Seiko Tachymeter Removal

[Jimbub]

Hello Everyone,

Does anyone know how to remove the plastic tachymeter ring and glass rubber from this Seiko 7T32 6M00. I am thinking maybe the fixed bezel can be prized off somehow?

Thanks

[jdm]

31 minutes ago, Jimbub said:

Does anyone know how to remove the plastic tachymeter ring and glass rubber

The crystal should have a nylon gasket that can be replaced without removing the bezel. On the caseback there is a special seiko code that represents the construction type.

 

31 minutes ago, Jimbub said:

I am thinking maybe the fixed bezel can be prized off somehow?

No, it should be removed pressing on the small lip which is under the pushers tubes. That requires custom made precision dies (as it needs to have cuts for the pushers tubes) and a good press.

[xyzzy]

The Seiko case type code, in the box after the model, tells you how to disassemble it.

But that is obviously a press fit bezel.  There will be a plastic gasket between bezel and case and probably some sort of shim under the bezel.

You should push it out from the back with a die of the correct size.  Remove the pushers, which you should clean and replace gaskets on anyway.  You might still need notches in the die for the pusher tubes.

The tach ring might be freed when the pushers are removed.  You can press out the bezel without the ring, but the ring is often a very useful size.  I haven't had one break yet.  Once the tach ring is out there might not be a good reason to remove the bezel.  It can be a real pain to reinstall.

Some cases need dies that are more exact than others.  That one doesn't look too hard.

You can also pry it up with a case knife. It depends on the case and bezel if there are good spots to get a knife in and lever it up with visibly marring the case. That looks viable too, with the spots where the bezel appears to overhang the case.

[xyzzy]

That tach ring looks distorted?  And the edge looks broken between 90 and 65?

[Jimbub]

Thank you indeed for all your replies and it is indeed a black nylon glass gasket, not rubber! (can't see how to remove it without removing the bezel though. I have attached another photo which might show how the tachy ring is fixed in place. If it wasn't damaged (as was mentioned above) the ring would fit snugly in a groove between 2 metal ridges and it seems to me the only way to remove the ring is to remove one of the ridges, removing the pushers will not release the ring. Stamped on the case back is "7T32 6M00" then "A4" in a box. I don't mind trying to prise the bezel off as was suggested but please can you tell me how I would re-fit the bezel, is it glued or just press fit?

[xyzzy]

Sometime the tach ring is trapped by the case and bezel, sometimes only the pushers trap it, and sometimes it comes out with the dial.

The 'A' means the bezel comes off, which was obvious anyway.  An 'R' would mean it doesn't.

The bezel is held in the same way as the crystal.  There will be a plastic gasket between the bezel and the case and it's press fit in.  You can not possibly see this gasket until the bezel is removed.

You push the bezel back in with the same press you use to remove/install flat crystals and to get the bezel off.  You might even push it back on by hand if you're lucky (or unlucky, as I think the plastic gasket is likely worn out and water resistance compromised if it goes on too easily).

What you should do is use a press.  Have a large die on the outside that presses against the case and not the bezel.  Then a smaller die on the inside that presses against the tach ring and NOT the pusher tubes.  

[canthus]

maybe this will help a little, if not now for later.

 

1383176349_03.CasingGuide.pdf

[Jimbub]

Thanks guys, I have these vice  presses, would they be suitable or do I need a different type?

[jdm]

On 9/12/2021 at 1:55 PM, Jimbub said:

Thanks guys, I have these vice  presses, would they be suitable or do I need a different type?

The press is no big deal, but you need to drill or cut grooves in the dies so they don't hit into the pushers or their tubes.

[Jimbub]

Okay, many thanks for all your help and advice.

[xyzzy]

You can use a die sized so that it presses on the back of the tach ring.  I haven't had a problem with a non broken ring breaking.  But your ring is already broken, so if you are trying to save it, then maybe that's not a good idea.

If you remove the pushers, then it looks like you will have a large target to hit the ring with your die without hitting the pusher tubes, without needing to cut slots in the die.

I've found a 30 mm die with a single groove for the crown side pusher often works when you can't use the tach ring.  It's enough to keep the two pushers on the other side from hitting.