2003 Mazda Miata Shinsen Version
During the summer of 2025 I got the bug for a sports car of some sort after watching extensive YouTube track day videos. I spent a while looking for a "hawk eye" or "blob eye" Subaru, which I've always wanted to own and drive, but could not find a fair deal on a decent example. I also always had a soft spot for Miatas and started to keep an eye out for a viable starter car for a mildly build daily driver / track car. The goal is to essentially put together a reliable stage 1 type build that we can still take out for easy drives on the weekend. We'll be balancing daily usability and on-track performance. The only item where I will lean further to on-track performance is safety; roll hoop and a good helmet will be on their way shortly.
I was able to find a fair number of Miatas in the market spaces and began contacting sellers. I looked at one British racing green Miata but that purchase did not work out. The owner did however point me to a Shinsen Version Miata, which I had already seen but written off. The photos of the car were all taken at night; it looked like a poor example and the photos were suspicious. I got excited about the car anyways and I was also ready to start the project. Seeing the car in person was worth the short drive and I struck a deal with the owner. This Miata is a relatively high mileage example, at ~247K miles and it also looks a bit neglected. I found further neglected maintenance items once I got it home. But, that is OK because I was looking for a project and I think getting the Miata back to a happy running state will be the best way to mechanically learn about the car itself.
Overview
The current big picture plan is to build the Miata up in a way that it is a reliable weekend street driven and fun sports car. I would also like to do several open track day events throughout the year. In my mind, this is a tasteful build with many stock or OEM elements and the car will generally appear as a stock example. I don't plan to do any significant engine performance upgrades and will focus on chassis, suspension and brakes. This should keep the learning curve on the track manageable since I'll be making incremental improvements to the platform along the way.
The Plan
Maintenance
1
2
Safety Items
3
Performance Upgrades
I think this poor Miata is way behind on maintenance and is currently leaking a mix of fluids which runs off the front/bottom of the engine block. Pretty much all of the fluids are going to get flushed. I'm already looking at the brakes and will service the rears shortly, along with an oil change and shifter rebuild. I have parts to service the clutch already as well but need to understand the process. Need to generally check the differential and the cooling system. I will also do a compression and leak down test to gauge the health of the engine.
Safety is both generally important and required by organizers at the track events. A roll hoop is required for soft-top NB Miatas since the windshield alone would not be enough to prevent harm to the driver in the event of a roll over. I'll be installing a purchased drop-in roll hoop and a SA2025 rated safety helmet. With adequate clearance between the roll hoop and the helmet, we should be in good shape. No plans currently to replace the seats or safety belts. This Miata came with "surf board" style seats which actually fit pretty well and I would like to see how they perform on the track with the standard seat belts.
The only performance upgrades currently on the roadmap for the Miata are a set of coil over shocks to replace the stock components and additional chassis stiffening braces.
The Progress
Maintenance
1
2
Safety Items
3
Performance Upgrades
Maintenance progress is going fairly well as parts and resources have been readily available to tackle any maintenance item. The muffler exhaust flange was welded to stop an exhaust leak, replaced the thermostat, replaced the radiator cap, rebuilt the shifter and changed the oil. I also took care of some cosmetic exterior/interior items. Lastly, the brakes have been fully serviced; new front rotors and resurfaced rear rotors, rebuilt calipers, EBC YellowStuff brake pads installed and brake fluid flushed and bled with ATE TYP200 DOT4 fluid. All wheel studs and lug nuts were replaced.
Installed a Hard Dog M2 Hard Core roll hoop with double diagonals and a bolt-in harness bar.
No progress beyond just research for coilovers but the addition of the roll hoop significantly improved the rigidity of the chassis.