Written by Chuck Maddox USA!
on 15 October 2000, certain rights reserved.
Last Revised: 3 December 2001 4:35 GMT

Recently there have been a flurry of requests for information on converting c.321 Speedmasters, which only came originally with steel case backs. In order to provide a place to direct future queries on this subject I have created this document... Here is a typical query on the subject...
Speedmaster Display Back Question
Posted By: xxx <xxx@xxx.com> (xxx.xxx.net) Date: 10/9/0 - 10:18:24

Hi, I have a '67 Speedmaster with a 321 cal movement and would like to get a display back. Should I get one through swatch? Would they sell me one and if so how much would it cost? I have seen display backs for sale on "that auction site" but have no idea as to what they are worth? Any advice would be welcome..... Thanks in advance

Xxxx Xxxxxx

Chuck Maddox
RJ Broer's
Edwin Leung
Steven Sugiyama
Bill Sohne
Caseback Wrench

Gerry Luppino posted
TZ Classic 1140: Customizing the Omega Speedmaster: Part 1 which detailed his journey in creating his display back. Originally Gerry had posted portions of this article and pictures of his c.321 in both the Omega and Public Forums. This prompted a number of us in the Omega Forum to do similar conversions.

Here are a couple of thoughts on the display back with regards to c.321 movement watches...

The current display back will fit on a c.321 movement watch, with either the pre-crown guard case or modern cases. Sometimes a spacer will be necessary in order to insure that the movement is held tightly without the anti-mag/dust cover in place, but it's best to check it out before worrying about the spacer (as you might not need one)

For some reason 1967 model year Speedmaster Professionals seem to be more easily adaptable to this conversion than previous models as it seems that a spacer is not necessary more than half of the time. I've had the display back on my 1965 Speedmaster Pre-Pro briefly... The movement was loose enough in the case I immediately took it back off, but the caseback threads on properly. With a properly made spacer there is no reason to think that you couldn't do a display back conversion on pre-pro model Speedmasters as well.

Here is a gallery of Speedmaster c.321's that have been modified with display backs:

The author's 1967 Speedmaster Pro c.321:

Author's 145.012-67 Front
Author's 145.012-67 Back 1
Author's 145.012-67 Back 2

I haven't converted my 1965 Pre-Pro Speedmaster to sport a display back yet. If, or once I do I'll update this article...

Robert Jan Broer took a different route on his display back conversion. In his own words:

" I also have a '67 Speedmaster Pro and I fitted a display back on it. Handmade, because the official Omega Displaybacks are VERY expensive and they have the ugly inscription in it. First watch worn on the moon, while mine was pre-moon. So that didn't sound too good. I bought a spare caseback for the new Speedmaster Pro and a goldsmith in my neighbourhood fitted a glass in it. the see through caseback on my watch was made by Gerton Van Der Laan who he deserves the credit for such nice work. It looks marvelous, the cal. 321 is very nice to look at. A seethrough caseback gives the watch a whole new dimension in my opinion. It is even more fun to wear!"
Robert Jan Broer's 145.012-67 Front
Robert Jan Broer's 145.012-67 Dial Detail
Robert Jan Broer's 145.012-67 Back 1
Robert Jan Broer's 145.012-67 Back 2
Robert Jan Broer's 145.012-67 Back 3

In the process of securing permissions to use the pictures used in this article RJ elaborated on the spacer issue in regards to his 1967 Speedmaster:

I think you already know it, but I didn't use a spacer ring, but an extra gasket... The new type of caseback (145.022 is printed in it) doesn't have the same dimensions as the caseback of the 145.012 or 105.012. It is a bit smaller and it doesn't have the same height. The smallness is bad for the waterresistance, but it will fit (for the eye). The lower height causes the movement to be loose in the case. Normally, the caseback keeps the movement in place by pressing it into the watchcase. I used an extra gasket to solve this.

The inclusion or exclusion of the standard Omega inscription is a personal choice. As RJ indicated it's a post-moon inscription. He didn't want that on his pre-moon watch. But to me, the display-back is a post moon item anyway, and both RJ's Speedmaster and my 1967 are most likely the same model that was first worn on the moon by Buzz Aldrin. Since the display back is not original, I'm not worried about the inscription being on the display back. But as I said it's a personal preference thing... To thine own self be true!

Edwin Leung also has done a c.321 Speedmaster conversion:

Edwin Leung's c.321 Conversion...

Click on the picture to see the full resolution version of this picture (442k download)

Edwin Leung writes:

"If PP5070 were Miss Universal with many professional people helping her to dress and make up, then I would say my Speedy Pre-Moon with saphire back were an innocent village girl ~ simple, natural but beautiful!! If I finally can keep only three watches among my collection, this should be one of them!!"

Stephen Sugiyama is a Speedmaster expert who has also done a c.321 Speedmaster conversion:

Steven Sugiyama's CK 2998 Front
Steven Sugiyama's CK 2998 Back

Steven writes:

"My watch is a ref. CK 2998 from 1962, and has a display back that was added by Gerry Luppino. I had Gerry polish off the inscription on a lathe. This is my favorite Speedmaster model with the dauphine hands, no-crown-guard case, 19 mm band, and cal. 321 movement."

Bill Sohne is a noted Chronometre and Chronograph collector with a strong collection of Omega's of all stripes. His 1967 Speedmaster is one he received as a "Hand-me-Down" from his brother Marshall. Bill's collection received an extensive write-up in the April/May 2000 edition of InSync.

Bill Sohne's ST145.012-67 Front
Bill Sohne's ST145.012-67 Back

It's interesting to note that if you prefer to have a standard Omega Display-Back part, but would rather not have the standard inscription on the back you can do as Steven has, and have the inscription removed and avoid having to make the part from scratch as RJ's Goldsmith did. So there is more than one way do to this conversion.

Recently on ebay another interesting c.321 display back appeared in an auction. I posted a picture of the watch in question on the TZ Omega Forum and received an interesting reply...
Hi Chuck,
the watch on eBay is from me; I sold the watch last year in September to the gentleman, who sells it now! I have a watchmaker, who produce this saphire crystal backs especially for me and my Omega watches; I'm a collector of Omega, especially Speedmaster watches, but from time to time, I have to sell some of my watches, because you can't only buy and collect, but I have to get some money for some new vintage watches, which I'm always hunting on! Feel free to contact me, if you have any further questions. There is no need to say, that all my watches(ref 2998, 105.003, 145.012, etc.) are all in mint/NOS and original quality, proofed by Omega CH!! Please feel free to post my information, perhaps it will be possible for me to help some other Omega Speedmaster collectors!
Kind regards, Dirk

RJ is absolutely correct about the display back adding a new dimension to the watch. The original metal back while of passing interest is fairly boring (at least the pre-moon ones are). But when you have the display back on the watch if you are bored you can always take off the watch and look at the movement count time away! This is great if you are stuck in a boring meeting or waiting for a train or plane!

So to sum up:

  1. The current Speedmaster Display Back will fit on c.321 Speedmaster Cases.
  2. The threads are the same so the back is screw on/screw off interchangeable.
  3. All you really need to try this out for yourself is a Speedmaster, a display back and a caseback wrench:
  4. Author's Case Back Wrench
  5. I bought the wrench from SEP Tools in the downtown Chicago Wabash Avenue Jeweler's mall. It cost me $8.70 {before parking!}.
  6. When I got home I took the wrench to the '67 and opened it up, removed the dust/anti-mag cover and tried it out. There is a very, very slight amount of play when I wind the Speedy but the rest of the time there is no play of the movement inside the case, so a spacer or gasket isn't absolutely necessary. I have added a couple of gasket's from the F&B bulk assortment (below) to minimize what play there is when winding the watch.
  7. Of the people I have talked to who have done this conversion on 1967 Speedmasters only RJ's example has needed a a additional gasket to hold the movement.
  8. On my 1965 Pre-Pro Speedmaster, the display back screws on quite easily, but for some reason there is a great deal of play without the dust/anti-mag cover, so for it (and I suspect many other Speedmasters) a spacer or gasket would be necessary.
  9. Frei & Borel sell an assortment of case back gaskets for $9.95 that may have a suitable gasket for this application:
    1. Frei & Borel Bulk Gasket Assortment
    2. Case Gasket Bulk Assortment

      This is a popular bulk assortment of 50 O-ring style case gaskets.  

      FB-2705 $9.95

      1. You can access this item via TimeZone's Tool Shop on the " Case Openers & Gaskets" page.
        1. I make no claim that one of the gaskets in this assortment would be suitable for this application, but at $9.95 it may well be worth trying...
  10. My advice if you are interested in trying this for your self, is to get a display back and a wrench and try it out before worrying about a spacer. It won't cost you anything to try it out first and might just be good to go as is.
  11. If you do need a spacer, you can try the bulk gasket assortment from Frei & Borel or I have recently located an Omega manufactured spacer made from a patented material called Accrolon 903. This is a nonmetal material with carbon and Teflon in its composition. This seems to be perfect for any Speedmaster and will fit perfect and remove the slack that exists from removing the dust cover/anti-mag shield... A couple of pictures follow:
  12. Omega Spacer Ring
    Omega Spacer Ring 2
  13. Dimensions (approximately) 30mm Outside Diameter, 28.5mm Inside diameter, 1 mm horizontal thickness, 1mm vertical thickness. Again these are approximate dimensions.
  14. Even though the spacer was made with the c.863/c.1863 in mind it works great with c.321 movements. The spacer took all of the slack from my 1967 145.012-67 Pre-Moon Pro, and I've also tried it on my 105.003-65 Pre-Pro and it works great with it as well!
  15. If you are looking to purchase a display back and/or spacer, email me and I'll provide information on how to contact the persons I obtained mine from. The typical price for a display back is in the area of $200 US, and the spacer in the area of $10 US. I do not sell these items or have a supply of them personally, but I will forward information to where you may obtain them.
  16. An estimate of the cost of doing such a conversion is as follows:
  17. Item:


    Display Back


    Spacer Ring:


    Case Back Wrench:


    If you intend to do the work yourself...

    Estimate TOTAL:


    Less Shipping expenses, taxes, etc. ...

  18. Of course if you need additional spacing you might have to combine the spacer ring with some gaskets from the F&B set.

-- Chuck


I'd like to thank Edwin Leung, Robert Jan Broer, Stephen Sugiyama, Bill Sohne and Dirk for permission to use the pictures included in this article. I'd also like to thank Gerry Luppino for his pathfinding work on this topic. Most if not all of us would be staring at steel backed c.321's without his efforts in this regard.

Statement of rights retained and permissions granted...

Permission is granted for Damon, Derek, Ross or RJ to include this article within the FAQ's they are writing as long as the people who have contributed to it (see acknowledgments above) are given appropriate credit, Permission for personal, educational or non-commercial use is granted. The author retains all other rights not specifically mentioned here... For all other use please contact the author.