# Manual transmission mainshaft locknut (1991)

Canonical URL: https://miatatorque.com/spec/mt-mainshaft-locknut-na-1991/

Applicability: NA 1991 (B6, 5MT)

Confidence: single-source

94–173 ft·lb / 128–235 N·m

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": "mt-mainshaft-locknut-na-1991",
  "name": "Manual transmission mainshaft locknut (1991)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NA",
      "years": [
        1991,
        1991
      ],
      "engines": [
        "B6"
      ],
      "trans": [
        "5MT"
      ]
    }
  ],
  "kind": "torque",
  "torque": {
    "nm": [
      128,
      235
    ],
    "ftlb": [
      94,
      173
    ]
  },
  "confidence": "single-source",
  "sources": [
    {
      "source": "mitchell1-1991-manual-transmission-overhaul",
      "page": "PDF p. 18",
      "as_printed": "Ft. Lbs. (N.m); heading on PDF p. 17\nMainshaft Lock Nut — Miata & RX7 94-173 (128-235)",
      "torque": {
        "nm": [
          128,
          235
        ],
        "ftlb": [
          94,
          173
        ]
      },
      "note": "Secondary M-type transmission table, explicitly applicable to Miata; limited to the 1991 printout. Other Mitchell1 documents count as the same publisher.",
      "document": {
        "id": "mitchell1-1991-manual-transmission-overhaul",
        "tier": 2,
        "title": "Mitchell1 1991 MX-5 Miata: 1991 manual transmission overhaul",
        "covers": [
          {
            "gen": "NA",
            "years": [
              1991,
              1991
            ]
          }
        ],
        "url": "https://www.mellens.net/mazda/Mazda-Miata-1991-1993/1991_manual_transmission_overhaul.pdf",
        "note": "Secondary service printout. Citations identify the Miata fastener and printed PDF page. Reproduced Mazda procedures are additional lookup locations, not independent factory evidence. Other Mitchell1 documents count as the same publisher."
      }
    }
  ],
  "jobs": [],
  "system": "transmission",
  "component": "manual-transmission",
  "componentName": "Manual transmission",
  "url": "https://miatatorque.com/spec/mt-mainshaft-locknut-na-1991/"
}
```