My 1978 GMC motorhome
- Thread starter Mike_H
- Start date
Neither do the late '70s T/As.
I bet a late 70's T/A is STILL faster than my 10,000 lb pig being pulled by an emissions choked 403! She does 0-60 in....eventually.
I have my harness project complete. Started with a Speedway Motors 22 Circuit kit.
https://www.speedwaymotors.com/22-C...ve-Aftermarket-Wiring-Harness-Kit,229874.html
I decided to go this route because it fits the original pass thru already installed in the firewall. Bonus is that my signal flashers are now relocated to the fuse box, instead of hiding up under the dash. With the extra space, I also added a couple extra circuits. One for my power mirrors (Ramco's), I added extra wiring for a modern radio (they all take a 12V batt feed and a 12V Ign or Acc feed), pulled in a tach signal wire and a Trans Temp Signal wire.
I was intending on replacing the entire harness, however it was not quite long enough to get what I needed. So, the bulk of the work was in splicing new wires in where I needed to. I basically replaced anything that looked questionable or that had previously been cut and spliced. So, this is now a mix of old and new. The speedway kit was nice, because the provided a LOT of the special connectors terminals and connector housings that GM was using at the time our coaches were built. Pack-Con and Packard Series 56 if you're looking for terminals and what not. A lot of that stuff is still available, if you know what to look for.
One other step I took was to eliminate the soldered splices that GM used. They were probably fine (most everything worked when this coach came apart) but for "peace of mind" I used butt splices and heat shrink vs the soldered crimp rings and nasty, sticky, black tape GM used.
Once the wires were all spliced in, I wrapped the harness in non-adhesive vinyl tape (which is what GM originally used). First time I've worked with this stuff and its pretty nice. Its easy to stretch and wrap around the breakouts, its clingy enough to not unravel (think saran wrap), and you can bundle the wires up tightly with it.
This is where GM left it. I took it another step, and added a braided split loom over the vinyl wrap. Just a little extra protection, plus it looks nice (not that anyone will see it). Tesa Cloth tape at the joints to help hold them together, and its ready to go back in. I will need to daisy chain a couple extra gage lights and a voltage feed once my dash is complete, but that is really easy to do and won't violate the rest of the harness.
https://www.speedwaymotors.com/22-C...ve-Aftermarket-Wiring-Harness-Kit,229874.html
I decided to go this route because it fits the original pass thru already installed in the firewall. Bonus is that my signal flashers are now relocated to the fuse box, instead of hiding up under the dash. With the extra space, I also added a couple extra circuits. One for my power mirrors (Ramco's), I added extra wiring for a modern radio (they all take a 12V batt feed and a 12V Ign or Acc feed), pulled in a tach signal wire and a Trans Temp Signal wire.
I was intending on replacing the entire harness, however it was not quite long enough to get what I needed. So, the bulk of the work was in splicing new wires in where I needed to. I basically replaced anything that looked questionable or that had previously been cut and spliced. So, this is now a mix of old and new. The speedway kit was nice, because the provided a LOT of the special connectors terminals and connector housings that GM was using at the time our coaches were built. Pack-Con and Packard Series 56 if you're looking for terminals and what not. A lot of that stuff is still available, if you know what to look for.
One other step I took was to eliminate the soldered splices that GM used. They were probably fine (most everything worked when this coach came apart) but for "peace of mind" I used butt splices and heat shrink vs the soldered crimp rings and nasty, sticky, black tape GM used.
Once the wires were all spliced in, I wrapped the harness in non-adhesive vinyl tape (which is what GM originally used). First time I've worked with this stuff and its pretty nice. Its easy to stretch and wrap around the breakouts, its clingy enough to not unravel (think saran wrap), and you can bundle the wires up tightly with it.
This is where GM left it. I took it another step, and added a braided split loom over the vinyl wrap. Just a little extra protection, plus it looks nice (not that anyone will see it). Tesa Cloth tape at the joints to help hold them together, and its ready to go back in. I will need to daisy chain a couple extra gage lights and a voltage feed once my dash is complete, but that is really easy to do and won't violate the rest of the harness.
Today was a good day. Real progress made! Last couple of work sessions have been working with the HVAC system.
I’ve been sealing the doors and testing / replacing actuators. Found all kinds of weird things that are now back to factory. Once the actuators and vacuum lines were confirmed good, I worked on installing the vent plenum.
I did find that the vacuum control from the dash slider was not working. The selector valve is supposed to be held together with a nylon clip. Well, after 47 years, the nylon had stretched and broken. After examining the control for any cracks or other issues, I replaced the with a stainless bolt and nylock nut.
And bench testing...I tested the control per the manual, and it works perfectly. Very happy about that. This particular valve is unobtainium. Lots of other versions out there, so I'm sure I could have made something work, but this is all back to factory.
Today, I also got the last of my insulation under the dash installed and was able to work on the harness. New wires are run for my tach and the trans temp gage. I need to replace the fuse box screws, since the originals are rusty and I can’t find em.
I am very hopeful about the sound dampening strategy I used as well. Now that it’s installed, I can hear a difference in radiated / reflected sound, even just talking in the cockpit area.
The final piece of the puzzle is figuring out how to attach the actual dash again. The screws are SO difficult to access with the windshields installed. I’m thinking Allen head screws, so I can use a ball end wrench, or maybe even some VHB mounting tape. I do feel like I could get them installed tomorrow, if I can figure it out.
I’ve been sealing the doors and testing / replacing actuators. Found all kinds of weird things that are now back to factory. Once the actuators and vacuum lines were confirmed good, I worked on installing the vent plenum.
I did find that the vacuum control from the dash slider was not working. The selector valve is supposed to be held together with a nylon clip. Well, after 47 years, the nylon had stretched and broken. After examining the control for any cracks or other issues, I replaced the with a stainless bolt and nylock nut.
And bench testing...I tested the control per the manual, and it works perfectly. Very happy about that. This particular valve is unobtainium. Lots of other versions out there, so I'm sure I could have made something work, but this is all back to factory.
Today, I also got the last of my insulation under the dash installed and was able to work on the harness. New wires are run for my tach and the trans temp gage. I need to replace the fuse box screws, since the originals are rusty and I can’t find em.
I am very hopeful about the sound dampening strategy I used as well. Now that it’s installed, I can hear a difference in radiated / reflected sound, even just talking in the cockpit area.
The final piece of the puzzle is figuring out how to attach the actual dash again. The screws are SO difficult to access with the windshields installed. I’m thinking Allen head screws, so I can use a ball end wrench, or maybe even some VHB mounting tape. I do feel like I could get them installed tomorrow, if I can figure it out.
Well, the Allen head bolt idea won’t work. Still too tight to get in there. I did pick up a new flex head ratchet to try out. I’m hopeful, but not holding my breath.
www.autozone.com
It’s got a swivel point right on the business end, so I’m hoping I can get into that area and drive some screws.
In other news, I started test fitting my refurbished dash pieces again.
And promptly broke the driver’s side.
So that came back out for more repair. It just happened to be areas I didn’t reinforce with fiberglass. Its not super noticable and they are already repaired again...but it took some deep breathing exercises to calm myself down.
Heading out for a boys 4x4 trip this weekend, so progress will stop for a few days. I was really hoping to get this done this weekend
Titan 1/4in Swivel Head Bit Driver
Shop for Titan 1/4in Swivel Head Bit Driver with confidence at AutoZone.com. Parts are just part of what we do. Get yours online today and pick up in store.It’s got a swivel point right on the business end, so I’m hoping I can get into that area and drive some screws.
In other news, I started test fitting my refurbished dash pieces again.
And promptly broke the driver’s side.
So that came back out for more repair. It just happened to be areas I didn’t reinforce with fiberglass. Its not super noticable and they are already repaired again...but it took some deep breathing exercises to calm myself down.
Heading out for a boys 4x4 trip this weekend, so progress will stop for a few days. I was really hoping to get this done this weekend
This is the best "tight-access" tool I've found. Not cheap, but it doesn't require much "head room":
https://www.amazon.com/dp/B005MVBGAU/?tag=wranglerorg-20
https://www.amazon.com/dp/B005MVBGAU/?tag=wranglerorg-20
This area is tight on swing AND vertical distance. I also have this from Hazard Fraught....it almost fits...but not quite. I honestly don't have a lot of faith in the Titan version either, but maybe with a creative use of extensions that are just the right lengths, it will work. I have some VHB tape and primer in my amazon cart too.
This is kinda what I'm up against. No scale here, since I just sketch in MS word...but its demonstrative. That block in the lower right is the rubber windshield seal and the flange I'm trying to screw into is the seam where the upper and lower parts of the coach are bonded.
Last edited:
That might be an area where some of those finger ratchets actually make sense. "Finger ratchet" probably isn't the correct name, but that's what I know them as.
Or maybe a 1/4" one way bearing screwdriver? You can cut up 1/4" Shank screwdrivers to fit. I have snap on but something like this might work?
https://www.amazon.com/Lisle-64250-Right-Angle-Screwdriver/dp/B0002BC0S2?tag=wranglerorg-20
https://www.amazon.com/Lisle-64250-Right-Angle-Screwdriver/dp/B0002BC0S2?tag=wranglerorg-20
I think he's alluded to them doing it prior to installing the windshield glass.
Let's hope not. Like he's doing, I'd explore every creative solution before removing a decades-old windshield. A windshield that's been in place that long would likely break during removal, and I'm guessing that's some pricey glass, if it's even available...
I recently had to have the windshield on my 2001 Expedition re-sealed due to leaks at the top of the windshield. They couldn't get the glass out without breaking it, so I had to replace it in order to re-seal. Fortunately, the glass cost was less than $200.
Windshields are available, though VERY pricey…on the order of 750 a side.
I will not be removing them…like I said, 3M VHB mounting tape will be the solution, if I can’t get screws in there. I do think the little screwdriver with a swivel head is going to work. I will have to make a custom length bit, but that is easy
I will not be removing them…like I said, 3M VHB mounting tape will be the solution, if I can’t get screws in there. I do think the little screwdriver with a swivel head is going to work. I will have to make a custom length bit, but that is easy
Well, the dash is in. I ended up needing to use the VHB tape. I just couldn’t get the torque I needed on screws, not matter the configuration or style bit. I’m not super concerned about it. In all reality, this refresh will either last the whole time I own this thing, or it will fail immediately, and I’ll need to redo it anyway.
No picture, but I have the column back in too. Progress!
No picture, but I have the column back in too. Progress!
Last edited: