How much weight off the back bumper?

[7river]

I have a 94 E350 single wheel school bus 12 ft box.
There is about 6' from rear axle to rear bumper.
I'm about to put a hitch on it so I can tow a 12' trailer with a couple drums of wvo and kids bikes in it.
Then I got to thinking. The weld shop had a three receiver hitch and I'm thinking if I have him make two arms for the outside receivers I can strap on a 120 gal aluminum tank. I would make a base frame for it with folding legs with screw jacks so I can lift if off the arms even if full. Figure it would be about 950 lbs back there...about 7-8 ft aft of the rear axle. Is that too much? I do have a 55 gal WVO tank just behind drivers seat. That will stay 3/4- full till the big tank is empty.
The bus weighed in at 7060 lbs with the seats and 1/4 tank diesel when I first got it.
The WVO tank is about 440 lbs
The diesel tank is just aft of the axle 35 gal 250 lbs
The shelves, bunks and stuff I put in...250 lbs
Family and stuff 500 lbs

I took out about 200 lbs of seats

That would be a gross of about 9100 lbs loaded

Do you think 950 is too much to hang back there?
Anyone know of any sites or tools to figure it out?
Thanks for any help

 

[Shadetreemechanic]

That much weight that far behind a single rear wheel would scare me. I would think it could get squirrelly on the highway in any sort of fast maneuver. Your trailer idea seems safer to me.

 

[7river]

Thanks for the advice.
Maybe I should consider a smaller tank? Anyone know of a site for figuring this out?

 

[Shadetreemechanic]

I don't think there is a site to help you. It will be a function of how you drive, the tires on the van, the road etc.
It may work fine most of the time, but a bunch of liquid sloshing that far behind your rear axle will put you in the ditch at some point.

 

[7river]

Yea I've been looking for a site. I figure the sloshing wont be a factor when it's full and the load imbalance is greatest, but once I use 1/2 a tank I will have sloshing with 500 lbs back there.
Don't get me wrong, I'm not dismissing the nays, that's what I want, honest feedback, it's a good point. The tank will have a baffle but 60 gals sloshing 8 ft back could be an issue.

 

[OLDBULL8]

Put the rear wheels on a scale, note the weight, then add the weight of whatever your going to add to the rear. Check the tire weight rating. If it exceeds that then good luck. You really should have a dually for what you want to do. You don't want the front end and headlights pointing to the sky.

 

[7river]

Thanks, that sounds like a good way to figure the rear tire load.
My tires are rated at around 3050 lbs each. My guess is I won't come close (800lb) to overloading them. Even if the total load was 9500 lbs.
I will check it though.

 

[grog85]

One thing to remember is as you add weight 8 ft. behind the rear axle, you are taking weight off of the front axle. If your rear tires are rated to 6100 lbs., and the GVW is 9200, with that 800 lbs hanging 8' back there, you might be pushing the limit of the tires. I'd do as was mentioned, and weigh the axles, then add the addional weight to it, and see if you are overloaded.

 

[sak778]

Yeah, Your not "stacking" the 800 lbs over the top of the tires/axle. That is 800 lbs hanging out at the end of a lever 8 ft long

 

[7river]

So your saying 800 lbs 8 ft back is gonna transfer some load from the front?
If thats the case I would have to weigh it with the tank full 8 ft back...sounding more and more like I should scrap the idea or cut it back to maybe 70 gals. I'm gonna sleep on it. I'll try to weigh the rear axle tomorrow.
Thanks for the input all.

 

[Compu Doc]

Single wheel I would not even have anything hanging off the back except maybe a spare tire.

 

[ocnorb]

I'm no expert, but I carry a two motorcycle carrier deal off the back of an SUV. Each bike weighs about 250 lbs and there is no liquid slosh. It gets pretty spooky sometimes in corners. We had a tire go low once and it became unsafe quickly until we figured out what was happening. Can't imagine what a blow out would do. We never go over 65 with this set up.

It works great with one bike, but the extra weight of a second bike further out acts like a lever arm that makes every little variable bigger.

Any way you can mount the tank on the trailer and use a draw-tite type hitch?

 

[OLDBULL8]

Do you think 950 is too much to hang back there?
Anyone know of any sites or tools to figure it out?
Thanks for any help

Got to thinking about this, and got a headache. But here is what I'm thinking.

Mathematics, Calculus = Calc is to calculate. ulus is short for useless.

So, by useing Calculus.

T = distance from rear axle centerline to rear maximum distance.

U = distance from rear axle centerline to front maximum distance.

V = weight of rear axle on scales.

W = weight of front axle on scales.

X = added weight and distance to rear.

Y = Y the hell an I even trying to figure this in calculus, because it's useless. Take two Aleve, lay down and forget about doing it.

Z = ZZZZZZZZZZZZZ uuuuumph ZZZZZZZZZZZZZ

 

[ocnorb]

Do you think 950 is too much to hang back there?
Anyone know of any sites or tools to figure it out?
Thanks for any help

If you do this you have to promise a video of you riding wheelies on roads like this:

You must be registered for see images attach

 

[nsjames]

it's probably got some sort of frame extension as well.

They're usually not that strong, which is why a lot of campers have paltry tow ratings. Check the splice very well, reinforce as needed before you hang 800 lbs off the back.