Loving the attention to detail in yours and @Fireindc 's recent projects. It gives me warm fuzzies knowing these cars are in good hands.

 

Looking good! I used the raptor liner "anti-corrosive epoxy primer" after watching a youtube review comparing about 20 different products and it came out near the top. I was looking for something tough and anti-corrosive that can be applied directly after phosphoric acid (OSPHO) without additional prep. This stuff seems pretty bullettproof, haven't had the slightest sign of flaking or adhesion issues, and it's basically unscratchable once on there. I put some good ole oil base rustoleum directly over it on my subframe, and underneath the chassis I was able to spray bed liner right over it. Seems like good stuff.

https://raptorcoatings.com/product/r...xy-primer-kit/

 

Same here. It makes me feel bad that I only hit my subframe with a couple spray paint touch ups when swapping it.

 

I went so far as to sanding mine for fifteen or twenty seconds before spray painting it!

 

You west coast guys have no idea how good you have it! Honestly, this thing probably could have soldiered on for the rest of it's life without issue, I'm just being a bit extra. My assumption is this rust came from years of sitting parked on dirt and with body panels removed while it was being parted out, not from its time as a working car. Condensation from underneath and rain sitting in the floorpan take their toll. It's been taking up my garage space for the past two years, and at this point it likely will continue to be garaged for most of the rest of it's life. A little fluid film or cam angle sensor leak would have protected it just fine!

I haven't touched this thing since the last update between Thanksgiving travel and the sickness that resulted from it. I'm trying to see if I can get some Ospho rust remover and a decent two part epoxy spray can paint from a local paint shop to seal up the underbody. Otherwise Bezos likely gets more of my money. I've tried to have a policy of spending my money and brick and mortar stores, but when Amazon or Rockauto can get me the stuff for 1/3rd of what the auto parts store wants it's difficult to walk through those doors and not feel like a fool.

 

One thing I did do over the long holiday weekend was go visit my uncle. And my dearly departed Roxanne, so that I can plan to grave rob.

She looks a bit worse than that picture I shared back in the first post. It's been over 9 years after all.



I forgot I removed the wheels. And the suspension. Crap, it'll be work to get it rolling.



I moved up to the 1.8 brakes just a few weeks prior to crashing it. I'll keep the calipers on the shelf.

Based on the damage to the unibody in front of the wheel, I've got to assume something back here is bent. It'd be nice if just one of my cars had a completely for sure straight left rear suspension.



The interior... well, it could be worse!



I checked the trunk and thankfully the original struts are still with it! And all four wheels are lying around! It'll take some work but it can roll again.

The engine is... present.



I didn't realize how far the engine flung over in the crash. The heater core hose barb is bent. Hopefully everything else that I can't pull off the auto, like the PPF, is fine. It did drive itself onto a trailer all those years ago.



I only popped off the oil cap, but the cam lobe is completely clean. That makes me hopeful the cylinders are nice and clean too! I'll squirt some penetrating oil, let it set for a few days, then follow with regular oil into the cylinders prior to turning it over by hand.

All in all, I'm happy with the condition of it. It has certainly fared a lot better than some of the cars my uncle should have sold to the junkyard several decades ago.



That one hurts.

 

Obviously things have slowed. I've reached a small pit of despair, or at least analysis paralysis, on the rust repair.

Below are the front and rear subframes orginal to this car. Rust always has a way of suprising me. I've never seen such a dramatic difference in the front and rear of a car.





I'm hoping this will be the secret sauce to cure my car's crusty butt. It's not the Ospho I was looking for, but at the end of the day pretty much all of these rust removers are some variation of phosphoric acid. I don't think I need to get too worried about the exact brand. I grabbed some 2K epoxy primer as well, hoping for something a bit tougher than Rustoleum.

What I am a bit less certain of is how best to follow up on the phosphoric acid.



Here's how bad the flash rust was after I followed it up with a rinse from the hose.

So, I'm in a bit of a pickle here and overthinking the next step immediately prior to paint. Rinse and sand? Wait for it to dry and wipe off the residue with some other chemical?



In the meantime, I've reapplied some of the rust remover and let it dry without a rinse. It leaves a white powdery residue (heh) once dry. The darker spots aren't rust, in some areas it seems to have turned the steel black. I'm picking away at small problem areas one or two hours at the time. There are lots of little pockets of deeper rust. I need to get some new dremel bits to clean them up as best I can, and then just accept that it is what it is.

I want to get this right, but at the same time I really think I'm stressing too much. I don't think I can mess up the paint prep so badly that it's worse than it was before I stripped the paint back.

 

I heard a story on the radio today about talking to yourself. They said it wasn't just for crazy people, so today I did just that.

__________________________________________________ _____________________________________________

"You know, there are other parts of the car you can work on. You don't have to agonize over painting."

"Right you are, other OptionXIII"

For a few weeks now I've forgotten the whole point of this build was to stop agonizing over the details and just get stuff done. So today I vowed to get back at it. Remember those holes in the floorpan? Time to stop letting them be a roadblock. Theres a bunch of tasks like this that prevent other progress, like putting the carpet back in.



I deburred the underside, spritzed some rustoleum on them, and went to looking for my butyl rubber sound deadening. Hmmm... not on the shelf.



Oh yeah, in one of my last garage cleanouts I used the last of it to quiet this noisy duct that made a massive bonging noise every time the AC kicked on.



I peeled one of the strips off and turned it into little squares to seal the holes off.



ECU bracket went back on, with no ECU behind it.



The cheapest "sleeping pad" off bigriver.com was where I got some foam to replace the carpet felt insulation.

Whoever buys this as something to sleep on top of for their first camping trip is in for a rough night. It's absolute garbage and only squishes once. Then it stays squished.



I dusted off the carpet and seats and put them back in. A deeper clean will be required, but for now they're taking up less space in my basement. I swapped on a few other parts as well and did some general tidying up - cleaning the inside of the doors, installing some trim pieces, re-mounting some wires, etc.

Progress is progress.

 

Cat given for this quote. Looking better than when it was torn apart! I agree with you. The longer the car sits, the more insurmountable the task at hand seems.

 

I approve of everything I see here so far. I know I commented in a DM about this, but for others following I had great luck using the ospho, not rinsing it but brushing off the white/flakey ****, and going over it with the raptor liner primer. That primer in specific is made to go right over their own phosphoric acid surface prep (which most say is basically just ospho) without rinsing. I too found that rinsing the area resulted in flash rust, though nothing as bad as that, it was enough to trigger me after all the de-rusting.

I also have successfully applied oil based rustoleium right over the ospho. For the engine bay, since I was using a normal automative paint, I did use a oil based "wax and grease remover" there to prep those surfaces, which also seemed to work and that paint adhered perfectly.

Good ******* work though, when I'm working on my FD project I keep telling myself it doesn't have to be perfect. Progress is progress and literally anything is better than what you started with. My advice is to not get hung up too much thinking and just do it. I like your floor hole repair, I have a similar repair on my NA in the trunk where the battery acid caused rust in the battery area. Basically ground down and treated the rust, then covered the swiss cheese holes with tape like that. It's held up great for many years, and I still wanna cut and replace that panel eventually, but if it works it works!

 

I was going to follow your advice straight up, but when I looked at the reviews they were all over the place on if the cans worked with lots of people having issues where they only got a few seconds worth of spray out. Hopefully this generic 2K will be almost as good!

I've used a welder to repair similar small holes in my NB Miata when I removed the rear seat mount humps and went a little overboard with drilling the spot welds. Sadly, I don't have a welder in my shop anymore. I aim to change that and fix these holes better... once I clear out some of the junk to make space!

I'll be welding in that area eventually is the plan, they'll get cleaned up then. I'd like to replace the frame rails with thicker steel as shown in this thread. I actually have had the material on hand for most of 10 years now (See thread title). Plus, drop floors on both driver and passenger side would be nice. I've grown to prefer having the race seat in my NB just because it sits so much lower.

Yep, I gotta keep this thing moving. Driving in the springtime is an ambitious goal at this pace, but I gotta keep at it. Stagnation can't be acceptable!

 

Every NA/NB I've ever owned has had HVAC sealing foam in terrible condition. The lightest touch will have it falling off like shown below.



Plus, there's clearly an impact to the effectiveness of the HVAC system. The air is noticeably hotter than ambient when set to full cold without the AC on, especially on my feet.

To try fixing it, I grabbed some 1/4" thick Neoprene foam off of SouthAmericanRiver.com and cut it to match he fresh air/recirc blend door. Most of these foams come with adhesive pre-applied, but I was a bit uncertain of the quality of that. I found one vendor without pre-applied adhesive and instead I grabbed a can of 3M Super 90 spray contact cement.



Looks good!



I measured the original foam before buying this, but was a bit uncertain that the stiffer neoprene would work as well as the open cell foam the factory used. It seems to be just right!



The blower motor was yucky. I gave this a decent cleanup and got probably 85% of the goo off.



A fresh seal to the outside air vent, and a bit of white lithium grease went on the pivots and sliding points. It's ready to go back in the car!



It was something of a PITA to install. I had to peel back the carpet and remove the ECU kick panel. I don't remember this being an issue on disassembly, or such a pain on my NB. Another strike against the floor mounted ECU! And of course, I forgot to connect the door wires that go behind this.

Next project is the main heater core box. If this works well, I'll have to take apart my NBs dash to fix it too!

 

Looks great. Man, there's so much room with the dash removed! My HVAC won't go into the cold range right now, so I'm jealous of the space you have.

I feel ya on forgetting the wires. Too many projects get to the last stretch only to realized I have to pull something back out because I forgot to install something.

 

Heater box is done!

It's pretty easy and straightforward to do this, if a bit tedious and time consuming of work. Definitely some lessons learned - it seems a fair bit of the factory foam isn't really necessary and doesn't seal up anything. Split the box and study the movement of the flaps if you want to spend more time trying to avoid work than it would take to just cut and glue on a few more pieces of neoprene. I only had to thin this 1/4" thick foam down slightly on one flap. It seems to fit well on the rest of them. Take pictures, keep the little levers sorted and separated, and you won't be wondering which almost identical looking part goes where.

I cleaned off the old foam with a scraper, followed by a bath in hot degreaser detergent in my ultra sonic cleaner. Then I scrubbed with a wire brush to make sure I'd gotten everything I could loose.


Ready for some glue.


Painted like spider man with a can of Super 90.


I cleaned the inside of the box...


... and the outside. It's way better looking now. Note the lack of heater core pipes though!

I lubed the linkage pivot points with some white lithium grease, but not the door pivots themselves. I didn't want the grease creeping up the doors and eating into the new glue.



Next trip to the hardware store, I'll grab some foam for the front seal and the two clamps that connect the blower, evap box, and heater box.



Mounted.

I swear I'm not obsessed with cats, he's obsessed with me! I was conned into getting this little guy, and now I can't work in the garage without him complaining about being left out.



The only other thing left is to get a heater core in the box. I've got two original ones to try, and I like to keep serviceability in mind, so I'll be modifying this by cutting the fixed tube off and using a rubber joiner like the other tube. That lets you replace the heater core without removing the dash. Some good background in this link - Replacing a 94-97 Miata Heater Core - Did It Myself. Lots of rust particles came out of this core - it'll get chemical flush before going back in.

Does anyone have a recommendation for how to make a hose barb? The brass tubing is pretty easily formed but a proper tool would be nice.

 

That's a handsome boy. You're making great progress in quick time. Wish I could help with the barb connection but I can't find anything either.

 

Here's another little "mod" for future ease of service.

Where the motor mount bolts through the subframe is a slot on the passenger side, and for some reason, two holes on the drivers side. I have swapped motor mounts a few too many times, and often the motor mount stud has incorrectly gone through the top hole. I saw someone slot the drivers side and told myself next time I was in there, I would do the same.


Making the cut.



And done! I cleaned it up with a file, sanded the area a bit for adhesion, and splashed on some Rustoleum.

 

You could try one of these:
Problem is the entire pipe you're beading rotates around the tool that's clamped into a vice. So you need to have room around for it to swing an entire heater core, but if the vice is mounted on the end of a bench it should be doable. Little late now, but I'd suggest going to a NB heater core next. Already removable heater core pipes, although they're still a total bitch with the dash out. I use a little impact drive with a #2 phillips head, and of course the 10/12/14 sockets, and just take the dash out in an hour or two. Really easy if you've got stock seats, remove them along with the center console, and you can straddle the trans tunnel and just sorta do a bicep curl...except with a dash.

 

Not at all too late, but for now the appeal of modifying the 90-93 version is to get the job done easy and cheap, and I've got 2-3 on hand already. I've heard a few people say the NB core pipe clamps are a pain to deal with under the dash, and it's an extra cost. If it becomes an issue after the car is running, I'll consider the swap then.

On a similar note about being too cheap, @Z_WAAAAAZ has provided me inspiration. Miata brake master cylinders are expensive. A whole $50!?! For a safety critical item? How absurd! I like a stiffer brake pedal, so I decided to look into possible swaps. I've looked on Rockauto to see if there's similar layout master cylinders that look like they'd be promising swap candidates. I compared a few Mazda, Ford, and other Japanese makes. So far, the most promising candidate looks to be a 1991 MPV. It has a larger 15/16" bore and has similar enough ports that I can either bend a new short line or modify factory lines to work. Only downside would be cast iron instead of aluminum for a few more ounces of weight. And it's $16 on closeout!



I'm guessing that 15/16 is about as large as you can go on this style/pattern of MC before needing to step up the size of the booster center bore.

 

Man I wish I would've seen that engine mount slotting strategy before I replaced my front subframe. I don't really see any downsides and that is always such a pain to get lined up.

 

I dig the slot too. I struggled with that before, but the key (and this is in the FSM) is to seat the non-slotted side first, then drop the slotted side in. Works and really not that bad once you get it figured out. But I don't really see any downsides to the slot, so slot away, friends!