Rolex 4030
ProbableThe first self-winding Daytona caliber, and the reason the 16520 is a different watch from the 116520. Calling it 'a Zenith' understates the rework and calling it 'in-house' overstates it; the accurate description is a Zenith architecture with Rolex's balance and regulation, and that is what should be expected on inspection. An in-house 4130 inside a 16520 is a movement swap, not a variant.
Specifications
- Movement manufacturer
- Rolex
- Base caliber
- Zenith El Primero 400
- Production
- 1988–2000
- Frequency
- 28,800 vph (4 Hz)
- Winding
- automatic
- Complications
- Chronograph · Column wheel · 30-minute counter · 12-hour counter
Architecture
A Zenith El Primero rebuilt by Rolex: the balance slowed from 36,000 to 28,800 vph, the date removed, and around half the components replaced with Rolex's own, including a free-sprung Glucydur balance.
Related calibers
Built on
Zenith El Primero 400Succeeded by
Rolex 4130
References using this caliber
- Rolex 16520Factory
Daytona · Whole production
Provenance of this record
Sources & Evidence
Rolex collector research on caliber transitions, dial generations and case marks
Rolex Forums, VRF and allied collector communities
- Accessed
- 2026-08-18
Cited for
HODINKEE — Reference Points series
HODINKEE
- Accessed
- 2026-08-18
Cited for
Last verified: Not yet reviewed