Vintage GMT bezel inserts

[southtexas]

Can anyone share how to tell which model an insert belongs to? Does its height determine it? I'm speaking specifically about the all black, and the Pepsi inserts.

Thanks


Sent from my iPhone using Tapatalk

[ahnets]

This is a very good resource which lists model numbers/years and available insert colors:
http://www.gmtmasterhistory.com/

There are experts on this forum who know these off by heart, alas I am not one of them :-)

[jedly1]

with regards the black .... lets start with the bit most people don't get which over the last few weeks I've discovered is news to a lot of people ....the 1675 was never supplied with a black insert, if you see a 1675 black it's a later insert.

the black insert was launched with the 167XX series....and the first few are with a smooth back are for plastic glass models same size as a 1675 insert.

when the bezel became unidirectional for the switch to sapphire model the bezel profile changed and the actual bezel insert has a 0.1mm bigger internal radius and debatably a 0.1mm smaller radius, thought this doesn't seem to always be the case , manufacturing variance or plan who knows, official sources conflict on this and most of the ones I've measured are the same.

the blue back pepsi was introduced for the 16750...the first being similarly with a smooth back, changing profile when the sapphire and unidirectional bezel came along.

many people have black inserts fitted on their 1675's for an alternate look , using either one of the smooth backs or ones of the more readily available profiled backs. Rolex themselves often supply profiled back inserts as replacements and carry out the adjustments below.

again worryingly , this seems to be news to people but when rolex fit a bezel, new or used it is adjusted to be a good fit, new out of the packet ones can bear very little resemblance to the dimension they should be ...manufacturing and wear tolerances mean that they aren't always a good fit , a bezel can be at the far end of a size, an insert at the low end and you get a loose fit ....or vice versa and you can spend hours trying to get one in to no avail ... any good watchmaker should adjust as required using tool 1006 (or its generic equivalent)

http://www.ebay.com/itm/ULTRA-RARE-O...-/291162179664.


so in answer to your question .....

pepsi ....

blue back smooth back ...belongs to 167XX plastic glass ...can be used, and was used ,as service bezel for 1675 - wont fit a sapphire.

blue back profiled. belongs to sapphire models can be used (often with adjustment) on plastic.

black smooth back....used on plastic 167XX glass can be used on 1675 , wont fit sapphire.

black profile back ....belongs to sapphire models , can be used ( often with adjustment ) on plastic.

[Vincent65]

...and the smooth (non-stepped), red-back ones were on the earlier 1675 - here's one of mine for ref. :

[springer]

The early 16750 GMT inserts were red backs. In my opinion, it changed to blue back inserts during the early 1980s. The sapphire crystal GMT Pepsi inserts have blue backs. The black and red/black inserts have a black back. The backs on the sapphire crystal inserts look different than the acrylic inserts and additionally, the dimensions of the inserts are not the same. All the service inserts are blue backs, whether for a 1675, 16750, 16760, 16700 or 16710. I have included photos below depicting the difference between the backs on both acrylic and sapphire inserts.

To quickly identify the inserts from the back, on the acrylic inserts, there is one thin outer ring and on the sapphire insert, there is a wider outer ring with a stepped, downward ring. Below are some photos for comparison. I have also included a few photos with what I consider the red back inserts from the mid 1960s to early 1970s, the mid to late 1970s insert and a blue back acrylic service insert.

The accepted dimensions for new inserts are listed below. If you measure a used insert, the dimensions might not exactly match the dimensions below.

sapphire insert: outside: 37.65mm inside: 30.7mm
acrylic insert: outside: 37.75mm inside: 30.2mm

[southtexas]

VERY COOL INFO. Thanks for all of the input and the pics guys. Makes things much easier to understand!

As to the "stepping" or lack thereof, to indicate a sapphire vs. acrylic crystal match--does the same hold true for the sub models?

[Vincent65]

^^ no - I've got the original stepped-back fat-font insert for my 1970 1680 Sub.

[Vincent65]

Sorry that pic wasn't very good - here's a better one of another, period-correct f-f insert for the 1680, and you can clearly see the step/ridge. It's a different set-up, even on the plexi/acrylic Subs.

[Frosty]

Great info and pictures, thanks!

[jedly1]

Originally Posted by Vincent65

Sorry that pic wasn't very good - here's a better one of another, period-correct f-f insert for the 1680, and you can clearly see the step/ridge. It's a different set-up, even on the plexi/acrylic Subs.

just talking gmt here, subs are totally different.

[jedly1]

agree john , for sure there are red backs on early 16750 ...if i wasn't clear , the blue back was introuduced during the 16750 series , not at its launch.

[Vincent65]

Originally Posted by jedly1

just talking gmt here, subs are totally different.

"As to the "stepping" or lack thereof, to indicate a sapphire vs. acrylic crystal match--does the same hold true for the sub models?"

erm… there was a specific question re Subs, by southtexas, which I answered… Yes, totally different, which I hopefully showed!

[JustinK]

The inserts I have purchased for GMT's that have ridges (saphire models) are too loose for my 16750 and 16753's. I have experienced this several times and avoid purchasing anything made for a saphire models. I thought they would never fit a 1675 or 16750.

Are you saying these can be adjusted to fit acrylic and how might it be adjusted to fit if it's too small. Would a coke insert from a sapphire model potentially fit my acrylics or did I misunderstand?

Great thread Blythe way!

[jedly1]

Originally Posted by Vincent65

"As to the "stepping" or lack thereof, to indicate a sapphire vs. acrylic crystal match--does the same hold true for the sub models?"

erm… there was a specific question re Subs, by southtexas, which I answered… Yes, totally different, which I hopefully showed!

sorry mate ...6am :

[jedly1]

Originally Posted by JustinK

The inserts I have purchased for GMT's that have ridges (saphire models) are too loose for my 16750 and 16753's. I have experienced this several times and avoid purchasing anything made for a saphire models. I thought they would never fit a 1675 or 16750.

Are you saying these can be adjusted to fit acrylic and how might it be adjusted to fit if it's too small. Would a coke insert from a sapphire model potentially fit my acrylics or did I misunderstand?

Great thread Blythe way!

yep..some used ones will fit once they have stretched a bit anyway your watchmaker should be able to put them in his 1006 and fit them no drama ...that will stretch a steel bezel without huge effort ..0.1mm is well within the kind of tolerances that a bezel insert can be both from original manufacture and certainly from being popped off and on a few times.

theres a whole raft of inserts that seem to have been made pearly 2000's that are an absolute nightmare to fit with the manufacture being off by about .
0.5mm+ to big. I've seen service centres remove metal from the bezel to actually get those in rather than compress the crap out of them.

what is worrying , is just how many peoples watchmakers don't have this tool judging from the emails I've had since i put this post up !

[JustinK]

I do not believe my watchmaker has one and he has a Rolex parts account. I know Rolex requires he buy certain equipment but possibly this is not a mandatory item.

Great information, thanks!

[Vincent65]

Originally Posted by jedly1

sorry mate ...6am :

no problem

[jedly1]

Originally Posted by JustinK

I do not believe my watchmaker has one and he has a Rolex parts account. I know Rolex requires he buy certain equipment but possibly this is not a mandatory item.

Great information, thanks!

unfortunately not much is , i know a couple ''rsc approved'' watchmakers that have little more by the way of equipment than very basic hand tools, a cheap ultrasonic tank and a cheap pressure tester , not even a lathe ...which i really don't get ..if and when there is an inspection ( done by BHI in UK) they borrow a load of stuff from friends to meet the requirements. Uk is REALLY tightening up though and putting big demands on them...this years requirement is a lapping machine which is a big ticket item and freaking a lot of them out, i know at least some are going to jack in the job.

[JustinK]

Originally Posted by jedly1

unfortunately not much is , i know a couple ''rsc approved'' watchmakers that have little more by the way of equipment than very basic hand tools, a cheap ultrasonic tank and a cheap pressure tester , not even a lathe ...which i really don't get ..if and when there is an inspection ( done by BHI in UK) they borrow a load of stuff from friends to meet the requirements. Uk is REALLY tightening up though and putting big demands on them...this years requirement is a lapping machine which is a big ticket item and freaking a lot of them out, i know at least some are going to jack in the job.

The guy I use told me Rolex will show up unannounced and file a report, he is then told what he has to do to keep his parts account. This could be installing a better filtration system, building cabinets for storage or purchase equipment.
It's crazy but without the parts account I imagine his income would be half.