Thought I'll post it up anyway.
The NEW GMT Rollie with the Correct hand stack
Since I did this post up in 2006, I have stopped servicing or repairing or working on any of the Basterdized modified ETA 2836-2 GMT models, they are far too problematic and troublesome.[/i] The only good GMT model is the genuine ETA version, the 2893-2.
This is the new version of the GMT model, it differs from the older version in a few areas
1. the hand stack is a-la Rolex, meaning the Hour hand is closest to the dial and the GMT hand is in between the hour and minute one
2. the movement is a 2836-2 (not even close to being designed as a GMT movement), which is poorly modified to try and sort-of-mimic-a-GMT movement, it fails on the functional side.
3. the Hour hand is Adjustable NOT the GMT one, this is an important point, as you will see later on.
Now, if your planning on taking one of these watches apart, be warned, on each and everyone I have worked on, the GMT hand gear comes apart (the tube pulls out of the gear) and requires re-assembly as you will see in the photos.
Here is what happens when you take the GMT hand off, the post that is part of the GMT gear is SUPPOSED to stay attached to the GEAR, not come off with the hand. Have a look and see here
This is the movement, and next to it, is the GMT gear, and the GMT hand with the post still attached to it
So I take the post out of the GMT hand, carefully cause if you loose it, your screwed big time or if you bend the hand
Here is what we have to work with, small parts that have to be perfectly re-assembled (or they will jam up the gears)
Reassembly is by using my jewel press to make sure the parts are exactly set at 90 degrees when they are put back together
GMT gear is re-installed on the movement and the rest of the parts are installed as you can see, quality and parts usage leaves something to be desired this is why I dont like these bastardized movements, no parts, poor quality of the modifications, and hard to get working after overhaul
In pieces after service
Overall view.
IMPORTANT POINT
This is not a GMT movement, it may look like a GMT, have the correct hand stack, but it doesnt work like a GMT model
Why???
As with all our reps that take a movement designed to do one thing, and add new parts to make it work like something else (Daytona Running seconds at 6 for example), there are compromises. The extra gears that make this ETA 2836-2 into a GMT model means that although it looks like a GMT and the hour hand is independently adjustable, it wont work correctly if you independently change the hour hand. Mechanically the GMT gear is actually taking the place of the hour gear, with an added step down gear (to slow the GMT hand to half the hour hand speed, i.e. one GMT turn for each 2 turns of the hour hand).
Heres what I am trying to explain, but first lets back up a bit to assembling a Date movement, before we get into this model it will be easier to follow.
When you put the dial and hands on a Date movement (which the 2836-2 is), you need to do one important thing,
that is to pull the crown to the 3rd position (the time setting one) and advance the crown (and therefore the time) until one thing happens:
the date switches over
As soon as the date switches, its Midnight, and
you dont move the crown anymore. At midnight the hands (hour and minute) should be pointing at 12. So you install the hour hand pointing at 12.
The next hand to install would be the GMT one. The GMT hand is independent and indicates - GMT time - where its installed on the dial
should not matter except for one thing. That is that the
GMT hand has to line up with a hour Marker on the dial. Which marker is really irrelevant, since the GMT hand is designed to indicate GMT time or a second time zone time. In this example, I lined up and installed the GMT hand with the 9 marker.
After the GMT hand is on, I install the minute one, again lining it up with the 12 position like the hour one, after all its MIDNIGHT on the movement. Remember that as long as I dont move the crown in the 3rd time setting position, its still midnight.
So far so good well that is until you start messing around with the hour hand
independently of the others (minute and GMT). You see on this watch, if you move the crown to the middle position (date change AND Hour hand position), you can turn the hour hand
without affecting any other part of the movement This is important to note, as I said earlier that only the
3rd position of the crown actually moved the date change time so if that is true, then moving the hour hand with the crown in the 2nd position would not affect the date change time.
On any movement with a date, the only way the date change
gear moves is by:
1. the watch running
2. you pull the crown to time setting position and advance the time.
In the time setting position,
all the gears on the top of the movement turn, cannon pin, hour wheel, GMT wheel, minute wheel, transfer gears, date change gears etc. this only takes place in the time setting positon.
So back to our modified movement. It stands to reason, that if the only time the date change gears move, is when your in the time setting position, then if you decide to move the Hour hand by itself in the second position of the crown, the date change gears are NOT going to move.
As you see this dial here, it has just turned to 12pm midnight the date switched over, I put the hands on and lined the hour and minute with the 12 the GMT is on 9 as that is a good position to install the hand and line it up with the dial markers.
If I push the crown in to the second position, and turn the HOUR hand alone, what time is it as far as the movement is concerned??? As far as the movement and date change gears are concerned, nothing has changed, Midnight it is. As the hour hand moves along
alone, the movement is not moving at all, its frozen at midnight. If you move the hour hand back by 3 hours to indicate 9PM on the dial face, the date will change over at
you guessed it 9PM. I hope this is clear and easy to understand.
If you want to use this watch as a GMT watch, then you can certainly set the Hour hand independently to wherever, as long as you dont care when the Date changes over every hour off of Midnight you move the hour hand, is an hour away from Midnight that the date is going to switch over its designed this way. I dont build them, only try and fix them
This is probably the reason ETA GMT movements have the GMT hand move independently in the second crown position that way the date change time stays at Midnight.
Not sure on the Genuine Rolex and how it works, but I suspect they have designed it to work the right way as a true GMT model, and retain the midnight date change with the Hour hand independently adjustable, or maybe not, I dont really know.
As with all these reps, they may LOOK like the real deal, hand stack and all, but for $200, and a Basterdized 2836-2 QUAZI GMT movement put together with case clamps and some new gears, its not going to work like the real watch costing $5000 or more - it cant - expecting it to do otherwise is unrealistic.
Thanks for reading,
