M1088 camper conversion

ckouba

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Have I thought about putting tanks under the bed, yes. Probably won't though, for a couple of reasons.

I don't want things cantilevered out at the far end of the camper. It will be a lot of weight when loaded up (batts, water, gear, etc...) and while I think I have adequately spec'd its construction, I don't want to design in a load in that location. Right now, the only load that will be out there beyond the structure's own weight is our clothing, mattress, and us when we sleep. And whatever adventure gear we throw in the cargo bay (spare will also be mounted in the cargo bay but directly attached to the subframe and its load will not be borne by the camper frame).

I would prefer to keep the heavy stuff low for C of G reasons. Not that I will be out-cornering Ferraris and Corvettes in the camper but I don't want to roll it over when things get uneven. Water and batteries will be a considerable load (although truth be told, I haven't actually spec'd out either system in detail), and having them 3+ feet lower and between the chassis rails is appealing.

Right over the rear axles is where the 1088 was designed to carry weight. It makes sense to position my heaviest components in that space.

I will make a well insulated sub-floor space, but even so, I figure I will end up with some sort of tank wrap for when I am in storage and heater ducting for when we're out in it. I can live with that.

The current plan is for a composting toilet with a fallback of a cassette, so the objective is to not have a black tank. We have yet to commit to this but it is looking like we will.

We'll have a grey tank which will be easily accessible.
 
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AllenF

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Chris,
You are doing a great job.

It sounds like you have a little wiggle room with your camper design. Here is a thought I have about warming holding/water tanks. Many camper/RV builders talk about blowing warm air into the tank area to help with freezing. In my experience it works only when the temps are just barely below freezing but it fails when things get real cold. It involves a lot of ducting and burning fuel for hot air generation etc. In other words it is inefficient and expensive and really does little to solve the freezing problem.

I like the diesel fuel water heater idea for several reasons. It heats the water faster than any air blower method. It is much more compact and thus frees up space for other items. When total prices are considered it does cost a bit more but is better at warming and is only one fuel which means you should be able to eliminate propane. This will free up even more space as diesel has more BTU's than propane and requires no pressure vessel. Saving more space again.

If you have your tanks inside then you have little to worry about as far as freezing goes. For the fresh water tanks you can circulate heated water into the cold water system using a small 12volt pump with a thermostat to regulate the water temps and pump cycling. The heat from the engine can be used to warm the water system while the truck is rolling down the road or the engine is running using this waste heat saves a little fuel too. You also can warm the truck engine which these beasts can be benefitted from as they are not the best cold weather engines.

If you do place your holding tank/tanks outside I would go with large electric tank heating pads as these will transfer more heat than the hot air method too. There is no ducting to worry about and so is more space and design friendly. Just try to insulate them as best you can.

If you know you will never be camping in freezing temps then build it any way you like as it is far simpler to stay in warmer areas as the seasons change. But if you are going into colder climates then the best method is to place all tanks inside the heated space as they will always be warm with you. The same for batteries.

Since your truck can haul the weight more water is possible and tankage too. You just have to figure out where and how much.

I am looking at 300+ gal of fresh water. About 85-125 gray and 25-40 black. Not sure if I will go with composting toilet. The fresh will sit over the tandem wheel area on the floor so that weight will be low and on the axels where it needs to be. Should help out a lot with the ride quality.

These large amounts of tankage should allow for extended stays which means we will be able to camp deeper and out stay others buy weeks not days.
 

ckouba

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Hi Allen,

Thanks for the bit of a reality check. We will be camping in colder climes, hopefully not extremely frigid ones but definitely into the teens but possibly lower. We've done it before in our Bigfoot campers (a truck camper and a bumper pull) and it seemed to work well enough with the tanks within the envelope but I am aware of the upside of having the diesel water heat as well.

A marine water heater (i.e., water heater with an engine coolant loop) is actually on my wish list and I have been thinking about it for precisely the reasons you document. I was thinking of adding the electric pads for the tanks for simplicity if shore power is available as well- in theory it should be easy to include them during the build, even if they are never actually used in practice.

So far, I have only casually planned out the system if connecting it to the motor. The location and plumbing of the expansion tank appears to be fairly convenient for splicing in a circuit to include an engine-based water heater as well as the auxiliary diesel fired heater. I haven't committed to it yet but it's under consideration.

Those are big tankage numbers. I would like to get that much on board and will be trying to do so but may be space constrained. I intend to put the largest of the tanks over the tandem axle assembly and as low as possible, like you, and for precisely the same reasons you cite. We are looking to maximize our ability to boondock as well and that'd go a long way toward that!

Chris
 

Reworked LMTV

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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!
Did you use anything special for the from mounting bolts. They look like 1/2" or slightly larger maybe? Love the mag drill!
 

ckouba

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They are normally available grade 8 hardware from the local Wilco (Ace Hardware), but if I remember correctly, they're 5/8's. The plates are 1/2" thick. I will be adding 2 more bolts in the empty holes in the lower rail but three is all the upper rail will be getting. The last two empty holes in the upper rail are were the tube was notched around the trans. The missing fasteners won't be added until after powder coating and such.
 

ckouba

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Happy New Year's Eve everybody!

Beyond that, sorry but no updates Doug. My parents both had a run in with cancer and I am helping them get set back up in their condo as they had been living at my sister's for the past ~8 months. They both appear to have dodged a bullet health-wise, so despite what 2020 has been for the rest of the world, our family has plenty to be thankful for. The progress on the build so far has been motivated by wanting to get a trip in with my dad before that opportunity disappears, and it's about the only activity I have pursued outside of work and traveling for family stuff.

All is not stagnant with my build though- I just won't be there to see it. I have arranged with Bryce to install lockers in the rear two axles, which he will be doing while I am away. Kind of a bummer because I would like to be there to "help" him, but the next window of opportunity was months out and I didn't want to wait that long.

Next update with substance won't realistically be until February.

Chris
 

19Detail

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ckouba, I am sorry to hear your parents had cancer and glad to hear they are doing well. I was thinking, if you are not doing a ton of winter camping, you could split the tanks. Have the majority of the water stored low and outside where it makes sense and a smaller tank inside for when you are in a colder climate. You could even have a pipe between the two to move water back and forth. Just a thought. Good luck with the build and thanks for the pictures.
 

Third From Texas

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ckouba, I am sorry to hear your parents had cancer and glad to hear they are doing well. I was thinking, if you are not doing a ton of winter camping, you could split the tanks. Have the majority of the water stored low and outside where it makes sense and a smaller tank inside for when you are in a colder climate. You could even have a pipe between the two to move water back and forth. Just a thought. Good luck with the build and thanks for the pictures.
Interesting concept.

I'd not thought of using both.
 

mauinate

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How are you putting a water tank above your rear axles? You’ve got maybe a max of 14” height between the axle parts and camper bottom. You’re maybe 100gal at most there. Am I missing something? Thanks!
 

ckouba

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How are you putting a water tank above your rear axles? You’ve got maybe a max of 14” height between the axle parts and camper bottom. You’re maybe 100gal at most there. Am I missing something? Thanks!
Nope. You're right. I'm not sure it will all go there and still haven't actually calculated what volume I have after accounting for clearances and insulation. I have no magic trick though, so may end up with more elsewhere (second tank) as already suggested.
 

ckouba

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ckouba, I am sorry to hear your parents had cancer and glad to hear they are doing well. I was thinking, if you are not doing a ton of winter camping, you could split the tanks. Have the majority of the water stored low and outside where it makes sense and a smaller tank inside for when you are in a colder climate. You could even have a pipe between the two to move water back and forth. Just a thought. Good luck with the build and thanks for the pictures.

Thanks 19, we are really lucky with both of them so far but life is definitely different for the whole family.

I really like the idea of a split tank and will happily incorporate that as needed. A transfer pump should be easy enough to include.
 

mauinate

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I’m running up against the same problem. I’ll probably end up with grey between the frame (105gal) and black (100gal) and fresh (200gal) on the driver side between the cab and drive axle.
 

Ambot

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So far, I have only casually planned out the system if connecting it to the motor. The location and plumbing of the expansion tank appears to be fairly convenient for splicing in a circuit to include an engine-based water heater as well as the auxiliary diesel fired heater. I haven't committed to it yet but it's under consideration.
I’m installing 2 espar D6L water heaters, 1 for engine and cab and 1 for the box with a shared plate heat exchanger. The engine heater will use the existing expansion tank and the box will have its own. I did it this way for redundancy and isolation. The espar controller allows 2 heaters to work in unison or separate, allowing up to 12kw if needed.

I’m looking to see the best place to splice into the engine circuit to be sure I hit the cab heat exchanger first and then circulate as much thru the block as possible and finally thru the plate heat exchanger.

I can’t find a good coolant flow diagram or consensus on the ideal interface points.

Can you expand on what you planned out so far?
 

ckouba

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Can you expand on what you planned out so far?
Not really... I've honestly got nothing concrete on paper yet, but no better time to start talking about it.

My experience with this comes from working on our boats where we've had hot water heaters with engine coolant loops built in to heat the water in the tank while the engine is running. None of this is researched for compatibility issues, but conceptually I want to have both a diesel water heater and a marine type of water heater (by "marine" I simply mean one with motor coolant loops). These would both be housed in the habitat and I am presently inclined to connect it to the truck system near the expansion tank.

For the sake of this conversation, let's call the tank with an engine coolant loop through it a "tank heater", i.e., a static volume of water in a tank which is heated by the passage of warmer fluid (in this case, motor coolant) being pumped through loops of pipe inside the tank. We'll call the D6L and the others like it a "water heater", as they heating the water directly.

There is a feed into the motor's expansion tank which, if analogous to gas motors I've worked on, should be the input to the tank, and the tap from the bottom should be going back to the motor. What I am thinking of doing is splicing into the line feeding the expansion tank and sending the motor's coolant through the "tank heater" and then returning the motor coolant to feed the expansion tank. This would heat the volume of water in the tank heater to motor coolant temp and get me hot water while underway.

That part feels pretty straightforward. I would make sure the expansion tank remains the highest point of the cooling system and still have to check for any other compatibility issues, but I think it's a pretty solid plan. Until someone here points out the obvious thing I missed...

From here on out, I am improvising for the sake of discussion.

There are two ways that incorporating diesel water heat could be done fairly easily. The simplest is a diesel water heater like the "tank heater" I described above except with the water being heated by combustion of diesel fuel instead of passage of engine coolant through the tank. A selector valve would need to be used to avoid pulling water from the motor side tank if it's already cold and I know we'll only use the diesel side tank. What's the down side? I don't think they exist.

The other fairly easy way is a tank heater which has a second set of loops through it. In a tank heater like this, I could use one set of loops for engine coolant (spliced in as described above) and the other one for the fluid heated by a "water heater" like the Espar. What's the down side? This system would require a bit more plumbing, using the water heater as a hydronic heater and pumping the hydronic fluid through the second set of loops, but the side benefit is we could also use the hydronic fluid for heat as well. It would also play into the other suggestions about avoiding freezing issues in the water tanks. The other downside? I'm not sure the dual loop tank heaters exist either.

Reality may force me to combine the two concepts. I would be inclined to have a tank heater plumbed into the engine cooling system and take advantage of the waste heat to heat water. In addition, a hydronic system might be used to heat water in another tank heater. A selector valve could be used to toggle between them based on what was already hot. It'd be a bummer to heat a full hydronic system on a hot day to just take a shower if the motor side is already cold, but it would be the system which does everything.

I have stumbled across the Aquahot products while casually surfing as I write this post. They sound awesome but good grief they are expen$ive... Are they gold plated?

Definitely open to suggestions, recommendations, etc...
 
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