Japanese mortise case and cylinder (MIWA / GOAL style)
Japan has its own dominant makers and its own case geometry, with a backset commonly around 64 mm rather than the European 55/60 mm. Replacement parts are matched by maker part number far more often than by a published standard dimension.
Also called: MIWA lock · GOAL lock · Japanese door lock
Anatomy
- Mortise case, often with a maker-specific faceplate
- Replaceable cylinder, sometimes a knob-integrated type
- Handle or knob set
- Optional electronic unit already fitted on apartment doors
Parameters to measure
Measure in this order: Backset (Dornmaß) → Centre distance, spindle-to-cylinder (Entfernung / PZ) → Faceplate width × length → Door thickness
| Parameter | Typical values | Tolerance that still fits | How to measure |
|---|---|---|---|
| Backset (Dornmaß) | 64 mm common; 51 and 64 mm appear most often | Match exactly | Door edge to the cylinder centre. |
| Centre distance, spindle-to-cylinder (Entfernung / PZ) | Varies by maker; record the actual value | — | Spindle centre to cylinder centre. |
| Door thickness | 33–42 mm on apartment doors | — | At the lock. |
| Faceplate width × length | Maker-specific; record width × length rather than assuming a size | — | Measure the strip on the door edge and photograph the maker's marking on it. |
Retrofit architectures that work
- Full lock replacement on the same footprint — The old lock case is removed and a smart lock with the same footprint takes its place. This is the dominant approach in East and Southeast Asia, where push-pull digital locks replace mortise sets on HDB, condo and apartment doors.
- Surface motor on a deadbolt turn-piece — An adhesive or screw-fixed motor sits on the door face and rotates the existing deadbolt turn-piece. Nothing is drilled. This is the standard approach for North American single-cylinder deadbolts and for many Asian rim deadbolts.
- Motor replacing the interior handle — The interior lever or knob is replaced by a motor unit that drives the 8 mm spindle directly. The outside keeps the original key cylinder and handle. This is the cleanest fit for mortise locks where the bolt is thrown by the key and the handle only retracts the latch.
Japanese apartments are the one market where smart locks arrived as a default fitting rather than a retrofit, so the aftermarket is thinner. Record maker part numbers — they are more reliable than dimensions here.
Related standards
JIS A 4702 (designation to be confirmed)
Reference devices
Recorded as engineering examples, not endorsements.
- Push-pull digital lock sets (Asian market category) — Full lock replacement on the same footprint ⚠ needs review
Questions
Can a euro-cylinder smart lock fit a Japanese door?
Rarely. The backset, the cylinder profile and the case geometry all differ; a euro clamp assumes a 17 × 33 mm profile cylinder.