Mazda Miata NA (1990-97) vs NB (1999-2005): differences, known problems and which parts swap
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Which is better, an NA or an NB Miata?
Short answer: It depends on what you want from the car. A 1994-97 NA gets the 1.8L, the larger 7-inch rear differential and an optional Torsen limited-slip; 1990-93 cars have the 1.6L, and 1990 to early-1991 cars should be checked for the short-nose crank. Every NB has a 1.8L; 2001-05 NB2 cars add variable valve timing and a regular 6-speed option, later cars get larger Sport brakes, and 2004-05 brought the Mazdaspeed turbo. Check 1999-2000 NB1 cars for coil packs and thrust bearings. Wheels and factory hardtops interchange between the two.
NA vs NB at a glance
| NA (1990-1997) | NB (1999-2005) | |
|---|---|---|
| US model years | 1990-1997 | 1999-2005 (debuted in 1998 as a 1999 model) |
| Engine | 1990-93: 1.6L BP-ZE. 1994-97: 1.8L, about 15 hp more (133 hp for 1996), OBD-II from 1996 | 1.8L in every car. NB1 (1999-2000); NB2 (2001-05) with variable valve timing; 2004-05 Mazdaspeed turbo, about 178 hp |
| Rear differential | 1990-93: 6-inch, viscous LSD optional. 1994-97: 7-inch, Torsen LSD optional | 7-inch (the 1994-2005 differential, driveshaft and axles interchange) |
| Transmission | Manual or 4-speed automatic | 6-speed: special-edition/option 1999-2000, regular option from 2001 |
| Front brakes | Smaller on 1990-93; 1994-97 same size as the standard NB | 255 mm standard; 270 mm Sport (2001-02 Sport package, all 2003-05) |
| Wheels | 4x100, 54.1 mm hub; factory 14x5.5 or 14x6 +45 | 4x100, 54.1 mm hub; factory 14 to 17 inch, mostly +40; 16-inch standard 2004-05 |
| Factory hardtop | Same shell 1990-2005 | Same shell; front latches changed for cars built from November 1, 2002 |
| Problems to check | Short-nose crank (1990 to early 1991), rust from clogged drains, CAS O-ring and valve-cover oil leaks | NB1 coil packs, 1999-2000 thrust bearing, 2001-02 clutch chatter, brittle radiator end tanks, front side-member rust |
Drawn from Hagerty's NA buyer's guide, Road & Track's NB buyer's guide, the SoloMiata drivetrain interchange guide, a used-parts dealer's NB-to-NA compatibility guide, wheel guides and owner forums (all listed under Sources). Per-claim confidence is on each linked page. We do not rank one generation as better overall; that depends on your priorities.
Which to choose, by priority
- You want factory turbo power: only the 2004-05 Mazdaspeed MX-5 (NB) has it.
- You want a 6-speed from the factory: look at 2001-05 NBs, where it became a regular option; an NB 6-speed can also be fitted to a manual NA with the donor's plate and shifter.
- You want the first-generation NA: a 1994-97 car has the 1.8L, the 7-inch rear and larger brakes; a 1990-93 car can take the later rear end and brakes, but as a set of parts.
- You plan to change wheels or add a hardtop: either works; both share the 4x100 pattern and the hardtop shell. On a late NB, check wheel spokes clear the Sport brakes and match the hardtop latches to the car's build date.
Detail: Miata wheel fitment guide · Miata hardtop guide · NA common problems · NB common problems
Fitment answers covered by this guide
Related known problems
- Short-nose crankshaft (1990 and early 1991) Confirmed
- Rocker and floor rust from clogged drains Reported
- 1990-93 1.6 uses a smaller 6-inch rear differential Reported
- Oil leaks from the CAS O-ring and valve cover gasket Confirmed
- NB1 ignition coil packs wear out and can damage the cat Reported
- Thrust-bearing failure in some 1999-2000 cars Confirmed
- Clutch chatter in 2001 and some 2002 cars Reported
- Plastic radiator end tanks go brittle; airflow blockage Reported
- Rust (front side members, East Coast cars) Reported
FAQ
What is the difference between an NA and an NB Miata?
The NA is the first generation (1990-97 in the US), with a 1.6L engine through 1993 and a 1.8L from 1994. The NB (sold from 1998 as a 1999 model, through 2005) has a 1.8L in every car, with variable valve timing from 2001 (NB2), a 6-speed that became a regular option for 2001, larger Sport front brakes on later cars and a turbocharged Mazdaspeed version in 2004-05. Both use a 4x100 wheel pattern and the same basic hardtop shell.
Should I buy a 1.6 or a 1.8 NA Miata?
It depends. The 1994-97 1.8 has about 15 hp more, the larger 7-inch rear differential, an optional Torsen limited-slip (viscous before 1994) and larger front brakes, the same size as a standard NB. The 1990-93 1.6 uses a 6-inch rear, and 1990 to early-1991 cars have the short-nose crankshaft, which Hagerty says affected about 1% of those cars. The 1.6 and 1.8 flywheel and clutch parts do not swap one at a time, but a complete 1994-2005 assembly fits a 1.6 car.
What is the difference between an NB1 and an NB2 Miata?
NB1 means 1999-2000 cars; NB2 means 2001-05. The NB2 engine adds variable valve timing and uses a different ignition system; sources report that NB1 coil packs wear out and can damage the catalytic converter. The 6-speed became a regular option for 2001. In the last two years 16-inch wheels were standard and the 6-speed cars got 3.90 rear gearing instead of 4.10, and the 2004-05 Mazdaspeed MX-5 added a turbo (about 178 hp).
Do NB parts fit an NA Miata?
Many do. Sources list NB wheels and the NB factory hardtop as direct fits, and the NB 6-speed, the 1994-2005 rear differential set, NB front brakes, NB sway bars and complete NB shock and spring assemblies as fits with extra parts or work. The NB radiator is listed as not compatible, and only the 1999-2000 coil pack is listed for 1996-97 NAs. Each answer, with its confidence tier, is in the table below.
What should I check when buying an NA or NB Miata?
On both: rust (clogged body and soft-top drains, and on East Coast NBs the front side-members), oil leaks, and timing-belt history. On a 1990 to early-1991 car, look for crank-pulley wobble (short-nose crank). On a 1999-2000 NB, listen for thrust-bearing rattle and check the coil packs; 2001-02 NBs can have clutch chatter, and NB radiators have plastic end tanks that go brittle.
Keep exploring
- Mazda Miata NA (1990-1997): all fitment answers · common problems
- Mazda Miata NB (1999-2005 US model years): all fitment answers · common problems
- Miata NA/NB hardtop fitment guide: NA vs NB, OEM vs aftermarket, latches and seals
- Miata NA/NB wheel fitment guide: bolt pattern, offsets, 15x8 sizes and brake clearance
- WRX GD bolt pattern: 5x100 vs 5x114.3 (2002-07 WRX and STI)
- 2002-05 WRX vs 2006-07 WRX: EJ205 vs EJ255, known problems and wheels
- Newsletter archive (past issues)
Sources
- Your handy (1990-97) Mazda Miata buyer's guide — Hagerty Media (Mar 2021) (editorial; read 2026-10-15; full page read)
- Miata Drivetrain Interchange Guide — Randy Stocker / SoloMiata (fixjunk.com) (editorial; read 2026-10-15; full page read)
- Everything You Need to Know Before Buying a Second-Gen Mazda Miata — Road & Track (Jun 2016) (editorial; read 2026-10-15; full page read)
- Common Issues with NB 1998-2005 Miatas — MX-5 Miata Forum (forum thread; read 2026-10-15; search excerpt only)
- NB to NA Miata Compatibility Guide — Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) (vendor article; read 2026-10-15; full page read)
- Used Miata Inspection List (2018 update) — Miata.net (editorial; read 2026-10-15; search excerpt only)
- Miata problems/maintenance by year — miatayear.com (editorial; read 2026-10-15; search excerpt only)
- 1990-1997 NA Mazda Miata Wheel and Tire Combo Guide — rimlist (wheel listings and guides; contains affiliate links) (vendor article; read 2026-10-21; full page read)
- 1999-2005 NB Mazda Miata Wheel Fitment Guide — rimlist (wheel listings and guides; contains affiliate links) (editorial; read 2026-10-23; full page read)
- The Miata Hard Top FAQ — Miata.net Garage (editorial; read 2026-10-20; search excerpt only)
Summaries are in our own words. Fitment is not guaranteed; wheels, hubs and suspension are safety-critical. Disclaimer.
Report a correction — spotted an error or have a better source? Email hello@chassisdex.com.