M1088 camper conversion

ramdough

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You do quality work. Really enjoying the build. Just catching up to this read.

Couple comments.

For your fixed mount.... will that be in front of the tranny notch or behind? If it is in front, you will have a more flexible frame section between your fixed mount and your first spring. That seems like an issue. Your frame will want to flex in one location and that may crack your subframe or your habitation box. I would consider scabbing something on the outside that restores some of the bending moment and torsional rigidity in the beam. I would extend past your cuts and taper your scabbed on part so you do not get a sharp stress concentration.

As far as access to the tranny bolts go..... I would make it so you just remove the camper..... then you have tons of access.

What is your total allowed displacement for your rear spring? I came up with a lot of needed displacement when I was looking into rail on rail designs.

To prevent your free end from skewing, I always wondered why no one put in something like a panhard bar there. Are you using side plates? Will they be tall enough to catch that large displacement?

Looks great. You do quality work.


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ckouba

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I hunted for a while regarding where to place that fixed mount for exactly the reasons you mention, although I was more worried about inducing issues with the chassis than the cabin (I think I spec'd the cabin construction to be stout enough that it would ride out any issues). I have positioned the lower rail to chassis forward fixing plate right at the end of the chassis reinforcements and it will pick up the two forward holes used for the transmission mount. In this respect, the fixing plate will bridge the last chassis reinforcement bolts for the interior plate to just the frame element. The exterior OE reinforcement ends just aft of where I am planning to attach my plate. I think this is an acceptable solution but still open to suggestions.

Camper will be de-mountable, but definitely not convenient. If anything mechanically catastrophic happens, that is the plan.

I forget the exact numbers for displacement, but it was somewhere around 6 inches. With the spring rates chosen, the forces ramp up pretty quickly to match the neighborhood of the expected weight for the camper, so I figure that was a good place to start. If it's too stiff or too floppy, the springs are easily swappable.

And quite frankly, I love the idea of a panhard bar for lateral control. That seems so much more elegant and appropriate than the catch fence concept. I'm not above stealing that idea. Should be totally reasonable to incorporate (famous last words!).

Thanks for your thorough review of what I'm up to. I appreciate the extra eyes looking for pitfalls.

Chris
 

coachgeo

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....
Camper will be de-mountable, but definitely not convenient. If anything mechanically catastrophic happens, that is the plan.
....
Chris
since your building your own camper box..... why not design in a trap door (and framing below) that allows for tranny access? Ton easier than removing camper box.

Am hoping to put my former ambulance box down as close to truck chassis as possible.... thus I'll be cutting out floor and re-framing that area. adding raised floor to go over tranny there. Im hoping roof structure is in good place above to actually add a point to hook a chain hoist too. So can not only access tranny.... but also unbolt and lower it down from there too.
 

ramdough

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I hunted for a while regarding where to place that fixed mount for exactly the reasons you mention, although I was more worried about inducing issues with the chassis than the cabin (I think I spec'd the cabin construction to be stout enough that it would ride out any issues). I have positioned the lower rail to chassis forward fixing plate right at the end of the chassis reinforcements and it will pick up the two forward holes used for the transmission mount. In this respect, the fixing plate will bridge the last chassis reinforcement bolts for the interior plate to just the frame element. The exterior OE reinforcement ends just aft of where I am planning to attach my plate. I think this is an acceptable solution but still open to suggestions.

Camper will be de-mountable, but definitely not convenient. If anything mechanically catastrophic happens, that is the plan.

I forget the exact numbers for displacement, but it was somewhere around 6 inches. With the spring rates chosen, the forces ramp up pretty quickly to match the neighborhood of the expected weight for the camper, so I figure that was a good place to start. If it's too stiff or too floppy, the springs are easily swappable.

And quite frankly, I love the idea of a panhard bar for lateral control. That seems so much more elegant and appropriate than the catch fence concept. I'm not above stealing that idea. Should be totally reasonable to incorporate (famous last words!).

Thanks for your thorough review of what I'm up to. I appreciate the extra eyes looking for pitfalls.

Chris
Sounds like you have put a lot of thought into your design. Please feel that any comment by me is meant to be collaborative and adding perspectives from outside. Feel free to steal any idea or reject anything I say.

How is the cabin being constructed?

When I was looking at doing a rail on rail design, I planned to place PE or HDPE plates between the rails and then attaching them to the subframe with bolts into bracket on the side (that way I can never pinch a bolt head).

Based on a few discussions I had with a camper builder, he estimated our trucks need a lot more than 6” of travel. I was getting 16” from his estimates.

I am really curious what you would see if you put 10,000 lbs on your frame and articulated your suspension. It may be worth loading it up with weight and no springs, and see what the free travel gives you.

I am months behind you on my build. I am scabbing on a few more feet of frame I stole off of a 1078A1R. Adding the whole rear clip to mine so I get the extendable hitch.


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ckouba

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Sounds like you have put a lot of thought into your design. Please feel that any comment by me is meant to be collaborative and adding perspectives from outside. Feel free to steal any idea or reject anything I say.
I have thought quite a bit about it but I still understand that I don't know everything. I genuinely appreciate the peer review feedback and will happily steal ideas where I see them!

How is the cabin being constructed?
It will be a mix of 2x3x.120 and 2x2 in both .120 and .080. The 2x3 stuff will be in the floor for the most part and the 2x2 for the remainder. I went with steel because it's something I am familiar with and can work with comfortably. And also for budgetary considerations....

When I was looking at doing a rail on rail design, I planned to place PE or HDPE plates between the rails and then attaching them to the subframe with bolts into bracket on the side (that way I can never pinch a bolt head).

Based on a few discussions I had with a camper builder, he estimated our trucks need a lot more than 6” of travel. I was getting 16” from his estimates.
I'm planning on adhesive backed rubber, but I also know that may not be up to the task. I have other thoughts for plan B but am sticking with plan A until it fails.

With the rail subframes, there will be torsional stress transferred to the cabin, unless you opt for no springs. My intent is to construct the cabin robustly enough to withstand what might get applied to it. With the mix of materials I've selected, I think this is sufficient. Time will ultimately tell though. I don't intend to rock crawl with it, but it should see a bit of off roading.

I am really curious what you would see if you put 10,000 lbs on your frame and articulated your suspension. It may be worth loading it up with weight and no springs, and see what the free travel gives you.
So am I. That has been part of a plan for a while, but need to work out logistics. Maybe not 10k but something... I want to see what the subframe does before I construct the box on it, but I hadn't thought about removing the springs. Would be an interesting exercise.

I am months behind you on my build. I am scabbing on a few more feet of frame I stole off of a 1078A1R. Adding the whole rear clip to mine so I get the extendable hitch.
Did you start a build thread? I am always interested in seeing others' work.
 
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ckouba

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Progress over the last 36h....

72 holes of 1" dia drilled into beam:


LOTS of fun!


36 crush tubes cut and beveled:


Crush tubes welded in:


Beams put back into position, more holes drilled- this time for lower rail spring perches:


After lots of frustration and a beat up thumb, rented a magic tool:


POOF- lots more holes accurately drilled with no further injury:


Next update will have the finished mounts of plates and the upper rail reinstalled (it came back out after the last pics above).
 

ckouba

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since your building your own camper box..... why not design in a trap door (and framing below) that allows for tranny access? Ton easier than removing camper box.

Am hoping to put my former ambulance box down as close to truck chassis as possible.... thus I'll be cutting out floor and re-framing that area. adding raised floor to go over tranny there. Im hoping roof structure is in good place above to actually add a point to hook a chain hoist too. So can not only access tranny.... but also unbolt and lower it down from there too.
Looking at what I wrote earlier, it may be misleading. I plan on doing exactly that. The "remove the box" option was for something truly catastrophic.
 

ckouba

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With the exception of lateral control at the rear, I think the subframe is... done!??!!?

Fully installed:


Lead edge of the subframe assembled (driver side; all holes in the upper rail have crush tubes installed):


Pass side:


Aft spring perch:


Looking forward:


The plate I had cut for fixing the lead end of the lower rail was a direct replacement for the spacer on the forward fuel tank mount. Worked out fantastically. I was dreading that install (without thinking, I had recently filled the tank) but it ended up only taking a few minutes to support it on jack stand and move it far enough out of the way to access the bolts and swap out the plate. It may have taken me longer to do the driver side.

Everything pretty much went together as intended- made the plan, executed the plan... The only mod I needed to do was open up the holes through the base of the perches to give just a little more clearance and prevent binding.

Next up is the layout of the cabin floor and getting the "joists" cut and welded in the proper places to the upper rail. Exciting times for sure!
 

ramdough

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Looks great!

Is that the upper frame rail of a 1083?

Reason I ask, is it is mounted upside down from what is on the stock 1083. I don’t think that matters in your case, but it is just something I noticed.

With the steel camper frame, you should have no problems with torsion.


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ckouba

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Looks great!

Is that the upper frame rail of a 1083?

Reason I ask, is it is mounted upside down from what is on the stock 1083. I don’t think that matters in your case, but it is just something I noticed.

With the steel camper frame, you should have no problems with torsion.


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That is exactly what it is. I was trying to find something appropriate to put there and Quade at overlandadventuretruck.com had them surplus. The inverted configuration seemed to work out best in my application.
 

ckouba

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Another single pic update... Doesn't look too different but everything is now rigidly fixed in position:



The open span at the front is for driveline access, at the rear for sub-floor storage. I started working on the stairwell and ran out of weld wire after tacking the first component. Perfect timing, must be time to go in for dinner.
 

chucky

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That's the plan. Hope to get them in the sub-floor space over the axles. Would like to locate the batteries in the same neighborhood as well but will see where we end up for space.
Have you thought about putting all your tanks pumps batteries inverter and such under your bed and put hinge top lids over them out of 3/4 for the mattress to lay on with a grill facing into living area for room temp air to flow thru and around in the winter ? You could bury the black water tank down in the frame rails if you pour some antifreze in each tank full but place the dump valve where you can reach it when time to hook up hose and dump you can put a manual or a 12 volt dump valve they are not very expensive both will require a small amount of maintenance o-rings seals and such so give your self room.
 
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ramdough

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That's the plan. Hope to get them in the sub-floor space over the axles. Would like to locate the batteries in the same neighborhood as well but will see where we end up for space.
Are you going Lithium or AGM batteries?

If you go lithium, I would worry less about where those go because they really are not that heavy. They could go where convenient instead of taking up space where water can go. They still are more dense than water, but with all of the air and electronics around them probably make the compartment less dense.

What kind of toilet are you getting? If you do a composting toilet, then you don’t need a black tank. I plan to build something like this, except with a permanent pee tank. So far every person I have heard of that has a composting toilet prefer them over conventional. Only the people that obviously do not know how to use them have issues.


Can’t wait to see more progress. Looks great.


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