Mounting a composite camper box on 4x4 E350 chassis
- Thread starter ScottPC
- Start date
rruff
Explorer
Spreading the load over the frame rails shouldn't be that tough... ? The nice thing about a 3 or 4 point mount (vs springs) is the ability to put nil stress on your box without a super-stiff subframe.
IMO flexy chassis are just annoying. If the frame of the vehicle was actually stiff you could just hard mount it and no worries! Better for offroad. Let the suspension do the articulating... and you only have to deal with one moving part that already has dampers (shocks) on it.
ScottPC... a newer F350 chassis actually is very stiff... so long as you get the one with a bed (not the chassis-cab). If you don't already have the van and don't have a low budget, I think that would be the way to go. Factory 4x4 is nice as well.
ScottPC
Active member
I get the appeal of the F series, but with the E350 you get a shorter wheelbase, shorter overall length and some of the 4wd conversions reduce the the turning radius compared to stock for a big improvement over the F series. The E350 Chassis version comes with a 40 gallon tank and has a performance engine version and an economy version both with tow haul mode which would be ideal for both touring range and serious offroad when you need it. In addition, the shorter sloped hood makes visibility a bit easier too. I may be mistaken but I think the box rides a bit lower for a lower CoG on the e350 too. I have a full size 1 ton chevy truck and a new to me older e350 6.8 v10 which is convincing me this is the right platform for this kind of build, though the newer 7.3L v8 6sp would be a much improved version.
For the mounting, I just want to get it right as I'd hate to invest in the chassis, box and interior build and skimp on the mounting piece so it fails with cracks and the like. There just doesn't appear to be a lot examples of this type of configuration.
rruff
Explorer
I definitely get the shorter sloped hood... modern trucks are terrible in that regard. Turning radius isn't good on the F250/350 either. CG? Kinda doubt it... don't know. Think you'll be giving up ground clearance if so. I'd still go for the truck for factory 4WD and probably less cost, but that's just me...
I recall this subject coming up not too long ago and I think the Ford box builder guide recommended rubber cab bushings between the frame and box. Seemed fairly simple. But this will surely depend on how well your box can flex... standard truck bodies are usually not that stiff. Do you have some ideas on that part? Foam and fiberglass sandwich, or....?
I recall this subject coming up not too long ago and I think the Ford box builder guide recommended rubber cab bushings between the frame and box. Seemed fairly simple. But this will surely depend on how well your box can flex... standard truck bodies are usually not that stiff. Do you have some ideas on that part? Foam and fiberglass sandwich, or....?
Victorian
Approved Vendor : Total Composites
you are correct, commercial truck bodies don’t care if they need to absorb some of the flex. A camper body on the other hand it matters a lot, especial if you have openings cut in the walls for windows and doors. You would get stress cracks in no time, no matter if it’s an aluminum or frp body. The same thing goes for the interior. You want zero flex otherwise your cabinets and other fittings will be wrecked fast.
I have seen bodies that flex and the interior held up well as it was built with crude 1x2 sticks and some plywood with generous spacing ? in that case, flex doesn’t matter. But put a nice interior in and it’s a different story.
I think in this specific case I would mount the camper to the drivers cab and create a spring mount at the rear.
ScottPC
Active member
The F series definitely has its merits for sure, and I actually have another thread on the comparison of the F 350 vs the E350 for this use case.
The reason I think the E350 CG may be better than the F350 is with all the builds I've seen of these type of boxes on the F350 they either a slide in or rest on a Flat Bed which raises the box a few inches. All of the F series configuration wheel bases and overall length is much longer and only if you're willing to go with the 176in (crew cab + LB) can you get the larger 48 gallon tank, the rest are just 34.
If the habitat box (FRP and foam sandwich), can be properly mounted, I like the compactness (shorter length, wheel base, hood length, and better approach, departure and brake over angles of the E350. It is nice that the Fseries has selectable 4wd and drive modes and either the 6spd or 10spd transmission and even two gasoline engine options. With the longer wheel base, the Fseries is going to ride better on the highway and tow better. The E350 does fine enough on the road and tows as much as I would ever need it to. With most of the 4wd conversions for the e350 you get very capable off road performance and on the fly 4WD if going a little slower (<55 mph) the Fseries allows the shift to 4wd at a higher speed which can be nice in certain conditions.
I've had a full size 1 ton truck with a truck camper and now an older E350 Sportsmobile and for my purposes, with this build, really just want to utilize the E350 platform for the characteristics I've mentioned with better pass through options but with better insulated interior layout and space utilization that you get with flat panel walls.
Cost is definitely a factor and regardless of E series or F series, there's a lot of it, so before starting, I just want to learn what I can from the experience and advice of those who have been involved similar builds. I appreciate all of the contributions!
Which one flexes more? Assuming wheelbases are identical (i.e. the short cab chassis).
I kicked this around for about 2 years but ultimately just landed on doing an EB with a high top. To get 6'+ standing height inside but stay below 10' total height (my own requirement, may not apply to others), I didn't see a way to do it without making the composite body a pop top. Mounting the composite body low enough seemed to be a pretty big challenge.
rruff
Explorer
That should not be too difficult. My camper with 74" interior height should be ~116" high with ~1.7" thick ceiling. I do have cutouts in the floor panel for articulation clearance, but these do not penetrate the interior, so it's flat inside. The floor is ~40" off the pavement. If you have things mounted to the roof it could become an issue.
Why the 10' hard requirement?
rruff
Explorer
Lots of work I think to do correctly. I'd favor making a stiff subframe and using Ford's guidelines for mounting it to the chassis. https://madocumentupload.marketinga...72908471f0ad38644fd076a79f054f2622ef&v5=False
ScottPC
Active member
With out experience to the contrary, this seems to make the most sense. I'm assuming the composite panels have little to no give which is different than a van body or truck camper to some degree. Being able to mostly isolate the box and using isolating body mounts along with good suspension, the box should remain mostly independent of all the action underneath.
rruff
Explorer
Yes... unfortunately a lot of guesswork regarding just how much stiffness, strength, flexibility you need!
Fiberglass has low stiffness (vs say aluminum which is ~3-4x stiffer), but when you use it as skins on a 2" foam core the panel is quite stiff. Then if you add furniture and cabinetry that ties edges and corners together, and have closed ends, you end up with a very stiff box. But is it *strong* enough to be the stiffest member in your vehicle's chassis and therefore take all the load? A stiff steel subframe with some flex or pivot attachments to the truck chassis seems the most common and safest bet.
Victorian
Approved Vendor : Total Composites
I have seen m12 bolts ripped out of floor panels after the subframe reached it limits. So yes composites bodies are stiff?Yes... unfortunately a lot of guesswork regarding just how much stiffness, strength, flexibility you need!
Fiberglass has low stiffness (vs say aluminum which is ~3-4x stiffer), but when you use it as skins on a 2" foam core the panel is quite stiff. Then if you add furniture and cabinetry that ties edges and corners together, and have closed ends, you end up with a very stiff box. But is it *strong* enough to be the stiffest member in your vehicle's chassis and therefore take all the load? A stiff steel subframe with some flex or pivot attachments to the truck chassis seems the most common and safest bet.
Is your van low to the ground? 116-1.7-47 = 40.3" to the interior floor. Factor in at least another 1.7" for the floor thickness and call it 3" for the supporting subframe and you're at 36.6" to the bottom of the subframe, which will be the top of the van frame. My van is lifted and on 35s, and the top of the high part frame rails is definitely above 3'. There's a sizeable hump over the wheel wells that needs to be accounted for either in the composite floor or the subframe. If you can get the composite body to sit pretty close to flush with the flat part of the frame rails, then you can do it.
My 10' limiter is my garage door. The van with a 24" high top just barely fits.