← Mazda Miata NA (1990-1997) problems

1990-93 1.6 uses a smaller 6-inch rear differential

Reported · Severity: Low · Years: 1990-1993

Symptoms

Not a reported failure on its own. It limits parts swaps and is described as not very strong.

Cause

The 1.6's rear end derives from an older design with a 6-inch ring gear; 1994 brought a larger 7-inch unit.

Fix (summary)

Moving to the 94+ differential requires the matching housing, driveshaft and axles.

Related parts

• 1994-2005 differential, driveshaft and axles (7-inch rear)

Sources

• Miata Drivetrain Interchange Guide — Randy Stocker / SoloMiata (fixjunk.com) (editorial; read 2026-10-15; full page read)
• 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)

Summaries are in our own words. Not repair instructions; consult the factory service manual.