Attatching camper to cab

[motas]

Hey all. I have a bit of an odd jeep which I am going to build a camper for. It is basically a FSJ chassis with a bobbed CJ body and a steel hardtop split into two pieces. Anyway I am at a cross roads with the design. I am trying to keep it as small as possible but just cannot fit everything into a 2.5x1.5m area. So I either have to make it wider or longer. Wider it would be sticking out past the cab on both sides risking not fitting down trails and makes the front corners very vulnerable. Longer means an overcab design, something I have being trying to avoid. In the normal configuration this means a fair amount of added height which is very vulnerable to branches and such and a higher centre of gravity and more wind resistance.
So what I have thought is if I remove the hard top I can build the camper attached to the back of it. This means I can put a bed over the cab with a very small gain in height. It also means if I fabricate a swivelling seat mount I can use them as internal seating, saving even more space and cost. I can still make it removable so I can slide it off at a camp site and make a soft top to cover the cab where it is missing.
However what I am wanting help on is mounting the camper. If it is solidly mounted to the body which it has to be in this design then it needs to flex with the body instead of the chassis which bears most of its weight. I doubt this chassis would have as much flex as a truck but I have no way to test it and don't want to run into problems later. So how can I design the camper to not stress the body? My initial thoughts are to do a 3 mount system with the two mounts at the front but it will still have a gap of about 0.5m between the body mounts and camper mounts. I do not want to modify the chassis to move them either. Otherwise the camper would have to be somehow made flexible to twist with the chassis.
Any ideas?
Thanks.

 

[geordie4x4]

Fiberglass.

Or see what you can get in glass reinforced sheeting then cut and fabricate.

Aluminium would be nice but it does crack with fatigue from flexing.

I have been toying with the same idea of making a pop top to fit on my Nissan Patrol GU wagon, but in the end I have settled for a hard shell roof top tent and I am trying to mount it as low as possible on a low profile roof rack.

Also have a look at the Ursa Minor camper for the Jeep JK they have some good ideas that you might get some help from.
http://www.expeditionportal.com/forum/threads/81780-Ursa-Minor-Pop-Top-Jeep-JK

For your body mounts do you have an open back where it is going to fit like a ute tray slide on camper?
Also can you use additional Jeep body mounts so there is the same amount of flex as the rest.

 

[motas]

Fiberglass is fairly inflexible isnt it? I thought around bolt holes etc would crack very quickly under constant tension and compression. Ursa minor is very cool but not much like my design because it is building right on top of a pre existing cab. Mine is a cab chassis so all the weight is supported by the chassis not the cab. I can usethe body mounts but the problem is the chassis flex. The camper mounts need to flex a lot more than the cab mounts and even more at the rear end. And Im not sure if I can get it to flex that much without too much stress on the cab.

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[geordie4x4]

Ah yes I get you.
If you are mounting to the chassis then would you need some sort of sub-frame for the base of the camper then that is mounted with rubber blocks to the chassis.
I did see somewhere on this site the big truck type expedition rigs use a rubber block to the chassis, but then the bolt that runs through the rubber is longer and has a heavy spring, big washer and nut under the chassis mount point. That way it can allow a lot more flex of the chassis as it pulls down from the sub frame of the camper when the chassis flexes.

 

[motas]

The problem I forsee with that though is they need to be stiff enough to hold the camper upright but soft enough that the cab moves the camper without putting stress on the join. Im worried that I wont be able to get tbat middle ground and it will crack the cab. Or the mounts will be too soft and the camper will sway a lot.

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[geordie4x4]

Yes I get what you mean, which I suppose is why the ute tray campers have quite a gap to the cab.

Can you make the sub frame for the camper to pick up from strong points on the floor of the cab so that it moves more with the cab than with the chassis. Then the stress would be at the floor and sub frame rather than where your camper top meets the roof of the cab and there is more movement and less structural strength.

 

[JHa6av8r]

This was actually done originally by FWC using the old Bronco and similar vehicles. The hardtops were removed and a pop-up camper built in its place.

 

[motas]

Yeah good idea I might be able to pick up from the rear body mounts, but id still need a very flexible solution for the rest of the camper. Dont broncos have a full length body though? Mines a ute so its a bit different. I may be wrong though im not familiar with broncos but I will check it out.
I might have to build the camper out of something that will twist and not crack.
Cheers for the help.

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[geordie4x4]

Maybe, you could think about a camper that is a tube frame and covered with plastic sheeting, alloy roof and canvas side pop-up top.
There are some great light weight but strong plastics now. Either a solid sheet like EVA, HDPE or there are also insulated light weight hollow plastic 'core flute' sheet.

 

[geordie4x4]

I also just spotted this thread which is building Jeep based trailers but might be good for ideas on camper costruction.

http://www.expeditionportal.com/for...ot-modular-trailer-topper-building-components

 

[motas]

I have been following that build closely and it is something I have very carefully considered but I dont think it suits my needs perfectly, but I think I will borrow a lot of the design as it will look perfect and is a good way to build it. However right as I was half asleep something occured to me. The cab section is tiny and the fenders and grill are quiet flexible so if I simply put softer mounts in the cab area and have a triangular subframe on the camper the cab should flex enough instead of the camper to make up for the flex between the mounts. Hopefully that would be just enough to make it work.

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[geordie4x4]

Good point about the cab body mounts. If you reduce the flex between the cab and camper by making the whole unit move together and more evenly mounted on the chassis that can only be a good thing. You will probably find that your old mounts have compressed and hardened up over the years anyway.