Vintage Military Porsche Design Chronograph powered by the Lemania 5100 Service and Repair Case Study
Servicing the Orfina Military Porsche
This movement was in good condition and ran very well after service. Its timing report indicated no more than a 7 second deviation between all 6 positions and did not exceed 2 seconds in deviation between the common positions, excellent performance (More on positional adjustment).
The chronograph module is a bit touchy to reassemble and care is taken with the “plastic” parts during cleaning. The case was quite worn and had excessive grime build-up. The case and band were carefully cleaned without further damaging the mat black finish unique to the Porsche.
Lemania 5100 History and information
Released in the late 1970s, the Lemania 5100 chronograph movement is a robust, accurate, and highly serviceable caliber—although admittedly not a traditionally attractive one. It features a smooth-action, cam-actuated direct-drive central sweep minute counter, along with a sweep chronograph seconds hand, a 12-hour totalizer, running seconds subdial, and a day/date calendar. Designed from the outset for durability and ease of manufacture, many components are stamped rather than milled, reflecting its utilitarian, tool-watch purpose rather than decorative intent.
This design philosophy made the Lemania 5100 especially well-suited for professional instrument chronographs, including those produced for Porsche Design. In the late 1970s and 1980s, Porsche Design—working closely with Orfina and later Sinn—chose the Lemania 5100 for its iconic military and aviation chronographs.
The Lemania 5100 is also notable for its generous use of modern materials, including plastic (Delrin / Polyoxymethylene) components. This high-tech thermoplastic is durable, fatigue-resistant, and naturally self-lubricating. While I am generally cautious about plastics in watchmaking, extensive hands-on experience servicing these movements has shown the material choice to be remarkably reliable. In practice, I have not observed major functional issues attributable to the Delrin components, though I have occasionally encountered cracking in the plate that covers the chronograph works beneath the dial—a known age-related issue.
The Lemania 5100 was used by respected tool-watch manufacturers such as Tutima, Sinn, Heuer, Omega, and most famously Porsche Design, where its rugged construction complemented the brand’s no-nonsense approach to chronograph design. Today, Porsche Design chronographs powered by the Lemania 5100 are highly regarded for their historical significance, mechanical resilience, and distinctive place in late-20th-century chronograph development. See CHRONOGRAPHY 4: LEMANIA 5100 for additional information on the Lemania 5100.
Have a Vintage Porsche Design, or a Chronograph utilizing the Lemania 5100 in Need of Service?
I regularly service the Porsche Design and the Lemania 5100 (also known as the Omega Calibre 1045) in my shop. 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.
