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How to disassemble a Chronomatic movement

Hi all,

some time ago I started to service some of my watches (the cheapest one like this Monza, surely not the Monacos ;-) ) and I documented, for myself, all the dismounting procedure...until now I don't think a similar post has ever been posted so I hope to please you all showing how an Heuer Cal15 (but is the same for a Cal11 or Cal12, chrono module apart) is made, part after part...
I only recommend, if you want to service one, to do it at your own risk, is easier to damage it rather than make a good job if you don't have a bit of experience and don't know some tricks (I started with a movement bought on Ebay and had the help of an exceptional person..thanks again mate).. but is neither so impossible...

This images are taken from the service manual and contain an exploded of the main parts (the chrono module and the basic movement):

First of all you have to uncase the movement from the case, assuming you have already opened the caseback start unscrewing the 5443 (sorry the image is wrong, is not 5446) setting lever screw (1.5 turns, not more !!) and pull outward the stem 401 with the crown, then unscrew the two 5166 casing clamp screws and remove (or simply push inward) the two 166 casing clamps:

Then take the watchmaker's cushion and put it upside-down on the movement, turn the watch together with the cushion and the movement should remain on the cushion while you lift the case.
Next step is removing the hands (you need specific tools to do it and can risk to bent or damage them, I always have a bit of fear every time I have to do it, anyway is a mandatory step and not the argument of this post) and the dial: to do this unscrew the two 5750 dial screws (are located on the movement's sides at 1.30 and 8.30):

Then take apart the 498 washer (very thin, take care) and the 145 dial rest:

Now put the movement on the clamp and remove the chrono module unscrewing the three blue 58510 screws (the following image is of a Cal12 movement, not 15, but screws are located in same place):

Take care because probably the 8086 oscillating pinion will remain attached to the chrono module, so remove it gently (avoid damaging with the plier its small teeth):

Take apart and store the chrono module as isn't necessary to dismount it, simply wash it with the ultrasonic bath, just some parts like the chrono bridges will be removed after washing for oiling some parts.
Now let's start to dismount the main module: remove the 1142 upper bridge for automatic device unscrewing the 51142 screws:

Then remove the 1143/1 oscillating weight (the famous "microrotor") unscrewing its two 51131 screws (the second one is under the rotor):

The microrotor with its bridge 1131 will appear like this (under the golden bridge there is the gear that allows the recharge):

Now remove the four wheels starting from the 1521 coupling wheel, then the 1482 driving gear for ratchet wheel, then the 1480 winding up wheel and 1481 reduction gear (the last two are identical, no problem to store them together):

Now it's the time for removing the 1141 lower bridge for automatic device, the 1500 wig-wag pinion and the delicate 1428 stop click (the one which allow that the mainspring doesn't unwind when recharged by the microrotor), obviously unscrewing the 51141 screws:

Then remove the 417 intermediate ratchet wheel and its screw 5417:

Now remove the 415 ratchet wheel (after having unwinded the mainspring opening gently the 425 click) and its screw 5415:

Now remove the 425 click and its screw 5425:

Remove the 105 barrel bridge BUT leave in place the two springs 430 (click spring) and 523 (setting wheel spring), otherwise they will squeeze into the hyperspace (and you will have a serious problem :-) ):

Remove the 180/1 mainspring's barrel pulling it up at the opposite side respect the 200/1 large driving wheel:

Remove the 424 intermediate crown wheel and its screw 5424, then the 420 (core) + 423 wheel taking care that its 5420 screw is a LEFT-HANDED screw (you must "normally screw" to unscrew it):

remove the 8060 driving wheel using the apposite Bergeon tool:

now the 110 train wheel bridge and its screw 5110 (if, after uncasing the movement, you put again the stem w crown you must re-open its screw 5443 by 1.5 turns and pulling out the stem):

now the 407 clutch wheel and 410 winding pinion:

now the 200/1 large driving wheel with cannon pinion:

the 225 fourth wheel (in the Cal15 supports the small seconds hand at 10 'clock):

the 210 third wheel:

and finally the 705 escape wheel:

and you will have the main plate free from any wheel (balance wheel apart):

Turn the movement on the dial side and start disassembling it. First unscrew the 52535 ones and pull-up gently the 2535 date indicator guard (take care not to damage the date disc):

now remove the 2557/1 date indicator, the 469 hour wheel guard and the 2576 date jumper (notice that its 2575 spring will remain attached to the 2535 date indicator guard):

now pull-up the 2558 double-toothing hour wheel (supports the hour hand) and the 243 cannon pinion (supports the minute hand):

now the 2556/1 date indicator driving wheel:

remove the 462 minute work cock and its screws 5462:

then the 260 minute wheel:

the 453 additional setting wheel and the 450 double setting wheel:

turn the movement again and let's go with the 721 balance wheel and its 121/3 bridge (correct name is balance cock for stud holder and shock-protecting device), then open the Incabloc (for Cal11/12/14) or Kif (for cal15) golden spring (lyra shaped) and remove the 324 Incabloc upper jewel or 370 Kif upper jewel (first time I did I lost it sqeezing out from the pliers, then understood that a small ball of Rodico with a toothpicker can help a lot :-) ):

close the Incabloc (or Kif) spring to avoid losing it and handle the balance wheel with care, its hairspring is the more delicate part of the watch:

make the same thing on the dial side removing the 325 Incabloc lower jewel from its case (or 371 for cal15):

then the 125 pallet cock (unscrew the two 5125 ones) and the 710 pallet fork:

if you need to service the mainspring (highly recommended) you must open the barrel pushing it on a hard surface, take care that the mainspring will squeeze out so do it gently:

then remove the 195 barrel arbor:

and you will have the mainspring ready to wash and putting back again using the specific Bergeon tool (mainspring winder):

this is my Monza completely disassembled, ready to wash and to be oiled and reassembled (but this is another long story):

Before leaving you all I want to thank the person (pro watchmaker) who helped me a lot every time I found a problem or had an undocumented step to do: you know who you are, and without your help I would never did it by myself, so thank you from the deep of my heart ;-)

Hope you will have enjoyed if you arrived until here.



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