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SEIKO 6138/6139 Repair Procedure of CENTER CHRONOGRAPH WHEEL

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SEIKO 6138/6139 Repair Procedure of CENTER CHRONOGRAPH WHEEL 

PREAMBLE: My Quest for a Repair Procedure of Seiko 6139B CENTER CHRONOGRAPH WHEEL  (PN. 888612)

I have on several occasions searched for information on how to repair the infamous Seiko (6138, 6139) CENTER CHRONOGRAPH WHEEL, to no avail. Threads about the subject matter are generally sprinkled with authoritative sounding comments that they cannot be repaired.

My question is why? Why can the number of parts  stacked on the extended pivot shaft, stacked above the fourth wheel not be lifted off of the shaft, giving access to the fourth wheel staking location? In my case I have 2 chronos where the staking on top of the fourth wheel, holding it in place, has loosened making the wheel loose)?

Logic leads me to believe, if I remove the 2-3 clutch parts (above the fourth wheel) off the top of the shaft, exposing the top of the fourth wheel, I could re-stake it and then re-install the parts in sequence, thus repairing my problem.

MY QUESTION: Has anyone had success removing the stack of clutch parts above the fourth wheel and/or know of and literature explaining the procedure?

NOTE (6138B): interesting that the Center Chronograph Wheel PN.888611 is listed, as one part, (a complete) and in the diagram it is shown as one-part, but in the part list there are a number of additional parts listed. I’m assuming this is the stack of parts sitting above the fourth wheel that make up the (complete).

So with all of this said, how do we lift these parts off the shaft without damaging them and the chrono ASSY so that the fourth wheel can be re-staked?   

Thanks in advance,

Will

 

SEIKO 6138 CHRONO Repair-001.jpg

SEIKO 6138 CHRONO Repair-002.jpg

SEIKO 6138 CHRONO Repair-003.jpg

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I have done that . I cut the stuck of clutch parts of a 6139B. It's often the springs that are broken.  The shaft is one unit from the top to the bottom. The  clutch parts with the finger is pressed on to the shaft. So to be able to repair it you need a special tool to remove that with. 

Think i could still have it here somewhere. 

I sent a couple of broken ones to a guy. He should see if he could repair them. Haven't seen anything yet.  Can maybe be done but think it's almost impossible. Maybe making new ones.  But they would be expensive. 

 

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Thank you @rogart63 for taking the time to respond. Should you come across the tool it would be a big help to see a photo and/or a sketch of where the tool fit and how it functioned. I am envisioning some type of puller that the clutch plate or the (heavy wall collar as seen at the top around the shaft) and a pin that pushes down on the pivot shaft.

I could be all wet just a vision based on nothing. A picture would be with a 1000 words.  

In my case(s) nether of my chronos have broken clutch springs, both are the fourth wheel pushed up and popping the staking. How do I know, I pushed against the wheel and heard them pop free spinning on the shaft? Not once, but twice, stupid I know!

That said if I can press off the tree parts above the wheel I can re-stake the wheel down then refit the 3 part assy.

Thank you again and take care,

Will

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10 hours ago, Wdc said:

Thank you @rogart63 for taking the time to respond. Should you come across the tool it would be a big help to see a photo and/or a sketch of where the tool fit and how it functioned. I am envisioning some type of puller that the clutch plate or the (heavy wall collar as seen at the top around the shaft) and a pin that pushes down on the pivot shaft.

I could be all wet just a vision based on nothing. A picture would be with a 1000 words.  

In my case(s) nether of my chronos have broken clutch springs, both are the fourth wheel pushed up and popping the staking. How do I know, I pushed against the wheel and heard them pop free spinning on the shaft? Not once, but twice, stupid I know!

That said if I can press off the tree parts above the wheel I can re-stake the wheel down then refit the 3 part assy.

Thank you again and take care,

Will

Hi Will 

Don't think there are such a tool. To remove you will probably have to make some kind of puller. If you look at Wristsushi you see that Dahasco tried to rebuild a chronograph wheel. I send him 2-3 old wheel to practice on . But he ended up buying a NOS wheel. 

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10 hours ago, rogart63 said:

Hi Will 

Don't think there are such a tool. To remove you will probably have to make some kind of puller. If you look at Wristsushi you see that Dahasco tried to rebuild a chronograph wheel. I send him 2-3 old wheel to practice on . But he ended up buying a NOS wheel. 

Thanks @rogart63

Your input is always appreciated and cleared up one of the mysteries I had with Dahasco’s post photos. The first couple of photo appears to be a metallic retaining washer, which I now think it is, originally thought is was a long collar passing  though the top three assy parts, (mine is also metallic with no staking marks).

Starting on the third photo the washer changes to brass, with a clear staking ring .5mm off the bore. the change in the washer from metallic to brass must be Dahasco using more than one of the units you sent to him.  

You can really  see the staking of the retaining washer on the sixth photo. Anther interesting point is the machined step in the bottom side of the washer, with I assume fits into the brass “Chronograph Finger for the Minute Intermediate Wheel”.

Again all of this is based on a lot of assumptions  on my part, while looking though the work Dahasco has provided.

What I have not worked out is why on the metallic washers there is no sign of staking, leading me to think it could be an interference fit pressed onto the shaft. 

A little more research on my end before committing my chrono wheel, filling in working on a Citizen 8110A bullhead I just received parts for.

Take care

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Gentlemen, for those that wanted to follow this disassembly it seems that I (by mishap) have failed you. I lost my step by step photos showing the disassembly,  when getting a message on my tablet photos where being saved on my SD card do to space it turned out, it was defective, and photos lost.

Summary:  the operation (for the most part) was a success, sadly the patient died

Starting, I did find I had a fourth wheel with a tooth missing, making the loss easier to take.

After studying @Dahasco photos, it was clear that the assembly (i.e. retaining washer, minute counter, heart-reset, spring clutch) was stacked on the extended second chrono shaft, retained by the staked washer.

 The challenge started with finding away to back-up the parts while using a stake to drive the shaft down though the staked retainer-washer and subsequent parts. The tool I decided on was a (modified) case splitter, flipping the dies over and squaring them so that I could fit the die edge between the heart and spring, essentially backing up the heart.

Using a stake, I tapped the pivot-shaft down though the washer, freeing the minute counter, heart-reset, leaving (on the shaft) the spring and fourth wheel. Now, this is where the patient died and one should take note. The above working so well, it thought I would proceed backing up under the spring assy, driving the pivot-shaft. This was a mistake, as I did not understand the spring assy is two parts. The upper spring half which includes an incorporated collar that fits over the shaft and a bottom backing plate (a fly-wheel of sort) which is attached to the fourth wheel. By backing up under the spring backing plate, tapping down on the shaft is bent the plate and damaged the spring. Patient died.

What did I learn and what to do different?  

The top half of the spring that needs to come off after the heat-reset is fitted to it’s own shaft collar. There are some groves on the collar that I could use my back-up tool to hold and drive the pivot-shaft though it.

 

Closing:

I am sad I lost the photos as it shows (those that follow me) that each part comes off without any damage. Springs then can be saved (harvested) and used elsewhere.

The photo of the chronograph wheel (compete) in the back up tool is a second chrono just to show you how it was fitted. I am not ready to disassemble it yet. Need time to maul the post-mortem before committing. Also based on this exercise I have anther idea how to fix a loose fourth wheel without disassembling the chrono assy.

Well I wish you all good luck and however takes this to the next step, please keep me posted.

Will

Concussion

Again, had I understood that the spring was two half’s I could have disassembled the chronograph wheel without damaging the spring.

Now whether this is wroth while, I am not sure. I guess if one had a chrono with a pivot, one could interchange the shaft, ect. This is yet to be seen. For me the challenge was can a chronograph wheel be disassembled. I believe my next shot now understanding how the spring is assembled that I can demonstrate it can,  without breaking any part including the spring.

SEIKO 6138 CHRONO Repair-006.jpg

SEIKO 6138 CHRONO Repair-007.jpg

SEIKO 6138 CHRONO Repair-008.jpg

SEIKO 6138 CHRONO Repair-009.jpg

SEIKO 6138 CHRONO Repair-010.jpg

SEIKO 6138 CHRONO Repair-011.jpg

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46 minutes ago, Seamuso said:

Hi, like you i also pressed on the wheel and it came loose. looking at what happened you when you try to disassemble the mechanism, i had a fear .

have a A239 - 20190607_224708.bmpA240 - 20190607_224836.bmpLook what i have so far.

When addressing only a loose 3rd wheel I found a less invasive and risky approach. Where I originally felt I could re-stake the wheel what I found while disassembling the chronograph assembly is that the 3th wheel is part of a three-part assembly including the pressure plate of the clutch. In short, you cannot get to the 3rd wheel without unstking the clutch pressure plate.  After reevaluating the risk as it related to the objective (secure the 3rd wheel). I found a less invasive approach which I've outlined in this link (bottom of page 1, continuing over to page 2). 

http://wristsushi.proboards.com/thread/19076/seiko-repair-procedure-center-chronograph 

I am getting much better at disassembling the chronograph assemblies, in fact I just replaced the date finger wheel on one of my units with no complications. The problem with a complete disassembly is removing the clutch off of the pivot shaft. It appears to be cramped and would require a very small stake to fit over the pivot and drive the shaft through the clutch hub. 

Good luck and feel free to contact me directly if you have any questions.

Will

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58 minutes ago, Seamuso said:

Hi, like you i also pressed on the wheel and it came loose. looking at what happened you when you try to disassemble the mechanism, i had a fear .

have a A239 - 20190607_224708.bmpA240 - 20190607_224836.bmpLook what i have so far.

Sorry hade not open your photos, it appears you've already disassembled the assembly . Your 2nd photo shows the clutch pressure plate which is staked to the 3rd wheel subassembly and the bottom of the clutch itself. I would be curious to see the flip side of the clutch (top side and raise collar) and to know how you were able to get it off of the pivot shaft without damaging the pivot? Did you punch the shaft down through the collar and if so, were you able to do it without damaging the pivot?

Take care and looking forward to your response

Edited by Wdc

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Hi, i used little prizing bars like what u would use for removing the hands from the dial. tiny amounts of pressure each time. i levered against the clutch plate,. this flattened the spring a little but i could stretch it again. have a look at the photo. 

One casualty as you can see from the picture of the centre small wheel. lost a tooth...

happened when i was staking it back on the large wheel.

A245 - 20190608_004710.bmp A244 - 20190608_004642.bmp A247 - 20190608_005336.bmp

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