Bell & Ross Sinn Chronograph with Lemania 5100 movement Service
Introduction
This case study documents the service and repair of a Bell & Ross by Sinn Chronograph powered by the robust Lemania 5100 movement. Known for its durability and tool-watch functionality, this chronograph required both a full mechanical service and a repair to the central sweep seconds hand.
Service Procedure
In addition to the hand repair, the watch underwent a complete overhaul:
- Full disassembly of the Lemania 5100 movement
- Inspection of chronograph components, including the central minute drive system
- Ultrasonic cleaning of all parts
- Proper lubrication with modern synthetic oils
- Regulation
Post Service Tests and Notes
- Complete Service Performed
- All original, no cosmetic repair
- Replaced Crown and Crown Tube
- Date and Day advancing properly both at 12:00 midnight and quick set: PASSED
- Chronograph tested for 12 hours: PASSED
- Reset to zero Sweep Seconds hand, Minuter counter hand, Hour Counter Hand: PASSED
- Ran on winding machine for 5 days, automatic working properly
Are you looking to Repair your Vintage Chronograph?
If you own a Lemania 5100 chronograph, Bell & Ross, Sinn, Porsche Design, or other vintage tool watch in need of service or repair, I invite you to contact me to discuss your watch, or visit getting started. Each piece is carefully evaluated with a focus on mechanical integrity and long-term reliability.
If you would like to initiate the repair of your vintage timepiece contact me directly, or visit getting started.
For additional information on watches we work on please visit these pages: Vintage Rolex repair— Vintage Breitling repair —Vintage Omega repair — Vintage Heuer repair —Bulova Repair, and Pocket Watch Repair. See my FAQ for additional information, and visit Watch Repair Case Studies.
After cleaning and partial reassembly
Brief History of Bell & Ross by Sinn and the Lemania 5100
In its early years, Bell & Ross partnered with Sinn to produce professional-grade tool watches designed for aviation and military use. These watches often utilized the Lemania 5100 ( also used in the well known Porsche Design Chronograph by Orfina), a movement introduced in the late 1970s and widely respected for its reliability under harsh conditions.
The Lemania 5100 is notable for its:
- Central chronograph seconds and minute display
- Direct-drive chronograph system
- High shock resistance
- Practical, legible layout designed for real-world use
Although not highly decorative, the movement was engineered for performance and serviceability, making it a favorite among military and professional users. For additional information see the service log of the Porsche Design by Orfina.