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Picture of Classic GMC Motorhome Repurposed for Elder Care
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I gutted the interior of a 1976 gmc motorhome and built my own, this was done to aid in caring for my uncle Neal who has dementia and diabetes.

As far as I am concerned, the gmc motorhome was the single greatest thing that general motors ever created. It's features were ahead of it's time for any vehicle, let alone a motorhome. These included, lightweight jet age construction, low center of gravity, front wheel drive and many more, it is truly a shame that they stopped production after just five years in 1978.

Of the vehicles numerous features, there were two that mattered most to me for this project. One being the low step into the vehicle, for Neal who has difficulty walking. The other being the fact that the gmc, not only has a proper automotive body, but one that was intentionally built to have it's interior finished by non heavy industry third parties. Including a structure of aluminum ribs that have generous flanges for interior use that fit within the confines of 4'x8' sheet goods.

Let me restate that, It's as if General Motors built this thing just for me, or anyone, to make your own interior using normal construction materials.

Add to this, the fact that many of the original interiors were pretty terrible, particularly when paired with such a wonderful chassis. The most egregious insult being the overhead cabinets that cut off the top portion of the vehicle’s marvelous large windows. The layouts ranged from quite functional, to quite dysfunctional. The one we got had a bathroom with this weird child sized tub and shag carpeting under the toilet. Some of them even had a central vacuum system, you know, to maintain that shag carpet,.. I kid you not.

So this forty year old treasure, is uniquely ripe for custom re-imagination by individual makers.

Step 1: Get One, and Make It Run

Picture of Get One,  and Make It Run
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The gmc was produced in two lengths, 23 and 26 feet, nine out of ten of these were the longer 26. I needed a 23 because it would just barely fit in our driveway. If you need a 23, expect to look a little longer and maybe pay a little more, as they are more rare.

A very good thing is that, for all things gmc related, there is a small industry of folks, selling and even making stuff specifically for the gmc, so getting parts for these is actually not a problem. In fact there are even upgrades that are readily available like rear disc brakes and improved suspension kits. There is also an active community of gmc owners in user groups or with websites sharing information on these wonderful machines, I will provide some links.

A forty plus year old vehicle will likely need more than just the interior worked on. Among many smaller repairs, I had the oldsmobile 455 engine and turbohydromatic 425 transmission rebuilt locally. I also had the final drive swapped for one with limited slip and also lower gears for better hill climbing while towing. Once the mechanic had removed the engine and trans, I had the vehicle towed back home so I could continue working on the interior, while the engine and trans were rebuilt.

The vehicle has ample power and handles well for something this big, I actually enjoy driving it.

chadarac5 months ago
LanceBuilt (author)  chadarac5 months ago
thanks, looks like some good info to have

This guide can be helpful with solar layouts and system sizing https://www.outsidesupply.com/rv-solar-guide/

BayRatt1 year ago

I love that so much thought and care was taken into the amenities and requirements of caring for someone with needs such as your uncle, and to take it to the extent of creating a special vehicle for the purpose. Good decision on opening up the windows - that makes it look so much more "homey" and inviting. Lovely job, and a very heartwarming, if bittersweet story. Thank you for sharing this with us.

BeaK3 BayRatt1 year ago

Ditto, what a loving thing to do.

LanceBuilt (author)  BayRatt1 year ago

Thank you,

I must say, It feels really good to be on the receiving end of such kind words as yours as well as those of others here.

mccoolll1 year ago

This is an awesome project and a great idea. Your Uncle is very lucky to have you.

LanceBuilt (author)  mccoolll1 year ago

Thank You

You built a heat exchanger. Impressive!! Did you bend the coils your self,??. hope you pressure test your tank to 350 psi, and have a spot on top the tank for T&P relief valve ( temperature /pressure) 3/4 " . Your building a type of bomb ,do your research... Im a boiler tech/ hot water specialist.. I know the damage these things can do.. now it's in a moving vehicle. Now you have to consider the safety of people moving past you outside on and off the road..
Something else regarding the p-trap for shower. Iooking at what you pictured, you could have installed trap under the floor in line going into waste tank ,with 3) 90 deg elbows. If no tank no trap needed, p-traps hold back the gasses, oder from sewer.. that's all they do..
GREAT WORK!

LanceBuilt (author)  plumbermike1 year ago

Thanks,

All good points, yes T&P on the tank and and an additional expansion tank as well. The copper I purchased already coiled up and sold as a wort chiller for folks who make their own beer. Yes stink is all I'm concerned with a trap for, the height between the deck and the top of the holding tank is very short, considered doing what you suggested with elbows but even that wouldn't fit unless I laid it over partially sideways. Just yesterday I learned of something called a hepvo water less trap, I think such a thing would do the trick if ever I do such a thing again I might do that. But I don't think we'll be showering a lot in the rig and if necessary will just stopper the drain in between showers to shut out any smell, I'm thinking that maybe driving around may cause the running trap to empty and allow stink to enter.

My friend sounds like you have you hydronic system well taken care of!! I going to boost your ego a little.. I thought I was a jack of all trades.. you are the make it happen captin!! Countless hours of research you must have done.. Long nights working fabricating, your ideas.. how long did this project take you??

Re: your shower trap.. without actually seeing it, I would confuse you, more than help you. To remedy your ptrap situation.. the water less trap,sounds like a type of check valve... Anyway GREAT JOB!!

Can't wait to see what your hydronic system looks like!!

TAKE CARE..

LanceBuilt (author)  plumbermike1 year ago

Thanks,

I didn't count hours, but yes lots of them, and a lot of difficulties and ideas that did not work, not covered here. I did most of it over the coursed of about six months and then once we started using it the pace slowed considerably, but I am still adding things here and there, like the ramp, additional grab bars and proper curtains.

Looks great! Take care

JustinB3121 year ago

I love seeing people building GMC's It's such a cool platform and you can do about anything you want with it with enough time and skill.
Some of your photos look eerily familiar!

GMC gutted.jpg
LanceBuilt (author)  JustinB3121 year ago

Wow I thought I took ours apart, Will this become an instructable?

Yeah we took it down to the frame, I tend to go a little overboard once starting a project!


Probably not on the instructable, but we've got a blog about the remodel here:


www.thegmcrv.com

LanceBuilt (author)  JustinB3121 year ago

WOW!!! I am thoroughly impressed with what you've done with your gmc, inventive and
absolutely beautiful. Have you considered going into business remaking
uber deluxe gmc motorhomes?

Thanks Lance,
I have given it some thought but the market is so small and the price would be crazy high if I were to do it for a profit. My coach has over 1000 hours of labor. Add design time, parts and materials and we're looking at a pricey upfit if I were paying myself!
I appreciate the kind comments and thanks for adding the link as well!

ChasK351 year ago

Great work on the rebuild, but I have a few things to note:

Per NEC 2017,

550.11 (A) - panels or disconnects "shall be located a minimum of 24" from the bottom of such equipment to the floor level."

And, they should have "a clear working space at least 30 in. wide and 30 in. in front of the panelboard... extend[ing] from the floor to the top of the panelboard."

In a pinch, you really want a good clear working area around your electrical panel/disconnect. Your current set up probably wont cause any dangerous issues as it is set up, but these working spaces and placements are there for your safety while working in the equipment.

LanceBuilt (author)  ChasK351 year ago

Thanks,

Yeah that would pretty impossible to comply with within the confines of a motorhome. I'm not too concerned as I'm not building this for the general public.

But section 550 is specifically for mobile homes. That being said, the main reason for those clearances is for your safety while working on the electrical equipment. Hope that never comes into consideration for you all! Love these renovations of old RVs, makes me want to do my own some day.

JethroH11 year ago
Awesome job on your solar system!
LanceBuilt (author)  JethroH11 year ago

Thanks

besamjohn1 year ago

Loved what you did here! I've been thinking about heat exchanger options for my motorhome as well, can't wait to see what you come up with!

LanceBuilt (author)  besamjohn1 year ago

Thanks

ScottI171 year ago
Great re-build. Did you vent the battery compartment? Just went through having a battery off gassing under the hood and gas getting into cabin of truck due to freash air intake location they can put off some nasty gasses.
LanceBuilt (author)  ScottI171 year ago

Thank you, Yes it is vented, but after similar concern raised by other commenters, one of whom suggested swapping the flooded L16's for agm batteries of the same form factor, as apparently they out gas far less, I am considering doing just that. I could always use the others at my cabin.

Blagadán1 year ago

Nice work. I like your "Get 'er done" work ethic. Love the GMC. I'm rebuilding a 37 year old C class Coachmen at the moment and I'm taking way too long on the project. 4 years into it at this stage. I wish I had your pace! I am very interested in seeing more about that Hydronic system you're building. I have the same idea bouncing around in my head for our RV... Is that a standard system you're cutting down to suit or did you "scratch make" the heat exchanger unit?

LanceBuilt (author)  Blagadán1 year ago

Thanks, Mostly from scratch, though I don't want to do much reinventing the wheel so to speak. The heat exchanger is a wort
chiller, something used for brewing beer. There are these plate type exchanger's that look great I may make some use of though you'd need to have a flow on both circuits, two pumps? for them. I'm interested in using this project as a smaller platform to experiment on before making a much larger system for our furure home and shop, where I've got a 1600 sq ft slab with pex embedded in it that I'd like to use geothermal for.

This valve, https://www.pexuniverse.com/webstone-pro-pal-4861...

is a very handy thing that allows you to fill/purge a system without making any breaks.

I haven't yet started playing with zone valves and what not, though I did do some some bench testing that led me to ever larger heat exchangers, even that 100' coil is marginal if the incoming water is super cold and if using it for the fresh water circuit. The hydronic setup has been on the back burner for the last several months though i may jump back on it soon.

holla20401 year ago

Great work on your Dad's new ride. I was expecting a lot of urban assault vehicle comments but I guess I'm the first. http://kudrav.blogspot.com/2007/05/stripes-em-50-urban-assault-vehicle.html

LanceBuilt (author)  holla20401 year ago

Thanks, first but not last I'm sure

My first thought as well :D

iceng1 year ago

Impressive Trash to Treasure..

We sold our RV last year because it just sat there.. We only used it once a year for a week of dirty land sailing..

LanceBuilt (author)  iceng1 year ago

Thank you, yes that's mostly how it goes with rv's and why some thing this old can have so few miles on it. I do find traveling by motorhome to be quite relaxed, not having to be concerned about finding a motel or what not.

glomms1 year ago

Awesome project! I bet Neal loves this. I have a travel trailer that developed a soft spot in the floor that eventually had to be repaired, turning into quite a project by the time it was all over too. I think the most challenging thing for me was the way the RV was constructed at the factory. It was not designed to make repairs at all. For instance, RV's are usually built from the inside out to make construction easier. The last thing to be installed are the outside walls. Repairs however, are usually made from the inside out. So many times when removing a counter or something attached to an outside wall, I found that the back of the screws were impossible get to. This was because the mounting screws had been driven from the outside of the frame, towards the counter on the inside. That little construction method alone caused a lot of unnecessary damage when removing interferences. So I was really interested in the gutted interior and the wiring pictures. It looks like your GMC didn't have this problem. I'm also not very happy with the plywood or sometimes even cardboard being adhered to fiberglass to make up the body of modern RV's. So I really liked the aluminum siding and framework of this GMC coach.

The only thing you might want to talk to someone about, that I saw, is the battery compartment. When batteries are charging they give off hydrogen, which is flammable. You might want to seal off the batteries a little better from the rest of the electronics and add a vent hole or two.

Anyway, thank you for taking the time to submit this Instructable. I learned a lot from reading it.

LanceBuilt (author)  glomms1 year ago

Thank you very much, Yes the gmc's are particularly well suited for replacing the entire interior. Most motorhomes don't have a real automotive body, just kind of a wood and plastic box on top of a truck frame. I don't think that the interiors of the gmc's were really any better that other motorhomes, but once you take it down to the body you can build it anyway you want. When I removed the interior it came apart in pieces too, of course I wasn't concerned with saving much of it. One really nice thing is that now if I want/need to take it apart I could, and put it back together without tearing it up, this has already paid off here and there.

The electrical compartment is well vented both high and low, though a better separation and venting for the battery compartment would probably be prudent. My experience is that hydrogen escapes quickly from all but the most sealed of spaces.

8kittys1 year ago
Wow, awesome build! I hope you all enjoy it for years to come. Bless you for caring so much about your Uncles happiness & well being. We could use more folks like you in this world :)
LanceBuilt (author)  8kittys1 year ago

Thank You

Did you know that the world speed record for a stock motorhome was held by the GMC motorhome?

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