I'm going to start a build thread for my current project. A few years back I got a big dose of nostalgia for the red 1990 NA I had back in college. This is what it looked like.



Ahh, memories. Senior year, a sports car, and a heck of a Senior design project. Adding to the nostalgia, I took this picture on film with my dad's old Pentax P3 SLR. I loved that car, and after college I drove it across the entire US and Canada, camping and touring as cheaply as I could for most of two months.

I crashed it later that year in 2015.



I had planned to reshell that car, but I got an offer I couldn't refuse and bought a 2001 for a heck of a deal, and have been loving that car for the past 8 years.

I knew I wanted another red NA eventually. And so at the peak of the NA Miata pricing bubble, I made a very regrettable purchase. I paid too much for an automatic 1993 Miata for my girlfriend.



I ignored every sign it was a POS because of her enthusiasm, and my poor decision has been a sore subject for me ever since as I kept uncovering new flaws. It turned out to have engine issues in addition to the crash damage I knew of at the time of purchase. The top window began to fall out. It started making a lot of white smoke, so I parked it over a year ago. It disgusts me because it's a shiny reminder of my mistakes and impulsivity.

And so in the back of the garage it waited for me to figure out what to do.



Not wanting to replace the engine in a mangled shell, I eventually found another POS for sale and made another overpriced impulse buy.



This poor shell was at one point a pretty clean 1990 manual that just needed a new engine. Instead everything else was torn off of it. It sat outside, the paint faded, and it got some surface rust. This fool brought it home in January 2023.

I quickly tore into it, removing much of what little remained on the car in to prep it to be rebuilt with every part off of the Automatic '93. Then life moved on and the project stopped completely. I had to fix the house, I was more interested in working on my NB, having a social life, etc.



It has sat for nearly two years now. Once that initial burst of work was over, I wheeled the shell over beside the automatic and ignore them. This bothered me so much I do not have a picture of how tightly stacked the garage was with three Miatas in it.

And that's not the end of it. The crashed Miata from college? I never got rid of it. I pulled the interior out of it to put in my NB, but it's been sitting in a shed at my uncles place for 9 years now.



"Ran when parked" indeed. This picture is 8 years old, but the car is pretty much in the same condition. The glass top hasn't even fell down.

The other day, my friend who is selling his car and got an interesting trade offer for a turbo S13. I kind of wanted it, but realized I can't take on any more car projects until I finish some. It lit a fire under my ***, and I've finally gotten tired of having two Miata shaped parts piles taking up the back of my garage. I knew I couldn't sell the automatic for any reasonable sum with all the problems it has. I want one pile of parts and less piles of regret. It's time to start this project up again so I can move on with my life.

And so it begins... again.

 

What's the goal here? Well, beyond atoning for the crash and bringing a functioning NA back into the world, and clearing out the clutter and assembling the best Miata parts I have into one car, I'm not entirely sure. My NB2 checks a lot of boxes - it's been dead reliable for DD use, it's track ready with little more than an optional tire swap, and comfortable enough for date night. The trouble is that it's been so good to me, I can't take the risk of ruining it by looking for more. So this car will have to bring me something else. I want it to be an outlet for the more labor intensive mods I've been tempted with. The things you don't want to do to a daily.

Phase One of this project will be stripping the automatic car of everything that could be of value to me. That'll be most everything outside of the suspension and powertrain skateboard.

Phase Two will be a light restoration of the recipient shell, the parts going into it, and making it a good platform for the future build. Right now I am planning on surface rust repair, fixing any damage to parts being installed, an NB subframe swap, and a cleanup of the wiring harness, with a focus on separating the engine and body wiring into two distinct harnesses for future engine management flexibility.

Phase Three is a loose idea that I'm not committed to, but I'd like to get the 1.6 running again. This may extend into playing with a standalone aftermarket ECU in order to have a bit of fun with a cheap engine. At this point I'll be happy with another Miata in my fleet.

At that point, I'll have a fantastic basis for whatever mods I want to do. I'm not sure what those are yet. Engine swap? Mk60E5 ABS? Drop floor pans on both driver and passenger side? Fastback? All of these ideas are tempting to me. This is Phase Four, a whole pile of unknowns.

 

Sub'd! Mainly to see how your mental stability holds up

Should be cool having such a clean slate to work with! I assume the girlfriend is no longer interested in driving it given the phases you've listed?

 

Of course she still loves the pop ups, but with the amount of labor involved in this project I was clear it's gonna be built to my preferences. She can learn stick if she really wants to drive it - it's a 35 year old car at this point. It's not gonna be as comfy as her daily.

I've addressed the main points of surface rust repair on the shell. It didn't look so bad in the initial pictures, but I took it all the way back to bare metal to ensure it wouldn't come back. As it becomes time to assemble, I'll replace the seam sealer that was removed. So far I've used a variety of paints - POR15, Rustoleum, and Steel It.

















Last week I got the interior out of the automatic.



Snap your fingers and the entire interior, down to the wiring harness, is gone.



Body panels, doors, seats, and the dashboard have been loosely installed on the recipient shell.

 

So I had this beautiful plan of how phase 1 would be only focused on removing parts from the Auto, then removing the Auto from the garage. Yeah, I can't commit to such a well focused path. I've gone off into the weeds on doing some prep on the shell.

My dad often reminds me that the most space efficient way to store car is all assembled together and not half strewn across the garage. Well, if I'm going to hang the parts on the new body, they may as well get cleaned up along the way.



I cleaned up surface rust in the trunk and on the gas line cover panel. I tried to get close to the right color with some rustoleum red. I later realized I missed a spot and had the Silver Steel It paint in my hand. So much for matching.



The battery mount brackets got satin black paint.

One of the J hook reciever brackets has a bolt broken off. I'll fix that when I get a welder.



The booster had some rust from the leaky master, as you'd expect from the rust I cleaned up in the last post. Hopefully Rustoleum has some resistance to brake fluid.



I recently discovered what this dremeled out bracket that was left loose in the floorpan used to do. It holds the steering column controls in position. Since the rest of this was removed, I went ahead and swapped the steering column as well.



With so many electronics and switches packed into here, and the shell having been left outside, this was probably something I should have swapped regardless of the missing parts. In the background on the floor you can see the Park interlock I removed from the ignition key barrel assembly.

Last night I got started on removing the Airbag system wiring harness. It's mostly seperate from the rest of the main harness, with just a few points of interface between the two.



What I've gotten out of the car so far.



These wires are under the steering column area. The three wire connector carries signals to the dash harness. I depinned and removed the central red wire with blue sheathing - it's for the airbag warning light.

The 1 wire connector has red-green on one side, red yellow on the other. Pretty sure it's some sort of power feed, because the Airbag computer has something like 4 different fused connections. I assume they want it to get power from anywhere it can in the event a wire gets cut in an accident, and it has a backup battery too. I just unplugged this wire.



Near the gas pedal is another power feed. This connector is just a junction point, the grey portion is 4 terminals all connected together to form a bus bar. They're all blue wires, I depinned the Airbag harness one for removal. IIRC it pulls power from the windshield washer fuse.



Lastly there's the airbag fuse at the interior fuse box. I removed this as well. Above is where I left off for the night.

I tried to be as tidy about removing this harness as I could, but there are some spots where it's easier to just cut and pull the harness out. The wiring harness goes behind the HVAC box. I didn't want to open that and see if it vented whatever was left, so I cut and pulled the wires out from behind there. I still have four connections left on the passenger side - I've removed the wires up to the pass through grommet, but the engine bay side of this harness is still held in place. I may just cut those connectors off and seal up the harness.

Overall, I wouldn't do this again, at least for where I am in this project. Most of the weight removed is in the impact sensors. For the person that values their time, just remove the impact sensors in the engine bay and the S sensor and computer under the dash, and move on with your life. If you don't want to see the connectors and want to visually clean it up, cut them off and tape the remaining wire tight to the harness.

Plus, in my research it seems the horn has an odd interface with the Airbag wiring harness. I may need to figure out another way to wire it.

I hope the less bulky harness will be easier to work with in the future, but it's mostly been a boondoggle.

 

If the green/red horn wire goes through the airbag harness, it's only because they both need to go through the clockspring, they're otherwise not related:

 

You can buy a can of color matched aerosol to have around for touch up of the areas not usually seen. After a couple years of dirt/grime it matches really well. I had a couple when I put the ‘91 back together.

 

Subbd, love to see progress on an old beater! Check out my Feral FD build thread for motivation with chassis cleanup and rust killing. It looks like you are doing a great job so far.

 

Thanks for the feedback. I have this diagram and couldn't find any connection other than the clockspring either. I'm just going off of what I read on the forums.

I find it pretty frustrating that this is the best I have to go off of and that I'm still bothering to read forum posts to get more info. Here's some examples of the kinds of wiring info that's readily available in publicly hosted Factory Service Manuals for most any 90's Jeep.



Every splice, connection, and pinout is named, location provided, and easy to look up either from its location or function.

I think that'll happen eventually, just not sure when it will make the most sense. On one hand I'd like to get one of those activated 2 part paint cans and get it all done at once, but on the other hand I'm already putting things back together that will get in the way of paint like the brake booster. There's a few parts of the engine bay and chassis where the sun has faded the paint down to the primer.

Oh yeah, I've been following your thread and trying to find other deep restoration threads like the "Stolen and Flipped" build. Thankfully I don't think I'll have as intense of rust repair on the underside as you have been doing.

 

I haven't been as productive these past two days with most of the easy parts removed. I still need to remove the exhaust, and I'll probably nab the brakes as well. After that I expect I'll only be salvaging hardware and give the old Auto a last pick over before taking to the dump... or at least outside the garage! My NB misses parking inside overnight.

Only major part swapped today was the windshield wiper linkage. I cleaned that up before bolting it onto the shell. I think I'll be removing all of this again in the near future to give the engine bay a splash of that color matched paint we were just talking about.



One thing that had been on the back of my mind was the state of the gas tank. I really, really did not want to remove two different tanks to swap this.



It's basically mint! Awesome. I'll run the old gas through my Jeep over the course of several tanks.

On to the side projects. First, I used my recently acquired 3d printer to create a radio delete blank faceplate. The stl I found on thingiverse fit perfectly.





"Why'd you buy such a terrible car?"

I don't know Pepper. Don't rub it in. He eventually helped me remove the hood. I got lucky here for a crashed car, it's actually an aluminum hood!



The automatic is a lot closer to being the shell now.

Before I stopped the project, I picked up an NB front subframe and uprights. The power steering bits are off my own NB - I depowered using a different used rack. There was some surface rust on the subframe, I cleaned it off and painted with Steel It.



The passenger side bracket is kind of groady though. I might as well break out the electrolysis setup I expertly crafted.



The battery that will power this thing serves as a large enough bank to make the smart charger be content to just push electrons and not overthink things. An old rear wheel hub serves as the sacrificial anode.

 

Nice progress. In for updates on how the electrolysis works out! I've never tried it, sounds like magic 🎩

 

It basically is magic, I can't believe you haven't tried it yet with all that rust removal you're doing!

Here's some before, during, and after shots of some parts I got off of a Michigan Jeep for my manual transmission swap - a thick steel transmission mount and a much thinner transmission tunnel cover panel. I knocked some scale off on the trans mount for fun, but otherwise didn't do any prep of the part. Just hung it in the solution.









The black coloration that remains wipes off pretty easily. I just ran the cover panel shown on the left through for fun. The cover panel on the right and the mount have been painted in the above picture if it's not obvious. Look at the reflections on the center bracket and how the light plays off of it - the rust on that thing was deep!

10/10 I definitely recommend it. If you've got a battery and charger, a bucket and water, some copper wire to spare, and go spend $5 on washing soda, you'll have all you need to remove rust with much less effort than scrubbing and scraping with naval jelly or other acidic methods. They're still a good choice to finish off with, but at least you can let electricity do most of the work for you.

 

I didn't get much done over the weekend. The time I did get in was mostly lying on my back, cursing that miserable SOB that worked on this car last. Someone cut the heat shield to access and cut off the cat studs, removed the catalytic converter honeycomb, and put it back together with mild steel bolts and no anti seize. But eventually it relented and I got the magnificent stock 1.6 exhaust off of the automatic. The heat shields under the shell were looking pretty ratty as well, so I grabbed those as well.

Tonight, I made some serious progress on getting more good parts onto the shell.



"Dude, where's my subframe?"

I pulled all the suspension off of the front end to replace and refurbish.



I bought these low priced LBJs back when I thought I was just going to do a front end service on runabout automatic. I'm not going to call this false advertising but it's pretty misleading to have such a stylized American flag looking background on your Made in China parts.

I've used Ultra Power parts before and never been let down, but never in such a high load and high risk location. If it gets to seeing serious track use, I'll probably upgrade to ELBJs anyways.



I get a strange sense of joy from being the first person to remove a bolt after 30+ years and finding it to be immaculate.



The FUCA got a slightly better name brand as Rockauto had some TRW units on closeout. The FLCAs just got a quick clean with a strong degreaser to take off the crud.



After a few hours I have an NB subframe in my NA.



There, much better than where we started. Plus, more parts off the shelf/floor and put back into service! Sure, most of it was bought for this project, but the MSM struts and the NB steering rack and pump previously were on my NB but too good of shape to throw out. At this point it was time to set the wrenches down for the night and clean up.

There's still a good bit to be done before I call this subframe swap complete.

• Drivers side hub will be swapped with a different used one. The NB uprights I got aren't the prettiest.
• Swap brakes from the automatic.
• Center the steering rack.
• install tie rod ends.
• Hook up the PS return side rubber hoses to the cooler loop.
• TORQUE EVERYTHING!

 

Have fun with the twerking or... uh... torquing. Having pulled control arms about 3 different times this year I can say that I'm a big fan of getting a torque wrench onto the long bolt.

 

Why does everyone struggle with the long bolt? People hate loosening it, torquing it, etc. I don't get it. I can easily reach it, break it free, and ratchet it off. I use my deep 21mm socket and ~2' 3/8 pivoting head ratchet. I'm spoiled with Snap-on tools (my bank account would probably use a different word than "spoiled"), but it's nothing exotic, and I've used other tools at home or friend's houses.

 

I've never had too much trouble with the long bolt. On this NA6, I had to loosen the rearward sway bar mounting bolt as it just barely blocked the bolt head and disconnect the metal PS cooler lines from the frame rail. On my NB, I depowered the steering before I ever touched the long bolt and had no interference issues I can recall. Maybe the longer 1.8 sway bar gives this enough clearance, or the bolts are slightly shorter? All in all, not too bad of a process and I don't have any special tools. It's twerked-ish - tight enough to get the bushing sleeves in contact with the subframe, but loose enough to still spin and not bind up the bushing.

I have alignment stands that I intend to use for torquing the suspension when the time comes.

In the meantime, I'm collecting torque specs for every bolt I touch or even come near. I've got the standard quick reference ones, but those don't include things like the subframe mounting nuts. I'll be scratching them off as I go, but so far I've only torqued the fasteners that can't be reached later after I block access with something else.

-------------------------------------------------------

Got a few more hours in this evening. First I centered the steering rack.



First I tried to measure turns from lock to lock, then I figured I'd just measure travel. It's about 4 and 11/16". When I went to the distance center, I found a pretty obvious flat spot where it had settled in, and just centered it off of that on the car. That's probably not ideal, but I doubt I'll notice when the car is in motion.

For the tie rod ends, I measured the amount of exposed thread left on the original steering rack and matched that on the NB rack. I used new TRW tie rod ends, again picked up when I thought this would be a casual auto cruiser.



I've never had this happen on a Miata before. The inside race stuck to the upright. A bit of heat got it loose, then I cleaned up the upright center stud with some 800 grit sandpaper lubed with a bit of oil.

This NB left upright I picked up is... suboptimal. It's probably in the worst shape out of all of the ones I have, but it's the only NB Front Left unit I have that isn't attached to an NB. The hub had one small spot of notchiness when I rotated it and one stud was only half there, so I grabbed another hub off of the auto. It made a bit of noise as well when transferred over, but not a bearing noise. Maybe the seal is having to seat on a new part of the upright, or theres a bit of rust eating into it? Oh well. If it becomes an issue I'll just get another upright. For now it goes back together.

I swapped over the NA6 9" heat shield with it. By the time I want to remove that for cooling needs, I'll be thinking of new hubs anyways.



I then moved over the clean brake rotors and horribly painted yellow calipers.

That's the major work for the subframe swap! I just have a few items to torque more tightly before setting it on the ground, and to hook up or cap off the low pressure side power steering cooler lines.

 

For me it's that my torque wrench contacts the frame when trying to tighten the nut and just barely gives the socket enough surface area to grip. On the passenger side it doesn't seem as bad, but on the drivers side I usually end up having to use a 1.5" extension and it still feels like the socket is going to slip off and round.

 

Nice work, it's satisfying even from behind my screen to see this come together. 👏

My only complaint is that in order to pull that long *** bolt, such as for shock removal, I also have to remove my racing beat sway bar mount reenforcements, which is actually a PITA.

 

Well, things are slowing down a lot lately with the easy disassembly work out of the way. Not too many pics to share, I've had less time to work and am getting more into fiddly bits of restoration.

Recent work is along the lines of:

• Chasing threads to clean out rust.
• Cleaning and painting various parts of the shell.
• Finished removing the last trace of airbag wiring in the main harness.
• Understanding the wiring harness and layout of electrical components.

Here's an example of the tediousness - the HVAC blend doors. The foam has long ago lost any sealing or expansion abilities and is only held together by habit.



Unless someone has a better idea, I think I am going to use some 1/4" neoprene foam off Amazon to replace what the factory used. I'm undecided on if I'll trust the adhesive most of the foam sheet comes with, or get some without adhesive and just go nuts with a can of 3M Super 90 spray contact cement.

I'm dealing with the last bits of surface rust in the cabin that I missed when doing the POR15. Before:



After spraying with Rustoleum Troy Built Red:



These holes drilled in the floorpan really bother me.



Who's the bigger idiot?

• The engineer that put the ECU in the floorpan of a convertible?
• The guy with a drill that added 13 DIY drain holes to keep water away from the ECU? Including 2 right next to a removable rubber plug? But he didn't bother to remove the carpet!
• The guy that bought the handiwork of the above two people.

For now the plan to "fix" this is to keep it simple until I get a welder. I'll used little squares of butyl rubber to seal it on the inside, and maybe some dabs of seam sealer or spray undercoating on the outside.

__________________________________________________ _________________________________________________

I've got one more major item I'm thinking of swapping - the rear subframe as an entire suspension system. The Automatic one is definitely less crusty, plus it has a non-leaking diff already installed in it. I did a quick measurement of it and it seems like the LCA alignment bolts are within tolerance comparing the two subframes. I figured there has to be a more complete and complicated way to check for straightness.

Well, Advanced Autosports sells this rear subframe check tool for $20.95.



I think I'll stick with just measuring things.

 

Today's installment: Don't go looking for stuff you don't want to find!

I looked at the shell and thought this wheel looked a bit far forward.



The finger gap to the tire was uneven, so I measured from the wheelwell front edge to the axle centerline on both cars, and this one was a half inch shy of all the others. I grabbed some help and measured from front to rear axle on both sides of both cars and got basically the same measurement.

Uh oh!

Anyways, I peeked around the shell and could find nothing obviously bent on the body, subframe or suspension. I measured the subframes again. The rear alignment holes were the exact same distance apart on both, so I proceeded with the teardown.



The subframe is out! It's easy with the diff missing - all I had to disconnect was the rear brake hard line junction at the right rear soft hose block, the hand brake lines, the shocks, and disconnect the battery cables from the subframe.



18 3/16" is The measurement I got between the inside edge of the alignment eccentric tabs at the front and rear of the shell subframe, and the rear of the auto subframe. I couldn't measure the front with the PPF in the way.

Then I turned my attention to the underbody.



It mostly just looked like stains in the paint. Wiping it off almost seemed to fix it.



The wire wheel told a different story though.



I know this is a bit deep, but I'm not chasing perfection here. I'm going to address what I can with some acidic rust remover (need to buy ospho instead of naval jelly!), clean it off, and paint.

If it's too hard to reach, I'll spray some fluid film on it and move on. This is already overkill for a car I intend to generally garage.

@Fireindc , I'm recapping your RX7 restoration thread, do you mind sharing what primer you're using after rust removal? And is it sold as a Raptor Liner product? I usually just go straight to paint with Rustoleum, or lately Steel it, but I'd like to do this one proper. That said, I'm trying to keep it light so I won't be adding any undercoating here.