What happened? Explorer power reserve now only ~33 hours

[DaveInLA]

My < 1 yr old Explorer Z series now only has a PR of 33-34 hours for some reason. I remember checking the PR a few months ago when I set the watch down after a full wind a few months ago and got something like 44 hours.

A couple days ago, the watch stopped after I set it down for only about 25 hours. I had worn the watch on consecutive days before that, and I DID wind it >40 times prior to wearing it that first day. I thought it was odd, but figured that maybe I didn't move my arms enough during the days I wore the watch. To confirm my suspicions, I gave the watch 40-50 winds (enough so that the slip clutch would kick in) and set it down; it stopped in 33-34 hours. What could've happened? I haven't dropped it or anything like that. It hasn't been exposed to water or any magnets. What would cause a relatively new, well-cared-for movement to do this over the course of only a few months?

[cody p]

http://www.rolexforums.com/showthread.php?t=71819

read what watchmaker has to say about 'mainspring creep'.

[DaveInLA]

Originally Posted by cody p

http://www.rolexforums.com/showthread.php?t=71819

read what watchmaker has to say about 'mainspring creep'.

Thanks, I read that before I posted here. Here's the post regarding creep.

Assuming like you said, that your watch is fully wound, the most common cause of lack of power reserve is 'Mainspring Creep'.

Creep is where the mainspring when wound abouve halfway, cannot grip the barrel wall properly, and it slowly (sometimes very quickly) unwinds itself. This is possible because, as has been pointed out in other threads, that a mainspring in an automatic watch is not fixed to the barrel.

Common causes of this are; The wrong strength spring has been installed. or. The barrel wall has been incorrectly lubricated.

When it does run, do you find it gains time? This is another side effect caused by creep.

My watch is relatively new, and like I wrote before, it had a full PR (~44 hrs) only a few months ago. The case has never been opened since leaving the factory. I don't see how the wrong spring has been installed or barrel poorly lubricated.

Also, the timekeeping is fine, +3-5 seconds, same as when new.

I really want to avoid sending this off for warranty work, especially since the BH RSC has closed.

[SLS]

If its under warranty, I would call the BH RSC and see what they say. It will take just as long at Dallas as BH. For me, peace of mind that everything was OK would be nice.
~Scott