Hey gang. I finally had a chance to dig into a CHS GMT Master II with a "broken" jumping hour hand. Thought I'd share what I found since I've hand several members reach out with issues.
So props to the rep factories for trying to engineer a solution to get the hand stack correct. Unfortunately, it fails in execution. In short, the parts are so thin and frail that I imagine this will continue happening until it's fixed.
The Jumping Hour is made up of 2 gears which sandwich a spring. Here is a gen 3185/86 version from my watch:
A strong, thick spring holds those massive fingers against the grooves. Now compared to the Asian solution:
And with the top on:
The spring has to be strong enough to move the top and bottom gears together when the watch is running but have enough give to let them jump independently when adjusting the hour hand. Unfortunately that spring is not up to the task.
As these are custom pieces there are no replacement parts. The only things that can be done are to A.) just live with whatever state the watch is in when broken or B.) glue the top and bottom gears together and reset the hands. This will insure that they don't become out of sync but you will not be able to adjust the hour/GMT hand independently.
Sorry for the bad news guys. Maybe the factory will engineer a better solution but I'd either never adjust the jumping hours or steer clear!
-TickleShoes
So props to the rep factories for trying to engineer a solution to get the hand stack correct. Unfortunately, it fails in execution. In short, the parts are so thin and frail that I imagine this will continue happening until it's fixed.
The Jumping Hour is made up of 2 gears which sandwich a spring. Here is a gen 3185/86 version from my watch:
A strong, thick spring holds those massive fingers against the grooves. Now compared to the Asian solution:
And with the top on:
The spring has to be strong enough to move the top and bottom gears together when the watch is running but have enough give to let them jump independently when adjusting the hour hand. Unfortunately that spring is not up to the task.
As these are custom pieces there are no replacement parts. The only things that can be done are to A.) just live with whatever state the watch is in when broken or B.) glue the top and bottom gears together and reset the hands. This will insure that they don't become out of sync but you will not be able to adjust the hour/GMT hand independently.
Sorry for the bad news guys. Maybe the factory will engineer a better solution but I'd either never adjust the jumping hours or steer clear!
-TickleShoes
