1976 GMC Motorhome

SONICJK

Reminds me of...me No, I'm sure of it. I hate him
In case anyone is interested in this I don't see the harm in throwing up a build thread here.

It's been going for about 6 months so it will just be old updates for now until I catch up.

We'll start from the beginning.

The GMC motorhome is the only motorhome ever manufactured by a major car company.
In the 70's it was the creme of the crop, 455 cubic inch beast of a motor from a Toronado, independent adjustable rear air suspension, luxury interiors, the whole package. Beast mode.

Fast forward about 40 years and now they are mostly dilapidated or kept running by a very devoted and passionate group of (old) folks.
I have yet to see any one besides mine that has the kind of attention to detail and modern design that I am going for.

As I brought her home:
4500 bucks, in decent shape other than the paint.


The original plan was to gut the interior and do her up nicely. That all changed, but we will start there anyway.
Did a sketchup of the basic design.


First thing I did was focus on the dash. I wanted to keep the retro feel to it but make it modern to fit the new interior.
So we recovered the old crazy 70's green pleather stuff with marine vinyl:


Also painted the funky green plastic with a white epoxy paint:


Then added some walnut accents to the dash vents:



From there I decided to really step the dash up and made a completely new dash panel from walnut and inlaid a tablet in it. The tablet is connected to a wideband 02 sensor for AFR, a vacuum gauge, a transmission and oil temp gauge, as well as controlling all the stereo stuff and gps etc.
Mockup:

And finished product:
 
It would be cool if you painted it like this....


MysteryMachine1.jpg
 
My dad was impressed by these back in the day, if only I had a place to store something this big...
 
Just what I want, now I'm on the hunt for one.

Looks neat man.
 
Thanks for the support guys I'll try to keep the updates coming.
Justin, your camper was part of my inspiration for this, so at least part of the blame for this crazy endeavor falls on you.
 
Installment 2:
After getting the dash mostly done I tackled the door panels.
Whoever designed this thing did a great job except for one thing. NO Fucking cupholders. Are you serious?
So I had to redo the door panels to have a cup holder, I didn't want to go through the trouble of fiberglassing:






Beautiful.
These will be covered in the same grey as the dash at some point. Took them to an upholstry shop to have them done after I failed miserably, and after 3 months the guy went out of business and I had to go repeatedly stand at his door until he showed up to get them back as they aren't replaceable. He said "sorry man i just couldn't do them for what I quoted you" "THEN CALL ME AND TELL ME THAT YOU ASSHOLE"

Onward
 
Looks like a sweet cupholder. I think I would have added two if I was going through all that trouble.
 
SONIC. said:
Justin, your camper was part of my inspiration for this, so at least part of the blame for this crazy endeavor falls on you.

Well, I sold that camper to Eric, and he sold it to someone else. Ha.

I am happy to see that you're actually going through with the Reno. Keep up the good work, man.
 
After that, I took a break from the dash to do some mechanicals.

The GMC has air ride suspension in the rear. 2 air bags are inflated and deflated individually to control the tilt and height of the rear end.
In stock form it has a tiny tank and a tiny compressor that takes forever to fill the bags to change the level. That wasn't going to cut it becuase well who wants tiny things?
So I yanked all that shit out and built my own compressor setup with a viair 444C and a 2.5 gallon tank. This will allow me to air up tires, tubes, balloons whatever the hell I want, along with run air tools on the side of the road if the need arises. Also it's cool.



The tank runs to a bunch of solenoids that allow me to air up and down from the dash, as well as to sending units for the air pressure gauge in the dash.


Getting it mounted was a bit tricky. The original compressor system is housed in the back in an interior cabinet. It's loud and obnoxious and takes up valuable interior space. So I put this one in front of the passender drive wheel, with soem rearranging of the start battery and a radiator hose, it worked out perfectly.

Here's the pressure gauge

I wanted one with dual needles so I could read both bags at once, as well as with remote pressure sensors so I didn't have to add leak prone plumbing into the cab. It's no fun driving down the road when one air bag looses pressure as you can imagine.

Once that was done and plumbed I started playing with the engine a bit.
When I drove it 3 hours home it wasn't wanting to shift very well. Had to really coax it into 3rd.
Ended up being really simple after a lot of searching, the vacuum modulator was hooked to the wrong vacuum port bu the idiot PO. Once I corrected that it shifted like a dream. And believe it or not this thing is awesome to drive.

Power steering and brakes, cruise control, air ride suspension, quiet as a mouse. It's really mindblowing that this came out of the 70's.

Next up was power. I had read that these things were crazy powerful. Mine would haul me down the road but I certainly wouldn't call it crazy powerful. I almost chocked it up to the fact that all of these are owned by people who would think a prius is "crazy powerful" but i started investigating anyway.
Pulled the engine cover and pushed the pedal to the floor and watched the quadrajet do it's thing. Or not do it's thing. Secondaries never opened. WTF.
Turns out the throttle linkage to the pedal was bent, meaning that when the pedal was on the floor the butterfly was only halfway open.

FUCKING A RIGHT
A test drive later and a bunch of grins and some new burnout marks on the road and she's a whole different animal. Cruises at 75 with no problem. 455 Cubic Inches of Big Block greatness.
 
Back
Top Bottom