This is the 1990 model, and it looks like it’s never been serviced before.
Zenith make their own movements, which I can only applaud – too many big name watch manufacturers use third-party movements, and Zenith could have easily used an ETA chronograph movement. But they decided not to, and that may be the “Defy” bit!
The movement beats at 36,000 bph / 10 bps, and there is a reason for that. When measuring time with a stopwatch, you want to be able to account for 1/10 of a second, and the only way to do that is to let the movement beat at such a high rate. Nothing gained for accuracy of the watch, but a stopwatch that can measure 1/10s isn’t to be sniffed at.
The movement is only sparsely decorated and fairly plain. Form follows function, and I think that’s right for a chronograph. Apparently, Rolex used this movement in the Daytona, albeit in a modified version that only did 8 bps.
This is no watch for the faint-hearted, and my wrist wouldn’t take it without additional support 😉
The left sub-dial just has a normal second hand, the middle sub-dial counts the hours the stopwatch has run, and the right sub-dial counts the minutes the stopwatch has run.
The case back is as chunky as the rest of the watch.
If you want to open a watch without risk of scratching, here is a tip I got from Owen Gilchrist – use a small children’s bouncy ball! You just press it against the back and turn it. That easy. The hard part is defending the bouncy ball against abduction attempts by my 5 children….
Feast your eyes on this! It’s only the top plate assembly as a technical drawing, and what I need here is the oiling chart. When putting together the watch, I will meticulously follow what the manufacturer prescribed. This is a highly complex chronograph movement, and you got to get it right.
Not for the faint-hearted! Apparently, the Zenith calibre 400 has 280 components, of which 225 are different. If you click on the photo to enlarge it, you can see that there is quite a lot of dirt.
You can see the dirt quite well in this photo.
The timegrapher confirms this – the lines aren’t straight, and the watch is gaining. Hopefully, cleaning it will set this right.
Slowly but surely ….
Before taking the balance out, I remove the top jewel for cleaning.
Lifting the balance out.
As I remove the components, I make sure to take a photo of each component with its screws – this will make putting the movement together a lot easier.
Now I remove the movement from the case and take the hands and dial off.
No expense spared when the movement was designed.
Now I work my way slowly through the bottom plate which is decidedly less complicated than the top plate!
Here, we have a broken unlocking date spring. Look at the spring at 2 o’clock of the balance jewel – the long arm is broken in half. No problem, as parts for the calibre 400 are readily available.
With the bottom plate done, I can turn my attention back to the top plate.
The wheel bridge covers large parts of the movement, and the escapement wheel has its own little bridge at the top of the photo.
With the wheel bridge removed, you can see the gear train.
No lack of dirt and old lubricant.
The barrel has “DO NOT OPEN” stamped on it – and for good reasons. The mainspring of this watch is a powerful little blighter, and if this thing is unleashed, it may well end up wrapped around the back of your eyeballs. You buy the mainspring complete with barrel for replacement.
And the top plate done.
Without detailed photos taken when disassembling the movement, I wouldn’t stand much of a chance of putting this baby back together again. Well, with the technical drawing, it would be ok, but the photos help immensely – especially when matching the right screw to the right thread.
Time to order parts, clean everything, and to take a deep breath!
Wednesday, May 30th, 2012
A quick update – the parts are cleaned, rinsed and dried, and now waiting in a clean, airtight container with a silica gel bag for reassembly.
Monday, June 4th, 2012
Cousins delivered the wrong unlocking date spring, and I’m now stuck in their returns process. I’ll give that another week, and, if it leads nowhere, I’ll make the spring myself.
The story continues here…