Gen Crown & Tube for GMTII

[Spy]

Hi all,

Having gone through a mad phase of trying to sell my BK Transformer, I have now fallen in love with it again.

Re-reading By-Tor's reviews saved me from a mistake I know I would have lived to regret

After a few messages back and forth with By-Tor, I now want to change the crown and tube on my BK Transformer and was hoping you could help.

By-Tor believes I need the 6mm twin-lock crown and tube, the same as that for the ExpI, ExpII and GMT 16710.

So a few questions:

1) Can you tell me where I can source a gen set of these ?

2) What are the Rolex part numbers I should be looking for to ensure I get the correct parts ?

3) Is it an easy mod i.e. does the tube fit straight in to the BK Transformer or does it need drilling ?

Any help is greatly appreciated guys.

Thanks

[freddy333]

So a few questions:

1) Can you tell me where I can source a gen set of these ?

ebay or Rolex. You will need to do the serious searching, but a quick search turned up a crown & a tube (though I have had good luck with Ofrei's Swiss-made aftermarket tubes - you need to choose new or old style depending on your crown & the tube tool you have).

2) What are the Rolex part numbers I should be looking for to ensure I get the correct parts ?

I am better with the early vintage GMTs, but I believe the 1675x GMTII uses the 6mm 24-603 crown & 24-6030 tube. Double-check with By-Tor before ordering anything, since he is the expert on the modern GMT.

3) Is it an easy mod i.e. does the tube fit straight in to the BK Transformer or does it need drilling ?

Relatively speaking, yes. But it all depends on the state of your case (what crown/tube is currently fitted in it) & your experience level.

Basically, you need to remove the movement & unscrew the tube from the case. Assuming the tube is aftermarket, you will need to slide a small 3-sided file into the center of the tube, wedge it in so it 'grabs' the inside wall of the tube & unscrew (in some cases, you may need to moderately heat the case if the tube was cemented into the case). Then, depending on the condition of the threading in the case, you may be able to simply screw the new tube in or, if the existing threads either do not match the new tube's threads or if they are worn/crossthreaded, you may need to tap the hole to renew the threads using the appropriate Rolex tap

[Spy]

Freddy, thank you for your prompt and comprehensive reply.

Thanks for pointing me in the right direction regarding the parts.

Looking at Freddy's response to question 3 where he highlights that the complexity of the mod depends on the state of the watch, I would be interested to know from anyone who has done this mod to one of BK's GMT's as to whether it was easy or hard e.g. was the tube cemented, did the case need drilling or heating etc ?

Also, reading Freedy's response, I am a little unsure as to whether I should try this mod myself. Does anyone know of a good watch modder in the EU ?

Is Tribal any good and if so, where is he based ?

Thanks guys.

[jdavis]

QUOTE

2) What are the Rolex part numbers I should be looking for to ensure I get the correct parts ?

I am better with the early vintage GMTs, but I believe the 1675x GMTII uses the 6mm 24-603 crown & 24-6030 tube. Double-check with By-Tor before ordering anything, since he is the expert on the modern GMT.

Interesting....the 24-603 is the same crown used on the Datejust and President and my chart shows this to be the case. However, I believe that the new model with the ceramic bezel uses a larger crown.

[Spy]

QUOTE

2) What are the Rolex part numbers I should be looking for to ensure I get the correct parts ?

I am better with the early vintage GMTs, but I believe the 1675x GMTII uses the 6mm 24-603 crown & 24-6030 tube. Double-check with By-Tor before ordering anything, since he is the expert on the modern GMT.

Interesting....the 24-603 is the same crown used on the Datejust and President and my chart shows this to be the case. However, I believe that the new model with the ceramic bezel uses a larger crown.

Mine is the old model, see picture below:

[jdavis]

GMT II with 24-603 crown

[freddy333]

The ceramic GMTII uses a 7mm Triplock crown, but the non-c GMTII uses a 6mm Twinlock. The 603 is the current version of the Twinlock, but older GMTIIs could have used a 600 or 602 (slight differences in shape & dimension). Again, check with By-Tor, who knows much more about modern GMTs than I do.

[By-Tor]

Most 1675 models use a 5.3mm twinlock. The size changed to 6mm at some point, maybe with 16750.

I don't know more, but I know all modern 16710's use a 6mm twinlock crown. I'm bad with numbers. Justasgood provided my gen crowns and tubes.

[Spy]

I am not sure whoich one I have - new or old ?

Does anyone know which ones are used in BK's watches ? I order in May 08 and received it at the end of July 08, does this make it a new one (and therefore a 603 part no.) ?

[jdavis]

Your watch is a newer version of the GMT II (Non ceramic bezel) model 16710. The genuine Rolex crown number is 24-603-0.

You may be lucky an be able to use the rep tube. I did not have to replace the tube on the 16713 that is pictured above.

This is a gen 16710 that will allow you to compare the crown to the one on your BK GMT.

[By-Tor]

Or alternatively read my 16710 rep vs. gen comparison. Both watches (gen and rep) have correct gen crowns: 6mm twinlocks.