Painting a Miata

[Blue_Heron]

Note to self: don't MIG weld in flip flops and shorts. More than a few minutes of practice welds and you are likely to have a sun burn on your exposed parts and slag burns between your toes. Ask me how I know...

[Loren]

He's not lying. Real welders always wear sleeves and gloves, too. UV is a harsh mistress!

[Loren]

Chris and I did a half-day Saturday. I guess that's Day 5.

No photos. Chris continued work on filling. Finished up the left side, got most of the hood done, and more sanding on the top. It's coming along nicely, aside from battles with uncooperative parts-store body filler that didn't want to properly harden.

I did a little bit of additional prep and cleaning. Removed the washer nozzles from the hood, and the rear latch hardware from the top. Cleaned some hidden areas where the front bumper goes, and cleaned a couple of chassis ground points. Cleaned all around the trunk and the area under the rear bumper.

Actually found some "rust". Chris chuckled. He's from the Frozen North where they actually have rust. But, there were some hints of rust here and there. At the top of the front fenders where they bolt on under the hood there's some sort of hole that's covered with cloth tape. The tape apparently holds moisture, and there's some rust under it. In the back, the area around the plastic fitting for the battery vent tube had some paint bubbling from rust. And under the trunk weatherstripping it looked like somebody may have dragged something heavy over the rubber, cut through it and scraped the paint... some surface rust there. I'll clean all that up and properly treat it.

[cdmiller]

Fixing Minnesota rust on a 64 1/2 Mustang


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[Loren]

Day #6 happened today. Made some good progress. All remaining dents were filled and sanded. Primer was laid down over all of those spots, ready for secondary sanding. And the most exciting part, Chris laid down some of the actual COLOR in the door jambs and on the rear fender as a test.



I ordered two cans of two-part epoxy aerosol touch-up paint in the proper color. We used one of the cans, and it seemed to spray quite nicely. (with Chris' experienced hand, not mine) The color is WAY darker than I expected. It does work out pretty close to what I expected in bright sunlight, and will do more so when larger horizontal areas are painted. I don't dislike the color. It's still "sort of a light BRG", just not as light as I expected. The SHOCKER was... it's metallic! Very metallic. That's where most of the lightness comes from. Reflected light from the very fine metal flake in it. I swear EVERY photo I saw of this color did not look metallic. But, it works. I'm gonna stick with it. Chris thinks we can still do it as a single-stage paint (mostly because it's very fine metal flake, so it won't end up "lumpy"). I'd be okay with clearing over it if we need to, though.

The strange part of the day was when I started cleaning up the driver's door jamb and door for paint. I removed the door seal on the door and found this:



Couldn't make sense. Looked like flaky rust at first, but it's NOT a rusty car! And it looks like it's cracked, with some displaced metal. What the hell, Ben?

Cleaned it up a little:


After some cleaning, and removing a plastic clip, it's obvious that this IS a crack that bridges two spot welds and also migrates to that hole. Clearly, some kind of repair is in order, but we need to hit it with the grinder first and see just how bad it is.

Applied my favorite tool:



After a bit of grinding, you can better see where the indentations of the two spot welds are. And the rust isn't too bad. From a cosmetic perspective, we could maybe weld up the cracks, clean it up and paint over it. But... what caused it?

The spot welds are where the inner door beam connects to the door. There is no flex in this crack from hanging on the door, which is good. A couple inches below this section is where a steel "cup" bolts to the door, and that cup wraps tightly around a rubber bushing when you close the door. I never thought of the door as being THAT structural. (and always thought that the stiffer door bushings that people sell were complete bullshit) But, clearly, it is structural. And years of autocrossing have fatigued the area of these spot welds and caused the metal to crack! Never seen it before... but, I'm going to start looking for it.

Unfortunately, because this is an autocross car, the only PROPER repair here is to replace the door. Doors are plentiful and cheap, and we're painting it, anyway. So, that's what we're going to do.

[Loren]

Oh, and there are a few more photos in the Gallery

[Loren]

Day 7 of Miata paint prep. Wet sanding with 320 grit was the order of the day. Then after the sun came out, we were able to get primer on the hardtop, bumpers, mirrors and fuel door.

Here's Larry, Moe & Curly sanding:



A replacement door has been sourced. It's not perfect, but no rust or major dents, and no crack. The guy who had this door had 3 of them. One of the three had a crack in the same place... only worse. This NB Door Crack thing appears to be a thing.



Next up will be prepping and priming the new door. Then wet-sanding the whole car again, as-needed. I have another can of aerosol touch-up paint that we'll use to paint the inside edges of the new door, the windshield header, mirrors and fuel door. Then after a thorough cleaning, the car should be ready for the paint booth!

We're looking at probably about 2 more days of prep work. Maybe 3.

[blacksheep-1]

Looking good..I always said the Miatas were the perfect sportscar that the British came up with. It's like an MG that doesn't leak oil, runs and doesn't rust.

[Loren]

Well, hell. I pulled the replacement door out of the back of the Mirage after picking it up from Valrico without really looking at it. (had someone else buy it for me, and it was supposed to be good) It's got the same damned crack in it!

It's nowhere near as bad. But, the cracks are starting around the two spot welds and there's a hint of rust there. Same situation. So far, 3 of 6 doors that I've looked at have had this crack. So, I can keep searching for the perfect door... and it's probably going to develop the same crack eventually. Or... we can just fix this one.

Gonna do some surgery on the blue door. Since all the exterior bodywork is done on it already, might just fix that one.

Will start by cutting back some of the inner sheet metal so that we can see how the door bar actually attaches inside the door. Then, I expect we'll probably clean things up and weld in some gusset plates to tie it all together so that it stays put without further cracking. Smother the whole mess with POR15, tack the inner door panel back in place and carry on.

How hard could it be?

[Magooiii]

What could possibly go wrong. [emoji23]


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[Loren]

What could possibly go wrong.

Well, lots COULD have gone wrong, especially if the welder were in my hands. But, Chris is pretty good at this welding stuff. We were able to accomplish what needed to be done WITHOUT cutting open the door.

Lots of narrative and detail in the photo gallery. Start after the last "green door jamb" photo.

Photo Gallery

In the end, we found not just two, but FOUR broken spot welds, and replaced them with three gusset plates, and about 15" of seam-welded joints. I think it'll hold.

[Loren]

In addition to that, we got some additional wet-sanding done on things like the hard top and those pesky door mirrors, and then applied primer to anything that still needed it... like the door we were working on.

Next up will be more wet-sanding, and then a shot of green from the second aerosol touch-up can to get the inside of the door, the windshield header, mirrors, fuel door, etc.

After that, we should be ready for final sanding, a major clean up... and final paint!

[Loren]

I'm a little behind here. Chris and I got together on July 6th. Did some more sanding, and laid down the second can of green touch-up paint. Got the edges of the driver's door painted, the windshield header, and a bunch of small parts like door handles, mirrors and the fuel lid.

Here's the painted fuel lid in bright sunlight. That should be pretty close to what the car will look like. More or less.



And then July 13th, we gave the car a good cleaning, hung the driver's door, reinstalled the door latch hardware, and did some additional sanding.

Here's Chris at work:



One more day of prep next Saturday, and we've got a tentative paint booth date of August 3rd.

[Loren]

Oh, BTW. Ever heard of POR-15? It's a special kind of paint that's often used in car restorations. Let's you paint over rusty metal, and... well... protects it. I'd never used it before, but I knew of it.

There's the tiniest bit of rust on this car in a few places. Like under the trunk weatherstripping, the hole where the battery vent tube exits the trunk, etc. So, I bought some POR-15, and used it on those places, and on the repair work inside the door. Seemed to work well. Paints on easily with a brush, and spreads nicely for a flat and glossy finish.

But, today... today, I had a bracket that I needed to paint for an unrelated project. It had some rust on it, which I mostly cleaned off. Figured POR-15 would be the proper thing to put on it. So, I grabbed my tiny can of POR-15 and tried to pull the lid off. This stuff is AMAZING! The paint had sealed the lid on so well that I ended up destroying the can in the process of getting the lid off! So, I guess part of what makes POR-15 so good is that it's a VERY hard and highly adhesive finish.

[twistedwankel]

The paint had sealed the lid on so well that I ended up destroying the can in the process of getting the lid off!

Must be what they use on all Rx bottles with child proof caps?

[mymomswagon]

Oh, BTW. Ever heard of POR-15? It's a special kind of paint that's often used in car restorations. Let's you paint over rusty metal, and... well... protects it. I'd never used it before, but I knew of it.

There's the tiniest bit of rust on this car in a few places. Like under the trunk weatherstripping, the hole where the battery vent tube exits the trunk, etc. So, I bought some POR-15, and used it on those places, and on the repair work inside the door. Seemed to work well. Paints on easily with a brush, and spreads nicely for a flat and glossy finish.

But, today... today, I had a bracket that I needed to paint for an unrelated project. It had some rust on it, which I mostly cleaned off. Figured POR-15 would be the proper thing to put on it. So, I grabbed my tiny can of POR-15 and tried to pull the lid off. This stuff is AMAZING! The paint had sealed the lid on so well that I ended up destroying the can in the process of getting the lid off! So, I guess part of what makes POR-15 so good is that it's a VERY hard and highly adhesive finish.

Corroseal is another one. Used it on the faces of those rusty steelies I bought 3 months ago. Turns rust shiney black, then I just primed over it with flat black primer.

[Loren]

More sanding and scuffing today.

Pretty much ready for paint. Booth is rented for August 3rd.

[Loren]

Picked up the paint Wednesday. Learned that the color we painted the door jambs and stuff with is, indeed, the wrong color. So, all that stuff has to be redone. But, at least the car will be the color that I wanted it to be!

I spent some time this afternoon scuffing everything that had been previously painted, getting it ready for another shot of paint. Chris came by in the evening and gave things a once-over.

Tomorrow's the day! And we're about as ready as we can be. Ken's bringing a trailer, Dan B's bringing some hands, Chris is bringing skills. I'm bringing... paper and tape. And a cooler full of water. And cookies.

[rojeho]

No pics yet?

[Loren]

Pics, yes. Time to post them here? No.