Fits Mazda Miata Battery Upgrade Kit - Fits Group 51R - 1989-1997 NA MX-5

Stop overpaying for a hard-to-find battery. The NA Miata (1989–1997) requires a Group 51R battery — a size that's expensive, small and scarce. This kit lets you ditch that spec entirely and fit a widely available, higher-capacity Group 51R battery instead. Pick one up at Walmart, Costco, or any auto parts store for a fraction of the cost. What's in the kit: Heat resistant spacer (accounts for width difference) Stainless steel hardware (won't rust or seize in the battery tray) Longer stainless bolt (accounts for height difference) Why this works: The Miata's battery sits in the trunk, not the engine bay. The Group 51R is slightly taller and narrower than the OEM spec. This kit fills the gap and secures the battery properly using the factory clamp and tray. No drilling, no modifications, no fabrication. Install takes about 3 minutes. Retain your top battery brace and battery tray from the original setup and use this kit to fit up the 51R battery. Compatible replacement batteries: Walmart EverStart Group 51R (~$79, 410 CCA) Duralast Group 51R (~$150, 500 CCA) Interstate Group 51R (~$135, 500 CCA) Mazda is a registered trademark of Mazda Motor Corporation. This product is not manufactured by or affiliated with Mazda.

• STOP OVERPAYING FOR A HARD-TO-FIND BATTERY — The OEM battery for the NA Miata is a rare size that costs $200–260 at Autozone, Napa, and O'Reilly when you can even find it. This kit lets you fit a Group 51R instead — a widely available battery stocked at Walmart, Costco, and every auto parts store.
• BETTER SPECS, LOWER COST — Group 51R batteries offer 410–500 CCA compared to the OEM spec's ~320 CCA, and cost as little as $79. You're not just saving money — you're upgrading to a better battery.
• 3-MINUTE INSTALL, NO MODIFICATIONS — No drilling, no cutting, no fabrication. Uses your factory battery tray and clamp. If you can change a battery, you can install this kit.
• STAINLESS STEEL HARDWARE INCLUDED — The Miata battery lives in the trunk where moisture and outgassing cause corrosion. Every bolt and fastener in this kit is stainless steel so nothing seizes up on you down the road.
• MADE FOR THE NA MIATA — Designed and tested specifically to fit 1989–1997 Mazda Miata MX-5. ASA polymer spacer handles the fitment gap precisely. Mazda is a registered trademark of Mazda Motor Corporation. This product is not manufactured by or affiliated with Mazda.