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Old 07-31-2020, 06:49 PM   #1
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How the factory determined your towable weights.

https://www.roadandtrack.com/car-cul...is-calculated/

Please read the article and tell me if I'm understanding this correctly. I have known of this for a long while but my logic is what I need checked.

If I don't drive a 12% grade at 100 Fahrenheit while doing jackrabbit starts...how is my towing capacity affected? Does it move higher by leaps and bounds or does it just let me understand real world vs towing capacity settings so I can quit measuring individual pounds?
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Old 07-31-2020, 07:27 PM   #2
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Quote:
Originally Posted by ducksface View Post
https://www.roadandtrack.com/car-cul...is-calculated/

Please read the article and tell me if I'm understanding this correctly. I have known of this for a long while but my logic is what I need checked.

If I don't drive a 12% grade at 100 Fahrenheit while doing jackrabbit starts...how is my towing capacity affected? Does it move higher by leaps and bounds or does it just let me understand real world vs towing capacity settings so I can quit measuring individual pounds?
Your towing capacity isn't affected at all. It is a set number regardless of grade, temp, road conditions, etc.

I remember when that spec was put in place: There was no way to compare the different OEM's tow ratings as they were all measured differently. Thus they agreed on a set of tests/specs that the trucks must be able to pass to be able to say it can tow X lbs.

Much like the EPA mileage ratings the values are more for marketing than anything else..

I also doubt very much that the E-Series stripped chassis, and F-53 chassis are put through that test to determine their tow ratings. Especially since Ford doesn't how many lbs the different up fitters will add when they put their "box" on the back.
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Old 07-31-2020, 07:58 PM   #3
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The article tells me nothing. One sentence says, "How do automakers come up with the tow rating on a new pickup truck? You might imagine it's a number calculated by engineers sitting at desks, a theoretical measure that's based on a truck's ideal capabilities." Then the article goes on about a test and its measurements. Then the article says, "For each test, the truck must be towing the maximum load recommended by the manufacturer." It never tells how the maximum load recommendation is determined. It tells how it is tested. So what do they do, start at 0 or start at 50,000 lbs. As usual, journalism and the editors of the press have lost the ability to tell us anything.
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Old 07-31-2020, 08:13 PM   #4
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THOR #13932
21,200 to 24,200 lbs
New f450 tow ratings based on DRIVE TRAIN, not truck frame.
How can that be?
Same frame(?) so it can't be frame and hitch engineering.
It's that 12%100f hill.

I hate word sellers more than most folks hate word sellers but the article was an easy, based in fact, read.
Lots of articles and the actual test requirements are on line.
I posted the article as an appetizer for those who might question how the drivetrain makes a difference.
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Old 07-31-2020, 08:33 PM   #5
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The article tells me nothing. One sentence says, "How do automakers come up with the tow rating on a new pickup truck? You might imagine it's a number calculated by engineers sitting at desks, a theoretical measure that's based on a truck's ideal capabilities." Then the article goes on about a test and its measurements. Then the article says, "For each test, the truck must be towing the maximum load recommended by the manufacturer." It never tells how the maximum load recommendation is determined. It tells how it is tested. So what do they do, start at 0 or start at 50,000 lbs. As usual, journalism and the editors of the press have lost the ability to tell us anything.
I think that the engineers just squint into the Sin, and then spit into the wind.
If the spit lands beyond their shadow: the tow capacity is higher...


And we get six more weeks of Winter!
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Old 07-31-2020, 08:55 PM   #6
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I think that the engineers just squint into the Sin, and then spit into the wind.
If the spit lands beyond their shadow: the tow capacity is higher...


And we get six more weeks of Winter!
That's kinda my point.
That hill was a spit in the wind. (I've done that hill dozens and dozens of times often dodging the test trucks. 3mpg at 35mph pulling a 28ft Bennington up that thing in a 5.3 avalanche ONCE. We won't be doing that again.)

We have some engineers here. What does a 12% grade add to the weight of the pull on the hitch? 199lbs, 1,000lbs, 2,000lb?

The 35mph was a spit in the wind.

So,
Now we know some of the parameters and they aren't exactly safety of welds and bolt grade based.

Can I, in the Midwest with no hope of a 12% grade confidently go what amount of pounds or percent over my tow capacity?
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Old 07-31-2020, 10:11 PM   #7
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You know somewhere engineers are figuring out how many foot pounds of torque with so and so sized tires on bearing made of whatever can pull so many pounds of lawyers up such and such hill. All the rest is just legal CYA and marketing to make brand F look better than R or C.
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Old 07-31-2020, 10:33 PM   #8
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Originally Posted by Lt Keefer View Post
You know somewhere engineers are figuring out how many foot pounds of torque with so and so sized tires on bearing made of whatever can pull so many pounds of lawyers up such and such hill. All the rest is just legal CYA and marketing to make brand F look better than R or C.
I figure even at that hill and temp and no barfing, they take it down a notch or two for lawyer reasons. I sure would.

I posted this thread so people would think beyond the factory putting a frame on a winch and tearing it in half at exactly 8,000 lbs.
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Old 07-31-2020, 11:25 PM   #9
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If you'll notice that 40k load was a low profile about 25' long triple axle utility trailer with the load centered directly over those axles so it's a very good test for those in the construction industry, but not so much for towing long tall heavy rvs. If that was a 5th wheel RV loaded that heavy the pin weight would be well over 8000lbs & to my knowledge there's not a 1 ton dually made by any of the big 3 with that kind of payload available.
As for class A gas or class C motorhomes with the long frame extension added by the RV manufacturer it's anybody's guess, or the spit in the wind shadow test, as to what/how a room full of engineers that likely have never parked their cheeks in the seat of any motorhome or tow vehicle came up with a number.
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Old 08-01-2020, 01:18 AM   #10
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Ouija boards maybe?
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Old 08-01-2020, 02:42 AM   #11
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Originally Posted by Travelin' Texans View Post
If you'll notice that 40k load was a low profile about 25' long triple axle utility trailer with the load centered directly over those axles so it's a very good test for those in the construction industry, but not so much for towing long tall heavy rvs. If that was a 5th wheel RV loaded that heavy the pin weight would be well over 8000lbs & to my knowledge there's not a 1 ton dually made by any of the big 3 with that kind of payload available.
As for class A gas or class C motorhomes with the long frame extension added by the RV manufacturer it's anybody's guess, or the spit in the wind shadow test, as to what/how a room full of engineers that likely have never parked their cheeks in the seat of any motorhome or tow vehicle came up with a number.
Holy crap. Someone knows their ____.

Then I read the rest and LMAO.

Thanks.
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Old 08-08-2020, 11:17 PM   #12
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My goodness. If I'm reading these comments correctly, some Thor owners are as anti science and anti engineering as the science denier's in Facebook. Are you just looking for an excuse to tow more than your ratings SMH.
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Old 08-08-2020, 11:24 PM   #13
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I hate word sellers more than most folks hate word sellers.. [/QUOTE]

What's a "word seller?" A journalist?
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Old 08-09-2020, 12:14 AM   #14
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Originally Posted by jgwmjw2 View Post
I hate word sellers more than most folks hate word sellers..
What's a "word seller?" A journalist?[/QUOTE]

Someone who writes articles about things they have no background history or education with or a best a semblance of a glancing blow of history with, and then sell that article by soliciting various outlets on a per word fee.
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Old 08-12-2020, 05:44 PM   #15
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My goodness. If I'm reading these comments correctly, some Thor owners are as anti science and anti engineering as the science denier's in Facebook. Are you just looking for an excuse to tow more than your ratings SMH.

I got the same impression. It does make me frustrated when people who don't make assumptions about how engineers work.

There are differences in the frames of those vehicles, very little is just an engine change. There are many things that affect the load rating of the vehicles. Brakes , springs, shocks, rear axle, drive shaft, frame, body geometry, and power train are all things that have to be considered. The US Department of Transportation And NHTSA provide guidance. The "test" is a relatively new wrinkle. Much of that stuff was "always" calculated in some fashion. You are right to say that the concern is "commercial" configurations in large part because there are many more commercial vehicles being regulated. There are specific items in the regulations applicable to RVs where they found issue.
I will admit to towing a 25 foot 1977 Mallard TT with a 1999 K15 Suburban with the Suburban cargo area fairly well filled. I got first hand experience with rear axle failure and smoking brakes close to failure. Theoretically I should have been ok. Towing capacity 6000 lbs - 1500 lbs of things, people and dogs in the vehicle and about 3700 lbs of trailer. That trailer was much easier to pull with a 2005 Silverado 2500 HD Duramax / Allison driveline. Got better fuel economy too. I still use that Silverado, but not for TT towing.

The person that made the observation comparing the test to RV reality had a good point. The combination of really poor aerodynamics and less than ideal weight distribution just adds to the tangle. I suspect that drag may have contributed to the rear axle failure.
I do agree that most "information" authors work from the limitations of their publications and personal experience and usually tell a piece of the story.

I'm glad my RV is on a purpose built Freight Liner Chassis and understand why I can only tow 33,000 - 28,000 = 5000 pounds regardless of where.
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Old 08-12-2020, 05:54 PM   #16
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VERY well-written!

And I almost understood most of it...
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Old 08-12-2020, 06:02 PM   #17
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Ouija boards maybe?

These days people do calculations, usually with a computer. It's not that difficult, especially with the computer. Then the thing that goes wrong is manufacturing error.
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Old 08-12-2020, 06:25 PM   #18
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"Man's best efforts being hamstrung by his worst abilities..."
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Old 08-12-2020, 07:52 PM   #19
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Calm down folks the ratings are for the max tow weight by a class 1- 3 truck that can safely carry using a fifth wheel or goose neck hitch. Bumper or receiver hitches were not considered. For Thor MC - MorRide does the chassis modification and receiver hitch welding and modification. They are the only ones certified in the production sequence to work or weld on the chassis. Engineering specifications are submitted by MorRide to the Ford engineering at the Ford plant in Lexington, KY for analysis as Ford's name and warranty is on the chassis and not Detroit Chassis or MorRide's. The actual receiver manufacture rates the receiver type hitch based on the vehicle it is specifically manufactured for. Universal hitches are rated specifically for the hitch and not the vehicle. What is stamped on the hitch is the hitch manufacture's recommendations. As for the tow limitations, that is in the Ford owners specifications and is based on the chassis capacity. This gross weight is on the Ford VIN sticker by the drivers left elbow on F-53 chassis.
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