Seiko 7A38 - by the numbers

can anyone advise if the movement swap from a seiko-7a38 chronograph is a direct swap for a ferrari formula chronograph.

i already bought a seiko7a38 gold chrono after i read that the movement was a 7a38 and was planning to use the movement but not sure how easy is the swap

cartier said they cannot help and dont even know the movement but i have discovered it is a 7A38. I have had the watch for over 20 years and watch has sentimental value.

Cheers

Hello, and welcome to the forum.

Depending on your capabilities, this is a relatively easy swap, which, if you have access to hand-pulling tools, you could do yourself.

See: http://www.seiko7a38.com/apps/forums/topics/show/7214274-you-need-hands-and-sometimes-need-to-pull-them-off-

The Ferrari Cal. 531 is indeed just a re-branded Seiko 7A38(A) movement. The only differences are the printed (Ferrari) and stamped (Seiko) back-plates and battery positive terminal plate. The only other possible difference might be the colour of the day / date wheels, but if you've bought a gold-tone Seiko 7A38 to use as a donor, then it's a fairly safe bet that it will have black on white printed wheels.

You need to carefully remove the dial and hands from the Cartier Ferrari movement, and swap them over onto the donor Seiko 7A38 movement. They will be a direct replacement fit. If you cannot do this yourself, any competent watchmaker can do this for you. Then replace the movement in the Ferrari watch case. As a finishing touch (so that it looks just like the original), before the watchmaker screws the case-back on, ask him to swap over the movement back-plates. Nobody (but you) will ever know the difference.

By the way, if you'd started to read through the long Cartier Ferrari Formula thread in this section:

http://www.seiko7a38.com/apps/forums/topics/show/7394242-ferrari-formula-fever-when-the-red-mist-comes-down-

The answer to your question was in the first couple of paragraphs.

Further down the thread is this small photo from an eBay auction in 2009 of a Cartier Ferrari fitted with a Seiko 7A38 movement:

I've never personally had the need to swap a Seiko 7A38 movement into a Cartier Ferrari Formula ....

But I have used a Seiko 7A38(A) to replace a badly acid-damaged Orient J3920 movement in a dressy gold-tone Orient chrono.

I also built this Franken Ferrari watch around a Seiko 7A38 movement, using Seiko components and Cartier Ferrari dial and hands:

http://www.seiko7a38.com/apps/forums/topics/show/7696547-my-franken-7a38-feiko-ferrari-fumblings-part-2

seiko7a38

Big thanks for the welcome and the information above. dont have the skills or tools to do it myself so need to find a watch maker to do it for me. i am located in Hong Kong. can you recomend anyone ?  what an absolute wealth of information on this watch. just beginning to read through some of the above. much much appreciated.

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. It is sometimes tricky to re-fit the hands so that the pointers hit the marks exactly. It gets easier with practice. Make sure you find a good watchmaker, who will know to take precautions to protect the dial. The Cartier hands are quite delicate and virtually irreplaceable, if they get bent or damaged in the process.

Well, not quite irreplaceable, but if you can find a set they will not come cheaply:

http://www.watchesulike.com/fr/ferrari/39-aiguilles-ferrari-formula-fv110-011.html (50 Euros = $485HK)

Trying to post a picture here:(

http://postimage.org/image/abkzq7nyf/

watch is a little bit battle scarred as it was my daily beater during my university years so excuse the abused look. still have the box and that is mint as well as the ferrari formula pen.

the ferrari chrono and the gold seiko 7A38 donor i acquired.

http://postimage.org/image/98isdo85d/

I can't quickly figure out how to post your photos for you using 'Postimage.org', so I've re-hosted them in my Photobucket:

Interesting.

Your Cartier Ferrari Formula appears to have been fitted with what I would consider to be the wrong hand set for this dial.

Have a scroll through the long 'Ferrari Formula Fever' thread I linked previously, and you'll see what I mean.

The early style red 'TestaRossa' dial nearly always uses the Dark Grey and Yellow hand set. Like this one:

Your watch appears to be fitted with the all black hand set (and shorter sub-dial hands), normally found on this dial:

interesting. I have had the watch since new and got it as a set with the ferrari formula pen (think it is OMAS or Cartier made). Only ever changed the battery and nothing else. does this mean it is early model or mistake ? LOL

no idea how many of the ferrari formula chronos were made. just know that i have only ever met one guy that was wearing one since i got mine in late 80's. seems there are a few around from the pics in this blog/website with loads of them emanating from Germany,

still have my original boxes and papers.

http://i1259.photobucket.com/albums/ii543/bigglesmclee/image.jpg

That's a nice set you have there. And given you're the original owner makes it all the more special. As Paul says, getting the watch going again should be easy for a competent watchmaker (you might see from some of my posts here that I've been doing my own repairs, and if I can manage it .......)

Good luck and keep us posted. 

I have had the watch since new .... Only ever changed the battery and nothing else. does this mean it is early model or mistake ?

My apologies. I didn't mean to imply that your watch was not original - just unusual - and unique in my limited experience of them. 

Seiko 7a38. No worries and did not take it as such. Any molten brown droplets of wisdom on the watch appreciated. Not a seiko7a38 aficionado and only dug deeper to find out the movement when Cartier could not help and hence discovered the movement swap. Tracked the gold one down a while ago and was unsure if this would fit with no hassles even though is same movement.

The gold-tone 7A38-7000 may have a slightly larger watch case and crystal, but if you were to pop the movements out of both of them you'd find that all the important dimensions matched perfectly. Overall diameter 31.2mm; distance between the centres of the 9 o'clock and 3 o'clock sub-dial hands 15.0mm, etc - and naturally all the pushers and crown positions line up perfectly, etc.. You might even be able to swap the movements complete with dials and hands between them, apart from a couple of variables: the Cartier Ferrari dial might be fractions of a millimetre thicker, and the 7A38-7000's lume pips might just foul on the edge of the Ferrari Tachymeter ring.

Funny thing - that expression of yours 'molten brown droplets of wisdom' struck a chord in my memory.

Of course, it should have, you already asked the same question on FerrariChat in the Ferrari Cartier Watch Info thread, 2 years ago:

http://ferrarichat.com/forum/showpost.php?s=5783162ff7b91867bfdd0dfc40f7bfe0&p=139551793&postcount=71

Do you know what quartz chronograph movements were used for the ferrari formula watch? ETA? JAPANESE ?

Your molten brown droplets of wisdom appreciated on what routes i can have this quartz watch fixed.

The person whose post Nathan referred you to, in his reply, was myself.  I've learned a little more about them since then. 

Yup was me. i managed to pick up the donor seiko7a38 a while ago and then completely abandoned fixing the ferrari after i went to Cartier and they said they could not guarantee it would be a perfect replacment as they were unsure if it was the same. Glad it is confirmed and am now seeking a watchmaker to fix it. took it to a old horological shop in Hong Kong that repair auto watches of all descriptions and said it was difficult to do and to go back to cartier !!!! Aghh

Are the movments easy to break on a swap ? is that why folks seems retiscent on changing them out ? still looking for a watch repair chap that can do it. hopefully can find one soon in Hong Kong

No, it's a piece of cake - honestly ! 

All that holds the dial to the movement are two tiny screws. If you're going to ask the watchmaker to swap the Ferrari Cal. 531 signed back-plate (and blank battery terminal plate) over for the Seiko 7A38(A) parts, that will involve undoing 7 more screws from the other side - which by watchmakers' standards are quite large. You will not disturb any of the components by swapping their back-plates (as long as the screws are tightened properly). The only slightly tricky part (which requires some practice / level of skill to do it well) is the pulling and re-setting of the 6 hands - especially with your watch's slightly smaller sub-dial hands.

Anyway, here's a slightly topical photo for you. My Cartier Ferrari Formula. It's the British F-1 GP today. Fernando Alonso is on pole.

Just a thought. There is one other thing - and it might be the real reason that other watchmakers would refer you back to Cartier ....

Getting the screw-down case-back off. The Cartier Ferrari Formula chrono's (theoretically) need a special 14-sided wrench to unscrew their case-backs. You may remember that somewhere in the FerrariChat thread, I asked Nathan if I could borrow his. He never came up with it. I have found (as long as they're not done up too tightly) you don't need the special Cartier tool. All you need is a 'Sticky Ball'.

Go search on eBay on 'Sticky Ball Watch Case Back Tool'. Most of them come from Hong Kong.  They even come in Red too. 

http://www.ebay.com/itm/Sticky-Red-Ball-Tool-Super-Watch-Screw-Back-Case-Opener-/300580378713