Project Bullet: The 2004 Mazdaspeed Miata - Updated: December, 2021
Latest Project: The 2004 Mazdaspeed Miata
JM1NB354X40407519 #2279/4000
I have always been interested in unique automobiles. Recently, I had acquired a 2004 Mazdaspeed Miata. This particular series of Miata had a fairly short production run of 5428 cars manufactured during 2004 and 2005. There were 4000 (2000 in Titanium Silver and 2000 in Velocity Red) produced in 2004. In 2005, only 1428 were produced…the production run ran short due to a fire at the manufacturing facility in Hiroshima, Japan. Afterwards, the Mazdaspeed Miata model was never revived. My particular car rolled out of the plant on April 1, 2004; it is number 2279 of the total production run of 4000 units in 2004.
The Mazdaspeed Miata was the only model that was factory equipped with:
Turbocharged (7.25 psi boost) 1.8L producing 178 HP with 166 Ft-lb of torque
6 speed short-throw gearbox with shot-peened gears
Larger radiator
Bilstein shocks – lowering the car by 7mm
Upgraded clutch
Torsen LSD with larger axles
Larger sway bars and heavier undercarriage cross-bracing
Tower brace
17 inch Racinghart wheels with a wider footprint
Therefore, this is a very cool car that is rather rare. I must admit that I have only driven one other Miata and it had nowhere near the power and ride this one does. The turbo spools up around 3500 RPM and can really move the car in a very short timeframe…you have to be paying attention to what the car is telling you. This car literally can go from docile to bullet in a fraction of a blink. The suspension is unbelievably tight and it is very responsive; it is just fun to drive – one feels totally connected to the vehicle as soon as you get in it. It is quite a machine.
Anyway, this particular car was purchased from an individual who was, I believe, the second owner. I was able to get the car for a fairly good deal – it needed a bit of work. However, projects like this one are the element that I thrive in and I suspect I needed something like this right now.
The car itself was missing several components and needed some maintenance. The body was in relatively good shape; it was obvious that it had been garage-kept most of its life. The previous owner told me that the person he bought it from wanted to set it up as a track car, but life got in the way. That individual started some modifications with some very good components, but cut some corners which made me question his skills as a mechanic. Mostly, it was the use of “whatever” components to secure lines and various other parts with things such as bread ties, speaker wire, etc. In addition, some critical parts that were removed from the car would have to be replaced (like the brace for the turbo). However, the parts that were added were very good components. These included a Hard Dog Deuce Roll Bar, Mitsumoto Aluminum Oversize Radiator, and Flyin’ Miata full stainless exhaust.
Someone in the car’s past removed the driving/fog lights from the bumper and simply cut the pigtails in half (all these had to be replaced). The engine undercover, lower air dam, and front fender splash shields were all gone; they have been since replaced. I am unsure why those components were removed as they not only protect the engine from road debris, but also make the undercarriage more aerodynamic; they, more importantly, assist in forcing air into the radiator. The convertible top had a hole in it and was fairly dry-rot; it has since been replaced with a Robbins 2917-SF SunFast Cloth Top with heated glass rear window – this was a very challenging job, but came out successful. I was able to acquire a used rear deck cover (parcel shelf) and custom fit it to accommodate the roll bar; I suspect that the original was tossed because the folks that put in the roll bar didn’t want to fit it. That was a pretty challenging job that involved making a cardboard template to get the cuts fairly correct before cutting into the metal deck cover.
I must give credit to the previous owner. When I was checking the car, I noticed that there was a fairly significant oil leak under the vehicle. Turns out it the oil return line from the turbo was compromised and blowing oil all over the undercarriage. The owner secured the proper line from Mazda and had a shop replace the line before handing the car over to me; since much of the oil was blowing back onto the turbo, he didn’t want the car to burst into flames while one of us was driving it – I find that relatively responsible thinking. It is hard to find honest folks like that these days.
Anyway, so far, engine oil and filter (original filter was STP – a sign that the oil was changed at a quick change oil place – since replaced with Purolator One) has been changed and now running Mobil 1 Full Synthetic, transmission tail shaft seal replaced and transmission oil changed to Motorcraft Full Synthetic - then the entire transmission was replaced (see below). In addition, the top was replaced with a cloth Robbins top, all engine under-covers were restored to the car, and the rear parcel shelf was added and fit to the roll bar.
As Murphy’s Law would have it, the other day I went to get fuel, drove around a tad, and came back home. I backed down the driveway, put the car in neutral to let it idle (to cool the turbo), got back in, and the car would not shift. I was finally able to finesse the car into reverse and back into the garage. Well, after a few days of research and testing, the verdict is that the transmission had locked up. Exactly why, I don’t know yet. After some additional visiting with a very good Miata mechanic, he stated that he was unfamiliar with the six-speed transmission and was not willing to crack the case to find the problem. He recommended that I find a used Mazdaspeed transmission and swap it. My search yielded numerous used transmissions that were mostly in the $1200 range. Luckily, I did find one cheaper and after $600.00 and a trip to north St. Louis, Missouri, I was home with it. The transmission did not weigh that much, I suspect it was around 90 – 100 pounds and it fit very nicely in the back of the 4Runner. It was advertised as a Mazdaspeed Miata transmission - they have a slightly different gear ratio in 4th and the gears are shot-peened and helically cut for added strength. Although Mazda made other 6-speeds that look identical, they are not shot-peened. I was curious how I would tell if a transmission is a true Mazdaspeed model. As I was doing some additional cleaning on the transmission, I noticed that it had a VIN plate riveted to the rear housing. After running the VIN, it was confirmed that the transmission was installed in a Mazdaspeed Miata – just 28 cars prior to mine. Once I fix the original transmission, I will reinstall it into the car so all VINs will match.
The transmission swap occurred on June 29 and 30 in my garage. Although I have changed clutches and dropped transmissions before, this was the first time that I have done this process on a Miata, or any vehicle solely supported on jack stands. I was initially apprehensive about getting under the car, but it turned out that the car is very stable on the stands; however, I did have jacks under the front and rear lift points as an extra safety measure. It was an interesting experience. I was very impressed with the solid engineering of the car and application of substantial cross-bracing under the car (much of which I had to remove to access the transmission and drop the drive shaft). The removal/replacement of the transmission was pretty much like any other transmission pull I have done; hardest part was re-mounting the starter. As a cautionary side-note, prior to the original transmission failure, I had a trusted shop replace the transmission oil and the tail-shaft seal. When I removed the transmission, I found that they had installed the spring (lock) washers that held the driveshaft to the differential on the bolt side. This is the totally wrong place to put the washers; they always need to be placed on the nut side. If they are not, the nut will work itself loose. In addition, they installed the tail-shaft seal wrong as well. This is why I normally do my own maintenance - I won't be using that shop (or any other) again.
Anyway, it is back on the road and fun driving about in the Bullet again; I hope not too many speeding tickets are in my future.
UPDATE: 10 March, 2020.
TRANSMISSION.
It has been several months and now, as it normally happens with most cars I acquire, it has turned into more of a project car than a “just hop in and drive” car. After surmising that it was not the shifter bushing and something to do with the transmission itself, I did some research on who could fix the transmission. After calling around, the cost for the transmission rebuild was quite extreme and the only Miata mechanic would not take on the job as he has never cracked the case on a 6-speed before. So, I was instilled with a quandary…more research. After a bit of searching, I was able to find a used transmission from a 2004 Mazdaspeed Miata on-line. After confirming it was from a MSM by running the serial number riveted to the transmission, I purchased it for a very good price. It turns out the transmission was only seven numerals off from my serial number and was released from the Hiroshima factory the same day; it also came from a MSM with 60K on the odo. After sealing the deal, I drove the 4Runner from Conway to just north of St. Louis to pick up the component.
After jacking the car up and removing the original transmission, the used unit was installed after replacing the tail-shaft seal. All went together well - the hardest part was putting the starter back on.
I did replace the throwout bearing, but not the clutch assembly or the pilot bearing. I have a Flyin’ Miata clutch ready to go, but since the clutch looked good and I did not find a local shop to turn the original flywheel, I put it off until I repair the original transmission and reinstall it. The new transmission works very well; I added the 5x Racing shift kit with a bronze shifter bushing and filled with Motorcraft Tranmission Oil. After the initial test-drive, I noticed that the tail shaft seal was leaking. After pulling the seal and inspecting the bore, there was a definite scratch/gouge in the housing where someone incorrectly used a seal removal tool and managed to gouge the area where the seal is. The gouged area had a burr that was gently sanded off and Permatex Transmission Gasket Sealing compound was used around the seal surface and the vicinity of the gouge. This fixed the leak.
Later, I plan on putting the original transmission back in with a new standard flywheel and Flyin’ Miata clutch assembly. It turns out, after removing the tailshaft housing from the transmission, there were some foreign objects in the housing that got caught up in the shift paws, whereby causing them to jam. After the pieces were removed, the transmission shifted flawlessly. As far as the objects go, I am not quite sure what they are or how they got in there. It is possible that they may have been from a failed shift kit or components that someone dropped into the transmission through the turret. It appears that the majority of the pieces were confined to the tailshaft area; I have not found any elsewhere.
Small blue pieces were locking the shift paws
REAR STABILIZER BAR – AFTERMARKET BACK TO OEM.
The car had a definite suspension knock coming from the rear end. It appeared that the stabilizer bar bushings were worn and in need of replacement. The stabilizer bar was also an after-market bar that was 16mm in diameter with 3 holes on the termini of each side to adjust the ride (it was set on the middle hole). In addition, the connecting links were aftermarket as well. After removing the bar, it turns out that the bushings were not the correct diameter; to mitigate without getting the proper part, the mechanic cut portions of the bushing out, causing the stabilizer bar to bang on the frame when going over bumps. The bar, I suspect, is from 5X racing and was rather rusted (it may have been purchased used as the condition of the rust was significantly different than chassis weathering on the rest of the car). I put some new bushings onto the bar and remounted it the same orientation and the knocking continued. I then noticed that the geometry of the bar seemed odd at the links and finally surmised that the bar was originally installed upside-down. After rotating the bar, the knocking went away. Not much later, I found an OEM rear stabilizer bar for an MSM and replaced the aftermarket bar with OEM. I did notice that the handling was more responsive; I think that is due to the fact the aftermarket bar was a thicker diameter – the OEM is 14mm.
INTAKE – OEM TO FLYIN’ MIATA.
I decided to upgrade the intake on the Bullet. The original components will be kept and stored. The installation of the intake consisted of the replacement of piping and the original air box. The diameter of the piping is larger than the original piping and has a more direct route for the passage of air. The stock MAF was used. In addition, a new blow off valve and Turbosmart Manual Turbo Boost Controller was installed. The OEM intercooler was replaced with a used OEM intercooler from another MSM. The cooling fins of the original were nearly all smashed flat from road debris strikes – one of them was clear through the intercooler. I was able to find a used intercooler on-line that was in much better shape, but needed several of the fins to be straightened; it is now on the car. When removing the old intercooler, there was a fair amount of oil in the bottom chamber. This will need to be investigated…I was able to find a good deal on another OEM MSM IHI turbo with about 60K miles in the event that the original had an oil seal out (which I found out later it di). I also acquired the Rebuild Kit for the RHF5/RHF5H Turbo (PN: 411-05302-001) from Kamak Dynamics USA Group. This will be used to rebuild the original turbo when it is eventually removed. There is a strong possibility that the oil may be occurring from blow by that is getting past the stock oil catch can as there is a fair amount of oil in the return line to the intake from the catch can. After cleaning the catch can, a small MOROSO catch can was installed before the return line reaches the intake. In order to install the can, the washer fluid reservoir was removed and an aluminum bracket was made for the can to be installed into existing holes on the reservoir mount (the reservoir was retained in the event that the car was to be put back to stock in the future). Since installation, there has not been any additional oil evident in the intake pipe south of the turbo outlet. Some oil is still making it to the blow-by valve and throttle body, but that may be residual from oil collected in the intercooler prior to the addition of the can. This is still under investigation.
The combination of the intake with the existing Flyin’ Miata Exhaust does seem to allow the turbo to spool up faster and it appears that the power band is much smoother. The waste-gate works very well now; I don’t think that it worked prior to the intake upgrade, which took the original plumbing to the waste-gate actuator out of the equation. Now, the waste-gate definitely is bleeding off air between shifts; it is rather noisy (which I assume is from not operating for so long) but is reducing its note as it is oiled and worked. The oiling was done with a copper-based synthetic oil made for high-heat applications.
When the OEM air box and ancillary plumbing was removed, the components on the turbo side of the engine became much more accessible. I did install the turbo and waste-gate actuator rod heat shields; they were missing – the shields came from a spare IHI turbo. All the OEM components and hoses were retained.
The intake has a very nice, throaty sound when the turbo spools up and it starts pulling air. The whistling sound along with the exhaust note is very pleasing to the ear. Unfortunately there is a periodic “quack” sound that I suspect is originating from the blow-off valve which should be rectified, or at least reduced, after the adjustment of the boost controller. The “quack” was funny at first, but now has grown to be very irritating.
Later, the "quack" was lessened by replacing the Turbosmart Boost Controller with one from the Australian Company GFB (Go Fast Bits); it uses a needle valve construction rather than a ball and spring configuration. The "quack" which I later learned was most likely "turbo flutter," was completely fixed after replacing the turbo (which did, in fact, have a bad oil seal that was allowing blow-by to enter the intake system, including the intercooler).
Factory Intake Setup.
FM Intake installed with TS Boost Controller (later replaced by a GFB brand) and new BOV.
UPDATE: December, 2021
FLYIN’ MIATA EXHAUST (Replaced with newer version of the same).
In June, 2020, I finally got around to replacing the exhaust system. The original exhaust was from Flyin' Miata and has most likely been on the car for quite a while. I believe that the cat and the muffler had internal components that were in the process of breaking down so I secured a new system from FM.
The installation was pretty much straight forward. Jack the car up and put it on stands, remove all sorts of underbracing and finally remove the old components and put on the new (downpipe/cat, mid-pipe, and tail/muffler). After reinstalling all the bracing, a more efficient routing of wiring for the sensors was established. I did have a stainless-steel bung added to accommodate the sensor for the AEM Air Fuel Mix gauge.
The exhaust seems to help the car breathe a bit better and still has the most excellent growl to it. I am glad the FM exhaust sounds the way it does; even though it is a tuned exhaust, I would have gone with another company if it sounded like a can of angry bees.
Miata Roadster Short-Throw Shifter.
Although the OEM shifter was already a short-throw design, I decided to replace it with a short-throw from Miata-Roadster. I had read excellent reviews of its quality, design, included parts, and function; I must say they were very correct. The machining of the shaft was made from a solid billet of 303 stainless steel and included all parts for installation – some created at Miata Roadster and several OEM Mazda parts such as the shifter dust boot (installed below the cabin shifter boot) and heat shield.
The shifter is engineered with a lower point of fulcrum so the shifts are quicker and more responsive. It comes in several shaft lengths; I chose the standard and topped it with a leather aftermarket MazdaSpeed shift knob. I also have the original leather knob for the MX-5 MazdaSpeed and the VooDoo Billet shift knob. Although the extra weight and low profile of the VooDoo seems to certainly assist in shifting, the aftermarket MazdaSpeed knob certainly has a classier look and has a better feel while resting the hand on it while cruising; it also has red stitching to match the stitching on the steering wheel and emergency brake handle. The original leather MazdaSpeed knob with the shift pattern pressed into it is not normally used just to preserve it (this is an exceedingly rare part as the shift pattern pressing wears off quickly and the red stitching frays).
UPCOMING POSTS:
Replaced injectors, orings, and plenum gasket.
Corrected routing on the emissions vaccum
Corrected routing on the VTCS (Variable Tumble Control System)
Replaced turbo with 60K unit.
Replaced radiator from Mitsumoto to a Koyo with new cap.
OTHER STUFF
Other components that were fixed, changed, or added include:
AutoMeter Boost/Vacuum Gauge – Corrected routing of vacuum source; originally t’ed into wastegate vacuum line (only showed boost) – moved to post-throttle body location to show vacuum and boost. Also attached light wiring.
EGR Valve – Replaced with newer used OEM unit. Did not seem to make any change…original unit seemed to be working fine.
Throttle Body – replaced with used, low-mileage unit with IAC valve and throttle body internal coating still intact. This did smooth out the idle a tad.
Replaced Antenna Mast – never retracted all the way due to a bent lower mast. The antenna mast was eplaced with OEM assembly.
