David_in_TX
Grand Prairie, Texas
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The answer to that question is the GVWR is set by the weakest component, as I have shown in my example for the F-150 above. The data I used was published data by Ford motor company, posted on a public (but not very well promoted) website. Every manufacturer of light trucks has this same data published on the internet for every model and every configuration of truck made (see below for links). There are a limited number of axles available for the truck manufacturers to use, and they are not made in an infinite range of weight ratios, in other words you can find an axle that is rated at 3,000 lbs, 5,000 lbs, etc. It is this very reason that you cannot sum the axle ratings and expect the GVWR to be set based on this alone. Manufacturers pick the available axle that comes closest to their goals (usually conservative - on the high side) and then the rest of the components, tires, springs, etc. On the F-150 I used, it was the wheels that were the weakest and that's what set the GVWR.
Here is all the data needed to check any truck made by Dodge, Chevrolet, GMC and Ford. Please feel free to check me, I'm confident you will agree.
Official Dodge Site - Body Builder's Guide
http://www.dodge.com/en/business/body_builders_guide/index.html
GM UPFITTER - Body Builder Manuals
http://www.gmupfitter.com/body_builder_manuals.html
Ford Truck Body Builder Advisory Service
https://www.fleet.ford.com/TRUCKBBAS/index.htm
Tee Jay wrote:Most LDT have a GVWR notably less than the sum of the two axle ratings, a major difference from MDT and HDT ratings. Why? Is it lawyers, brakes, or something else?
http://www.linkedin.com/in/davidnicholstx
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David_in_TX
Grand Prairie, Texas
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I would like to see an example of this, please post where this information can be found.
JIMNLIN wrote:Many states allow uprate GVWR/or tonnage/tags/plates/stickers/higher registration/etc for combined towing. So simple saying being over GVWR isn't safe isn't correct.
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lesmore49
canada
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Joined: 11/25/2004
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David in Tx says;
"I have thought about what you said about the Sienna vs. the Sequoia and here is my take. As you know, the Sienna is a unibody and the Sequoia has a full frame. In general, the reason the Sequoia has a higher tow rating is because of it's full frame, attaching a hitch to a unibody structure is very difficult and will not be as strong as with a full frame. This has to do with the thinner sheet metal that is present on a unibody vs. the thicker frame rails on a full frame. You cannot feed high loads into sheet metal like you can with thick frame rails.
I also disagree about the unibody being safer in a crash, while the unibody designs have designed in crumple zones that absorb the impact energy, so do all modern vehicles. A full frame is much stronger as an individual component (see above) and it contributes very much in absorbing crash loads. The unibody design's strength is due to the shape of the entire structure, the localised areas in a unibody are the same as any type of metal auto body designs. I think a full set of airbags contributes the major portion of any vehicles safety. There are many factors to consider, rollover crashes, side impacts, frontal impacts, handling (like you said), etc. too many to generalize that unibodys are safer than full frames."
David,
I agree.
I appreciate your opinion, which seems to be equal parts of engineering background, coupled with an informed, well thought out rationale, with the addition of a strong dose of common sense.
Les
lesmore49
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blt2ski
Kirkland, Wa
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David,
In Wa st where I live,"STATE LAW" says a rig must be licensed for 150% of its tre wt. So if you take a 25 series crewcab diesel that wieghs in at 7-8000 lbs, which many do, you need to be at 12K lbs. As this state sells tonnage to "ALL" owners of trucks in 2000 lbs increments, and that is the legal limit on the hwys and biways I travel. So for my 3500 I can legally go down the road at 12K lbs Which is what I have paid for. My 2000 C2500 has a paid for license of 8000 lbs, that is the max I can run down the road at with out a potential for an overweight ticket. My navistar has a manufacture GVWR of 18200, I am licensed for 26K, been pulled over upwards of 27K GVWR, with NO over weight ticket. I am also limited to 20K per axel, 34K per tandem, and 600 lbs per inch width of tires, which follows the "Federal Bridge Law". The manufacture rating are considered "performance and warrenty" per "EVERY" WSP I have been pulled over by, be them a weights and measures enforcement officer, or a typical trooper.
My dually's, ie my 3500 and my navistar, get 20K max for the rear axel, and 11400 on the front axel with there 245 tires, 9.5" times 600 times 2 tires, or 11400. My rear axles have 215 and 225 width tires, about 9". 9 time 600 time 4 equals 22800, BUT, per the road bed design max I can put on the road, per federal law, I get 20K lbs. It would not matter if the manufacture design of the RA was 25K lbs, which do exist, I get 20K lbs on that RA max!
You may think, as do others, that states enforce the manufacture limits, they do not! some do have a quote that the manufacture limit exists, but many do not. Washington state where I am does not enforce maaufactures ratings/limits etc.
marty
05 Chev CC D/A LS Dooley
92 Navistar dump truck, 7.3L 7 sp, 4.33 gears with a Detroit no spin
00 Chev C2500, V5700, 4L80E, 4.10, base truck, no options!
92 Red-e-haul 12K equipment trailer
3 Single axle utility trailers
Check RV.Net Blogs at: blog.rv.net
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Tee Jay
Port Angeles, WA
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David_in_TX wrote:The answer to that question is the GVWR is set by the weakest component, as I have shown in my example for the F-150 above.
Well, I looked at the site you provided and didn't find anything helpful.
The tires are "E" rated at somewhere around 3200#. The door sticker says Front Axle 5,000#, Rear Axle 6,000#. GVW 9,000#. We know it is not the tires or the wheels or the frame or the powertrain that limits the GVW to less than the sum of the axle loads. So what is the weak component?
It has to be somewhere between the lawyers and the ether, because the parts on the 3/4 ton are the same as on the 1 ton, except for the spring pack. And the spring pack is already able to handle the front and rear loads shown on the door, as are the wheels and tires and so forth.
The GVW rating simply makes no sense and cannot be understood by a competent user given the available information. An SAE standard that shed some light on this kind of issue would be most welcome.
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David_in_TX
Grand Prairie, Texas
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As I have said earlier, some people will not listen, they have made up their minds (especially on this topic) and I truly believe that they will hold their ground no matter who tells them different, even if from an engineer straight from the truck manufacturer.
I have provided a detailed example (the F-150), but some people want more. There is no way I can do the math on this forum for every truck made, there are literally hundreds of different combinations of trucks from GM, Dodge and Ford. The web site doesn't just give you the data for your truck, you need to dig for it as in my example.
I never said anything about being against any law, but some have gone off on this tangent. Just because it isn't illegal in your state doesn't mean it is safe. When you overload a truck, you are taking a chance that something will break. There are a lot of things in life that are legal, but common sense says you shouldn't do it. The government is not there to protect us from ourselves. I have backed all of my posts with hard data and facts, I wanted to be sure you could follow my argument and see the facts. Most if not all the people who disagree have not shown anything substantial to back their case up. If you disagree then show us all why with data from the manufacturers. I cannot say anything more on this, I am done.
Tee Jay wrote:David_in_TX wrote:The answer to that question is the GVWR is set by the weakest component, as I have shown in my example for the F-150 above.
Well, I looked at the site you provided and didn't find anything helpful.
The tires are "E" rated at somewhere around 3200#. The door sticker says Front Axle 5,000#, Rear Axle 6,000#. GVW 9,000#. We know it is not the tires or the wheels or the frame or the powertrain that limits the GVW to less than the sum of the axle loads. So what is the weak component?
It has to be somewhere between the lawyers and the ether, because the parts on the 3/4 ton are the same as on the 1 ton, except for the spring pack. And the spring pack is already able to handle the front and rear loads shown on the door, as are the wheels and tires and so forth.
The GVW rating simply makes no sense and cannot be understood by a competent user given the available information. An SAE standard that shed some light on this kind of issue would be most welcome.
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Tee Jay
Port Angeles, WA
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David in TX
It is not a matter of won't listen, or made up mind, or anything else. It is simply a matter that using the information available to the consumer that the ratings make no sense.
It would make sense if the manufacturer said "The GVW reflects long term performance of all the sytems in this truck and exceeding the GVW will, in our opinion, result in increased maintenance costs and premature failure." Or something to that effect. Or maybe "This truck will do exactly what we said it would in engineering, but maybe not quite what marketing implies, but the attorneys are scared snotless that you will actually try to do that and they don't think you have the skill to pull it off and will sue us, so we put in a giant fudge factor to placate them, cause they are the ones making the final decision."
The SAE could do the manufacturers and the customers a real service if they can bring some clarity to this whole ratings issue. If people actually understood how these are arrived at I wouldn't see folks pulling an 18,000 FW with a 15 year old 250 and telling me it's ok 'cause it has a Banks kit.
You clearly don't like it that "they" don't understand this when you find it so simple. Marty has real world examples of if-then-else. He has clearly used a lot of vehicles for a lot of purposes for an extended time. And, as he points out, state laws vary all over the place, some more rational than others.
I don't want to pick a fight with you because I believe you do know what you are talking about. But if you want to pick up your ball and go home, I'll understand.
This forum can be a way to educate and inform, and I would like to learn more. I understand your F150 example. I don't understand my example.
Anyway, I went and got a baby Freightliner to move a trailer with a 2,000lb tongue weight as it would have slightly exceeded the GVW of the 2500 but would not have been anywhere near the max axle load.
But if you have any thoughts on the limiting factor in the example I cited I'd sure be interested.
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blt2ski
Kirkland, Wa
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Did I say loading my dually 3500 to the max allowable by law is Safe? If anything, I would not recommend it, unless you are really dumb!
Here is some literature I would like to see for light duty truck applications. Same info I have in my Navistar spec book, same stuff I use to figure out what my Dmax will do on grades doing what "I" need my truck to do. The question still becomes, "WHAT are" the specs behind the GCWR's. GVWRs are suspect to more than one of us, in that the GVWR is usually less than the axel limits combined. How does one take 2+2 and equal 3? last I checked 2+2 =4! That is the question of the day, how does my truck with tires, axels, springs etc that total over 14K, get an 11400 rating? how does the F150 you show with a chassis pkg greater than 5400, equal 5400 GVWR from the manufacture? what is the weak link?
That is why an SAE std would be nice. Or some other numbers, so those like myself can be convinced, that there is a "safety part" behind the gcwr figures, other than the parts and pieces. That is easy to figure out too. Jut look at the parts used. BUT, if all the parts show 26K GCWR, and the thing is rated for 15K, why? If all the parts show a GVWR of 15K, then why is the rating put at 11400? What is the missing part other than someone saying we need a deduct factor of _____% for crazies like marty!
I know when I ask my step dad what are the factors behind whey a boeing airplane can only take off with X lbs of cargo, he can back it all up. No one has backed up the GCWR figures.......so far........Other than look at the parts and pieces, which add up to MORE than the GCWR figures! hmmmmmmmmmm
TIme for bed........GAWR's, I can see the reasons, GVWR's for LDT's, no reasons, GCWR's are performance figures, ie go power, to who's spec tho. Yours or mine, or TeeJay, o Larry, or Jimmy or __________.
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BenK
SF BayArea
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Joined: 04/18/2002
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There are more things than what we can see, or touch involved with
any specification, which turns into the ratings published.
Repeat that all things are designed/engineered not for the good days, but
for the bad/worst day out there. AKA...Murphy's Law, or designed for
that 'idiot and gorilla' (kinda sorta derogatory, but a real and a
common designers term).
Most everyone only sees the product ratings only applied to a fairly
new vehicle, but there are other attributes to the age of the vehicle.
Of course warranty that most know, but do you know that there are hidden
laws governing all vehicles on public roads? Like that 'major' smog
components and systems must last 80,000 miles?
Or that braking is not just that one time, but several times in the
worst or maximum conditions and at GVWR. Wonder if GCWR is also in
that certification testing, but do not know for sure.
Ditto getting it going from a complete stop on the max incline, max
temp, max altitude, GVWR and again wonder if GCWR is in that certification
test.
How does these certification test results apply to a vehicle with
50,000 miles on it and still under warranty? Do the forgive some
performance, or do the ever re-test any vehicles with tens of thousands
of miles on them?
Is the weak link/component the tires, or the diff fluid? Or the bearings
in the axle. Or the tranny fluid, or engine fluid, or what???
What are the maximum conditions? DeathValley during the hottest summer
day? Pikes Peak? I've never towed in DeathValley, but have off roaded
and saw many broken down. Mainly over heated. None were towing but
were loaded with camping gear. Risked my own rig when I gave my last
gallon to that family, but I had enough drinks (sodas) to use in a
pinch.
For me, always amazes me how folks use their vehicles into their
safety margins (either knowingly, or just ignorance). Lucky they
generally don't go much off the beaten path.
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
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JIMNLIN
Big Cabin, OK
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Joined: 09/14/2003
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David
First you need to understand how to load a truck and it isn't by using GVWR. Thats the function of axles and tire capacities. I've hauled combined commercially for a number of years and the only place I'm aware that GVWR is used is for purchasing combined tags for combined towing (tow vehicle plus a trailer = combined).
Your from TX which is a state that allows uprating GVWR for combined purposes per your "weighing for overloaded vehicle" TX 621.402 through .404 regs. It says if your over GVWR you may elect to purchase more at that time. Keep in mind this is combined towing so the truck GVWR plus the trailers GVWR = what you can pull. The same 621.402-.404 also says vehicles axle and tire caps can't be exceeded.
In my state (Oklahoma) I may or may not elect to purchase more ladin weight (GVWR) for commercial combined purposes up to 15k max for a 2500 or 3500 DRW truck from OK tax commission. But, just like TX the vehicle is still limited by the vehicles axle and tire caps.
There are lots of commercial/LTL type webs, just as there are lots of RV webs, for folks to find out how to haul/tow combined legally by the numbers. Its amusing at all the different opinions on RV.net as to how or if those numbers are used.
These trucks are certifed by their manufactures for max GAWR's and GVWR. Its up to the operator to understand how to use those numbers for loading and pulling.
"good judgment comes from experience, and a lot of that comes from bad judgment" Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach Linex
'97 Park Avanue 28' 5er with two slides 16" BFG Commercial LTs
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