Quote:
Originally Posted by belk7
The Crown Method
Another method for discerning a 3185 with the 3186 movement is through the the Crown Rotation Method. This method is another way to discern the type of movement without having to remove the caseback. Because the calendar and hour-hand setting mechanism was redesigned in the 3186 movement, the number of turns of the crown to turn the 12 hour hand is different on a 3186 than it is on a 3185.
To perform this test, unscrew the crown such that the crown is in the hand setting position. With the crown face-up, count how many hours the hour-hand travels with one full revolution of the winding crown.
■3185: one complete crown revolution makes the hour hand jumps 6 timezones/hours
■3186: one complete crown revolution equals 8-9 timezones/hours
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just to repeat from another thread, a salesperson at the rolex store here in paris (not an AD; direct Rolex store) said that the crown test was bogus and that there should be no difference between the two in this respect. this is the same person who said that one should never trust forums, so, you know, take his comment with a grain of salt....LOL.....
i tried the test and my M series watch made 8 revolutions. i don't have an older 3185 to compare it against, so i decided to have the horlogist open it up to confirm and certify which movement it is. if it comes back a 3186, then either the crown test is valid or it's just a pleasant coincidence. if it's a 3185, i'll be sure to post a follow up.