GAWR (axle) stickers for regular/max tow and EB/PB

[Wengg77]

I wish that was the case as I could give up the 20" wheels but this truck (post #33) is almost the same, has the 20" wheel and it has the 4150lb rating. Only difference I can find is the 3.5L or possibly the FX4 package.
https://www.f150gen14.com/forum/thr...-for-regular-max-tow-and-eb-pb.872/post-13052

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[Roger350]

OK, I think we are all chasing down a rabbit trail and may need to stick our heads up and look around and look for a new perspective.

Other than the 4800 lb rear axle, which may in fact be something different than all the others, I'm going to throw out the possibility that there are only really two distinct axles for the F-150, the 8.8" and the 9.75."

We all (including myself), have been seeing these axle weight ratings and assuming there is something physically different between these axles. Like a 4150 lb GAWR axle is a different design and part number from a 3800 lb GAWR axle.

I don't think that is really the case.

The GAWR may in fact have nothing to do with the axle design, and everything to do with the Vehicles Center of Gravity (CG).

Ford has provided us weight ratings we must follow for towing / hauling. They gave us the GVWR, which is the absolute heaviest weight our truck is rated for. If you put your truck on scales and it exceeds the GVWR you have exceeded the the design capability of that truck.

They also give us the Payload capacity, which should be the GVWR - Curb Weight. That just shows how much weight we can add in people and stuff.

Then they give us the Front and Rear GAWR which our the weight limits for the front and rear axles. In most cases, the front and rear GAWR numbers add up to a number higher than the GVWR. This didn't make complete sense to most of us, and we wrote it off as the fact that the axles must not be the limiting factor on the GVWR, it must be the frame, or the powertrain / gearing which all factor into the GVWR.

I now think the GAWR are there because going back to the scales, you get readings on both axles separately.

So in order to ensure you are within the design limitations of your truck, you have to compare the total weight calculated by the scales to the GVWR. The total weight cannot exceed the GVWR or you are over limit.

Then you have to look at the Front Axle weight and compare it to the Front GAWR. Again, the scale weight must show lower than the GAWR, or you are over the limit.

Finally you compare the Rear Axle weight to the Rear GAWR. The scale weight must show lower than the GAWR or you are over the limit.

Any of these three comparisons can throw you over the limit. But as long as you are not over the GVWR, you can move things around in the truck to try and correct the front and rear axle scale readings to be within the GAWR limitations.

Based on all that (TLDR I know), the GAWR has way more to do with the wheelbase and where the weight of Ford components like the drivetrain, power tailgate, etc, fall with respect to the Forward and Aft positioning , and where that positions the Truck's Center of Gravity.

With the FWD/AFT location of the CG defined, they then set the GAWR such that loading extra weight into the vehicle, either with people, gear, or even a trailer tongue weight, does not shift the CG to an unacceptable position. Because a CG too far forward would make the already overloaded front brakes work too hard, and might make the truck difficult to steer. And a CG position too far AFT would lift the front end too much making it understeer, and would allow the tail to wag the dog so to speak.

So I think the GAWR is not an indication of how heavy duty the axle design is, it is limitation set based on an acceptable range of positions for the truck's CG so that it drives and handles in a predictable manner.

 

[Crapblaster]

This is for my 2021 King Ranch with no tow package and powerboost.

 

[daemonic3]

This is for my 2021 King Ranch with no tow package and powerboost.

Impressive! No moonroof or spray liner? Is this a 601A or 600A? Actually, can we just see the window sticker? I haven't seen a powerboost this high yet!

 

[Crapblaster]

Impressive! No moonroof or spray liner? Is this a 601A or 600A? Actually, can we just see the window sticker? I haven't seen a powerboost this high yet!

No moon roof, liner or fx4. It is a 601A though.

 

[Camptruck]

Thanks for this data point! It matches the King Ranch 3.5EB maxtow that I physically saw. It is making me question the other data point in my sheet that says 3.5EB but rear was only 3800#. I want to go try to find that source, as it is mind boggling there are 2 rear axles for 3.5EB max tow....

From the specs document (section below) a 4x2 with can have rear GVWR of 3800 if not max tow or 4150 with max tow. A 4x4 only has 4150 with or without max tow. So something is definitely off with that line.

 

[kavm]

OK, I think we are all chasing down a rabbit trail and may need to stick our heads up and look around and look for a new perspective.

Other than the 4800 lb rear axle, which may in fact be something different than all the others, I'm going to throw out the possibility that there are only really two distinct axles for the F-150, the 8.8" and the 9.75."

We all (including myself), have been seeing these axle weight ratings and assuming there is something physically different between these axles. Like a 4150 lb GAWR axle is a different design and part number from a 3800 lb GAWR axle.

I don't think that is really the case.

The GAWR may in fact have nothing to do with the axle design, and everything to do with the Vehicles Center of Gravity (CG).

Ford has provided us weight ratings we must follow for towing / hauling. They gave us the GVWR, which is the absolute heaviest weight our truck is rated for. If you put your truck on scales and it exceeds the GVWR you have exceeded the the design capability of that truck.

They also give us the Payload capacity, which should be the GVWR - Curb Weight. That just shows how much weight we can add in people and stuff.

Then they give us the Front and Rear GAWR which our the weight limits for the front and rear axles. In most cases, the front and rear GAWR numbers add up to a number higher than the GVWR. This didn't make complete sense to most of us, and we wrote it off as the fact that the axles must not be the limiting factor on the GVWR, it must be the frame, or the powertrain / gearing which all factor into the GVWR.

I now think the GAWR are there because going back to the scales, you get readings on both axles separately.

So in order to ensure you are within the design limitations of your truck, you have to compare the total weight calculated by the scales to the GVWR. The total weight cannot exceed the GVWR or you are over limit.

Then you have to look at the Front Axle weight and compare it to the Front GAWR. Again, the scale weight must show lower than the GAWR, or you are over the limit.

Finally you compare the Rear Axle weight to the Rear GAWR. The scale weight must show lower than the GAWR or you are over the limit.

Any of these three comparisons can throw you over the limit. But as long as you are not over the GVWR, you can move things around in the truck to try and correct the front and rear axle scale readings to be within the GAWR limitations.

Based on all that (TLDR I know), the GAWR has way more to do with the wheelbase and where the weight of Ford components like the drivetrain, power tailgate, etc, fall with respect to the Forward and Aft positioning , and where that positions the Truck's Center of Gravity.

With the FWD/AFT location of the CG defined, they then set the GAWR such that loading extra weight into the vehicle, either with people, gear, or even a trailer tongue weight, does not shift the CG to an unacceptable position. Because a CG too far forward would make the already overloaded front brakes work too hard, and might make the truck difficult to steer. And a CG position too far AFT would lift the front end too much making it understeer, and would allow the tail to wag the dog so to speak.

So I think the GAWR is not an indication of how heavy duty the axle design is, it is limitation set based on an acceptable range of positions for the truck's CG so that it drives and handles in a predictable manner.

Excellent post!

All the payload discussion focuses on the axles and differences in axle specification. However, I have seen no mention of the springs. Aren't the springs directly influencing the payload? My sense is that Ford is not varying the springs by the trim/options/tow packages much and that's why the payload is low...

 

[daemonic3]

Excellent post!

All the payload discussion focuses on the axles and differences in axle specification. However, I have seen no mention of the springs. Aren't the springs directly influencing the payload? My sense is that Ford is not varying the springs by the trim/options/tow packages much and that's why the payload is low...

I believe the springs are matched to the axle rating for either front or rear... All I could come up with was the frame rating, axle (with matching springs) rating, tire rating, and brake/accel capability as what may limit the payload (when taken across the whole vehicle). I feel like the braking ability would not come into play for stationary curb weight vs GVWR, it would only affect the max towable GCVWR. I am not an auto expert so I'm just trying to reverse engineer how they do it. Tires (summed) are more capable than the axle according to specs, but they SHOULD be as going over bumps and whatnot the instantaneous load can be uneven so you want margin there. So that left frame as my theory. I like Roger's addition of center of gravity though! That's a really good point. Unloaded the center of gravity is also very front heavy while loaded it likely is rear heavy, plus going over bumps/dips the load is not distributed equally so you need margin per axle, so that's why I wanted to figure out their derating factor (which looks inconsistent in PB with more axle margin than EB with less axle margin). Anyway, streaming too many thoughts and probably not making sense here so I'll stop.

Here is where the spring ratings I saw were. It sure looks like they match it to the axles.

 

[kavm]

@daemonic3 - I was just trying to understand why PB trucks have a low payload. I believe that it is not the axle ratings that are driving it but the fact that the weight of the batteries has added while not upgrading the springs.

 

[daemonic3]

@daemonic3 - I was just trying to understand why PB trucks have a low payload. I believe that it is not the axle ratings that are driving it but the fact that the weight of the batteries has added while not upgrading the springs.

Gotcha. I think they *did* upgrade the springs with the axles. It just wasn't by more than the whole hybrid system weighs (300 upgrade vs 550 weight).

Can you imagine how many would buy the powerboost if you could get the HDPP? It would surely cannibalize the superduty sales until they integrate the hybrid propower and 12" screen over there! (the superduty length is still a showstopper for me but not most folks)

 

[lcrain]

Gotcha. I think they *did* upgrade the springs with the axles. It just wasn't by more than the whole hybrid system weighs (300 upgrade vs 550 weight).

Can you imagine how many would buy the powerboost if you could get the HDPP? It would surely cannibalize the superduty sales until they integrate the hybrid propower and 12" screen over there! (the superduty length is still a showstopper for me but not most folks)

I was going to buy a 250, but they are just huge. I wouldn't be able to park in my spot at work because it is too tall. Length is an issue for me as well.

I would probably consider the powerboost if it fit within my payload needs.

 

[daemonic3]

I was going to buy a 250, but they are just huge. I wouldn't be able to park in my spot at work because it is too tall. Length is an issue for me as well.

I would probably consider the powerboost if it fit within my payload needs.

It's a tough spot to be in! I'm just shedding 400# of rear bed weight and moving some chairs from my trailer tongue to behind the axles. Then I will be at parity/ahead of my current XLT. But with a 250 it wouldn't even matter!

I'm amazed at how often the answer is just "get a 250!" when they may not work in cities or dense urban areas. A supercrew superduty is minimum 15" longer and my F150 is *already* hard to park everywhere and sticks out into the lanes at my condo's parking garage.

 

[Crapblaster]

Here are the axle and spring pics. Maybe someone will compare these to a Max Tow and see if they are the same. Mine doesn't have any kind of tow package. Mine also came with a Yaw sensor kit.

 

[Wengg77]

All trucks I've seen with the Max Tow package have the 3 leaf rear suspension. I want to confirm if all trucks with the 3 leaf rear suspension have the upgraded rear axle. I thought they would but want to confirm, could explain why the 5.0 with max tow I was looking at only had 3800lb RAWR.
It was mentioned that the pumpkin is different on these upgraded axles. I'm planning on stopping by a dealership in the next couple days to snap some pics of the rear diffs from some different trucks. Any other pics that would be helpful? Probably won't be getting inside any of the trucks.

 

[Roger350]

All trucks I've seen with the Max Tow package have the 3 leaf rear suspension. I want to confirm if all trucks with the 3 leaf rear suspension have the upgraded rear axle. I thought they would but want to confirm, could explain why the 5.0 with max tow I was looking at only had 3800lb RAWR.
It was mentioned that the pumpkin is different on these upgraded axles. I'm planning on stopping by a dealership in the next couple days to snap some pics of the rear diffs from some different trucks. Any other pics that would be helpful? Probably won't be getting inside any of the trucks.

Yeah the 8.8" Axle pumpkin is a squarish shape pretty symmetrical from left to right, whereas the 9.75" Axle pumpkin is not the same left to right. It's hard to describe the shape. I was hoping Crapblaster got a shot of the pumpkin.

I'd really like to see if the axle part number on the stickers in Crapblaster's pictures is the same as the Max Tow axle. I guess if you can get a pic of those stickers for a truck with an EB or PB with Max Tow we'll know if the axles are the same with and without Max Tow.

That way, if I call my dealer and find out my truck still hasn't been scheduled, and that I'm getting hit with the $650 price increase for Max Tow, I can at least decide If I'm willing to ditch it to save money. We're already paying double for almost all of the content of Max Tow on a Powerboost Truck. And with the low payload numbers most of the 1,400 lb increase in trailer weight for a Max Tow truck cannot even be realized because the tongue weight is eating up all the payload, so Max Tow looks even more expensive and useless. It basically just becomes slightly larger rear brakes and the ability to get the tow mirrors. Those are some very expensive brakes and mirrors.

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