1990–2005 Mazda MX-5 Miata (NA & NB) chassis stiffening
4 kits to stiffen the body shell, from frame rails and connectors to braces and roll bars.
- How it's built
- Steel unibody
- Weak spots
- Rocker panels rust from clogged drain holes, rear wheel arches rust, and NB front frame rails are a known rust point. Bushings and dampers are usually worn, and the open-top body flexes noticeably.
Stiffening kits
| Area | Kit | What it is | Price |
|---|---|---|---|
| Frame rails | Flyin' Miata Flyin' Miata frame rails v2.0 (13-69011) | Bolt-on stainless rails over factory rails; FM reports 17.5% torsional gain. | $259 Listed price; stock status unclear Source |
| Chassis bracing | Flyin' Miata Flyin' Miata shock tower brace for 1990-05 | Front shock tower brace; listed sold out at time of check. | $259 Source |
| Floor & rocker reinforcement | Flyin' Miata Flyin' Miata complete butterfly brace v2.1 | Stainless underbody brace with frame rails and cross-braces, ties to front subframe. | $658.44 Listed price Source |
| Roll bar & cage | Hard Dog (sold by Flyin' Miata) M1 Hard Dog Hard Core roll bar | Bolt-in roll bar for NA; NB only with plastic window or no top. | $935 No-diagonal version; diagonal options $1,005-$1,155 Source |
Prices are from the linked seller pages and change often. Confirm fitment for your exact year and body style before ordering; many weld-in parts need professional installation. Some links earn us a commission.
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