noob with a project.

[morgred]

Hi all,
Finally got tired of lurking, would like to post a question to you all.
I have a 1 ton gm 4x4 with an 11 foot utility bed on it. I am putting a Dana 70HD axle under the rear.
Would I be able to put an 11 foot slide in camper in there? It will be running 1 ton springs with overloads, swaybar, load range E duals, stock steel wheels.
This is going to be my base camp, towing a toyota 4by. I am concerned about that much weight on the truck. The utility box has a diamond plate bed and gobs of storage. I am thinking of making this a permanent camper install. What do you think? What would D.O.T. think?
Has any body done this? I have been looking for pictures, but can't find any.

 

[IdaSHO]

Not a flat bed, but a utility bed?

Those utility beds are notoriously VERY heavy.

Run that truck across the scales, take a look at the door tag, then do the math.
Regardless of actual safety concerns based upon the rear axle and tires, max GVW provided by the manufacturer is max GVW.

It would be a great setup, and many folks have done just what you are looking to do. But legality should always be a concern.

 

[apexcamper]

Absolutely right with regard to the legality, but on top of that there are some other things to consider.

Just because you have a stronger axle under it doesn't make it better suited for the weight. The factory weight rating, while having some wiggle room, is based around frame strength, suspension mounts, performance ratings and a whole list of factors in addition to axle rating.
There are several examples in other threads on this forum where frames have cracked or broke or axles have completely come loose after suspensions shattered. If that happens while towing a truck, it could quickly create a very serious situation.

I am in no way a professional here, and hopefully some of the serious HD truck guys will jump in on this. I do know that running at or above gross weight off road is something to seriously be avoided.

I agree that going to the scales would be an important place to start.

 

[IdaSHO]

Yes, and please by NO MEANS assume that legality is my only concern.

Safety when approaching max GVW ratings is always a concern.


Fortunately when it comes to modern or late model 3/4 and 1-ton trucks the TIRES is traditionally what the max GVW revolves around.


Todays chassis, brakes, suspension and axles are "rated" well above the max GVW. Take my '96 F250 for example.

*It weighs 7200lbs empty.
*It has a max GVW (as assigned by the MFG) of 9900 lbs or so.
*The OEM Firestone tires it came with had a 2500lb per tire load rating. 4 tires on the ground, thats a MAX rating of exactly 10,000 lbs. Right at the max GVW

But thats not where it stops. You have to look at axle ratings to really find out where that weight can be distributed front to rear.

The max rating for the TTB Dana50 front axle is 4600lbs
The max rating for the sterling 10.25 full float rear axle is 6250

Together thats 10,850 Nearly 1000lbs north of the max GVW.

But looking that the rating difference between the front and rear axle brings some problems. 9900lbs evenly distributed between all 4 tires puts the front axle OVER its max rating.
So you need to distribute the weight back, to utilize the rear axle more. But then you find another problem.... If you take that 9900lbs and split it 40/60 to avoid overloading the axles, you will have now overloaded the tires.

9900 split 40/60 is 3960 up front, and 5940 in the rear. 5940 /2 (tires) = 2970lbs.


So As I said... tires are typically the FIRST limiting factor.



If you provide the exact specs for your truck I could do a similar workup.
I find it really helps to put things into perspective when running heavy. The weight REALLY has to be in the right place.

 

[apexcamper]

@IdaSHO:
Crazy good info...So in your trucks case, did the manufacturer put the wrong tires on it, or did they expect no one to do the math?

Even if you are sitting on flat pavement at 40/60 and just below GVW, now lean the truck, hang one tire in a hole, put one on a rock, anything other than flat. 40/60-gone, even left and right being even-gone. I can see how a tire rating could get away from you QUICK.

@Morgred: I am trying to keep my finished product about 33% below GVW. This should allow me to mildly go just about anywhere I can fit her without worrying that I'll break something. I have worked a lot with military vehicles and they regularly give two ratings, on road and off...with the off road weight rating being half that of on road...just food for thought

 

[IdaSHO]

@IdaSHO:
Crazy good info...So in your trucks case, did the manufacturer put the wrong tires on it, or did they expect no one to do the math?

??

The tire rating even from the factory was greater than the MFG applied max GVW.

Not by much, but as I said, with todays 3/4 and 1-tons the primary limiting factor is the tires. So the tire rating will be just that, slightly higher than the MFG applied max GVW

@Morgred: I am trying to keep my finished product about 33% below GVW.

While that might be possible with large trucks, it will be impossible to do with a 3/4 or 1-ton

My "light" 3/4 ton diesel EMPTY doesnt even allow a 33%. Empty it weighs 7200lbs. GVW is 9900. Thats a 27% difference, EMPTY.

Toss a 2500lb camper on it and you are running at max GVW all the time.

 

[IdaSHO]

@IdaSHO:
Crazy good info...So in your trucks case, did the manufacturer put the wrong tires on it, or did they expect no one to do the math?

Oops, maybe I mis-understood the question.

This might make is more worthwhile...

In the US, you can get into sticky DOT (license, insurance) issues whenever you operate a pickup with a 10,000lb+ GVWR. It changes state to state. Placing a sub- 10k max GVWR allows the MFG to avoid all that. The trucks are capable of much more, Ford owners have proven that over the years :sombrero: Hell, Ive had more than 5,000 lbs worth of gravel in the back of my pickup on more than one occasion. :Wow1:

 

[RoosterBooster]

morgred

you may want to go to "Pirate4x4" and do a search there (may search the "towrig" as well as the "expedition" area of the forum) .... i remember that there was a thread running with nothing but "campers on utility beds" (lots of pics)

my 2 cents;
this is fine for a weekend camping rig ... it seems to be a good idea with lots of storage...
... but for a rig that will see extensive rough road use i have to agree with apex and idasho to may look for a lighter solution.

one thing i learned from building "dual sport" (sand/desert) cars was that it is not the impact into a single pothole that is killing stuff (like bearings, springs, suspension, gears,...), it is the constant pounding you encounter on whoops/washboard roads.

imho if you want the camper permanent on the truck i would try to eliminate as much unneeded weight as possible. (less weight= less pounding for your drivetrain)
so for me it makes no sense to slide one "self supporting" structure into another (like sliding a complete camper floor over a already strong utility bed floor )
i would prefer a lighter, single structure (with one floor ) for the back of my truck.

stephan

 

[apexcamper]

@IdoSHO
My tire question came from the math of the truck at a 9900lb gross weight.

If you somehow perfectly balanced the 9900lbs to be at the front axle's exact rating of 4600lbs, leaving the rear with 5300lbs, then the rear tires have exceeded their rating.

If you balance the truck perfectly to put the max weight on the rear axle that the tires will allow of 5000lbs, that leaves 4900lbs for the front axle, exceeding it's rating.

I was looking at it more from a liability and warranty side. Just seems to me that at the "manufacturer" gross weight there is no way to have that truck within the "manufacture's" maximum ratings.

I watched my father in law put 2000lbs of stuff in an F150. It made it home just fine. I would never go off roading like that, but it made it home just fine.

@Morgred:
Will this end up being more of a toy hauler than an off road camper?
It the end it will be a risk assessment that only you can truly decide on. I think you get the trend here...the truck can probably handle the weight, how you are going to use it should be more of the determining factor than axle rating.
RoosterBooster is absolutely right...washboards are killers. Even the original Earthroamer got bit pretty hard by them (Story here, link starts you were the problems start). His problem wasn't the axles, or the tires, but overstress of body mounts.

 

[trailrunner]

Well, one thing to consider is that everything on your vehicle is downrated before they apply that GVWR. There is a safety factor applied against everything that is designed. If we take wikipedia at its word, automobiles are designed with a safety factor of 3. That means that the components on your vehicles should theoretically be designed to withstand 3 times as much stress as they are rated for. I think this is well proven in the third world, the number of vehicles that are consistently loaded well above their GVWR and don't continually break would seem to point to this. As far as the braking systems, reliability, and safety, exceeding the rating shouldn't be recommended, however in my opinion approaching GVWR is probably not as big a concern as some seem to make it. Especially considering how gently (if we're truly honest) most of us use our vehicles.

 

[IdaSHO]

in my opinion approaching GVWR is probably not as big a concern as some seem to make it.

Get into a wreck with another vehicle while traveling over your MFG applied GVWR and you will QUICKLY change your tune. All it takes is one incident, and you are in a WORLD of legal hurt.


While I agree that vehicles will always withstand a good deal more than their rated GVWR, you must also take into account age, mileage, corrosion, and overall state of maintain.

 

[trailrunner]

Very true, I wouldn't recommend exceeding it.

 

[dsw4x4]

IDasho that is interesting I never thought of it from a legal point but smb rolls most of their vans off of the line way over ford and chevys gvwr and you never hear of legal issues, however you hear a ton of complaints about handling and ride which is expected. Drives me crazy how most rv manufactures do not seem to care about weight when they build them.
Derek

 

[IdaSHO]

SMB?

 

[Soobarubin]

Sportsmobile
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-Jaren