don't think it's an issue to be there either, that's why the rating exists. To me the bigger issue is that if I do a mediocre job of estimating weight's and I'm at 75% of capacity, I'm probably still fine. With less of a buffer, one needs to put in more effort to insure what the actual weights are to insure you're still safe.

In short, it's just easier to be well within spec because it takes less effort to insure you still are.
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Old 03-16-2019, 11:56 AM
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Originally Posted by 2018LLB4x2 View Post
I don't think it's an issue to be there either, that's why the rating exists. To me the bigger issue is that if I do a mediocre job of estimating weight's and I'm at 75% of capacity, I'm probably still fine. With less of a buffer, one needs to put in more effort to insure what the actual weights are to insure you're still safe.

In short, it's just easier to be well within spec because it takes less effort to insure you still are.
I agree with this. (I have a very, very accurate weight estimates of my truck. They are probably accurate to within 1% lbs on both axles.)
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Old 03-16-2019, 12:00 PM
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Originally Posted by marshallr View Post
I don't have a problem with driving a truck loaded to the GVWR occasionally. Even slightly over GVWR for short distances on rare occasions. There has probably never been anyone who didn't overload their trucks from time to time.

But I don't think it is a good idea to do so on a daily basis, especially in mountainous areas. The truck will pull its guts out and not last as long. You see people with 1/2 tons that buy trailers rated near the trucks limits, but by the time those trucks are 10 years old they are worn out. But you see a lot of 20-30 year old 3/4 ton trucks out there still chugging along that have been pulling the same weight. But it is only 75-80% of what they are rated for.
I agree with what you said, but I'd like to add one thing. My opinion, is that it usually isn't desirable to have a truck that doesn't "wear out" at all from an efficiency perspective. I likely bought too much truck for the task if it never feels taxed.

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Old 03-16-2019, 08:04 PM
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Interesting discussion here. I often hear the superduty lasts forever and it's only partially loaded up, but the design requirements are so much higher for a superduty than an F150. Unloaded, by design, an F150 won't last like a superduty. Ford considers an F150 a consumer vehicle, and the superduty is designed to a different standard because it is not viewed the same by the manufacturer.

That superduty is designed for the 1% use case of the hardest possible scenario. The F150 is designed to a lower life target and to an average use cycle. Those 1% extreme users will probably experience a lower life than a 50% typical used would. But that 1% extreme users may also be operating outside of the ratings.

My opinion is that operating to the maximum is acceptable and meets the design constraints that Ford was using when setting those standards. The key bit of info we don't have is the expected life target and assumptions at those limits that form the design constraints.

I'm 100% confident that Ford has validated that the truck will operate at max limits and meet their life target, but we don't know what the designed life target is or what the assumed duty cycle and variables are for that life target.

If your real world scenario doesn't match the assumptions and use case of the validation, then you are in uncharted territory and no one knows what will happen.

It's hard to argue that maxing out will put more stress in the wear components like the brakes and clutches in the transmission. Your bearings will be under more load, but may be perfectly acceptable or may have a shorter life curve based on the design on a case by case basis. Your cooling system will be taxed harder. Again, what are the design targets and assumptions on that system?

In the end, where do I stand? I don't know... Run it maxed out when you need to, it's rated for it. But, know that you could end up in uncharted territory from an overall life expectancy.
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Old 03-17-2019, 08:22 AM
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I guess you can say it’s true if you only consider the static vertical loads on the vehicle. When hauling and towing at GVWR there’s other forces to consider though.
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Old 03-17-2019, 08:26 AM
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Originally Posted by markag View Post
Interesting discussion here. I often hear the superduty lasts forever and it's only partially loaded up, but the design requirements are so much higher for a superduty than an F150. Unloaded, by design, an F150 won't last like a superduty. Ford considers an F150 a consumer vehicle, and the superduty is designed to a different standard because it is not viewed the same by the manufacturer.

That superduty is designed for the 1% use case of the hardest possible scenario. The F150 is designed to a lower life target and to an average use cycle. Those 1% extreme users will probably experience a lower life than a 50% typical used would. But that 1% extreme users may also be operating outside of the ratings.

My opinion is that operating to the maximum is acceptable and meets the design constraints that Ford was using when setting those standards. The key bit of info we don't have is the expected life target and assumptions at those limits that form the design constraints.

I'm 100% confident that Ford has validated that the truck will operate at max limits and meet their life target, but we don't know what the designed life target is or what the assumed duty cycle and variables are for that life target.

If your real world scenario doesn't match the assumptions and use case of the validation, then you are in uncharted territory and no one knows what will happen.

It's hard to argue that maxing out will put more stress in the wear components like the brakes and clutches in the transmission. Your bearings will be under more load, but may be perfectly acceptable or may have a shorter life curve based on the design on a case by case basis. Your cooling system will be taxed harder. Again, what are the design targets and assumptions on that system?

In the end, where do I stand? I don't know... Run it maxed out when you need to, it's rated for it. But, know that you could end up in uncharted territory from an overall life expectancy.
This was a great reply btw.

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Old 03-17-2019, 08:27 AM
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Originally Posted by 8100hd View Post
I guess you can say it’s true if you only consider the static vertical loads on the vehicle. When hauling and towing at GVWR there’s other forces to consider though.
SAE J2807 was a hauling and towing test, and that determined the GVWR. So I'm unsure what other forces we need to look at.

Edit: I was mistaken, SAE J2807 only determines GCWR, as pointed out by 8100hd below. Apologies.

Last edited by kehyler; 03-21-2019 at 07:56 AM.
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