No.

And it looks like you DO have sufficient understanding about the rear GAWR of your truck. Your post of your certification label proves it.

It is more likely the folks who assert that the rating of YOUR axle as the 16,000 lbs that they may have read in a marketing press release that Dana issued back in 2012 at a commercial vehicle show in Germany, when the M300 family of Salisbury style drive axles was being introduced for Class 1 through Class 5 light commercial vehicles,,, who might not understand enough about GAWR. It is obviously up to you who to believe... the manufacturer of your vehicle who federally certified your GAWR at 9,900 lbs., or some enthusiasts on the internet who determined your axle rating buy catching wind of an advertisement.

What they may not understand is that Dana builds the same named axle... using different parts inside and out, depending on application. A principle feature of the M300 is the use of broader faced gears and tapered roller bearings and a number of other evolved improvements summarized and advertised by Dana as AdvanTEK gears. Dana uses the same AdvanTEK gear technology in their 23,000 lb GAWR truck and bus axles. Yep. The M300 has that technology. Does that mean that Dana uses the same parts? Does that mean the M300 can "really" handle 23,000 lbs, but it is just derated in the pickup for regulatory purposes, as some seem to suggest? The answer to these questions are obvious, so let's look at the not so obvious.

Dana builds axle housing with different material thicknesses, even where the outside diameter measurement is the same. Reducing material thickness to the tubes in Salibury style axles like the M300, as well as in the boxed sections of the one piece banjo housings like the S130 in the previous generation F-450 pickup, saves material cost, and reduces unsprung weight. Maintaining a common outside diameter of the tubing or square ends makes the axles more attractive to OEM buyers like Ford, because fewer styles, types, and sizes of suspension parts like U Bolt plates need to be inventoried to mount the axle to a truck. So an axle of the same name may appear the same on the outside, but the axle housing itself can be rated less in one application, such as the F-450 pickup, versus another application, like the F-550 chassis cab, even though both applications utilize the same product family of axles. Yet the capacities of the different iterations of that product family are different, and are thus rated as such.

The axle housing structural rating plays such a significant role in the final GAWR of otherwise similar, and even identical axles, that Dana significantly DE RATES the same model of axle, with the same material thickness of housing, and with the exact same carrier and gear set, when the application that the axle is mounted to differs. The key differences that Dana specifically cites that would directly result in derating or even eliminating a model of axle as being appropriate are:

• TW (Track Width) – The distance between the dual tire centerlines or the distance between the tire centerlines on a single tire.
• SLR (Static Loaded Radius) – The distance from the centerline of the axle to the ground, underrated tire capacity, with the tire at rest.
• SMC (Suspension Mounting Centers) – The distance between suspension mounting points on an axle.

As most folks who would bother reading this far on an axle topic already know, the TW and SMC of the F-450 pickup are wider than that of the F-450 chassis cab. Hence the terms "wide frame" and "narrow frame". The wider SMC and TW of the pickup are contributory factors in Dana derating the axle. To skirt around the bias of any forum fueled folklore surrounding the M300, let's look at the previous generation F-450 axles for examples, which with their square tube, banjo housing, drop in third member carrier appear to look much more like a big rig axle anyway, which inspires even beefier chest beating bragging rights...

Taking a Dana S130 axle made with nominally 5/16" material thickness (0.31") for the housing:

• 70" Maximum TW = 13,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 64.5"- 65.0"
• 72" Maximum TW = 13,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 66.5"- 67.3"
• 74" Maximum TW = 12,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 68.8"- 69.3"
• 76" Maximum TW = 11,000 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 71.2"

Observe the steep, (1,000 lbs), and then the much steeper (2,500 lbs) drops in GAWRs for every 2" increase (just 1" per side) in track width beyond the 72" standard Dana uses to nominally rate their axles.

Now taking a similarly named Dana S130 axle made with nominally 3/8" material thickness (0.39") for the housing:

• 70" Maximum TW = 15,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 64.2" - 64.88"
• 72" Maximum TW = 15,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 65.0" - 66.5"
• 74" Maximum TW = 14,500 lb GAWR Inner Bearing Shoulder to Inner Bearing Shoulder 68.8" - 69.2"
• 76" Maximum TW = (not rated at this width)

Here is a photo of a Dana S130 axle under a 2015 F-450 pickup... having a wide frame, at 38" frame width (versus the National Truck Equipment Association's standard of 34" frame width, like all narrow frame chassis cabs have, along with every other commercial truck), and as such also having wider suspension mounting centers (SMC), at about 46" SMC (versus the 38" SMC that Dana bases their nominal axle ratings on)... that is indisputably at the widest and therefore weakest end of the available spectrum of track widths that Dana publishes ratings for:



Can one tell from looking at the photo how thick the structural housing material is?

The S14-130 and the S16-130 both have the exact same 4.25" by 4.25" box section width and height. Identical. Yet one uses 8mm thick material in the housing, while the other uses 10 mm.

Can one determine from a four character name, like S130 (or M300)...short hand Dana monikers that cover an entire family of axles having different ratings for different applications and different OEM customers... what specific parts are inside?

Take axle shaft diameters...

• S14-130 Axle root diameter 1.57", spline diameter 1.75", spline count 34
• S16-130 Axle root diameter 1.61", spline diameter 1.89", spline count 36

How many F-450 pickup owners have pulled their rear axle shafts just to count splines and mic diameters in order to try and second guess what their axle is "really" capable of?

Take ring gear size.

This one is too easy. There is the 11.8" ring gear of the S14-110, 111, etc, and then there is the huge honkin 12.2" ring gear of the S16-130.

Let's have a look at the other side of that "S130" under the '15-'16 F-450 pick up... to get a sense of the size of that rear end



And what about the even larger 14.25" ring gear of the yet earlier generation Dana S135? Have a look at that too...



Can one tell, based on a ring gear diameter, or by eyeballing the size of these pumpkins, what the GAWR "really" is?

The fact is, this big rig style Dana S135 axle shown above, with a 5" box section height on the housing, instead of just 4.25", and with it's unquestionably larger ring gear, at 14.2" diameter, that dwarfs the 11 and 12 inch ring gears offered in later models of F-450 and above axles made since, is "only" rated at 13,500 GAWR. There are S16-130 axles, and even M300 Salisbury style axles, each with smaller ring gears, under the same F-550 chassis application, with the same track width, same SMC, and same SLR (same tire and wheel size), that are rated at 14,706 lbs GAWR. So one cannot tell by looking at the size or style or model number of an axle what the rating is or should be or could have been if Ford wasn't so hell bent on fooling the feds at the expense of their own profits just in order to give us secret load carrying capacities not cited on the federal certification label.

Let's forget the fact that the S16-130 is rated for 1,200 lbs more than the S135 for just a minute and review the weight of the iron doing the actual work.

• The standard Dana S16-130 weighs 190 lbs. Add 10 lbs for limited slip.
• The Dana S135 weighs 250 lbs. Add 15 lbs for the True Trac limited slip. So 265 lbs.
• Without brakes or wheels, the S135 has 25% more beef in it's patty than the S16-130.
• Nevertheless, in near equivalent Ford applications that both of these axles were used in, the vegetarian was rated higher.

How can that be? Well, we can look at the S135 axle family. With no change in any of the internal parts of the S135, in other words, same ring gear, same diameter axle shafts, same carrier, same bearings, same everything... same shape housing even... but for 1 mm of difference in material thickness at the spring seat for that housing, the Dana S135 becomes the S150, rated for 15,500 lbs GAWR.

Who can look at an axle and discern a 1 mm difference of material thickness at the spring seat?

So bring this all back up to date with the new line of M300 axles, how thick are the tubes swedged and plug welded into the combo housing/carriers in the various models of M300 rear axles?

I don't know, but Alaska

Warbird's photo of a D-451-A model M300 is posted above.

Here's a a few photos of the D-531-A model M300 on the truck I'm building right now:










I can't see any visual difference between the M300 in AlaskaWarbird's photos, and the M300 in my photos. Except for the label wrapped around the axle tube. But what's a label? A meaningless piece of paper, right? Would Ford save product and production costs by specifying less costly, and more importantly, lighter weight ingredients to axle versions within the same model family that were not intended to be operated above the vehicle's capacity? Are Dana drivetrain engineers crazy to believe that the beam strength of an axle depends on the structural capacity of the axle, which is largely determined by the material properties and thickness the housing is made of?

Some axles housings are made with High Strength Low Alloy steel, to maintain strength while shedding weight. Other axles are not, as they are not intended to be called upon to support a load exceeding their rated capacity, and as such the expense of higher grade steels can be saved. How does one know by looking at a single paragraph press release announcing a new axle family by it's short hand name?

None of the specifications above should be construed as applicable to the OEM versions of axles that Dana produces specifically for Ford, and Ford very likely only publishes some, but not all. of the details that Ford demands Dana build the axles destined for Ford vehicles to be built with. Only a detailed comparative analysis of the Bill of Material number for each and every part produced, along with the details of the application it was produced for, including arcane details like tire diameter, track width, and spring mounted centers, would prove whether or not there is only ONE model of M300, the 16,000 GAWR model.

So Alaska Warbird, that was a long winded way of saying we're in the same boat. I understand just as little about GAWRS as you claim to, perhaps a lot less. But like you, I know how to do simple stuff, like open a car door.

And when it comes to knowing the GAWR of an axle in a given vehicle, that's all the understanding needed.

 

More like 3,750 lbs per wheel. Not a guess.

 

so.... can i put two pallets of pavers on a dana M300 ? LOL

 

I hauled two pallets of stone in my F-550, a couple of times, and I felt every bit of it. It definitely changed the vehicle dynamics. I scaled each time. Average of 5,500 lbs load, with a tare of 11,500.

 

DANG MAN! That's a great analysis! Thank you. I tried to give you reps but it wouldn't let me. Appreciate you taking the time to tell it like it is.

 

I have been saying the same thing!
If someone doesnt stop in time and rear ends another car do they weigh the rig and say " hey, you where under all your weights. Your not at falt?
Of course not, if you hit someone else because you didnt stop in time it's your falt.
If you crossed the middle line and hit someone you are at falt, it is not going to matter why. And it doesnt matter if you where over or under a weight.
I do agree with one thing they say, if you cant drive the load safely you should drive it.
Problem is, there is a lot of people that cant drive an unloaded car safely.

 

There is a Pony under this blanket! Now help me find it.

As an engineer, I enjoyed and appreciate the piece you posted.

That said the 'pony' I am looking for is either an F 350 Dually or an F 450 Dually to meet my buy of a Host Mammoth Truck Camper ( Alaska Warbird has same and I have been dialoging with him on this matter) That truck camper fully loaded out for use will tip the scales around 5500 lbs add on dogs and pots pans, etc and the weight heads toward 6000 lb gross added to the truck.

That said what is your thinking on my 2020 order coming up, do I go with the F 350 dually (this would be my 3rd dually) or do I go with a F 450.

NOTE: I drove my F 350 Dually for 8 years with a 5500 lb Truck Camper loaded in the bed, my truck handled and performed well inside of what I call my safety and performance envelope.

If read Fords print the choice is simple, buy the F 350 but I feel the better choice would be the F 450.

Your thoughts on this would be appreciated by many more than just myself.

 

Y2KW57
Thank you for that information. This was what I was looking for on DANA’s web site, but all I could find was that the M300 was rated for 16000 lb.
so, with that.......yup, I was wrong. Sorry guys.

 

I think one thing we are missing here is that the rear axle rating from Ford is rated to the weakest component is the system, It could be the tires, wheels, axle, Springs, shocks, or spring mounts.
Looking at the specs on the Ford body builders guide I do believe the limiting component is the rear springs.
It is easy to check the tire ratings, it is printed on the tire sidewall, and in the USA that is going to be the legal limit for most pickups. but other components are not that easy to find, but it appears the springs are what limits them.
Next, when it comes to engineering its easy to calculate yield strengths with a static load, but automobiles travel down roads that my or may not nice and smooth. We all know that a deep enough pothole at sufficient speed will do damage to an unloaded truck. So what is an acceptable speed to certify the weight ratings. Almost all components will have more load on them as the vehicle speed increases. Same with brakes, takes more to stop a weight at 80mph that 20mph. It is possible that the numbers we see at set for 80mph as it is the highest speed limit in the USA. Its possible that at 60mph the ratings could be higher, or maybe the weight rating are calculated at 60MPH. I know its that way in industrial equiptment .Equipment will post a max load AT a max speed.
There is also L-10 life. How long will moving parts last under certain loads. Probably the weakest component in the rear axle is going to be the bearings. they may last 500,000 miles in a lightly loaded truck and 50,000 in a heavily loaded truck. which one is acceptable life? Ford does say that going over the GVWR could jeopardize you warrantee
When it comes to the 17 and newer F450 there are a few things we need to look at.
First, why the 19.5 tires and wheels? 17" tires have more than enough capacity for the axle rating. Why is Ford spending the extra money for the extra capacity? In fact from 2011 to 2013 or 14, the F450 DID have 17" tires (I am only talking about the f450 PICKUP here). But Ford went back to the 19,5s for some reason. It could be because it did allow for MUCH larger brakes front and rear. but by the Ford numbers there is no need to the high capacity tires and wheels on the F450. and the larger brakes didn't change GVWR, but did change the GCVWR.
It has been mentioned often that the F350DRW and the F450 have the same 14,000lbs GVWR, the max for a class 3 truck. I do completely believe that Ford DOES de-rate the F450 to keep it in the class 3 truck.
One reason for this id that almost ALL the extra weight if the F450 over the 350 is UNSPRUNG. The axles, springs, and frame do not carry any of that weight, so the F350 will have more load on the suspension at 14000lbs than the F450 would, but all the suspension components are the same between them. That tells me that there is more available than what is posted on the door jamb.
When it comes down to it, the door sticker does NOT carry and actual physical weigh, it is just a sticker. Changing the sticker does NOT change the physical components of the truck. changing the components does not change the sticker. I am more concerned about the parts that carry the weight,
As far as laws go, each state is different, but all of the states I have checked the rules are very similar and the ones that would apply to a pickup are
1 no axle over 20,000lbs except for RVs and busses, they are 24,000lbs
2 No more that 80,000lbs GVW
3, (the one that will limit most all pickups), no more weight on an axle then the total capacity as printed on the sidewall on the tires on that axle, or 600lbs per tire width, whichever is less.
Some states have restriction on RV length and/or weight, and some have requirements for the driver to have special license.
This is for RVs FOR PERSONAL USE. Rules for utility trailers can be totally different. Same with commercial and "for hire" trucks (another whole new set of rules and in some states the rules overlap). Some states sat that all truck over 10,000 GVWR are commercial, even if for personal use. With commercial you do have to register for the weight you want to carry. I know several pickup that are used commercially that are registered and carry more that the door sticker weight.
All this has been a great discussion, I do believe there is NO SIMPLE answer to how much over the door sticker a truck can carry and for how long and what will be the component that would fail first. I do know that if driven responsibly a truck CAN safely carry more that what is posted inside the door. I worry more about the jacked up pickup with 37" tires and a 40' toy hauler at 85mph than I do the responsible driver in the right lane doing 60mph.
The most important safety device in a vehicle is the driver. There are many that are safer over the door sticker that those driving empty.

 

Right on, Bob. Especially on the part about driving in a safe ans sane manner.

I also think about the old early to mid 1950’s farm and dump trucks......F5/500, F6/600 rated for 20,000 lb GVW, with 8.25-20 bias ply tube type tires, drum brakes, etc. I do believe that a modern F450, either pickup or C.C. In much more capable than any of those. True, the newer trucks are also capable of much greater speed, but everything on them is much better built.

 

As they say in the Boxing arena the "tale of the tape"!

So after reading the post by Y2KW57 I went to my /19 F 350 CC LB 6.7 PSD SRW King Ranch to see the tale of the tape(s) as found on the door jamb. Very interesting: The first one applies to the wheel/tire combo and tips the scales at 3149 lbs. But the 2nd pic on door jam tells a bit different story: "Rear GAWR 7230 lbs"

Take away: With those tires and wheels, I should never exceed 3149 lbs of cargo and occupants! But with the same tires and wheels, I can run 7230 total weight on the rear axle. What I am not sure of is just how much payload I can carry. I believe it to be over 4000 lbs. But I may be wrong????

 

Thanks Y2KW57.

 

Yep, those old log trucks that had to have a water tank to cool the brakes! that is overloaded!
I often think of the 60s and 70s campers, all wood construction, while not as heaver as todays, most of them where on 1/2 ton pickups. Pickups with biased ply tires and drum brakes.
My Dad had a 10' camper on his 1970 International 1200. 750X16 tires on split rims. That truck was DANGERIOUS! The home made sliding rear bumper weighed so much it probably overloaded the truck without the camper on
The brakes sucked, and no sway bars at all. it was impossible to keep the wind and the passing semis from blowing you around. I remember driving it when I was 17, at night (headlights sucked too), wind and rain storm, on I84 in the columbia river gorge. a place KNOWN for high winds. I do believe I was on two wheels a couple of times.
Although I now have a MUCH larger and heavier camper (eagle Cap 1200) I am way safer today than I ever was with a camper before. The new F450 is a beast. you can talk all you want about the numbers on the doorjamb.This think will handle MUCH more than what is on the doorjamb, but ONLY if driven responsibly!

 

It is PRECISELY because of the unsafe camper loading (and over loading) history that you describe in the 50's, 60's, and very early 70's that you describe, that federal legislation had to be passed to force both truck and camper manufacturers to make it easier on consumers to figure it out. That is why the numbers on the door jamb are there. These weight ratings are given on the vehicle certification label that is located on the left side of the vehicle, normally on the dash panel, hinge pillar, door latch post, or door edge next to the driver on trucks manufactured on or after January 1, 1972. The entire purpose was, and is, to reduce the number of contraptions on federal highways that your Dad rolled the dice in back in 1970.

In the early 70's, I used to ride chariot on the freeway standing on the back of a 1959 GMC open flat deck flatbed, with no stakes or gates, hanging on to my Goodyear baseball cap with one hand, and the headache rack with the other, at 60 miles per hour. The man who bought the truck spent all of my meager savings for college to pay for it, and we used the truck to collect scrap iron, before "recycling" became a household verb. The truck was exactly like the one pictured below, down to the color. Can you imagine the citation a driver would receive today, for permitting a young man to ride in the back of an open flatbed? On the freeway? At 60 mph? (There was no room in the cab, nevermind seat belts). The only reason I can talk about it today is because I got lucky and lived. Many others did not. Nowadays, even dogs are required to be restrained if riding in the back of a pickup bed. Comparing the good old days of dumb luck to the broader intelligence of accumulated statistics... is just that... dumb luck.



I posted a photo of this truck for another reason. There was more iron content in the factory front chrome grille bar of this truck than there is in the entire body, and bed, and all bolts and brackets included, of a new Super Duty. If one melted down all the sheet metal of any given 50's or 60's light truck into an ingot of steel, it very well might outweigh a comparative ingot melted down from the HSLA boxed steel frame of any given brand new pickup made today. So in overbuilt brute force there was a fudge factor. But to meet today's federal fleet fossil fuel consumption reduction requirements, light truck manufacturers are engineering the margin of error out of the forgiving nature of brute force iron that trucks of yesteryear had going for them.

In the old days, one could climb up on top of the hood or roof of a car and do the lindy hop in a drive in. Such a stunt on top of one of today's cars would result in a moonscape of pot marked and deeply dented roof and hood skins. Yet that same old iron boat that could so easily survive a pelting by a couple of pairs of spirited Vans sneakers... would be utterly lethal to the wearers of those Vans, if they were occupants in that vehicle during a crash.





In these retro crash test studies of how older, much heavier vehicles with thicker body panels would fare if put through the rigors of crash testing imposed on vehicles built today... the dummy occupants in the rugged old cars were obliterated. Dead. Done for. Whereas the dummies in the newer, lighter, more intelligently engineered cars fared much better. But the new cars do dent more easily. This might be analogous to the loading of old trucks versus new trucks. Better performance in the targeted metrics, but less margin for error in ancillary unplanned for abuse.

It sounds like some folks still may want to judge performance by metal content or model number, rather than what is on the label in the door jamb. The posting of photos of these crash tests is intended to help illustrate that engineering toward targeted metrics can yield more optimal outcomes for the metrics targeted than merely throwing more metal, more mass, or more model number at the concern. Since vehicle engineering today is all about removing metal and mass, it might be safer to assume that the ratings on that door sticker really are representative of the capacity of the equipment as validated by the manufacturer. Since I don't know what all is entailed in achieving that validation, and lack the personal resources to verify the validity of that testing, it is a heck of lot easier to simply open the door and take advantage of all the professional testing and validation that I already paid for with the ungodly price of the truck.

 

^^^Y2KW57^^^ King of the internet. Informative, concise, and entertaining. Well done!