This Panerai Luminor Submersible ref PAM 243 came in recently for a service and I thought it would make a good subject to post about simply due to the fact that it uses the calibre OP III movement which is based on the venerable Valjoux 7750 chronograph.

The caseback is a typical Panerai 12 sided affair and looks very substantial. Note the strap bar release buttons on the crown side lugs, another Panerai feature.

With the back removed we get a glimpse of the OP III movement which is unmistakably a modified Valjoux 7750.

Remove the oscillating weight, out of harms way!

Here the movement is removed and turned over ready to remove the so called “sausage dial” and handset.

There’s a lot of perlage decoration on the plates but the differences are already apparent between this and a 7750 chronograph.

Compare the above picture with the 7750 below and you can see the 7750’s top plate is a lot more complicated to account for the day/date wheels and sub register pinions, this particular one is date only hence the missing day wheel finger.

Back to the Panerai and the top plate is off in this shot and you can see a completely different date actuation system.

The calendar work removed here with just the keyless work left to go.

Again, check the differences between the 7750 and the Panerai most notably the hour register wheel, brake and reset hammer.

However once the Panerai has had all it components removed the mainplate isn’t a whole lot different from the 7750, I presume it was more cost effective for Panerai buy them in like this.

However with the movement flipped over to strip the train the differences are vast.

As you can see when comparing the valjoux 7750 below (which looks a bit odd as I’ve rotated the image 180 degrees to get a similar orientation) with the Panerai above this side has the greatest differences. Where the chronograph cam and start/stop lever is on the 7750 there’s just a large spacer to pack out the area on the PAM.

With the spacer and autowind bottom plate removed it’s almost ready to have its train bridge removed, just the ratchet and driving wheel to remove first.

And now we’re down to this level the differences are minimal between the two, the PAM above, the 7750 below.

It’s now ready for cleaning and inspection.

The parts count is a lot higher on a 7750 though 🙂

Once cleaned and inspected the rebuild begins, a new mainspring was fitted first.

The train is refitted here….

….and the balance is on in this shot. The movement can now have the timing adjustments roughly set.

The movement is turned over here and the keyless work is starting to be refitted.

It’s ready for the dial in this shot….

….and has it all fitted here.

The movement recased….

….and the autowind components fitted here.

It’s all buttoned up and pressure tested in the final shots, I must say I do like Panerai’s Luminor Submersibles, a very substantial piece of kit! 🙂