PressY4Pie

This build has been in the process for about a year or so now, off and on between different projects. For anyone super interested in the live-tweet-style updates, here's the original thread. For anyone whose time isn't worthless, i'll try to do a quick up-to-speed in this post and layout the overall goals of this project.


I bought this lovely car way back in 2016 or so. I loved it, but my previous car to this was an NA miata, and the only thing i really wanted from the rx8 was for it to be lighter. anyway after exactly one lengthy series of poor decisions, i bought the 06 NC GT, mostly because it was the only miata available for sale at the time.


And if i'm being honest, the NC is probably my favorite car i've ever owned. I got the cheapest one available, and it was HEAPS better than any of the NAs i had owned before this. Unfortunately my fate with the NC was not to keep it stock no matter how much i promised my friends that i wouldn't mod it.



was out for a drive one morning and was greeted with the noise of neglect - a wavy rod trying to escape the crank case. I just sat on the car for a while after this. I got a new job, moved a few states over dragged the car with me. I pondered a bit about how i work from home and don't really need to own a car at all, let alone three of them. Ultimately decided the only logical thing to do was to take as much of an rx8 as i can and jam it into the NC.

The original plan was to buy just the engine and piece together the rest. This was a super huge mistake, but i didn't know that at the time. This will become a theme. I got so far as to install the engine and transmission in the NC. But ultimately stalled out here once the mechanical components were sorted.


Now i know this is the million dollar question for anyone familiar with he NC and RX8 platform - Which components from which car were used?
The easiest way to answer this is to say "if in doubt, it's probably from the rx8". The original plan was to use:
0) rx8 subframe
1) rx8 engine (duh)
2) rx8 transmission
3) NC PPF and driveshaft
4) NC steering
5) NC ABS
6) NC radiator
7) NC wiring harness

The more "in the weeds" i got into this, the more i realized how unlikely that would be. The real winning combo turned out to be:
0) rx8 subframe
1) rx8 engine
2) rx8 transmission
3) NC PPF and driveshaft
4) rx8 steering
5) rx8 abs
6) rx8 radiator
7) rx8 diff
8) rx8 wiring harness
9) rx8 everything

This entire thing was based on the concept that the subframes were the same bolt layout and could be interchanged. This is very cool but kind of masks how much work the rest of this entire project would be. I was very much hoping to get out of this without having to invent a part, but alas that didn't turn out to be true. I spent a few weeks learning some basic cad and had a part machined for the swap. This part is the magic that lets me use the NC PPF which is super light, and more importantly already exists and doesn't need modification. First photo shows the problem. The top mount of the rx8 transmission doesn't line up with the bolt holes of the PPF. (i think the ppf is upside down in this photo, but the problem exists when mounted the correct direction) Second photo shows what i came up with to solve this problem.






by the point i had this part made, i was already kind of losing motivation. I took a break from it for a handful months, then another month etc until i did enough mental gymnastics to convince myself to buy a different car.


I bought this gem with no engine or transmission or wiring. Whipped it together over the winter and now it is in a perpetual state of "ran when parked".

Went and got married, moped around for a while etc and finally found a path forward on the NC. The solution was really simple. The little voice in the back of my head was telling me this the entire time. just buy a car that runs, idiot.




One very cool 2004 Mazda Rx8 with the heaviest automatic transmission i've ever had the displeasure of dragging across my garage floor. Speedrunning one rx8 disassembly, I pulled the wiring then connected up the , and then the . once i had this running on the floor, it was basically "ready to go" just had to drop the harness into the stripped NC. it totally worked first try and didn't take 6 hours of work, but finally the first start happened
. Which is where it sits right this moment. My goal is to get it ready for a first drive this weekend. We'll see how likely that is.

Verwah

Sounds like you work on your NC project at about the same rate as I do. A build thread can be a strong motivator, so good move starting one. Now that I'm interested in the progress its expected you'll be driving it around this weekend. Ha, don't mind me I am just projecting.

Houleo

Much fun, love the rumble and linear power of Wankel engines.

PressY4Pie

as of yet, my biggest motivator has mostly been being made fun of for having a broken car in my garage

Yeah i've always loved the engines but whenever i have one, i just want it to feel like a miata as well. I'll never understand why Mazda didn't make a special edition rotary miata with any of the generations. oh well.


Haven't had as much time to work on the NC this week as i wanted, but i've done a few things in the time i have. Pretty much just picking things at random to tackle until i feel i have a reason to do otherwise. Replaced both headlights. I lost one of the parts too the headlight during disassembly some time last year which sort of sucks, but that's how it goes i guess. Also did a bit of scoping out the interior wiring. haven't fully decided how i want to tackle this yet, but it will likely involve throwing parts into the cabin until they all work. i went and repaired a few of the wires that needed it from the previous owner's handiwork.

PressY4Pie

making progress at a snails pace. Realized that i haven't taken the hard top off one time since getting it, so i probably don't need to waste all the room on it. It's ripped to shreds anyway, so out it came. The NA or NB can be the top down cars if ever i decide i want that.
next i chased the harness about the rear of the cabin, and into the trunk. Some emissions component whose name escapes me is on the opposite side of the NC rear subframe, so i have to extend that. RX8 only has one door sensor (i think?), yet the NC has two. I haven't decided
if i care enough to fit the other door sensor. Fit up the Bose amp, the DSC gyro etc etc.

i didn't notice this at the time, but looking at these pictures made me notice that my drain holes are mega clogged. Yikes. Gonna try to finish up the trunk and rest of the interior tomorrow. high hopes i guess, feels like i'll never be done






by the way, for anyone wondering why the interior is covered in dust absolutely everywhere... womp womp. Wondering if that's what clogged my drain holes. looks like the same sort of dirt.

HarryB

Nah, they were clogged before fitting the HT. There's no way that water gets to them with the HT on.

PressY4Pie

Would believe that too. Is the trombone cleaner still the best move for NC, or is there some other method?would like to clear em out even tho i won't be running the soft top, seems foolish leave a drain full of dirt lol

PressY4Pie

Was planning on accomplishing more today, but this took me way longer than i expected. Goal was to get the dash, and maybe interior trim back. Started by chasing down the door harnesses from the NC, and laying them over RX8 one. You can sort of see the driver's door connector from the RX8 harness ziptied out of the way in the first photo. There are 9 wires in total that must be joined to the Rx8 harness. Took me a few hours of flipping thru the FSM and Wiring Diagrams to match the circuits up. I don't currently have a stereo to install, so i won't be able to test the door speakers, but i am pretty sure i did it right.





I must say, i expected this next part to go a lot faster than it did. it took me quite a few tries to get it right. i couldn't remember how either dashboard was routed originally, so that made fitting the rx8 one to the NC, and even harder to fit the NC HVAC on top of it.
In the end. Ultimately what i ended up doing was fitting the driver's side components first, and worked my way all the way over by bolting the ground terminals where they felt about right. once i got as much of the rx8 harness in place as i could, i draped the NC harness over it, and spliced it into the harness.
interestingly enough, pretty much everything in the rx8 harness "has a place". Even the Bose Audio microphone thing. The other really crappy thing about this was the previous owner of this rx8 really had his way with this darn harness. there were random cut wires and busted connectors everywhere, so of course i had to repair all of that. probably 5 or 6 wires total, but they were all broken in their own unique, head-*** way.




I fit up all the components as i was able. It's about ready to go back in now. Harness is secured to the dash. Cluster even fits quite nicely. The auto cluster i have is in really awful condition, but i'd rather mess it up than my good one anyway. I think i'll probably try to make up a little cover for the exposed portion of the cluster face. I was really excited to see that the dash cover fit onto the gauges fine. I think this is the final fit of everything before going back into the car.




This all feels like a lot of work right now, but hopefully tomorrow it'll be looking a little closer. I can't believe how heavy the stupid dash is compared to an NA or NB dash.

PressY4Pie

Another day spent working on the NC, another day wasted. Went in with the intent to put the interior together, figured i'd start the day out by repairing the wires in the engine bay. This wound up taking up my entire morning. i just kept finding more and more rubbed through wires. Pretty much all 8 wires on both headlight connectors were worn thru in different locations. i don't usually choose to post closeups of wiring for the same reason i don't post closeups of welds, but i don't have anything else interesting to share, so here's a couple.





Also connected up the headlights, running lights and fog lights. Why, one might ask did i do this instead of the interior like i said? So i could pretend the car is complete again. Bumper is absolutely scuffed from getting kicked around the garage all year. i'm just not gonna think about it for now. The entire paint is a C+ at best, i've been considering a wrap some day. Guess i should get it driving before then. Hopefully back to the interior tomorrow.

PressY4Pie

Reinstalled most of the interior today. Had to start with connecting up the door harnesses. this was pretty easy, needed some keyless entry wires, the window switches and an ignition wire. Wrapped all that up, tied it back and then installed the dashboard. really starting to feel like a real car again.





Once everything was installed, i started testing each circuit. Headlights, tail lights, blinkers, windows, mirrors, etc. Almost everything worked first try. There are two things that don't work currently - the HVAC and the horn. The horn didn't work when i got the car. i thought i had fixed it by repairing a couple wires, but that didn't seem to do it unfortunately. the hvac not working is kind of annoying, it seems like it should be. I have a couple working theories on this, the top one being that i just killed the module a while back. Ran out of time to debug it, but there's also the possibility it's just the fuse. that would be lucky.

Last major job is replacing the ABS pump. this doens't seem that hard, but i'm not really looking forward to it anyway. will hopefully get it started tomorrow. once that's done, i think it's time for first drive.

Satisaii

I am impressed with your wiring perseverance. I am not intimidated by wiring, but I don't know if I could have gone that route.

I prefer velcro straps over zip ties since they can be undone to add in more wires as needed.

PressY4Pie

believe it or not, this has been the easiest way to handle the wiring so far. I've tried it 2 or 3 times up until this point and failed miserably each time.

This was my first attempt. I had planned on using the NC body harness, and was going to combine the rx8 engine harness into the NC harness + fusebox. After stripping both harnesses down and getting rid of that nasty gunk that goes on the grommets, i decided this was not going to be the move.



The next attempt was to just run the rx8 engine bay harness, and connect it up to the NC body harness. this would have worked on paper, but would have required a lot of work.

Ultimately, just running the entire RX8 harness has been very simple conceptually and easy to accomplish.

Alejo_NIN

iTrader: (2)

sometimes the hardest path ends up being the shortest. so good call on doing that.

PressY4Pie

Got started on the ABS swap today. Had to cut away a portion of the strut tower material to make room. took a few passes to get it all due to not wanting to cut **** that didn't need to be cut. Can also see from the pics where i cut away the old ABS pump mounting point.




Once there was enough room, i just jammed the pump in the spot to see where it might fit. I tested each orientation and ultimately landed on this. i believe this is reverse of how it is on the rx8 originally, but all the ports lined up (after some light bending)



The two lines that go from the MC to the pump are an M12x1.0 on the rx8, the NC lines are M10x1.0. I think i've read that later pumps use M10 on the rx8 as well, but both of the ones i have are the bigger ones.
The lines being on the top instead of the "back" of the pump also made it such that they didn't quite reach easily anyway, so a short extension helped here. I went to 3 or 4 different parts stores until i found a suitable set of fittings and adapters.
In the end, the combo was a short extension with M12x1.0 on one end, and 3/8 on the other plus a union from 3/8 to M10x1.0.




I can't say i'm super happy with how it looks due to all my hand bending and adapters etc, but it seems functional for now. I was going to pressurize and bleed the system, but i forgot to pick up fluid while i was at any of the stores, so it'll have to wait until tomorrow. I'll also have a fair amount of cutting and grinding still until i have a bracket that actually locates the pump rather than just hanging it by the lines. There's a pretty good chance that i'll redo these lines some day, but for now, as long as it seals, i'm happy.

Alejo_NIN

iTrader: (2)

i was going to bend my own pipes but ended up using AN3 fittings, talk about a nightmare to find the stupid fitting and adapters etc!

def get yourself a pipe vender although those factory lines are made of solid steel! ******* things are hard to ebdn but you won't risk kinking. aline and ******* yourself over.

also, the doubleflare is not that difficult to do.
i bought these from the Forrest store

these people sell premade brake lines, PTFE in different lenghts

PressY4Pie

Thanks. yeah i have all these tools, i've just never had good results with them for whatever reason. Every flare i've made has leaked, and every time i use the bender, i end up kinking the line. I probably just need more practice with it, and maybe a better tool. I'm gonna run what i have for now, but once the car is running and driving these lines will probably be the first on my list of stuff to replace.
The lines that go to the rear of the car are terminated at a nice little block, so i can feasibly make just the lines for the front of the car at some point. it would look much nicer than what i have.
Will hopefully be finishing up the bracketry today for the pump. Went outside with the grinder and welder in hand but realized it's 9:30 in the morning and my neighbors probably wouldn't like that too much.

PressY4Pie

Went to work on the ABS pump today. spent about an hour cutting and grinding the frame rails and killed all 3 of my batteries. Will hopefully finish it up tomorrow, just need to fix the bracket to the car now. Haven't decided exactly how yet, it has three studs on the bottom where it was originally mounted to the rx8. there's no similar spot to fix them in the NC, but 2 of them are kind of close such that i could make it work. Might riv nut the third and use a bolt thru it instead of the exist stud. or i'll just weld it in so it can't be removed again. not my favorite solution but it'd work.

Still had some time to work on it after my batteries died, so i tossed em on the charger and started putting everything else in the bay that needs to be there. Surprisingly, everything seems to fit quite nicely. i'm probably not going to keep this wacky K&N cannon forever, but for now it's the easiest solution - the stock airbox is nowhere near fitting. Both the ECU box and fuse box are sort of just floating about in these photos, i'll have to come up with a way to fix them in place. The rx8 uses captive nuts inside the frame rail making me think i can probably use riv-nuts for this as well. The installed battery is also not the correct one. this is the original rx8 one. it does technically fit, but the NC battery box actually still fits, so i'll likely be using that with it's original battery instead. smaller and lighter.

Also sorted almost all of the coolant hoses. the only one that didn't fit was the heater core to water neck one on the passenger's side. It probably could have been stretched to fit, but there are a bunch of brake lines in the way now. i'll probably go get a joiner from the parts store and cobble something together.
Wont be long now. list of remaining tasks is quite small

Scotty Dugg

You're making great progress, following with interest, I wonder what this will do to the weight distribution.

PressY4Pie

i'm pretty interested in that too, i plan to weigh it when i'm done. it'll need an alignment anyway so that'll be a good time to throw it on some corner weights. Just a gut guess, but the front of the car seems like it'll be quite a bit lighter. the rotary engine sits back quite a bit farther than the original 2.0 did, and everything in front of the wheels is about the same. the weight difference between the two engines is negligible, between 20 and 50 pounds according to some light googling. as far as weight goes, all i've done is move the heaviest object lower and back towards the center of the car. the engine is still "behind" the steering, so i guess it may as well be about the same? guess only time will tell

PressY4Pie

Bit more misc progress today. ABS bracket is pretty much finished. Was able to get away with simply bolting it in via 2 or the 3 original mounting points. Gonna pull it back out one last time tomorrow to grind down any remaining sharp edges. I sliced the hell out of my finger feeling around for the heater core hose.
Should probably lay down a coat of paint on it as well for good luck.




A similar treatment is still needed on the other side, if you look at the photos of the engine bay from yesterday, you can see the fusebox doesn't quite sit right either. All the batteries are chargin' again so maybe i'll finish that up next time. Really starting to wish i had a second angle grinder so i can have a cuttoff disc and the grinder wheel at the same time.

Otherwise, i just went about doing up misc stuff. Torqued all the subframe bolts, installed the PPF and driveshaft etc etc. I want to put it on the ground so bad, but it's not quite there yet. Soon tho.
I'm having a hard time deciding what to do about exhaust. i have the rx8 system that is too long, and the NC system that is too small. I'd prefer to be able to drive it a little bit before dropping it off at an exhaust shop to have one fabbed up from scratch, and i don't particularly want to drive around open header either. Currently, the best idea i have is to either cut the flange off the NC exhaust, and try to fit an rx8 flange to it. if i remember correctly the ID of the OEM NC exhaust is 2.5", compared to the ~3 of the RX8. The other idea i have is to take the rx8 exhaust, fit it up best i can, mark and cut it and chop about 1 foot out of it, then slap it back together. Maybe i'll just go grab a few sections of pipe and use the NC muffler. I'm having a hard time getting my hands on a cat for a prices i think is fair due to CARB laws. I'll probably try to ****** a used one when i get the chance.



Other misc job i tackled was reinstalling the steering column and wheel. took a best guess on the wheel placement, will probably need to recenter it once it's back on the ground, but i just couldn't help it. Threw the seat in to remind myself what it feels like to be in what is almost a real car.