d-rock Posted January 23, 2011 Report Share Posted January 23, 2011 I'm looking to go with a gen crown on the GMT II and Explorer II. Seems I recall reading that while the correct gen crown is the 24-603 6mm, some say it's actually too small and have used something else though I don't recall what that "something else" was. Anyone know which it is for the 16570 and the 16760 Exp II and GMT II. Thanks guys. Link to comment Share on other sites More sharing options...
nakortheblue Posted January 23, 2011 Report Share Posted January 23, 2011 24-603-0 is correct for both. Link to comment Share on other sites More sharing options...
d-rock Posted January 23, 2011 Author Report Share Posted January 23, 2011 24-603-0 is correct for both. Thanks for the info, my friend. Link to comment Share on other sites More sharing options...
alligoat Posted January 24, 2011 Report Share Posted January 24, 2011 6mm crowns are a little tricky. If you're trying to put a gen 6mm crown on a rep, you're going to have to determine what the case tube is first. If it is the 5.3mm case tube, a 603 crown will work. If your rep has a 6mm case tube, you'll need a 24-602 crown which is an older crown. The difference is the size of the hole in the case- a 5.3mm case tube goes in a 2.5mm x .25 hole and the 6mm tube goes in a 3.0mm x .35 hole. The 6mm hole is the same size as the hole for a 24-7030 tube. Most of the sellers on the bay have no clue about the difference between a 602 and a 603! I've got a spare 603 crown even though I specifically asked if it was a 602 crown. Link to comment Share on other sites More sharing options...
d-rock Posted January 24, 2011 Author Report Share Posted January 24, 2011 Isn't that the truth. Is there any way to determine which size tube was used simply by the version of the rep or does the back and the crown have to be removed to physically get the dimensions?? Link to comment Share on other sites More sharing options...
alligoat Posted January 25, 2011 Report Share Posted January 25, 2011 Since the OD of the crowns is around 6mm, you have to measure the tube. That means removing the crown and stem and checking the tube with your calipers. You could buy a 6.0mm tube and a 5.3mm tube from Ofrei to help you compare. Or you buy a 6.0mm crown and a 5.3mm crown and use whichever works. A set of taps would also be a good investment as well as the case tube wrench for installing them. If it's a one shot deal, you need to find a watchmaker to help you so it only costs you say $50 or so all told, maybe $60- $40 for the crown and $20 to install it- certainly no more than $80- 50/30. Link to comment Share on other sites More sharing options...
Cats Posted January 25, 2011 Report Share Posted January 25, 2011 This is what i used on my GMT II Cats Link to comment Share on other sites More sharing options...
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