This batch is for the s2000 front suspension. When I get around to the rx-7 I'm gonna go nuts. This place had massive bins of giant brake calipers they were doing by the thousands. She told me that just a couple of hours and they do it all day every day.

I'ma have half the damn car zinc coated lol.

 

i love carburetor cleaner. i use it for more things than i should, but i must admit after i read that first sentence, i cringed for the amount of time that it took me finish the paragraph. glad you didn't ghost your instrument cluster.
your experience with this wire coming loose is exactly the reason why i don't crimp-only! no matter how many people swear by that practice, i can't bring myself to do it when i'm wiring anything on a car. i do both - crimp and solder.
it was out of desperation, but i still give you props for finding it and McGyver-ing it to get you home.

oh, and on the fuel pipe and tube ... phenomenal. i really need to get off my duff and learn how to weld. also, i'm not sure if you're interested, but i POR-15'd mine when i did my fuel tank. you mentioned it possibly rusting from the inside, so i guess the POR-15 can't stop that, but hopefully i'll learn to weld before that happens.

good stuff! you're the man.

 

Yeah, I tried to be pretty careful with it. I picked carb cleaner because it will dissolve grease but still has some lubricating properties. Plus it has that little red nozzle to let you target it.

I probably could have done a better job by disassembling the actual speedometer, but I don't know how they work inside and damaging it was too big a risk.

I'll be taking a close look at any other pre-crimped terminals I've used and probably flowing some solder into all of them. Any crimp I have made myself with a proper tool has been solid, but there have been a few times where pre-crimped terminals have failed on me.

I'm also going to consider getting higher current relays. The one I used for the fuel pump was pretty warm, despite being rated for 30A and the fuel pump probably drawing <10A.

I'm not sure how warm is normal for a relay though. It does have power flowing through it constantly. Even the OEM circuit-opening relay under the dash was warm, and all it does now is switch the relay at the back.

Don't take my welding as advice! I'm decent at getting things to stick together solidly, but I don't practice enough to be really good at it

POR-15 is pretty good stuff. I actually have some that I could have used, but chose an enamel paint I had around since it dries a lot faster and I wanted to drive my Rx7 the next day. I knew I would chip it on reinstall anyways, so as a precaution I fluid-filmed the tube and also the entire area under the car.

For the inside one could probably use one of those fuel tank sealant products. I don't think it will matter much though, as the inside of the original tube was in perfect condition. It probably doesn't see much moisture.

 

So, I spoke too soon when declaring victory on the fuel fill tube. Today I went to fill up the tank, and noticed a loud "pssht" on unscrewing the cap. I figured maybe that was normal and I hadn't been hearing it due to the crack in the breather, but then my tank would only take $0.20 worth of fuel at a time before the handle would click. A very tedious 15 minutes of manually clicking the handle later, I had filled 1/2 tank.

I'm guessing that my factory breather system is somehow not performing properly, and backwardly enough, the crack in the breather tube had been helping to cover for it. So I'll need to try tracking down what the issue is. Any suggestions are appreciated.

In the meantime I may try and find a vented gas-cap to prevent pressure buildup, although filling the tank over 30 minutes will become tedious rather quickly.

 

check valve stuck/bad? Charcoal canister clogged?

 

I tested the evap line from the charcoal canister, and found it was unblocked. Then I had a think about the fuel filling so slowly, and decided to take a look in there and see what was up.

I have one of those articulating borescope camera, and conveniently it fit down the filler neck. I immediately saw the problem. Remember this sock thing?



Putting the borescope down the filler neck, I could see it was folded over. My borescope doesn't have a feature to capture the images, so here's a quick 11:45pm MS Paint depiction of what I'm talking about:



That sock thing is one of two socks, both of which sit inside of the outer bellows thing. The idea is that one sock's OD nests into the ID of the other, and then the outer bellows acts as a backup. The bellows looks sort of like the exhaust coupler on a boat, and I think it's just there as an outer seal.

Anyways, the borescope revealed that one sock was folded over and was obstructing fuel flow. This may or may not affect venting, but it's definitely the cause of my fuel-filling woes.

That was all the diagnosis I was going to do for today, but then I was feeling a bit defeated. And I have a rule that I never go to bed feeling defeated. So I went back out and started trying to fix it. I dropped the muffler off it's hangers and removed it's heat shield so I could access the sock, and then this presented an issue.

The order this was intended to be installed doesn't seem to be the order I was installing it. The outer sock (coming from the filler side) is supposed to nest inside of the inner sock (the photographed one, coming from the tank side). Then the bellows fits over them. I think the proper way to install this is to remove the outer fill neck and install the bellows over the socks first, then attach it to the outer neck and pop it back in. I investigated that possibility and realized that the inner side of the outer neck (I know, I'm sorry about the bad terminology) is held in with two 10mm nuts.

I looked up and found two vaguely cylindrical things that MAY have once been 10mm nuts, but they certainly weren't coming out without snapping the studs. Snapping the studs means I couldn't secure the filler neck bellows onto the neck again, which means replacing the studs, which are only accessible by de-skinning the quarter panel. That is a non-starter.

I did try removing the inner sock and just using the bellows, but that resulted in the following:



No matter how much I tightened the clamp, fuel would still leak out of it. The ID of the bellows is sized to include the sock, and it just won't work without it.

So what I ended up doing over the course of about 2 hours is meticulously rolling the outermost inner sock up (ironically as one would an actual sock). Then I installed the other sock into the bellows, and from the gas cap side used a screwdriver to feel around inside the bellows and unroll the outermost inner sock into the innermost inner sock. Then I had to manhandle the bellows and sock over the end of the fill tube I reproduced in my last post, which was no easy feat since they did not want to stretch over the end as a unit. This resulted in the following, which is how it is supposed to be:



That doesn't fully capture how much of a pain in the *** this was to achieve, but I tested and I can now see the butterfly valve clearly through the filler neck with the borescope, and I also found no leaks when I did a test fill from a jerry-can. This may or may not fix the venting issue, but it will almost certainly fix the filler flow-rate issue.

I apologize if that was incoherent, but it's the best I can do at this hour. All of the above took about 4 hours beginning to end. I'm going to go wash the Rx7 out of my hair, then go to bed feeling accomplished.

I'll report back with my findings next fill-up. Until next time

 

I had a very similar issue to your hole in the breather tube. Symptoms were almost the same except if I filled the car completely with fuel I would get a small amount on the ground under the car in the driveway later as well. That fuel fill tube assembly was pretty rusty, so I got one at a local junkyard (this was around 2001 so parts were easier to find back then). It's been a long time so I don't remember my exact investigative process other than it involving my fingers a flashlight and an inspection mirror, but I found a small crack IIRC where the filler tube goes into the top of the tank. At the time I cleaned it up as best I could through the access hole and mostly by feel put fuel tank repair putty around the tube that goes into the tank. It's similar to liquid steel or JB Weld stick. Like a two part metal epoxy putty. Anyway problem solved. I had the tank out a few years ago to get a hole repaired on the bottom where a support strap had rubbed through. I can't find my pictures (They are in a folder of pictures I took off my phone somewhere) I took to verify but since it was still not leaking I don't think I removed the putty and had them repair that. I think I just cleaned up the exposed metal from the leak years ago and sprayed undercoating on that area.

 

I'm happy to report that my fuel filler now works properly, and fills at the normal rate. Which is a good thing, since my testing methodology was to coast into the gas station on fumes, so failure was not an option.

I had some plans change unexpectedly yesterday which gave me a little bit of time for some car stuff. The Bosch L-Jetronic fuel-injection system that came with our cars uses a MAF. In S4 models, it's a big flapper-door inside of an aluminum housing. This flapper door gets pushed open by the flow of air past it, which outputs a 0-5V signal to the ECU and tells it how much air is flowing past.






Since I'm running speed-density with my MS3X, the MAF does nothing at all. I have basically been ignoring it as it's only job now is to adapt the square outlet of the airbox to meet the round tube that goes up to the throttle-body. I've also said many times that the stock intake is excellent and the MAF doesn't pose a restriction, but I may need to eat my words on that (details to come). This is why I didn't delete it in favour of a cone filter, especially since a cone filter will be inhaling hot engine-bay air instead of cool outside air like the stock system.

Anyways, forum member Malic was kind enough to share this design he found on Thingiverse that allows you to eliminate the stock MAF entirely. I had been thinking about designing one of these, but this saves a ton of time. After about 18 hours printing I pulled out the airbox to install it:



I printed in PETG since it's what I have on hand, and it should be resistant to engine bay temperatures. 100% infill for rigidity.

Here's a comparison between the two parts:



I think the pipe is a bit longer than the MAF, but fitment is excellent. One weird thing I noticed though:



The person who designed this pipe made the [wise] decision to use all of the available height for the rectangular opening on the airbox side. The opening fits the MAF perfectly but is smaller than the actual opening on the pipe. The thing is, there's nothing behind that piece of plastic. Mazda could have made it larger, but chose not to for some reason.

Then if you look inside the airbox:



That odd looking piece with the half-cylinder at the end is also just a piece of flat plastic. If one were to cut out both of those pieces they would increase airflow, with seemingly no disadvantages. I didn't because I thought there might have been an engineering reason behind it (airflow is a complicated topic), but thinking about it, I wonder if this was a decision made to make it match up with the Nippon Denso MAF rather than for actual engineering purposes. I've seen similar MAFs on the internet for other cars, so it's possible that Mazda added that plastic piece because Nippon Denso used the same MAF housing in multiple applications.

Adding to this, I used to always say the MAF was not a restriction. The reason for this is that A: Many people make lots of power on the stock MAF and B: A small opening flows a lot more air than people think.

But then I started the car with the intake tube open, and held my hand near it, and when I pushed down on the throttle with my other hand I was shocked at just how much air it inhales. It actually almost pulled my hand in.

My fist is here for scale:



I installed the airbox back in and re-tightened the clamps:



And now that I've tested it out, I have to say, it absolutely makes a difference. I don't think there is any difference at WOT, but on snapping the throttle open or taking off from a stop, there is a definite difference. To the point that I had to add fuel in the 1200 - 2000 RPM range of my VE table because it had started to buck slightly, and I'm going to have to play with Acceleration Enrichment as well. I'm thinking that maybe the flapper door isn't a significant restriction for overall flow, but does have a dulling effect on throttle transitions since the air has to push the door open before making it's way to the engine.

I'm really surprised, and this has me considering taking a spare airbox and cutting out those two plastic pieces to see what happens. The top of the airbox where the snorkel enters can also be trimmed back for an easier transition for the air (photos will make this clearer) which might also help.

Is it a huge difference? No. But for about $3 in PETG and < 20 minutes to install, it's absolutely a worthwhile change.

While in the area I decided to save some weight by removing some of the other stock EFI stuff I had around. I like everything to be reversible (and it still is, since I haven't altered the harness), but at a certain point you have to accept you aren't going to be returning your car to stock. I don't know where exactly that point lays, but I've definitely passed it.

I took out the stock MAP sensor (not in use), idle mixture varistor (not necessary), TPS check-light (redundant), Air-Bypass Relay (controls something that is no longer needed or installed), and some miscellaneous brackets. Then I tied all of the harness stuff down with some zip-ties:



Remind me to get a 6 pin Yazaki for that relay that has been installed with spades into the harness connector. It only controls the retractor headlight motor, but still, better to do it right.

That ring terminal ground is there just to replace the low-coolant sensor since mine broke, and it makes a very loud noise when not grounded. I relocated it under the airbox.

The next thing to remove would be the stock CAS, but removing it would leave a hole in the front cover. I did design and print this part for use as a plug on the Turbo II engine:



However, I don't want to put it on an engine that will actually be running, since I don't feel comfortable leaving it exposed to such heat. Clogging my oil pickup with PETG would be a bad time. I might have some carbon-impregnated Nylon filament coming for a future project, so I would probably print this part and another MAF tube with that since I can reduce infill and optimize both parts.

Since I'm using a Ford Taurus alternator and custom bracket, installing that plug would make it easier to run shorter belts and tuck the alternator lower. This prevents it colliding with the intercooler on the Turbo II engine, and theoretically having it lower is better for handling.

All of the above (plus emptying my interior of excess stuff) saved about 7lbs. And while it's unlikely to matter, incremental savings help to offset all the weight I've added over the past few years.



There are probably some other easier pickings too (smaller AGM battery), but in the meantime, I have some more weight coming in the mail. Hopefully it arrives soon so I can post about it.

Until next time

 

if you send me a STEP file for the CAS cover I can likely machine an aluminum one for you.

 

dont tell him to take his time though, he's almost as bad as me!



also what the hell did you print on to take that long? mine says 3 hours muahah

 

hey now.....

 

dude i haven't even TOUCHED mine in how long? also here's some **** for you both...

 

I might take you up on that, but for now I'm going to try printing it. Like I said, I've been eager to try the carbon-nylon for awhile now and I have some other part ideas that would benefit from it.

Also, I still haven't invested the time to learn Fusion and I am still designing in Blender - which won't export STEP, only STL. Plus I have a few non-manifold faces in my design to rectify as well (they don't affect printing, but unsure how they play with CNC).

Ender 3 V2 with Sprite extruder.

I printed at 100% infill, and I think my travel speed was set really low from a previous print. I didn't think too much about it, since machine hours != man hours.

That's what I find so cool about the 3D printer. Press start and walk away, and then a fully functional part is ready when you come back. No intervention required (other than inevitably fixing the Ender once a month).

 

Man, those look amazing.

 

i know youre on a budget, but if you get the $$ and the notion, the bambu X1C is the ****. i gave my heavily modded ender 3 away after i bought mine. it's not even a comparison.

also i have CF nylon and CF petg if you need me to print something.

 

DUDE...$145US and i can take up to 300lbs for that cost. im gonna have half the rx-7 zinc coated.

 

Wow, just freaking wow. Something like that has me rethinking the fact that I replaced a lot of my hardware. Pretty sure I kept all the old stuff, but I don't like some of the markings on bolt heads on the new stuff.

That is simply amazing looking and makes all the difference in the world when trying to make everything look new again.

 

Sorry for the thread derail Wondrous. Yours is the only one I get alerts on.

 

No need to apologize, I always like a good conversation about fasteners

Good to know it's not just me that worries about that sort of thing. I still wake up at night sometimes and think about how many of my M8x1.25 bolts have 13mm heads instead of JIS 12mm heads...

 

its fastenating?

sorry i couldn't help myself

 

It's been near 6 months since the last update. How are you? How is the car? I assume nothing drastic has happened but it's mildly concerning.

 

Rumours of my death have been greatly exaggerated

I appreciate your concern though I'm well, and the car is well too. It continues to be pretty reliable and now that it's winter I've parked it. I've been pretty busy with other aspects of my life, so other than driving it and some minor maintenance (resealing the water pump, replacing a tie-rod) it's been mostly status quo. I did install a MAF from a 300ZX and learned all about MAF tuning, which was neat and has further improved drivability.

I have completed a couple of small-ish projects, but they ballooned out to months long since I was only dedicating an hour or two here or there. I have all the photos and as soon as I have the time I'll sit down and write a few proper updates.

I also have a neat idea for a project / experiment that dovetails into the turbo swap. I'm not sure how it'll all pan out, but it's something that people might find interesting since I don't think it's an experiment that's been run too many times. Details to come once I am sure of the shape it will take, but it won't be until at least spring since I don't want to expose the car to salt.

 

That's fair, thanks for the quick reply though! Hope all works well and I can't wait to see the future of this car take shape!!! Really interested in seeing the write up on the MAF swap

 

lol, i still have a torn apart car with zero done in what? 2 years? hell i tore the *** end out of the s2000 for the "clutch job" and now all of THAT is at the zinc plater. i'm not sure i'll ever get to the damn rx-7.

 

So, I realized I had actually written most of this post awhile back and never actually posted it. I ended up finishing it last night, but it is kind of hard to formulate all of the work in this update into one cohesive post. I am going to try and relay it in the order that makes most sense but I can’t help but feel it’s a bit unpolished. So if anything seems confusing, just remember that it probably made sense in July when I did it.

What does it take to get decent audio in an Rx7?

Someone I know asked me that awhile back, and my answer was that one needed to install 6 ½” components in the doors, tweeters on the door triangles, and a set of 8” subs in the shock towers (a proper box would be better but space is already limited).

This isn’t what I’d done though. I had installed 5 1/4” in the doors. This shouldn’t be a problem in and of itself, but the secondary problem was partial obstruction of the cone. I’ll get more into this later, but the long and short of it was that I needed to make some improvements to my speaker setup.

So join me for this quick two-hour project that spiralled into a multi-day effort spread over a couple weeks. Strap yourselves in for a long post.

I’ve ranted many a time about the deficiencies of the stock system, so I won’t go into them too much. The lack of bass is addressed pretty easily by sticking 8” subs in the shock towers:




I’d done that awhile back.

For proper vocals and clear instruments though, I needed door speakers. The stock 4” under-dash coaxials point down at your knees, so even if you upgrade them the poor placement and aiming is the real killer. Really the correct solution is component speakers with drivers on the doors and then tweeters on the triangles, aimed at head level.

S5 Rx-7s had optional door speakers, so a set of S5 door cards makes for a good starting point. These are what I have been using for a few years. Unfortunately the S4 door has the window track mount in a different location, so the driver can’t be installed in the optimal location and the cone is partially obstructed.

When I installed the 5 ¼” speakers, I thought the obstructed cone wouldn’t be too big a deal, but after driving around with them for awhile I really started to notice it. I ended up having to disable the crossover for the subwoofers so they would help with the vocals that were getting lost in the door (up above 400hZ even) and just living with the distortion.

But it was time to rectify my errors, and I decided to make things even harder by upgrading to 6 1/2” drivers. The 5 ¼” would probably be fine if the position were improved, but I decided to go big or go home. This meant locating the bigger speakers in the center of the door opening, and the window track mount would need to find a way to be okay with that.

Pulling off the door card, you can see my previous install:


You can see a few issues. The moisture barrier has come loose and was held on with tape, not to mention the 15 holes cut in it. I would need to replace them as part of this project.



The bigger issue though, is that water was clearly dumping onto the speaker. The driver’s side crossover (zip-tied to the back of that panel) was also wet, whereas the passenger side one was dry in the same position. More investigation would be required later, but wood is also a sub-optimal choice for this application. It works, but there are better options.

I also wanted to take the opportunity to neaten up the wiring for the power locks and the window relays. There are in-fact some crimps under that electrical tape, but not using a connector there just doesn’t sit right with me. The relays for the windows are also mounted in a poor place, and water has started to corrode the contacts. They would probably work fine for many years, but I’d rather do it right.

Starting with the new speakers:





Obviously they’re wider at the cone, but the coil and the frame at the back are also significantly beefier. I really like JBL speakers in terms of value for money. There is better out there, but at the price I am usually quite happy with them.

One thing I was kind of surprised by was that the frame is plastic. I know there are all kinds of different plastics, but when you pay decent money for speakers I would expect a metal frame. This is a non-issue, but just something I noticed. Either way, I got a good deal on these so I can live with it.

Looking at the back of the door card:


I had modified the leather insert from my old S4 door when I last assembled these panels, so you can see where I cut back the material for the driver. That would not be nearly enough for this application, but even if it was:



The door card itself has this sort of baffle-thing cast into it. Mazda obviously designed this around a 5 ¼” driver in the S5 location, so this simply won’t do. I then disassembled the entire door card:


One thing I should mention in case anyone else is in a similar situation:



The door vents are super fragile. You don’t need to remove them for this project, but in my case they were coming out so I could touch-up the vinyl panel. If you remove them, take the utmost care.

To be continued