# Front brake disc thickness after machining — minimum (NB1)

Canonical URL: https://miatatorque.com/spec/front-disc-after-machining-thickness-nb1/

Applicability: NB 1999–2000 (BP-4W) — Other years inferred from 1999 factory evidence.

Confidence: fsm

18.8 mm {0.74 in} minimum after machining

Always confirm against your factory manual. Match every restriction and follow all stages and procedure notes. Disputed claims must not be automatically resolved. The complete record below preserves every printed unit, source claim and procedure.

```json
{
  "id": "front-disc-after-machining-thickness-nb1",
  "name": "Front brake disc thickness after machining — minimum (NB1)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NB",
      "years": [
        1999,
        2000
      ],
      "engines": [
        "BP-4W"
      ],
      "note": "Other years inferred from 1999 factory evidence."
    }
  ],
  "kind": "non-torque",
  "value_text": "18.8 mm {0.74 in} minimum after machining",
  "procedure": {
    "notes": "Machine with disc installed on vehicle to avoid excessive runout. This limit is separate from discard thickness. Applies to original factory NB1 brake equipment."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1999",
      "page": "04–11–13 (PDF p. 398)",
      "as_printed": "Minimum thickness after machining by using\na brake lathe on-vehicle:\n18.8 mm {0.74 in}",
      "verified_years": [
        1999,
        1999
      ],
      "document": {
        "id": "fsm-1999",
        "tier": 1,
        "title": "1999 Mazda MX-5 Miata Workshop Manual",
        "covers": [
          {
            "gen": "NB",
            "years": [
              1999,
              2000
            ],
            "engines": [
              "BP-4W"
            ]
          }
        ],
        "url": "https://www.mellens.net/mazda/Mazda-Miata-1999-2001.pdf"
      }
    }
  ],
  "jobs": [],
  "system": "brakes",
  "component": "inventory-pass-2026-10",
  "componentName": "Service measurements and fasteners",
  "sequence_diagrams": [],
  "url": "https://miatatorque.com/spec/front-disc-after-machining-thickness-nb1/"
}
```