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Building a franken 3714 Portuguese Chrono

DRBAFC

Renowned Member
23/3/12
937
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I recently modded my own 3714 case to fit gen parts thanks to some great tips from great members here. It's been a long journey trying to find someone to take this on. But if you have the necessary parts and tools in hand, you can actually do it yourself in a few hours. Again, this is not the only way to do this but the easiest.


In my experience, the best case to use is the older one (V1) with the extra set of holes in the midcase for the bezel screws.


In my opinion the new cases (V3) seem off. I think the bezel is much thicker. Plus these are the bezels that are pressed in. If you wanted a gen tachy, you'd need to have heavy machinery to mod both the bezel and midcase


Mid-case


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The movement will fit in the case, no problem! However, the gen movement is thinner than the rep. The resulting issue is that the tube hole for the case and the stem hole for the gen movement don't line up.


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Also, the holes for the movement tab don't sit flush with the case


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Solution...to be updated.


Result:
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Bezel


You can see the differences between the gen and rep bezel and their respective tachy rings. The major plus is that the gen bezel can fit right on the rep mid-case without any work!
This is because the 4 holes in the rep bezel have the same alignment as the 4 holes in the gen tachy. Therefore, you can tighten the gen tachy right to the mid-case.


Top view
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Bottom view
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The caveat is the rep bezel screws are too big to fit into the gen tachy
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Bezel+Tachy+Crystal assembly
This is the worst part of the whole building process. I always have trouble pressing the crystal into the bezel and actually shattered a crystal doing so.
You'll need two crystal gaskets (sorry but I don't know the size exactly. Once I find my calipers, I'll update this). One gasket goes around the gen tachy. The other goes around the crystal. Tachy can be pressed into the bezel from the bottom. It has a bottom lip that will prevent it from going too far. Crystal can be pressed from the top of the bezel.
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Dial+Hands+Movement assembly
To be updated
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Crown+Stem
The gen and rep crown/stem are interchangeable with the gen movement. Since the cal 79350 is a 7750-based movement, you can use an ETA 7750 stem (tap 10, 0.9 mm)




Final Assembly
This is a front loaded watch so the dial+movement has to be set from placed from the top. The dial has a larger diameter so the outer portion will sit on upper lip of the case. The bezel assembly will then sit on top of that and sandwich the dial.
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This is an incomplete write up (which I intend to complete in the future) because:
1. I don't have necessary tools like a vernier caliper to give you exact measurements
2. There's a lot more involved and I don't currently have the time and all the photos to go through the details.
 

chromed.

I'm Pretty Popular
26/5/10
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wow! just wow! i still hope to own a franken of this someday.

great work!!
 

concepta

You're Saying I Can Sell?
DO NOT TRADE WITH ME
23/12/13
58
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WOW really good work buddy!
And you found a -31 dial!
 

higginsd

I'm Pretty Popular
31/10/12
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275
83
Thank you for starting this thread! It's good to know exactly what is the problem with putting the gen movement into the rep case.
 

concepta

You're Saying I Can Sell?
DO NOT TRADE WITH ME
23/12/13
58
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I guess the biggest problem is finding the V1 case :(
 

rhc22

Active Member
26/11/11
485
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0
Not that I am aware of apart from the earliest 3714 reps had '4' ticks between each marker on the index ring and the correct number of ticks are 3. Therefore if the index ring has 4 ticks then it is very likely to be a V1 case but not guaranteed. Only real way is to take the case back off. Even with a V1 case it still has to modified to take the gen movement. The V1 case has the bezel fixed by screws the same as a gen so it allows you to fit a gen bezel and index ring without having to drill the case.

Is there any way to visually identify a V1 from the outside without taking the back off and checking for the 4 screws?
 

kennycoder

Renowned Member
Supporter
Certified
10/9/12
651
52
28
Will the gen dial fit on the rep movement? I mean the dial feet are in the same positions or need to be re-glued?