Following the 67-9038 in my last ‘Featured Watch’, it seems logical now to present the other automatic chronograph line by Citizen, this time with one sub-dial. Both movement types were introduced in 1972 – the twin sub-dial being the 8110a (there was never a ‘b’ version!) and the single sub-dial 8100. As with the 8110, this type has 23 jewels and uses the central sweep hand as the second counter, whilst the sub-dial counts minutes. Otherwise its features are the same, running at 28,800 beats per hour with hand winding and ‘flyback’ (instant reset and restart of chronograph function without having to stop it first).
Good examples of the 8100 are not easy to find, rather like some of the lesser known 8110 models.
As far as I am aware the 67-9577 was made with two dial designs, in the same black case with stainless steel bezel (edit on 10th December: possibly a third dial design now found which will be shown on the Chronographs page once I’ve finished it!) . Here’s the first type, with black dial and lumed white main hands and orange chronograph hands:
This one was produced in October 1972:
And is shown in the relevant ‘museum book’:
The second design is a more colourful model, featuring a blue dial and white inner tachymeter ring, with a brightly contrasting orange hand set and orange highlights on the hour markers:
This was produced in July 1973:
For reference purposes, note the different dial codes for each model: black is 900071-Y, blue is 900062-Y.
Finally, here’s a group shot of these two 8100’s alongside the 67-9038, to illustrate the design similarities and differences: