'66 Monaco Resto-Mod

[Jack-Stand]

That's freaking sweet!

Thanks man! It's been a lot of years coming. She'll be an ugly duckling for a while, while I shake out the bugs, but it'll still be a blast. Not going to lie, it's kind of an odd car to drive just because of how smooth it is for the power and suspension performance. Normally for decent suspension performance it has to be a lumberwagon, but it's like riding on a cloud. lol

 

[LocuMob]

It sure is weird to hear the diesel when looking at a Monaco!

 

[Jack-Stand]

It sure is weird to hear the diesel when looking at a Monaco!

It's still a big block. Just a high compression turbocharged one.

One of my neighbors has a '66 Galaxy 500, and he snapped his head pretty quick when I drove past. He looked thoroughly confused.

 

[3C's & a D?]

My mom (original owner) and dad are coming out for the weekend, and I'm going to surprise her with a ride.

I'm sure they will be quite surprised!

 

[fury fan]

Comments are disallowed on your YT video.
Afraid???

 

[Jack-Stand]

Comments are disallowed on your YT video.
Afraid???

Haha they are? I didn’t realize that was a thing for plebes like me. I figured only important people had that ability.

 

[Jack-Stand]

Unfortunately mom didn’t make it out (health issues), but I did get to take the minions for a spin last night. They’ve already asked if we can take it out this morning.

 

[67_300_Convertible]

I did get to take the minions for a spin last night. They’ve already asked if we can take it out this morning.

Sounds like they're hooked on the car... Nice!

 

[Jack-Stand]

Sounds like they're hooked on the car... Nice!

Haha thank you much! They’re definitely hooked. Crash (my little man) was all about it. He was playing with his cars the rest of the night and all day today, and anytime I stepped outside he came running after me to see if I’d take him for a ride. Looks like I need to focus on getting her fully ready for the road and licensing.

 

[Jack-Stand]

Been a few months since I last posted, but still making progress. There’s still a bit left to go before she’s ready to be licensed, but between the first drive and now, I’ve made a few mods. The biggest one(s) were that I dove back into the suspension/steering and modified the upper/lower control arms and the steering rack mount on the crossmember. I also did my best to clean up and conceal the under-hood wiring in wire loom, and I had the unfortunate need to swap my brand new cold case radiator. The radiator leaked under pressure, but props to cold case for warrantying it without major question. A little disappointed in the product, but happy with the customer service.

So the basics of the suspension mods were that I replaced all the bushings in the upper and lower control arms with uniballs (think of heim joints without the threaded stub). There was nothing wrong with the original suspension, I just saw small things that could be improved upon, thus making it that much safer for my family. On the lowers it’s a massive 1” bore uniball that has reducers to a 3/4” bolt. Unfortunately the uniball cup and the reducing bushings needed some machining to fit my mounts, but overall everything went together as I hoped. The fun part with that was figuring out how to keep a hole saw on centerline while cutting the control arm, so I machined a piece of sacrificial aluminum to match the bore of the lower CA bushing, and stuck a 1/4” piece of steel dowel in the hole saw instead of the drill bit. Greased everything up, and let it cut. Then I had to figure out how to maintain center after the bushing was removed, so I machined a piece of nylon stock to the press bore of the bushing to cut the opposite side. For the upper control arms, I replaced the bushings with 1/2” bore uniballs and machined spacers to make up the gaps left to right. I started by hard bolting a couple of tabs to each bushing, and then I tacked each of the tabs to my fab table so that all of my relative dimensions were maintained. That allowed me to machine my bushings so that it was effectively a drop in application.

 

[Jack-Stand]

Completely forgot to mention in my last post, I also managed to get the AC configured and working in the car. So now the car that never had AC, now has REALLY COLD AC. It was a bit of a task, but I was able to use the AC compressor that came stock to the powerstroke, and wire/plumb it to the Vintage Air Gen 5 magnum evaporator, the condenser, the drier, etc, and sure enough it all works. Same with the heat. It’s really exciting. The sad part is that I wasn’t able to retain the stock controls in the car, so they’ll unfortunately be for decoration now.

For the steering mods, I ended up Bringing the rack mount back towards the firewall. Much like the control arms, there wasn’t anything wrong with it as it was, just I just now have greater variability in ride heights relative to the angle of the rack ends.

For the wiring cleanup, I had to pull the trans to PCM harness so that I could shorten it up a couple feet, and I also had to shorten the speedo wires by several feet. Turns out the donor truck was substantially longer in the wheelbase than my Cbody lol who’d’ve thunk it? I also focused on trying to clean up/conceal all the wiring under the hood, and while I don’t have many pictures of the final result, you can somewhat see the results in the picture with the back of my ugly mug in it. Still chaotic, but is organized chaos lol

 

[3175375]

Completely forgot to mention in my last post, I also managed to get the AC configured and working in the car. So now the car that never had AC, now has REALLY COLD AC. It was a bit of a task, but I was able to use the AC compressor that came stock to the powerstroke, and wire/plumb it to the Vintage Air Gen 5 magnum evaporator, the condenser, the drier, etc, and sure enough it all works. Same with the heat. It’s really exciting. The sad part is that I wasn’t able to retain the stock controls in the car, so they’ll unfortunately be for decoration now.

For the steering mods, I ended up Bringing the rack mount back towards the firewall. Much like the control arms, there wasn’t anything wrong with it as it was, just I just now have greater variability in ride heights relative to the angle of the rack ends.

For the wiring cleanup, I had to pull the trans to PCM harness so that I could shorten it up a couple feet, and I also had to shorten the speedo wires by several feet. Turns out the donor truck was substantially longer in the wheelbase than my Cbody lol who’d’ve thunk it? I also focused on trying to clean up/conceal all the wiring under the hood, and while I don’t have many pictures of the final result, you can somewhat see the results in the picture with the back of my ugly mug in it. Still chaotic, but is organized chaos lol
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Excellent work!

 

[3C's & a D?]

Amazing work! As always.

 

[Jack-Stand]

Excellent work!

Amazing work! As always.

Many thanks gents! Hopefully I can get it licensed soon and start hitting some of the cruise nights. I’m just wondering how much flak my ugly duckling is going to bring when I finally start taking her to shows and such. Lol

 

[Jack-Stand]

Had a bit of an emotional, but awesome day today. After 12 years of my car not being licensed for streets, I was successful in getting her licensed and driving around. My lovely lady rode shotgun and snapped some pictures of me enjoying my old toy. Mom (original owner) of course had to provide a throwback to previous days and how far everything has come. My old girl is still a long ways off from being finished, but I just wanted to extend my genuine and sincere thanks to all the wonderful folks on this forum. Your encouragement, expertise, and guidance have been invaluable, and I’m blessed to be part of this Community. Thanks for helping make this day a reality!

 

[patrick66]

Absolutely loving this build!

 

[Jack-Stand]

Absolutely loving this build!

Many thanks! It’s been a blast, but there’s still a ton to do. I actually got to take the kids to and from school in it late last week, and my little guy’s (5) face was priceless. He could barely reach the window, even in his booster seat, but he had his arm up and was leaned out and cruising. Brought a huge smile to my Face.

I also managed to give the car its first bath in almost 2 decades, and turns out, she’s still got some shimmer. Still needs a ton of work, especially the cancer in the rear quarters, but I was pretty impressed at how well she cleaned up.

 

[Jack-Stand]

Still working out the kinks on the car, but thus far, they’ve been minimal (knock on wood because I drove her to work today).

Biggest thing that’s happened was that the front passenger shock tower decided that it no longer wanted to be attached, and it tore a nice hole in the K-frame. Some 3/16” square tubing for a fish plate, fully weld it, and finish it out with 4-7/8” rosette welds, and she was back together. I went ahead and did the driver’s side too, just because they were the same design/attachment.

In other news, I had a bit of fun and had some custom Stickers made for the tail of the car. Since she’s a high performance Mopar-ish, I had to pay homage to the superbee, but since she’s a diesel that weighs as much as the titanic, I had to also pay homage to that. So I had these made, I get tons of laughs and thumbs ups.

 

[fury fan]

Nice artistry/imagination on the decal!

Overall your fab work looks good. But based on how long the shock absorber and the mounting pedestal are, and the fact that they aren't perfectly aligned (which isn't possible due to the geometry of the situation), there's going to be a bit of bending and twisting load on this. The undercuts of the weld (circled) are in the worst possible place - that's where the cracking will start next. (but it's hard to weld such a place without getting undercuts) Right now your weld at the red line isn't really doing much because the shock will be pushing toward the front of the car, and if the undercuts fail and crack forward that red-lined weld becomes a broken hinge.

I presume that mount was a piece of boxtube that you cut into this shape? It would have been more robust if it had been reversed, with the rounded corners (and tube surface) facing toward the shock, which would eliminate any sharp corners, and would put a weld along the width of the tube, in tension (blue line), and the trailing edges would've behaved as gussets. (but that would've needed something different geometry for mounting the shock at the top) That would have allowed a continuous weld around both corners of the boxtube, too.

Why did it not fail that way before, some folks may ask?
Well, it's like a chain. Weakest link. The framerail material isn't really that thick, it's roughly 1/8", but definitely thinner than the bracket.
As repaired, that weak link has been addressed.

Easiest fix that I see:
Either gloop in some weld buildup at those corners. (maybe that will be enough?)
Or better yet - also add a gusset facing forward. (weld it to the edge of this mount, the corner is the strongest point)
Point the gusset inline with the angle the shock is pushing for best effect.

PS - It's not that I'm so smart or skilled, it's just easiest to analyze a design afterward, esp if something has broken.

 

[Jack-Stand]

So this is napkin sketch math, and yes you’re correct with regards to stress concentrations at the undercuts, however one important assumption that is being made in your analysis is that The material is plastically deforming to the point where cracking begins. Given that it’s a dampening system, it’s not impossible, but it is very unlikely that the material from the tower and the fish plate will see the forces required to plastically deform it, even at the undercut. When the old one failed, it failed along the heat affected zone on the frame-side attachment (thin material that was weakened by the welding and is weaker than both the parent material and weld material).

When designing for fatigue in mechanical systems, the material strength and modulus of elasticity are taken into account and so are its surface flaws (rough cut finish, undercuts, etc). With steel, as long as it’s adequately overkill in it’s design, technically “N” (number of cycles to failure) is infinite, whereas with other materials, such as aluminum, the material’s fatigue coefficient prevents it from being able to be considered for infinite number of cycles. Granted we’re not dealing with aluminum here, but given that the moment acting upon the joint is now distributed across a fish plate that’s 3/16” thick, the webs that attach it only have to overcome the moment that the shock absorber imparts on it. So the calculation for that is the horizontal force times the distance from the attachment, but since majority of the force is in the vertical, the primary concern is the moment imparted by the horizontal distance times the upward force. The distance from centerline to centerline horizontally is about 3”, so for sake of being conservative, if we assume the upward impulse force imparted by the shock absorber is 2,000 lb, if we multiply that times the distance (to calculate our moment) and we come to a rough moment of 500ft-lb. Given that the welds themselves are 2” on each leg, and fully filet welded on both sides, they’re capable of withstanding substantially more of a moment than 500ft-lb (now strength is limited solely by the fish plate). In reality the forces, even though impulse, are likely less than 2,000 pounds, but even in that facet, it should be strong enough without adding steel.

Key word there… should