TAG Heuer
TAG Heuer, founded in 1860 by Edouard Heuer in St-Imier, Switzerland, began as a small workshop producing silver pocket watches before relocating to Biel and turning its attention to precision timing. In 1887 Heuer patented the oscillating pinion, a chronograph coupling mechanism so effective that it remains in use in mechanical chronographs today. The company built its reputation on measuring ever smaller fractions of a second, introducing the Mikrograph in 1916 as the first stopwatch accurate to 1/100th of a second, and serving as official timekeeper at the Olympic Games of 1920, 1924, and 1928. Its most celebrated creation, the Carrera, was designed in 1963 by Jack Heuer as a legible driver’s chronograph inspired by the Carrera Panamericana road race. In 1985 the firm was acquired by Techniques d’Avant Garde and became TAG Heuer, carrying a legacy of motorsport timing and chronograph innovation into the modern era.
Grand Carrera Calibre 8 RS Grand Date GMT (c. 2010)
The TAG Heuer Calibre 8 GMT, used in the Grand Carrera collection from 2008, is an automatic movement built on the well-proven ETA 2892-A2 base and fitted with a Soprod TT651 module that adds a grande date and an independently adjustable GMT hand. Rather than a conventional 24-hour hand, the module drives a rotating disc read against a fixed index, a solution in keeping with Grand Carrera’s rotating-system dial language. The 2892-A2 foundation is prized for its slim profile, robustness, and smooth automatic winding, while the Soprod module contributes a large double-aperture date and a local-hour function that jumps in one-hour steps without disturbing the running of the minutes and seconds. Together they make the Calibre 8 a practical traveller’s movement with a distinctly engineered character.
Technical Information
Ligne/Size
11½'’’
Jewels
21
Frequency
28,800
Movement Type
Automatic
Power Reserve
42 hours
Restoration Notes
This was the most complicated movement I had restored to date. In fact, it was the watch that first inspired me to learn watch repair, but I knew I needed to work my way up through simpler complications before attempting it. After restoring about 20 watches over three years of practice, I finally took on the challenge. What made it especially difficult was that the Soprod GMT complication had no reference material or online media, so I had to figure it out on my own.
Cleaning and Polishing
Troubleshooting
Replacing the Mainspring
The mainspring was broken and needed replacement. I sourced a ETA 2892 mainspring that fit perfectly.
Lubrication
Moebius D5 on barrel, 2nd and 3rd wheel pivots; Moebius 9010 on 4th and 5th wheel pivots; Moebius 9010 on balance jewel; Fix-o-Drop Epilame on escape wheel and pallet jewels; Moebius 9415 on pallet exit stone; Moebius 9501 for cannon pinion and keyless works. Lubetta V105 for reverser wheels. Please find my lubrication chart for the Soprod module here → link.
It is also worth noting, from the pictures above, what appear to be beads of lubrication on the rim of the backside of the dial’s GMT display. I presume this because the beads of liquid are placed so precisely. If this is correct, the rim was likely treated with epilame to keep the lubricant from spreading elsewhere. The only function I can imagine for this lubrication is to support contact between the lip of the disc and the inside of the GMT rim.
Reassembly
Below are pictures of the base movement 2892-A2 movement...
Check out my notes on how to calibrate and assemble the calendar so it works correctly → link. Below is a short video of the reassembly of the Soprod TT651 module...
Regulation
Timegrapher readings at full wind, across five positions - DU, DD, CU, CD, and CL:
Delta Rate: 6 sec/day
Mean Rate: -0.4 sec/day
Amplitude Range: 266° to 306°
Mean Amplitude: 287°
Beat Error Range: 0.2 to 0.7 ms
After one full wind, the watch worked for a total of 47 hours.
