# Center-support front brake piston stroke (SB4A-EL 4AT)

Canonical URL: https://miatatorque.com/spec/center-support-front-brake-piston-stroke-sb4a/

Applicability: NB 2001–2005 (BP-Z3, 4AT) — 2003–2005 factory references identify this component manual; 2001–2002 inferred within NB2 non-turbo family.

Confidence: fsm

Air pressure
390 kPa max.
Piston stroke
0.78—1.32 mm

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": "center-support-front-brake-piston-stroke-sb4a",
  "name": "Center-support front brake piston stroke (SB4A-EL 4AT)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NB",
      "years": [
        2001,
        2005
      ],
      "engines": [
        "BP-Z3"
      ],
      "trans": [
        "4AT"
      ],
      "note": "2003–2005 factory references identify this component manual; 2001–2002 inferred within NB2 non-turbo family."
    }
  ],
  "kind": "non-torque",
  "value_text": "Air pressure\n390 kPa max.\nPiston stroke\n0.78—1.32 mm",
  "procedure": {
    "notes": "Use a dial indicator while applying and releasing compressed air through the indicated passage of the center-support front brake assembly. Maximum air pressure 390 kPa; never apply air for longer than 3 seconds at a time because this damages the seal. The procedure also calls this the front clutch test. No identification with the differently named technical-table brake rows is assumed."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "workshop-sb4a-el",
      "page": "05–13Y–52 (PDF p. 64)",
      "as_printed": "Air pressure\n390 kPa {4.0 kgf/cm², 57 psi} max.\nPiston stroke\n0.78—1.32 mm {0.04—0.05 in}",
      "verified_years": [
        2003,
        2005
      ],
      "document": {
        "id": "workshop-sb4a-el",
        "tier": 1,
        "title": "Mazda SB4A-EL Automatic Transmission Workshop Manual",
        "part_number": "9999-95-422H-99",
        "covers": [
          {
            "gen": "NB",
            "years": [
              2003,
              2005
            ],
            "engines": [
              "BP-Z3"
            ],
            "trans": [
              "4AT"
            ]
          }
        ],
        "note": "The 2003 (PDF p. 1234), 2004 (PDF p. 1254) and 2005 (PDF p. 1388) MX-5 manuals explicitly reference part 9999-95-422H-99; the supplied copies are identical to the previously audited component manual."
      }
    }
  ],
  "jobs": [],
  "system": "transmission",
  "component": "inventory-pass-2026-10",
  "componentName": "Service measurements and fasteners",
  "sequence_diagrams": [],
  "url": "https://miatatorque.com/spec/center-support-front-brake-piston-stroke-sb4a/"
}
```