Bought Someone’s M1078 Camper Project- Seeking Direction on a Couple Issues

[sue]

The truck made the 250mi drive from Florida with no issues fortunately. I drove overnight to take advantage of less traffic and cooler temps in hopes of reducing the chance of a tire separating from heat, especially since my spare has a date code from 2001.

The subframe is direct bolt-mounted to the existing frame. Pictures are attached below. My limited research leaves me to believe a pivot style torsion-less system is the best subframe mounting option. I’m not sure how easily I could modify the current mounting to that style. The other option would be a captured spring style system. It’s seems like this would be a simpler system to adopt, but I’m not clear on the drawbacks. I believe if I went with the captured spring system, I could replace the OEM mounting plates with new plates that incorporated the captured springs. And I would not need to lift the box off the frame to complete the install. I plan to call Dave Anderson on Monday and get his professional opinion, but I’m curious to hear the forums’ thoughts as well.

Coachegeo- to address your question from earlier in the thread, the skins are attached with 3M VHB tape. And the roof is secured with fasteners and 5100 over the top of the fasteners.

We’re in Tulsa Oklahoma, if you get this way on your travels, we have a place to park and do maintenance at our shop.
we have drove up to Alaska and western Canada so we know it’s not short drive. We went again last summer. PM us if interested. And good luck.
And P.S we experience in serious modifications to heavy trucks, trailer's, etc.

 

[sue]

A

We’re in Tulsa Oklahoma, if you get this way on your travels, we have a place to park and do maintenance at our shop.
we have drove up to Alaska and western Canada so we know it’s not short drive. We went again last summer. PM us if interested. And good luck.
And P.S we experience in serious modifications to heavy trucks, trailer's, etc.

And sorry if our earlier post was late to you, just got back from Colorado late yesterday.

 

[VoslickZ]

Just shooting from the hip here:

Captured spring designs are for durable and reasonable stiff boxes. Even if you put that box on another subframe, you need to ask yourself how durable and torsion resistant that box is. Every spring mounted torsion free frame will have some twist.

Those welds look a little rough (not super clean and professional) and VHB may not last forever. I would probably consider this box as not overly durable. I cannot judge how stiff it is.

Commenting on @coachgeo comments. For springs, the rear end is the most structurally sound place to mount. That portion of the frame has the least stress on it, bumps do not cause the rear end to bounce, and your fixed point is closest to your tires so your clearance requirements are less. With that said, most people with passthrough opt for front fixed mounts (like me).

I would probably opt for a 3 point pivot system for that truck given your box design.

Hope that helps.


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My understanding of the feasibility of captive spring designs lends more to the stiffness of the frame rather than the box. Can you elaborate on the integrity of the box playing a role in it? I'm leaning away from a 3 point system because of the extra height required to accomplish incorporating the system.

I personally don't trust the VHB long term and am planning to use Cherrymax rivets to secure the skins to the aluminum frame.

 

[coachgeo]

My understanding of the feasibility of captive spring designs lends more to the stiffness of the frame rather than the box. Can you elaborate on the integrity of the box playing a role in it? I'm leaning away from a 3 point system because of the extra height required to accomplish incorporating the system.

I personally don't trust the VHB long term and am planning to use Cherrymax rivets to secure the skins to the aluminum frame.

as to Captive springs and rigidity..... IMHO both need to be rigid... but chassis usually is already quite rigid. Long ago chassis had more flex intentionally... not the case for long while now in truck designs though adding more wisely (so not to crack chassis) may be needed sometimes. Hence why more and more are using Captured spring... chasis just dont flex as much as they use too due to more rigid designs from manufacture. Do agree box has to be rigid enugh to pull against the spring and not the spring pull the box out of shape some before resistance is exceeded allowing for spring to finally put thru its stretches.

 

[ramdough]

My understanding of the feasibility of captive spring designs lends more to the stiffness of the frame rather than the box. Can you elaborate on the integrity of the box playing a role in it? I'm leaning away from a 3 point system because of the extra height required to accomplish incorporating the system.

I personally don't trust the VHB long term and am planning to use Cherrymax rivets to secure the skins to the aluminum frame.

A true three or four point mount that is properly designed with a subframe can be torsion free. A spring mount by definition is not torsion free, so your box needs to be stronger to take the twist. You will be putting torsion into your box with captive springs.

Some boxes are really not strong enough to take the twisting forces.


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[ramdough]

as to Captive springs and rigidity..... IMHO both need to be rigid... but chassis usually is already quite rigid. Long ago chassis had more flex intentionally... not the case for long while now in truck designs though adding more wisely (so not to crack chassis) may be needed sometimes. Hence why more and more are using Captured spring... chasis just dont flex as much as they use too due to more rigid designs from manufacture. Do agree box has to be rigid enugh to pull against the spring and not the spring pull the box out of shape some before resistance is exceeded allowing for spring to finally put thru its stretches.

I would say the strength of the spring is your least concern. For me it is the overhanging weight of your unsupported corner when one side of the box lifts off of the weight bearing surface.

 

[coachgeo]

I would say the strength of the spring is your least concern. For me it is the overhanging weight of your unsupported corner when one side of the box lifts off of the weight bearing surface.

yeah that was the (attempted) point..... as in the box needs to be strong enough to not deflect its shape at this point..... all shape change must be at the spring.

 

[montaillou]

I would like to point out that what factories do to vans/RV are often driven by cost when they are building thousands. You are building 1. Companies pinch pennies. If a better solution might cost a little more, consider it. You're not reinventing the wheel, you're making a better one.

Will you be going off road and/or unimproved roads much? Or will you mostly be going to campgrounds?

One specific point about this is your exterior skin. Certainly budget is often a good consideration. I've been looking at various ACM panels but recently came across some fiberglass honeycomb panels, used in the air craft industry, at an auction.

 

[eaw46]

Expedition Portal

The global resource for overland and adventure travel.

expeditionportal.com

A lot of good info here.

 

[coachgeo]

I would like to point out that what factories do to vans/RV are often driven by cost

same with military and often that goes to lowest bidder that claims/shows to- meets the prescribed standards.

 

[VoslickZ]

I would like to point out that what factories do to vans/RV are often driven by cost when they are building thousands. You are building 1. Companies pinch pennies. If a better solution might cost a little more, consider it. You're not reinventing the wheel, you're making a better one.

Will you be going off road and/or unimproved roads much? Or will you mostly be going to campgrounds?

One specific point about this is your exterior skin. Certainly budget is often a good consideration. I've been looking at various ACM panels but recently came across some fiberglass honeycomb panels, used in the air craft industry, at an auction.

The budget is probably more limited than some of the builds I’ve seen on here in the short term. But I’m also willing to delay completion of certain aspects until finances allow if there’s a justifiable reason for the added cost. If it takes a decade to “finish” it, I’m fine with it because I intend to use it in all stages of the build. I’ve looked at ACM panels for the roof because I want it to support walking on it. The ceiling is framed on 12” center so it won’t take a very thick panel to do it.

This rig wont be visiting traditional campsites. If so a traditional RV would be cheaper and easier. With that being said, I’m not planning any trips to Argentina. It will be more of a remote mobile base camp than anything. Ninety percent of its life will be in Alaska, with maybe the occasional trip down south. Are you suggesting the skins won’t handle the abuse of going off-road? I intend to add a 1/8” diamond plate panel to the lower 18-24” to protect from punctures and abrasion from the alders.

 

[montaillou]

Are you suggesting

Just curious what you want to use it for, for consideration. This brings me back to my original point - commercially produced RV's use almost paper thin aluminum skins. However, unless you have a local source or deep pockets ACM panels can get very expensive due to shipping. I will probably use ACM panels for my interior floor. If you plan on taking the Alaska Ferry back, you'll be passing near me and I can show you a local supplier (on this end) of ACM panels.

I want something tough for the exterior skin for two reasons, tree branches and security. I figure a tough skin might be the difference between waking up to someone standing over me and waking up while they're still trying to break in.

The inspiration for my build has always been Mt. Conner, Australia. I want to visit some libraries in Mauritania, though I'm not sure about how safe that will be.

 

[coachgeo]

Just curious what you want to use it for, for consideration. ....

The inspiration for my build has always been Mt. Conner, Australia. I want to visit some libraries in Mauritania, though I'm not sure about how safe that will be.

View attachment 901639

if I recall right a few post up says his goal is geographically opposit of yours.. he plans to use it mostly in Alaska

 

[montaillou]

he plans to use it mostly in Alaska

Yep, got that. I was just responding to that notion.