Mounting a Composite box to E350 Cutaway Chassis?

[CalgaryMcLean]

Originally Posted by fjefman

Are you saying you don't want to go lower than the floor level (which is above the frame) or lower than the bottom of the door sills (bottom of the frame)? I won't go lower than the lowest part of anything mounted to the frame...which will likely be the exhaust and/or transmission crossbeam.

Don't want to go much lower than the bottom of the cab door sill and/or frame.
Some exhaust and crossmembers might hang lower.

Dragging on a crossmember typically won't do much damage.
If I tweak the exhaust, it can easily be repaired and improved.

Really wouldn't want to bend the box and then have the door not open and close properly. A much tougher repair.

[fjefman]

Originally Posted by mk216v

Take a ride in a ClassC E350 RV that's had a lot of off-pavement (not even talking off-road) miles. Hear all those noises? That's the cabinetry falling apart. Heck, E350 SMB vans do this after off-pavement/off-road miles due to their lower quality construction. And sadly even a brand new Winnebago Revel (Mercedes Sprinter) does it new off the lot!

So yes, you're right that these are cheaply built without much thought having been put into engineering/design for true off-pavement use. That's because they're mainly meant for pavement, and the RV companies spit them out as fast as they can. So it doesn't mean that if you're going to take such a rig off-pavement/off-road, that it'd be optimal to follow suit with the same design/construction.

A chassis-cab with a box att'd to it is very different in terms of flex (2 separate units in different planes at times) than a solid E350 van body.

Every RV and most vans I've ever been in make noise. I've spent weeks trying to diagnose and eliminate noise inside my van...and can honestly say that I've been 99% successful...but my interior is built with 80/20 and screwed and glued plywood so it is all very structurally sound...I just had to add a couple crossbeams, tighten a few brackets etc to get it essentially noise free.

My point is that noise/movement is because of cheap construction methods all around...and most of the time it has nothing to do with chassis flex. The structure will only be as stiff as it was designed to be/built to be. As you say almost all RVs are built with speed and profit being the primary drivers.

Commercial moving vehicles (Uhaul/Penske) and shuttle busses on the E-series chassis are built to a different, higher standard. Almost all have a solid mounting to the front cab and I've not seen anything other than rubber bushings used to connect the back of the box to the cab.

As has been mentioned Ambulances/rescue vehicles are built to an even higher standard...and yet when I look under them I don't see anything other than normal body mounts.

Crawling under 30+ vehicles isn't good on my knees or back, but it has tonight me something.

So, yes, flex is a critical item to consider, but I do think most people tend to overthink the need for complex frame mounting on a medium size van-series chassis. Yes, the box manufactures recommend it...but they also have a lot of liability for everything they say. I wouldn't expect them too say "no, you don't need anything special."

There are plenty of examples of structures bolted to a E-series cutaway chassis without a torsion mounting that have had a long, functional life. Yes, a truck chassis is a very different story.

A quality box, solidly mounted to the cab and with good structural support along all seams/joints, and with an interior designed to connect the walls/ceiling/floor and add strength/stiffness of the entire structure will make it essentially an inflexible single piece big box/tube which will keep the chassis flex to a minimum. Sure flex is better for true off-road situations but I think the point here is that we are not talking about designing for best off-road performance, we are talking about keeping the box from tearing itself apart....

For me 98% of the miles will very likely be pavement, 1.98% FS road and .02% real off-road so I think I'll be fine.

I actually just ran some math...last year I did a ~7,500 mile 3 month trip from GA to CO, CA and UT and maybe did 30 miles of off-road in the van so 99.6% pavement. ;-). I did do about 3,200 miles off-road on my motorcycles so I was getting offf highway quite a bit.

But yes, everybody has their own context/needs.

Jeff

[fjefman]

Originally Posted by VanHallen

If you're you're going to spend money on a dedicated vehicle chassis, 4x4 conversion, composite box, windows, and systems, and either a professional or DIY build out, you want to be assured that the way the box is mounted is going to last. Otherwise it's money wasted. Until that is known through engineering and testing and not just conjecture, it's hard to take the plunge.

Agree...Do you have any thoughts on how we make the unknown, known? I think all of the current builders are busy enough doing their own thing to take an entirely new business direction like smallish box on an E-series cutaway. The market is not yet established and the commitment and risk is high. So, I think if anybody is waiting to see a company turning these out the way they want they will be waiting a long time.

Personally, I'm a bit of a "do good research, make good decisions and then go build it with the best materials/design that you can" sort of guy. And if I make a mistake I will learn from it, improve on it and move on.

My sticking point with my potential build has nothing to do with chassis mounting...specifically thinks I'm still working through are this.

How to have strong, big double doors in the back - Use ambulance doors, build my own?
How to get a big opening in the side (door and a half maybe)?
How to properly connect the overhand above the cab to the cab roof so it looks integrated?

[geoffff]

If any of you are already familiar with Sketchup (FYI I found it disappointingly awkward to get myself somewhat proficient at it), I've shared my E-Series box-van camper model online here: https://3dwarehouse.sketchup.com/mod...way-Van-Camper

[b. rock]

Originally Posted by CalgaryMcLean

Current concept attached.
138" SRW chassis.
Box interior dimensions: 3000 long x 2045 wide x 1950 high
Still some tweaking to be done.

Looks great. Subframe plans? Is the floor a bit elevated from the cab area?


Side note, I noticed that the 'new' V4 was on coilovers front/rear and what looked like a 3 link front and some kind of 4 link or something rear (hard to tell from a single side pic). Off roading will clearly be its primary role - so I think the answer on Chris's thoughts on flex and mounting will be apparent soon enough. Granted it's likely to be a full flatbed, not just a camper subframe.

[fjefman]

Originally Posted by b. rock

Side note, I noticed that the 'new' V4 was on coilovers front/rear and what looked like a 3 link front and some kind of 4 link or something rear (hard to tell from a single side pic). Off roading will clearly be its primary role - so I think the answer on Chris's thoughts on flex and mounting will be apparent soon enough. Granted it's likely to be a full flatbed, not just a camper subframe.

Yeah, his flatbed on 1st Gen V4 was a foot or so higher than the cab floor and unattached so the body of the van so it is a different animal all together.

I’m 6’4” and when standing next to old V4 the bed was about chest level.

[VanHallen]

Originally Posted by fjefman

Agree...Do you have any thoughts on how we make the unknown, known? I think all of the current builders are busy enough doing their own thing to take an entirely new business direction like smallish box on an E-series cutaway. The market is not yet established and the commitment and risk is high. So, I think if anybody is waiting to see a company turning these out the way they want they will be waiting a long time.

Personally, I'm a bit of a "do good research, make good decisions and then go build it with the best materials/design that you can" sort of guy. And if I make a mistake I will learn from it, improve on it and move on.

My sticking point with my potential build has nothing to do with chassis mounting...specifically thinks I'm still working through are this.

Ideally, if a company were to see the potential and specialize in one of these builds they would research and go with what they thought was a cost effective decision. Similar to what I understand SMB did with fiberglass classic, with their first build, they'd run it through some flex tests and monitor for cracks, delamination, and other likely defects. They might video internally and externally to do some slow motion analysis to visually see how things are moving. I'm sure there is some level of vibration analysis that can happen to. Assuming all of that is good, it would be okay to move forward with other components of the build and closely monitor in a similar fashion.

As part of the research it is really finding the right comparison to base the decision for my use case. While it may be true that most don't go off road, this one will ( I live in Utah and want to surf in Baja with this). So I'll want to find vehicles carrying similar boxes in similar terrain.

The box material cannot be overstated..it's integral to what mounting solution will work best. What works for a van body, ambulance body, cargo body (metal or fiberglass) may not work at all for the composite box. Some offer structural integrity to the overall vehicle and others are very flexibility and can absorb the punishment. My understanding with composite boxes, while very strong and rigid, they aren't designed to either absorb nor add structural integrity for the vehicle. Yet the offer a very structurally sound and well insulated habitat. They work best if they are isolated from the vibration, twists and flexes of the vehicle not directly subjected to them. They've been successfully used with larger vehicles using 3pt pivot and 4 pt mounting solutions.

In short, I'm more closely researching those body on frame vehicles and subframes with a composite box in rougher terrain and opting for a similar solutions rather than considering solutions of vehicles with less similar offroad characteristics, less capability, doing less difficult terrain and assuming those mounting solutions would work in this case.

Given that none of these costs are trivial...they all add up quickly...I consider how this box is mounted to this frame as one of the most critical elements of this kind of build. I wouldn't skimp on a pivoting subframe solution if the builder thought that was the best for this application. Now, if I wasn't willing to invest in a capable 4x4 conversion/ solid floating axles / suspension / larger tires and resigned myself to milder travel then I would probably select a different vehicle entirely for this sort of thing.

I know SMB had some challenges with the fiberglass body construction while prototyping, so I would want to know a little more in how those issues where overcome while still recognizing that that body is a very different animal than a composite box construction. To my knowledge that is at least one of the most off road capable "production" e350s with the UJORs as some the most capable custom off road conversions. If I can learn more about the flexes of those converted vehicles before the body installation that would be a huge help in deciding what's best.

Now if I can just figure out how to procure a 2021+ e350 I can get this project off the ground Anyone have an inside angle with Ford e350 sales?

[mk216v]

Originally Posted by VanHallen

Agreed...love Geoff's renderings and have followed Burly's thread...He loved the Ujoint 6 in conversion btw.

I agree that quality doesn't come cheap and also that simply spending more does not guarantee quality either. If you're you're going to spend money on a dedicated vehicle chassis, 4x4 conversion, composite box, windows, and systems, and either a professional or DIY build out, you want to be assured that the way the box is mounted is going to last. Otherwise it's money wasted. Until that is known through engineering and testing and not just conjecture, it's hard to take the plunge.

That said, there appears to be a lot of interest for a well built true four season off road capable rv on an e350 chassis. It needs to be in the price range near or below that of a new SMB /FV Classic and much cheaper if it's just a shell. The shell option would be preferred as it's easier to get exactly what works best for each one's intended use.

It seems like there are a few manufacturers who could do this if they recognized the need and would provide the added benefit of qualifying the build as an RV for all of the financing / insuring benefits. There are others who could successfully extend their current service offering that would help make it easier to at least get a 4x4 converted chassis and properly mounted subframe so the box could be added separately ... it's a real challenge to coordinate as an individual, so this would fill a need and likely earn a nice profit in return.

I enjoyed my UJOR 6"/35s, but then drove a few ExpoVans/MG conversions, and was definitely sold on that setup from that point on.

"Spending more doesn't insure quality either;" that's true more than ever. Lots of converters asking healthy prices for conversions, even more so with full builds like interiors and such. Instagram famous doesn't equate to off-road durability. Pretty sad. Moving on...

"There appears to be a lot of interest for a well built true four season off road capable rv on an e350 chassis;" depends what you mean by RV. Are we talking about a standard E350 van converted to RV-type interior features (bed, sink, toilet), are we talking true ClassB or ClassB+ conversion? (I don't think we're talking ClassC conversion here, in terms of long-term reliability for off-road).
Remember that qualifying it as an RV means it can't be a shell; would have to have a dedicated bed, sink, bathroom/potti, and maybe a stove too IIRC. I do agree that a bare shell would be smart, so that DIY'ers could take it from there on their own. That might keep such a cabin manufacturer from offering only a fully built interior OR a shell, for some companies are a bit hesitant to have potential customers question "Who's interior is that, is that the cabin mfr's interior with those yard-sale cabinets?"

Offering a 4WD chassis and subframe, where a customer adds their own box(which isn't such a straightforward process in itself), would probably mean that the box would be non-pass-thru, for a pass-thru should be professionally engineered/constructed vs leaving up to the DIY customer.

I like your ideas, well done!

[mk216v]

Originally Posted by VanHallen

Now if I can just figure out how to procure a 2021+ e350 I can get this project off the ground Anyone have an inside angle with Ford e350 sales?

There have been quite a few on autotrader and commercial truck trader.

[VanHallen]

mk216v, All good points and to be honest I don't the minimum requirements of an "RV" I think it's sink, bed, and few other things, but know it's attractive for financing and insuring, so it an upfitter can take a vehicle to that point it makes it easier for customers wanting to go that route.

As for ExpoVan, would love to what aspects of their conversion you liked most?

fjefman, Regarding one of my earlier posts regarding testing. As I think about it more, there should be a static or bench test if you will, ideally with the exact material. First, test the a 4x4 converted e350 using a ramp or fork lift without a subframe and attach a flat piece of foam or plywood or the actual product and then drive each wheel on to ramp or lift with a fork lift. The idea is to see if the flat board remains on plane or does it try to bend or buckle. Does the leading edge of the board, move independently of the cab during the flex? It could be the board is in plane but changes relative to the cap. Take vertical measurements to the the ground on four corners with each wheel lifted. Then repeat with the mounted subframe in question taking similar measurements and looking for relative movement of the leading edge to the back of the cab as this will determine whether the box should be hard mounted to the cab or to use some sort of boot mounting to allow for that movement. I'm sure actually doing this test would invite other questions and solution ideas.

After this static test, then doing the driving test (similar to my previous post) with the best solution identified during the static test.

Next, add the box without windows and doors, assuming the cutouts are there for those windows and door. Connect the pass through. Repeat the static test looking for cracks, buckling, delamination, mounting fatigue, etc in the panels, joins and cutouts. Then take it for the dynamic test and evaluate.

During the dynamic testing, looking for the amount sway and whether the box movement is abrupt or tempered. A good slow speed run on rutted, fireroad, and traversing undulating terrain would be a good start.

At this point adding the door windows and redo the static followed by the dynamic. In theory if the box with all the windows and doors survived with now issues in panels, joins, or cutouts, that would suggest the box was successfully isolated so it's safe to add the windows doors and interior build out.

I'm sure there is some sort of protocol that expedition vehicle builders using similar boxes and articulating chassis follow for this sort of thing. This may seem like over kill, but it's got to be safe on the road and last through thousands of miles of varied and sometimes harsh terrain in order to justify spending on this type of build, imo.