BP SD4k 116600 Rep - move to gen tube/crown & other questions

[yuggoboy]

Hi guys

I have a very nice BP SD4k rep where I replaced both dial and movement (A2836 with 3135-look) to VSF3135 and 3135 rep dial by BP

However I have some questions for you.

Background:
The crown tube has strange size while the case-side thread is appr. 2,43 mm wide on the tube that came with the rep, the crown-side is appr. 4,90mm wide. I replaced a tube and crown on my older 16600 rep and was hoping to be able to use that but the sizes are, of course different, because why should it be so easy.

This are images of the original tube (TB1):


These are images of the new tube (TB2) which I ordered for 16600 as replacement:



As you can see the TB2 is slightly larger than TB1 on case side and smaller diff on crown size.

So I have these options:
- Go for aftermarket tube+crown but I need to adapt the hole and enlarge it (need to drill + tap of course)
- Go for gen tube+crown but have NO idea of size there and what tap to use there

So...what are you suggesting? Is there a good quality aftermarket crown+tube which are very close to gen? Or why is gen much better?

Also how to enlarge the current case, I have no idea...any suggestion where to find the tap and/or drill (what sizes etc?)
What are sizes (width, length, height) for the gen crown & tube, what is the lenght of the gen stem?

And how does the actual gen & crown look like. In order no to be fooled by some ebay seller


Thank you in advance!

 

[alligoat]

You need to tap the hole in the case- 3.0mm x .35 tap. If it were a smaller existing hole you can drill with a 2.65mm bit, but I think your hole is already close enough to just tap. Aftermarket case tubes from Clark's and WSO990 have worked for me in the past- I actually prefer WSO990 tubes.
You can pick up used Rolex 703/704 crowns on ebay for $80-100. Or you can try Aliexpress and get a rep 116610 silver crown which is a 703/704 copy for less
https://www.aliexpress.us/item/3256...coBROBs&gatewayAdapt=glo2usa&_randl_shipto=US
You can use some threadlocker when you install the tube- blue is what I've used. You also might have to chamfer the top of the case hole so that the tube sit correctly in the hole- just use a slightly larger drill bit- maybe 11/64 or 3/16- you'll have to figure it out on your own. Hope this helps.

 

[yuggoboy]

Thank you for your answer and advice I have just ordered necessary taps M3x0,35. Its very helpful!

Regarding the taps, I have heard from experts that you need 2 taps, one for "starting" the hole and second one for "finishing" the hole and threads so that threads are of best quality

Would anyone or you by any means know what would be the "default" length for the 3135 stem on Rolex 116600 ? Is the stem length same on Sub as is for Sea-Dweller? Im wondering

 

[alligoat]

If you have a tap for starting the hole, you should be able to run that one all the way thru.
I'd just buy a few extra stems and go from there. When you change the tube and crown, who knows what will happen.

 

[yuggoboy]

You need to tap the hole in the case- 3.0mm x .35 tap. If it were a smaller existing hole you can drill with a 2.65mm bit, but I think your hole is already close enough to just tap. Aftermarket case tubes from Clark's and WSO990 have worked for me in the past- I actually prefer WSO990 tubes.
You can pick up used Rolex 703/704 crowns on ebay for $80-100. Or you can try Aliexpress and get a rep 116610 silver crown which is a 703/704 copy for less
https://www.aliexpress.us/item/3256...coBROBs&gatewayAdapt=glo2usa&_randl_shipto=US
You can use some threadlocker when you install the tube- blue is what I've used. You also might have to chamfer the top of the case hole so that the tube sit correctly in the hole- just use a slightly larger drill bit- maybe 11/64 or 3/16- you'll have to figure it out on your own. Hope this helps.

I just got info that tap for the gen tube n crown is 3x0.30 and not .35 ... its also very rare to find 3x0.30 tap as well.