My 1978 GMC motorhome

[Mike_H]

In other news...I made some modification to my home shop so I can get this big bastard back at my house to work on it. Currently, its being stored at my parents place. He has a GIANT barn built specifically to house his coach, my coach, and some of his other toys. I've been working on it over there. Its not a huge distance away, about 8 miles. BUT...its not a short walk out of my backyard, which means getting over there after work is a challenge for me.

Having it at home will move this project along at a much faster pace, since my tools are all nearby, the project is nearby, and I'll be motivated to get it done, since it will pretty much take over my whole shop (and I won't be able to do the Jeep projects I want to do!)

This wall is supporting my stairway to the 2nd level storage area of my shop. It interfered with getting the MH in by a couple feet. I took three feet out of the wall and placed a beam in to support the stairs, so I'll be able to get my 27 foot long motorhome into my 30' long building. I still have some rearranging to do, and some stuff to get rid of, but this is going to be a HUGE benefit going forward.

 

[B1Toad]

You got off easy! In order to fit mine I had to extend the front of the garage 3 feet, raise the header 14" and install a 20X11 commercial roll up door. I would have had enough length but had to add 3' onto the front with a higher ceiling so the roll up door could fit up in there out of the way. In the picture you can see where the old front used to be (I stripped off the stucco and covered the studs with OSB). Then in the ceiling between the old front wall and the new one my rollup door is tucked up in there. Where you see the 3 - four foot lights is the bottom of the original header that I raised then there is a new header over the new opening. I have about 4-1/2 feet in front of the MH to work and just enough room on the driver's side to extend my 2 slides which are only 2' deep.

You can see the motor for the rollup in the upper right corner and you can just see the black rubber door bottom seal peeking out at the top of the opening. It all fits nicely up in that pocket.

 

[Mike_H]

You got off easy! In order to fit mine I had to extend the front of the garage 3 feet, raise the header 14" and install a 20X11 commercial roll up door. I would have had enough length but had to add 3" onto the front with a higher ceiling so the roll up door could fit up in there out of the way. In the picture you can see where the old front used to be (I stripped off the stucco and covered the studs with OSB). Then in the ceiling between the old front wall and the new one my rollup door is tucked up in there. Where you see the 3 - four foot lights is the bottom of the original header that I raised then there is a new header over the new opening. I have about 4-1/2 feet in front of the MH to work and just enough room on the driver's side to extend my 2 slides which are only 2' deep.

You can see the motor for the rollup in the upper right corner and you can just see the black rubber door bottom seal peeking out at the top of the opening. It all fits nicely up in that pocket.

View attachment 534455

It’s not in there yet! Everything should fit, but only because I haven’t put my rooftop units on. I think those will make me too tall and I’ll crash into my o/H door. 10 foot sidewalls and the MH is 9’ with A/C

 

[B1Toad]

It’s not in there yet! Everything should fit, but only because I haven’t put my rooftop units on. I think those will make me too tall and I’ll crash into my o/H door. 10 foot sidewalls and the MH is 9’ with A/C

That's one of my favorite things about those front wheel drive GMC's, their low profile. Even an Airstream trailer is 9'6" to 9'8" with AC! With my garage I spent a lot of time researching stuff that was under 10 feet and there's hardly anything which is why I ended up raising the door to 11'. My garage was initially built as a business expense to stash my work trucks and supplies in.

 

[B1Toad]

The Micro Air is amazing, I can run my 13.5K unit on my Honda 2000 at 2,200 feet on ECO mode and the Honda doesn't miss a beat. Startup current is reduced to under 12 amps. It is also quieter now with no thump every time the compressor starts.

The air flow mod worked great too, I can now feel the AC blowing on me from the driver's seat which wasn't possible before. All it takes is some sheet metal, a way to bend up an inverted vee and some Nashua 324A foil tape, the very best foil tape made IMHO.

 

[Mike_H]

That's one of my favorite things about those front wheel drive GMC's, their low profile. Even an Airstream trailer is 9'6" to 9'8" with AC! With my garage I spent a lot of time researching stuff that was under 10 feet and there's hardly anything which is why I ended up raising the door to 11'. My garage was initially built as a business expense to stash my work trucks and supplies in.

I just realized you had a Winnie Via. My folks had one of those before they got their Dynamax DX3. Pretty nice little unit. I honestly think they liked that better than their Dynamax. Its short inside though, and my dad is 6'1" Every time they went camping, he would come home with a new wound on his head from the overhead cabinets.

The Micro Air is amazing, I can run my 13.5K unit on my Honda 2000 at 2,200 feet on ECO mode and the Honda doesn't miss a beat. Startup current is reduced to under 12 amps. It is also quieter now with no thump every time the compressor starts.

The air flow mod worked great too, I can now feel the AC blowing on me from the driver's seat which wasn't possible before. All it takes is some sheet metal, a way to bend up an inverted vee and some Nashua 324A foil tape, the very best foil tape made IMHO.
View attachment 534514

I bought two brand new Furrion rooftop units (about a year ago!). They are 13,500 BTU and I bought the heat pump option. They only pull 13 amps at full boogie. Compared to the 45 year old dometics I pulled off, I should notice a HUGE increase in performance. I really hope they work...they've been sitting in a box since I bought them, never used, and the warranty has expired!

 

[B1Toad]

I'm 6'2.5" and on the drive home after buying it I hit my head hard enough to draw blood on one of the cabinet pulls over the cab. This made me realize what the 3 sections of pool noodle were for in one of those cabinets! What I did was remove those stupid "trendy" pulls that stuck out 2" and replaced them with curved strap type pulls, have not hit my head since. My wife knows never to leave a cabinet door open and I replaced all the shocks so they stay all the way up. The bed is a bit short but I can deal with that. I can also deal with the 14.7 MPG on the Via! (not towing)

I think Furrion is a decent brand? I also heard Houghton was good. The prices on them have doubled though just like most everything else.

Since you'll have your plenums open you might consider doing the air flow mods (If you have ducted air). I was amazed at the difference, totally was not expecting that much improvement.

You need to get out and enjoy that rig!

 

[Mike_H]

I'm 6'2.5" and on the drive home after buying it I hit my head hard enough to draw blood on one of the cabinet pulls over the cab. This made me realize what the 3 sections of pool noodle were for in one of those cabinets! What I did was remove those stupid "trendy" pulls that stuck out 2" and replaced them with curved strap type pulls, have not hit my head since. My wife knows never to leave a cabinet door open and I replaced all the shocks so they stay all the way up. The bed is a bit short but I can deal with that. I can also deal with the 14.7 MPG on the Via! (not towing)

I think Furrion is a decent brand? I also heard Houghton was good. The prices on them have doubled though just like most everything else.

Since you'll have your plenums open you might consider doing the air flow mods (If you have ducted air). I was amazed at the difference, totally was not expecting that much improvement.

You need to get out and enjoy that rig!

No ducts. Furrion is Lippert and Lippert is basically everything in RV. I do need to get out an enjoy it...but I gotta finish it first. I should get my waste handling done today, with the exception of a couple more supports. Then I go to Relocating my propane system (really just running a new piece of tubing under the coach). That should finish up the stuff underneath I have to do. I'll be able to focus on the interior again and get my electrical done.

 

[Mike_H]

My Tanks (and plumbing) are installed! I'm happy with how it turned out. I used some Fernco flexible couplings to give the tubing some "flexible rigidity" and allow for fixing it down the road. Poo Chute is centered up in the rear of the rig. The Blade valve is mounted to a flange I welded to that skid plate/ cross member. It worked out really well.

I was planning on extending the tubing to the back bumper, but then a thought hit me about dragging the ass of the rig when a drive is elevated over the road. In fact, I repaired the corners of the skid earlier, and I reinforced it with some 3/4" tubing I had left over from another project. So, I used a piece of angle as a straight edge to see where my "safe zone" is.

You can see the blade valve is just inside that (the lower edge of the steel), so I'll just have the hook up be under there. Its only about 10" under the bumper, so not a bad reach. If its too terrible, I have room to put another 90 in and dump to the side which is how it was set up before.

And, the little jog that resulted from me assuming the tanks would be the same size as what I have, and giving Ronco the incorrect measurements.

You can also see I used some cork gasket making material to provide separation between the steel and plastic. Trying to prevent rub through. All in all, the tanks fit well in the space provided and I'm pretty happy with how they mounted.

I do still need to fab up a reinforcement for the cross-member I cut away. I think a 16" long piece of 3/16" 2 x 2 angle will be sufficient.

One more step closer...

 

[Mike_H]

I've also been working on the other things that need to be done to at least get this thing driveable again.

Got my new taillights mounted (soon to be for sale to other GMC nuts like me)

And I've been working on the repairs necessary to the "door cards" in the cockpit. I don't have doors, but that is the location they go, so I'm sticking with that term. They will be retextured and painted before installing. They, like most of the other plastic in this thing, were very fragile and needed some repair.


The passenger side was very bad (mostly because I hip checked it off a table and it smashed on the floor). I brought out the heavy guns for this.

Aluminum window screen melted into the plastic to hold the crack together

I had to make a filler patch to cover up a hole that was there from the previous owners

And I fiberglassed the backside to hold everything together and stiffen things up. I hate fiberglass, but it does have its place. This is an example, but I did all the repair areas I made.

Next step is to fill in and smooth out the cracks on the "A" surface and shoot a coat of adhesion promotor and some texture. Then it will be painted blossom white like the rest of my trim.

 

[B1Toad]

Mike,

Check out the last post (#3716) in this thread:
https://www.irv2.com/forums/f65/post-your-vintage-photos-here-49238-266.html#post6815183

 

[Mike_H]

Mike,

Check out the last post (#3716) in this thread:
https://www.irv2.com/forums/f65/post-your-vintage-photos-here-49238-266.html#post6815183

Oh, Elsinore! I think she’s either for sale right now, or just sold. Iirc, that’s a buskirk conversion. He was a builder and made a nice rig even nicer. He did three or four extensions too, where he stretch em to around 30’!

 

[BlueC]

@Mike_H Does your unit have this fancy "ejection orifice" option?

GMC Made a Motorhome That Pumped Sewage Through Its Exhaust on Purpose​

You've heard of rolling coal—now get ready for rolling Taco Bell.


"One of the options available for the GMC Motorhome was a system called Thermasan... The premise of the Thermasan “waste destruction system” was simple: Dump black water through the hot exhaust to sanitize and dispose of it. According to a maintenance manual for the 1973 model, this was done using a wiper motor-powered pump connecting the black water tank to the exhaust, where it was plumbed in just upstream of the muffler. A screen prevented solid waste from entering and clogging the system, which would’ve been hellacious to fix. Amusingly, Thetford called the exit an “ejection orifice.” The jokes write themselves."

https://www.thedrive.com/news/cultu...-pumped-sewage-through-its-exhaust-on-purpose

 

[Mike_H]

@Mike_H Does your unit have this fancy "ejection orifice" option?

GMC Made a Motorhome That Pumped Sewage Through Its Exhaust on Purpose​

You've heard of rolling coal—now get ready for rolling Taco Bell.


"One of the options available for the GMC Motorhome was a system called Thermasan... The premise of the Thermasan “waste destruction system” was simple: Dump black water through the hot exhaust to sanitize and dispose of it. According to a maintenance manual for the 1973 model, this was done using a wiper motor-powered pump connecting the black water tank to the exhaust, where it was plumbed in just upstream of the muffler. A screen prevented solid waste from entering and clogging the system, which would’ve been hellacious to fix. Amusingly, Thetford called the exit an “ejection orifice.” The jokes write themselves."

https://www.thedrive.com/news/cultu...-pumped-sewage-through-its-exhaust-on-purpose

You're the second person to send me that link in as many days! I do NOT have the Therma-San System, though I have read the documentation for it...They are pretty rare now...for good reason, I'd assume.

 

[Mike_H]

Working along, but not much picture worthy stuff. I start making a reinforcement for the cross-member I chopped up to make room for my poo-poo pipes. Used a piece of 3 x 3 x 3/16 angle and chopped out an 8" section of web to allow me to bend it. Kinda kludged a bend fixture together from some scrap steel. That got me most of the way, but I had to heat it up and use a hammer to finish it off. Pretty happy with how it turned out, but it cemented my decision to buy the SWAG offroad finger brake to go in my 20T Hazard fraught press. Next step will to be clamping this in place and drilling a few holes to bolt it in. I will be able to officially call my tank replacement DONE at that point.

Getting closer and closer to getting it back to road ready and back to my house so I can do the interior and woodworking here.

 

[Mike_H]

Finally have my cross member brace complete. The paint is drying and I’ll finish up tomorrow. Be nice to FINALLY have the waste tank project behind me and get back to where I thought I was in April!

I entered up pulling the gray water tank back out so I have room to work. Pulled the black water piping for the same reason. Cross member is in, and all my bolt holes line up! That’s a major win for me, lol.

I’ve also been working on getting my wiring closer to completion. I added some features that didn’t exist in 1978, like power adjustable mirrors and a backup camera. So, those wires are run to their respective control centers now. Still need to pull 12v for the mirrors, and install the joying radio for my rear view camera.

BUT, the wires are installed for those things, which means I won’t need to pull them later. I’m leaving the dash alone, until I decide what to do with it. I’m debating designing my own dash and gage cluster, or paying for a “Mac dash.” I’m leaning toward the deluxe set up, but I’m pretty sure I can do that myself with a little help from send cut send.

http://www.custominstrumentpanels.com/gmc.htm

I will power up the mirrors tho, since it’s nearly impossible to set those things without having two people if they are manual. The camera and joying radio though, we’ll see. That’s probably a nice weekend project or project at a campground when we’re using it vs something I need to do now.

 

[Mike_H]

Waste tank project complete! Tubing is supported, tanks are mounted, everything is painted that needs to be.

 

[Mike_H]

Next step is running a new supply line for my propane, since I moved it back to the rear of the coach. I need about 40,000 btu / h supply, and the charts I found said I need 1/2” line. I only had 3/8” copper available so I had to order some new stuff. Should be here Wednesday. Hopefully, by next weekend, I’m back to where I thought I was I April this year!

 

[Mike_H]

Propane system is coming along. Got my tanks mounted, and my tubing is mostly all done. The main line is under the coach, and I have my QD outlet installed off a branch Tee. This will be to run my propane accessories (mainly a Black stone). I have to install some adel clamps to secure things, and install one more Tee to branch off my hot water heater and main heater.

I’m really quite happy with how this is turning out. Going from a 60 lb tanks to two 20 lb tanks will make filling and replacing propane much easier. With the big tank, I would have to take the motorhome to a propane station…with the two 20 lb tanks, almost any fuel station will do an exchange for cheap.

 

[Mike_H]

Propane system is done. Everything is tied up and checked for leaks. That's been done for a bit. Next project is getting the dash taken care of. I bought some powered remote adjustable mirrors. The old mirrors were manual adjust and they were impossible to reach from inside the motorhome. So, if they were set up for me, and then we changed drivers, it was a giant PITA. The power adjust is a much needed and welcome addition, even with the amount of work installation is. Honestly, without having the rest of the coach pulled apart, I don't know that it would be possible to install them.

First order of business was to run the wires. There are 5 wires per mirror (3 for the motor and 2 for the heater) which have to be routed to the controls. The controls were never intended to be installed in a GMC, so I had to figure that out too. Finally, what I thought would be a minor issue, turned out to be kind of a pain, and that was picking up a non-switched 12V supply. I've had the control wires run for a bit now. That was the easy part.

I also redesigned the Map Pocket inserts in the "door" cards to be a bit more useful. When this was a new vehicle, paper maps were the only type of maps you had, so the pockets they included in the side panels in the cab were pretty useless. Very narrow and very deep. Great to stuff an atlas or Gazetteer in, but not so great for sunglasses or phone. I redesigned them to be a bit shallower, since I am planning on an in-dash GPS, and need more useful storage when were driving. I'll have to get some pictures of those. I 3D printed the new pockets and also included the mounting area for the new Mirror controls.

Last couple days, I've really been focused on getting the mirrors wired up and working. You'd think it would be a piece of cake to grab 12V from somewhere...but there really isn't much of anything that is "live" without the ignition being on, and I decided I wanted the mirrors to be "hot" all the time. Since I was installing a new radio anyway, and radios ALWAYS have a 12V battery feed, I decided to pull that. Well, that was installed in an area that required pulling the whole dash apart...No pictures because, like everything, the dash is broken and falling apart. I do have pics of the damage.

Missing piece circled in Yellow

That plastic "birdcage" in the lingo of GMC'ers is all ABS plastic, which is 47 years old and very brittle. Its holding all the gages, the radio and heater controls, all the idiot lights, and every other control necessary to interact with the coach while driving.

I did get the radio out, and found the wire I thought I wanted to use. It was only protected with a 10 amp fuse though, and the mirrors need 10 amps, just for themselves. Back to the drawing board. After studying the wire diagrams, I decided to pull my power from the main ignition wire. Its very heavy gage, and protected by a fusible link. I installed a separate 10 amp fuse that I can use specifically for the power mirrors. Felt good to get these things moving.

And as I'm looking at wires...I find a bunch of splices done by previous owners. Most look like this.

And they have a single flap of electrical tape wrapped around them. No joke. I've said it before, but I'm still amazed that this coach hasn't burned to the ground yet. Since I keep finding these, I am going through all the wiring in the dash. Found an age related issue in the Speedometer....a couple of the pins that control the lights (not sure which yet) on the PCB have broken off. Not sure how I'm gonna fix that yet

And I'm cutting all those terrible splices out and replacing them with non-insulated step-down butt splices and some adhesive lined shrink tube. That is about done. I need to hook up one more item and I think that will be complete.

Next step is to rebuild the plastic frame for the dash panel to mount to. I'll get the plastic reassembled, then I think I'm going to get some sheet metal to reinforce it. Maybe a piece of 1/4" plywood, but I think bonding some sheetmetal with Epoxy will fit the dash bezel and pads better. I'll probably replace the speedo with another, used one (will need to look into setting the milage on a mechanical Odometer) and I need to mount the New Single Din, Joying 7" android radio. We'll see how much I get done this week, since I took the week off to work on this project, specifically.