Movement Reassembly: Zenith El Primero Defy calibre 400

The broken spring that I’ve ordered for Dave’s Zenith still hasn’t been replaced with the correct one, so I though I might as well start to reassemble the movement without completing the bottom plate.

As usual, I start off by putting the balance jewels back in and oiling them. I’ve got an extensive oiling chart to follow here …

There is no shortage of lubricants needed to put this movement together! A small mortgage secured on your house will make sure you can buy them – this stuff is super-expensive. Up to £10,000 per litre. Good thing you only buy some of them in 2ml installments.

Now I mount the transmission wheel to the wheel bridge – here, Moebius D5 and KT-22 are used.

The escapement wheel has its own little bridge.

The centre wheel and the barrel with barrel wheel are put in. You can see the two drops of Jismaa 124 on the barrel wheel, which is blue.

The wheel bridge is mounted.

I wind the mainspring by barely half a turn, put the pallet fork and balance assembly in, and the movement starts beating.

For a movement like this, it’s great to have an oiling chart. I follow it and tick the oiling points on the chart as I go along. That way, I won’t forget any and will apply the right lubricant to the right place.

With the mainspring only wound 1/2 a turn, this looks excellent. Gone are the wobbles, and we have super straight lines. This shows me everything is clean and properly lubricated.

I put the bottom plate together as far as I can without needing the unlocking date spring which was broken.

And back to the top plate.

Chronograph assembly back in place. From the previous photo to this one, several hours have passed. This is a labour of love, and I slowly put in all the components, testing and lubricating as I go along.

This looks very good, and now I have to wait for the new unlocking date spring. But most of the movement is back together and working, and I’m pretty happy about that!

The positional variations are as follows:

Position Beat Rate Amplitude Beat error
DD 0s 300 0.2
DU -3s 300 0.2
CR 0s 291 0.2
CD +7s 286 0.5
CL +1s 293 0.4
CU -4s 275 0.3

That is pretty impressive!

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