Custom bumper assembly

[simonov]

I am working on a 1993 26 ft Jamboree on the Ford E350 chassis with a 460. There is very little storage with this model, so I am designing a replacement rear bumper that can secure a 10x16 foot shade canopy, about 3¾ cubic feet of firewood and a steel elevated fireplace made from an old washing machine tub.

In the image below, the red and gold elements are steel angle and tubing. The pink boxes are to be made from pine, as is the blue rack for the fireplace:



Because of the relationship between the spare tire, the trailer hitch and the Yakima bike rack (the green thing), there is very little room to work with. Still, I believe I have arrived at a design that will work, and extends out only a little more than 17 inches from the rear of the RV.

My concern is with the weight. The main bracket alone will weigh some 60lbs, while the firewood cage (the tall red structure) will weigh another 25lbs to 30lbs empty. The shade canopy is one of those heavy-duty set-ups with steel tubing and weighs some 70lbs. So I am looking at 160lbs on the bumper alone, plus the fireplace that hangs off the ladder weighs about 30lbs.

The four bolts that secure the bumper to the frame are big and stout, so I'm not worried about that. My concern has more to do with drivability and other rig capacity issues.

Here's another more up-to-date illustration of the design:



Does anyone one have any suggestions of what else I ought to be concerned with here? Anyone ever done a project like this?

[simonov]

Thanks for the input, guys. I haven't yet weighed the vehicle, but I've decided on a couple of radical changes:

1. In the rear, the firewood will be hauled in a plastic carton secured to a rack that will replace the bumper. I just need to find the right plastic box.

2. The shelter parts, the heavier part of the load, is almost certainly too heavy for the rear, whatever the numbers turn out to be. So I plan to design a rack that mounts using the front bumper bolts and swings out in front of the bumper (not replace it).

Here she is in camp:



That shade canopy is strong and effective, and will stand up to the wind when secured to spikes driven into the ground. But it is heavy!

[jamesa403]

I second the motion about hauling firewood. In Canada is it illegal to haul more than a few miles due to the Pine beetle (kills pine trees) and the ash borer (kills ash trees). Usually there is firewood in or near campgrounds being sold for campers. This would greatly reduce your weight, and be a lot more respectful of the trees you could kill in the campground area. A campground looks pretty sad with no trees.

[IAMICHABOD]

I had the same problem with my old Class A,not enough storage for the same things you want to take along.

I thought about a rack on the rear, as you did, but that old P30 Chassis with the short wheel base and long overhang with the fuel tank in the rear, made it overweight when fully loaded. I had no extra to play with. The front axle was way under from its Max capacity,so I needed a way to transfer the weight up front.

My solution was to mount a Cargo box on the roof as far forward as I could. I mounted it cross ways with the hinges facing forward. It was large enough to put my EZ UP in plus a few bundles of wood. I also used it for other heavy things like cases of drinks.

I have seen others that had fabricated a box on the roof to do the same thing.

This did transfer weight to the front axle,and gave me more storage space. I also used one of these that I modified a bit to haul my wash tub fire pit on the rear ladder.

[pauldub]

deprived wrote:
Just yesterday I was looking at a used 2008 Jamboree 26J and the salesman told me that there is an 800-pound lead weight in the rear bumper. I don't know if this is true, but i'm puttin' it out there.

I wouldn't be too surprised to see weight added to the front, but not the rear.

[DrewE]

If it makes things any easier to figure, many areas of the country have rather strict restrictions on importing firewood to control invasive pests. The rule of thumb for Vermont, if I recall, is no more than 30 miles from the origin of the wood, and importing from out-of-state is generally forbidden unless the wood has been kiln-dried or otherwise treated by some approved method.

I do agree that hanging things off the ladder seems like a bad idea. The ladders are none to sturdy to begin with. Do you perhaps have some unused space underneath the rig in which you could rig up some fixtures to carry your items?

[mikeleblanc413]

While this conversation is most interesting, I don't see where anyone has mentioned not hauling items strapped to the ladder. Strapping items to the ladder would be creating a situation waiting for an accident to happen.

[Gene_in_NE]

simonov wrote:
I guess that's what I'll have to do. On Monday or Tuesday I'll take it out to get weighed with the tanks half filled. It's already a bit squirrelly, so it will be interesting to see what kind of leeway I have.

I understood there would be ramifications with more weight back there, which is why I was looking for some specifics. I didn't think the equivalent of a 200lb man laying on the rear bed was going to render the rig undrivable, but I'll see what the numbers say. Slightly different when the man would not be on the bed, but on a lever about 3' behind the bumper. 🙂

That is the important thing having it weighed. This discussion usually comes up when someone wants to haul a scooter or motorcycle, but the same logic applies.

There are several things you need to check. You need to know what your current "ready to go" weight is on the front and rear axle compared to the GAWR (usually on the door post). Know the capacity of the receiver hitch - usually 350 or 500 lbs.

There is a simple formula - Know the weight of your motorcycle. Add the weight of the carrier for the motorcycle. Measure the motorhome wheelbase (distance front axle to the rear axle). Measure the distance from the motorhome rear axle to the center of your motorcycle carrier. Now multiply the weight of the motorcycle plus the carrier by the distance behind the rear axle. Divide this answer by the distance between the axles. This is the amount you are lifting off the front axle (the see-saw effect) and adding to the rear axle. If for example:
1. motorcycle weighs 300 lbs
2. carrier weighs 50 lbs
3. motorcycle carrier is 8 feet behind the rear axle
4. wheelbase is 12 feet.
(300+50=350 x 8 feet = 2,800 divide by 12 feet = 233 lbs). In this example the motorcycle is lifting 233 lbs from the front axle and is adding 533 lbs (350+233) to the rear axle.

[deprived]

Just yesterday I was looking at a used 2008 Jamboree 26J and the salesman told me that there is an 800-pound lead weight in the rear bumper. I don't know if this is true, but i'm puttin' it out there.

[pauldub]

I did a little test at the weigh station one day to see what the unloading effect would be on the front axle. I stood on the trailer ball on a longish extension in about the same place the motorcycle c.g. would be. 180 pounds on the rear caused about 120 pounds of unloading on the front axle. This may not be the same for your case unless your wheel base and rear overhang are similar to those lengths on my 24' moho.

[pauldub]

I'm planning (or dreaming) of doing something similar so I can haul a 250 pound motorcycle on the back. My plan is to ballast the front bumper with lead IF the weight of the motorcycle makes the front end too light. I have plenty of load margin on my rear axle so more load might even improve the ride for me.

[woodgeezer]

Take your rig to a custom hitch builder and get his opinion after looking at the undercarriage. Many bumpers are simple add-ons without support to the true "frame". Extensions for the coach are often smaller than the chassis frame. My Chevy frame is a unibody and not real strong the custom hitch I added tied the frame with the extensions and the bumper, it still will only handle about 750 pounds weight, but pulls over 7500lbs. Think of the five pound weight held in your hand tight to your body and then extend your arm out. Heavier? No, but dynamically you are pushing the connection a lot more.(That may be a weak analogy, hope you get the point). The farther you extend out from the main frame, the less weight you can carry. It also could beat your frame to death.

[simonov]

tatest wrote:
How much of that stuff might you consider hang in front of the MH, if a weighing shows it to be light on the front axle? A front receiver hitch can be a starting point for carrying a useful load up there.

I've considered that. I wouldn't use a front hitch, I'd do the same thing I'm thinking about for the rear: remove the bumper and fabricate a replacement bracket/rack that bolts right to the frame.

My biggest concern with this idea is cutting off airflow to the radiator. I will be using this rig almost exclusively in the desert, between May and November.

[tatest]

How much of that stuff might you consider hang in front of the MH, if a weighing shows it to be light on the front axle? A front receiver hitch can be a starting point for carrying a useful load up there.

[-Lqdskier]

Is towing a small trailer an option?