Rolex GMT hand "slipping"

[dickbrowne]

This is a slightly frustrating issue...

I have a 1968 Rolex 1675 which is a marvellous performer, and the only issue I've ever had with it was a slipping canon pinion which gave very odd timing issues, despite the watch being perfectly in beat and adjusted.

With all that a dim and distant memory, I note another issue - take a look at this and see if you notice the problem:



Yup, that's right, with the hands set at midnight, the GMT hand should be pointing the same way, not at "4".

I first noticed the issue a few months back and took the hands off to re-align them, and all was well for a while. It's recently slipped out again and I suspect that it will stay "out" by this amount for quite some time if I leave it (although I have nothing to justify that thought).

Anybody else seen this behaviour before?

Cheers

Richard

[walkerwek1958]

Can`t give an explanation because I`m not familiar with how this GMT works, but there's got to be an answer somewhere! Does it have 2 cannon pinions? I`d need to get my head around how it works to fathom out why it isn`t working..........taking it apart might be the best option.

I`m sure you've thought of this but I`ll mention it anyway; is the GMT hand a tight enough fit? It's usually obvious when refitting hands whether they're loose or not so it seems unlikely.

We'll await the answer explanation in due course

Paul

[dickbrowne]

Thanks for the reply Paul, the hand fit was my first thought but it appears nice and tight.

I think a(nother) careful disassembly is the way forward

If it's of interest I shall certainly keep you updated on progress as and when it's made.

[andrew]

Thanks for the reply Paul, the hand fit was my first thought but it appears nice and tight.

I think a(nother) careful disassembly is the way forward

If it's of interest I shall certainly keep you updated on progress as and when it's made.

As the 24h hand operates like the conventional hour hand of a regular watch (ie is slaved to the minute hand and is not independently settable in the way that ETAs are) then cannon pinion slippage could result in erratic hand movement even when the watch is beating away normally via its second hand. But that would also result in the minute hand slipping as well, as the minute and hour hand are typically connected by toothed wheels and can't normally be decoupled. So my guess is also that there's a second cannon pinion that allows the GMT hand to slip relative to the rest of the movement - and thus the main hands. I await the outcome of this one with interest as well!

[shedlock2000]

Sorry to bump an ancient thread, but I wondered if the OP resolved this issue — I have the same problem on my 1675


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[dickbrowne]

Hi Steve,

Sorry it's taken a day to reply - I'm off work at the moment and not being tied to email, it sometimes takes a while to realise something interesting is happening :)

I shall reply here rather than the message you sent via TT - that way everybody can see the response, if that's OK?

So, the short answer is... No, I haven't yet sorted my slipping GMT hand.

The slightly longer answer is that I wanted to leave the watch running for a significant amount of time to see if there was any variability in the slipping, in other words, having slipped by 4 hours, would it get any worse? And the answer to that is no. I wear the watch regularly and it's still keeping really good time, the beat error is negligible, the oscillation is really good and the GMT hand is still out by exactly 4 hours.

Then, having realised that the slippage wasn't getting any worse, my motivation to deal with it reduced as other "problem" watches came in and demanded my attention.


Until your reply, my plan (in as much as I had one) was to simply leave it until the next time I serviced it in three or four years - seems a lazy way of dealing with a problem, but it's not really a problem which is causing me any issues. Taking a dial off of a vintage watch is always a time of risk in my mind - the hands could bend slightly, the dial could be marked, lume could be displaced if it's old and crumbly. I always use a good-quality hand-remover and a proper dial-protector, and I've never had a problem with bending or marking, but I have had lume crumble, which is always a problem. Regardless of paranoia, these three problems prevent me from removing hands and dial from a vintage watch without good cause.


I think that the replies above give a good idea of what may be happening - it's one of two things; either the hand is set upon a second cannon pinion which is able to slip slightly due to, maybe, malformed teeth on one portion of the pinion, or maybe the hole in the hand itself has a slight ovality, which allows it to slip a certain amount, but no more - it's unlikely I know, but I'm exploring all possibilities.

I shall take a closer look at the movement and properly investigate the GMT part of the movement to see how it works - if I find anything I will post it to this thread and would ask that you do the same if possible?

Sorry I can't be any more helpful, good luck with your 1675 - beautiful watches - I shall take a look at mine with a more critical eye.

Richard

[shedlock2000]

Hi Richard,

Thanks for replying with information on the thread — I agree it is beneficial to the tread in a way a PM isn’t.

My situation is a bit dissimilar, in that rapid adjustment of the time (say, to set the date) generates noticeable slip — in some stages, 6 or 7 hours can be adjusted without the gmt hand moving. That said, the gmt hand does rotate around the dial once every day or so. There’s no hand drag on the dial or other hands which may pre-load the axle; it does seem like it might be a misaligned gear train. Curiously, it also has developed a habit of stalling at about 7am. I am not certain if this is connected somehow to the gmt hand issue.

The issue is vexing for me at the moment, as I am living in Finland and need to know the time back home (in Canada) in order to chat with the family. The inconsistency in time is quite annoying. I am shipping my watch back to my watchmaker who will strip it down, service it, and send it back out. Unfortunately, that will be costly and time consuming (not that a solution from you would have made it less costly or time consuming, but I’d have had info to send to him which might have pre-warned him of a potential failure!)

I’ll report back when and if I find out the cause. This is the only thread online that details this specific issue which, according to other posts elsewhere, can’t be a problem. Given the way in which gear trains work, it’s of mechanical interest to me how this fault can exist!


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[Nigeyp]

might be the angle of the pic, but the cyclops looks too far towards the crown?

[Andyg]

I have a similar issue with my 16753.

Great time keeping. Quick set function works. Date changes after spinning the hands twice at 12.05 just as it should, however the GMT hand points to 6.00.

Not an issue because all I need to do is rotate the bezel, but it is irritating

[dickbrowne]

might be the angle of the pic, but the cyclops looks too far towards the crown?

Not sure of the relevance of the observation Nigey - the angle of the cyclops isn’t going to affect the movement of the GMT hand, unless I’m missing something?

Oh, and yes, it is just the camera angle that makes it look a little odd; in the real-world it’s a perfectly normal, love it or hate it, marmite cyclops.

[stefmcd]

Have you tried adjusting the GMT hand back 4 hours to match the main hour hand since the 'slippage'?

If so does it just steadily slip again till its 4 hours out?

You say slip, has it slipped 8 hours or gained 4?