Crown tube for Tudor 7935

[RyanH]

Hi there. I am restoring this ladies Tudor 7935 to gift to my fiancé. The movement is running great so now on to the case. I noticed that the crown wasn't screwing down onto the threaded case tube so I removed it and replaced it with a suitable replacement. Before I put the case tube in, I checked that it screwed in to the crown correctly. However, when I install the case tube into the case, the crown no longer screws down. I thought maybe I deformed the case tube even though I'm using a horotec tool designed for the job. In any case, I ordered a new case tube, again checked that it screwed down before installation, installed it, and the same thing happened. What could I be doing wrong? Any suggestions?

 

Note that if I take the crown tube out, the crown also no longer screws in after having been installed. So something is happening during installation

[AndyGSi]

First question is are you using the correct tube.

Second question, is it the correct tool as it doesn't look right to me.

[RyanH]

1 hour ago, AndyGSi said:

First question is are you using the correct tube.

Second question, is it the correct tool as it doesn't look right to me.

I think it's the correct tube since it matches the measurements, supposed to fit rolex, screws in, and pre-installation matches the crown. The horotec tool is advertised to work for crown tubes and pushers but if there's a better alternative I'd be interested in suggestions. Thanks so much

[AndyGSi]

12 minutes ago, RyanH said:

I think it's the correct tube since it matches the measurements, supposed to fit rolex, screws in, and pre-installation matches the crown. The horotec tool is advertised to work for crown tubes and pushers but if there's a better alternative I'd be interested in suggestions. Thanks so much

So what's the part number for the tube you're using.

There are at least 6 different sizes for crown tube tools depending on the spline size and if they're internal or external.

This is what the correct tool should look like for external splines but looking at your tool it appears
to be for internal splines and there also appears to be a lot of the splines have been worn away?

[mikepilk]

I have just changed the crown tube in a 7935. I got the 24.5300 from Cousins. It fits perfectly, but I had to ream out quite a lot from the centre for the crown to fit.

I have another 7935 case where I need to change the tube, so this time I got the 25.330 - same thread sizes, but bigger centre hole, so the crown fits without any reaming necessary.

I don't have the necessary tool, so I will use a smoothing broach or Torx bit to tighten it. With some Loctite, I should be able to get it tight enough.

 

 

 

[AndyGSi]

2 minutes ago, mikepilk said:

I don't have the necessary tool, so I will use a smoothing broach or Torx bit to tighten it. With some Loctite, I should be able to get it tight enough.

I suppose it's difficult to justify the price of the correct tool if it's going to be a one off.

[RyanH]

On 10/30/2024 at 7:53 PM, mikepilk said:

I have just changed the crown tube in a 7935. I got the 24.5300 from Cousins. It fits perfectly, but I had to ream out quite a lot from the centre for the crown to fit.

I have another 7935 case where I need to change the tube, so this time I got the 25.330 - same thread sizes, but bigger centre hole, so the crown fits without any reaming necessary.

I don't have the necessary tool, so I will use a smoothing broach or Torx bit to tighten it. With some Loctite, I should be able to get it tight enough.

 

 

 

Thanks for the info on this. Turns out that I was indeed using a tool inappropriate for the job. Bought the rolex spline tool. @mikepilksince I have you here, do you have any idea how to source a suitable crystal for the 7935? I have bought a few contenders but nothing seems to both fit the lip on the case and allow me to press the ring into place. The old crystal works structurally but is old so it has some lines embedded in it. I even ordered a pricey rolex 25-1 crystal which I thought would work but no luck.

[mikepilk]

1 hour ago, RyanH said:

do you have any idea how to source a suitable crystal for the 7935?

Yes . As you say, it has to fit over the lip on the case, and inside the bezel. I managed to find a fit Sternkreuz XS178.198

I have just finished two 7935s. The first one the glass fit perfectly. The second one, I had to file the outer edge of the acrylic a touch.