Screw-down caseback doesn't go in fully and pops out crystal --- JLC Memovox E875

[Knebo]

Hello all,

I have a weird problem with my Jaeger-LeCoultre E875 that I recently services (see walkthrough here:  https://www.watchrepairtalk.com/topic/29824-jaeger-lecoultre-calibre-916-memovox).

The caseback won't screw down fully and leaves a gap of about 0.3mm. If I force screwing it further down very hard, eventually, the crystal will start pushing out and pop out.

I am not sure if this was the case before my service, unfortunately. Searching for many photos online for this exact watch, I did find some pictures that had a visible gap, but also many where no gap was visible. It's very notable that MANY of the watches have water damage and I'm not sure why this is so common. Maybe the issue I'm observing is related to this.

I did replace the crystal (maybe original, but cracked) with a Sternkreuz ATC armored crystal (chrome ring) that pushed in nicely. The previous crystal, which I unfortunately didn't keep, was of the same type.

 

1. The picture isn't great, but I highlghted the gap with two orange lines and you can see my oiler going into the gap.

 

2. Here is a drawing of how I THINK the case is constructed. Please don't hesitate to question this (but ignore exact scale and the large empty area between movement and caseback...). 

 

As you can see in the drawing, the dial rests against the chrome ring of the crystal. I'm sure of that and can be seen here: 

I am therefore wondering primarily if the chrome ring of the crystal is too wide!? 

I have photos from the front of the dial with the previous and the new crystals:

with OLD crystal:

 

with NEW crystal (please note that the chrome ring is shiny like a mirror and reflects the slanted dial edges --- the dots show the place where dial and chrome ring meet:

 

From the other side, here's a picture of the movement, movement holding ring and case

 

...and with the gasket in place:

 

Tests and observations:

- WITHOUT dial and movement, the case screws in fully -- with and without gasket.

- while the movement holding ring appears to fall into place nicely around the movement and over the crown tube, it required pushing down and tends to push back up one one side (usually the opposite side of the crowns). 

 

So, I think it has to do with the dial being pushed against the chrome ring of the crystal. What do you think? If so, any ideas which other brands make "armored crystals" with thinner chrome rings? Online, I've found a few vintage crystals by Robur, Verlux and Tenax, but I have no idea if their chrome rings could be less wide. I may have to order them all to try...

Or am I missing something? Or is it ok like it is?

 

 

 

 

 

 

[praezis]

There are a lot of special armored Sternkreuz glasses besides ATC, also with „revised“ rings. Search their catalog if yours is listed.

Frank

Maybe those cases without gap simply lack the gasket?

Edited Tuesday at 11:42 AM by praezis

[Knebo]

11 hours ago, praezis said:

There are a lot of special armored Sternkreuz glasses besides ATC, also with „revised“ rings. Search their catalog if yours is listed.

Frank

Maybe those cases without gap simply lack the gasket?

Hi Frank / @praezis,

Thanks! Unfortunately, the ATCR (recessed / revised ring) is only available up to 33.4mm.. and I need 33.6!! So close, yet so far. 

And there's only on "special" glass with 33.6 diameter and it's all wrong for this watch. 

 

I was also wondering if the gasket is behind this. But it's not. I found watches online with gasket and no gap. 

[Knebo]

Ok, I can now confirm for sure that the issue was the crystal. More precisely the width of the tension ring. 

The dial is 31.7mm wide and the internal diameter of the crystal/tension ring is 31.2mm. So dial, movement and movement ring didn't go in fully and the caseback couldn't close fully.

I confirmed this by turning around the tension ring (which is triangular in profile). Normally, the flat side of the tension ring faces down and the pointy side upwards. By turning it around, I now have a slightly ugly flat side pointing up and the pointy side downwards so that there's a wider internal diameter for the dial to go in. While I don't intend leaving it like this, I can confirm that the case closes fully. 

I'll be hunting for other crystals with slightly larger internal diameter. Or, worst case, file away a bit of the tension ring...

 

[VWatchie]

2 hours ago, Knebo said:

Ok, I can now confirm for sure that the issue was the crystal. More precisely the width of the tension ring.

Good work! 

I've had a couple of very tricky situations that took a lot of time and effort to sort out. The nice thing is that once you've figured it out it feels like you've already solved the problem, even though the job remains to be done! 

If of interest here are a couple of links to those tricky cases.

https://www.watchrepairtalk.com/topic/25822-need-help-fault-finding-why-the-train-of-wheels-is-binding/#comment-215574

https://www.watchrepairtalk.com/topic/11959-what’s-wrong-with-this-eta-2824-2-movement/#comment-114127