Seiko 7A38 - by the numbers

In case you need any further convincing of the interchangeability of these re-branded Seiko 7A38 movements, here's a good example.

This is a Kamatz 517000 I bought on eBay recently. From the seller's description I had a feeling it was going to need a bit of work:

Although the watch is roughly the same overall size as the Cartier Ferrari Formula (40mm across), the crystal and dial face are much smaller (visible) diameter. However, pop the movement out, and you'll find it's exactly the same overall 31.2mm diameter, and that the subdials (which are much smaller than those in either your 7A38-7000 or Cartier Ferrari Formula) are on the same 15.0mm centres.

Note the two small screws which hold the dial to the movement. The cut-outs on the Kamatz dial will be very similar to those of your Cartier Ferrari dial. The two small holes in the dial at 12 o'clock and 6 o'clock are to locate the plastic Tachymeter dial ring spacer.

As you can see from the photo, the movement has suffered from water damage - ingress through the screw-down crown.  I've got everything working now (including the rusted-up pushers in the watch case), but I think I may still have to do a full strip and re-build. 

Here's a shot of movement from the other side:

Note this movement is printed Shimauchi Ltd. V906 in the same places where yours has Ferrari, Prancing Horse logo and Cal. 531.

This differently signed version of the 7A38 movement was used by C.G.H. (in effect Seiko France) in the Yema, Jaz and Kamatz N8's.

You could directly swap all and any components between this movement and a Seiko 7A38(A), Ferrari Cal. 531, Orient J3920, etc. 

seiko7a38

do you think the seiko service centre in Hong Kong would do this ? just a thought. Have tried 2 more watchmakers and they both said no.

Unbelieveable !  It really is such an easy conversion / fix.  I guess you could try Seiko, but their answer may well be the same. 

nb. thanks for the above info and i am convinced with all the information. for some reason, the two i have gone to have said they would not be able to do it and they BOTH repair and rebuild automatic watches. seems odd to me as i would presume doing an auto watch rebuild is far more difficult than movement swap and changing hands and face ?

Remember what I wrote in the 5th post on the previous page:

Any competent watch maker can do the swap for you. You don't need to go back to Cartier.

Just find a reputable watchmaker who has worked on Seiko quartz chronographs, and who has steady hands.

If you can't find a reputable 'professional' watchmaker in Hong Kong to do the swap for you, you might want to try ....

Jake from '10Watches' (now trading as Dagaz Watch Ltd.) See: http://www.10watches.com/infocustomwork.htm

He will probably do a better job ! If he needs any convincing, please feel free to email him a link to this thread. 

See also this thread on WUS: http://forums.watchuseek.com/f21/seiko-hong-kong-714702.html

and quote: Jake has told me on a number of occasions that HK is watch shop paradise ....

Yeh, good news !!! Gave my watch to a friend who said he has a watch chap that should be able to do it. Got the watch back literally this morning. Happy chappy now. Thanks all for the advice to date !