On My Bench - Seiko 6309-7040

JimInOz · Apr 20, 2020

Another Turtle has landed on the bench. Problems described were very stiff winding (time setting) and low power reserve.

I started discussing it here, but figured a thread of it's own was warranted.

A nice watch, showing some wear but overall in good condition.

Front view.

Back view (serial blocked because everyone does it 😉).

Movement view.

Thought I'd add this from the other thread so it's all in one place:

I'm now looking at a 6309 with poor power reserve. When manually wound it will run for 48 hours. I also noticed manual winding (via ratchet screw) was stiffer than normal and the bridle slip was very noticeable.

I put the autowinder back on and while it rotated freely from "unwound" it quickly tightened up and rotating the watch as a wearer would resulted in practically no movement of the rotor.

My first suspect is an overly strong mainspring so I'll investigate that.

Other than that, any ideas?

From Al:

Jim - Seikos are very efficient winders, so barring any defect in the automatic winding section, then a strong mainspring is certainly a possibility. You noted it felt heavy to wind, so it's either that or something else is binding...let us know what you find when you get it apart.

JimInOz · Apr 20, 2020

The Stiff Winding Problem

Checking the time setting with the movement out of the case didn't present any abnormal feel, it was quite smooth, however, with the crown in the case it was quite stiff.

While the stem/crown tube looked OK, I polished it with a plastic sleeve and metal polish to remove any roughness that could be contributing to drag.

The case was then cleaned in the ultrasonic and while that was going I changed the crown seal, making sure it was properly lubricated with silicone grease.

The case was dried and I lubricated the tube with a tiny amount of silicone, put it together and it's now very smooth, although slightly tight due to the new seal, but not as stiff as before.

Now to find out why the power reserve is so low.

JimInOz · Apr 22, 2020

After finding out that the autowinder rotor would not do a full revolution after only a few winds from dead, I removed the barrel.

The mainspring appears to be normal, just very dirty, the barrel cover is badly worn. I haven't seen one as worn as this before.

I removed the mainspring, then the arbor and I re-fitted the arbor to an empty barrel and back into the movement to see if there were any external influences causing the problem.

As we can see here, the rotor can be rotated quite freely.

There is some slight resistance at points. This is caused by the rotor overcoming the pressure of the click spring on the ratchet wheel. Rotating under it's own power is no problem.

A quick spin on the watchwinder shows normal operation.

So that excludes the auto mechanism/movement.

On to the mainspring.

JimInOz · Apr 22, 2020

Comparing the subject MS with an original from an old donor.

As can be seen, they a very similar and both measure up to the GR2534X dimensions.
The only major difference is the bridle. On the "dodgy" one, the bridle is flatter and the weld join is further back along the MS.
Maybe the flatter bridle is putting too much tension on the barrel wall?

Next I had to make a very flat surface to see how much twist was in the spring.

With the bridle end of the MS held flat, I was able to see that there was (to my mind) a significant twist in the MS.

This is the arbor end. Not normal I feel.

So I suspect that the MS is the culprit, maybe confirmation or otherwise from @Archer, @ChrisN, @Canuck?

Luckily I know of some one with a spare MS 😉, so I'll contact him and get a decent replacement.

jsducote · Apr 22, 2020

JimInOz
So I suspect that the MS is the culprit, maybe confirmation or otherwise from @Archer, @ChrisN, @Canuck?

Luckily I know of some one with a spare MS 😉, so I'll contact him and get a decent replacement.

SQotD (stupid question Of The day) -
Are mainsprings not able to be repaired and/or straightened?

Archer · Apr 22, 2020

Hi Jim,

Both the mainspring and the barrel should be replaced, IMO.

Cheers, Al

Archer · Apr 22, 2020

jsducote
SQotD (stupid question Of The day) -
Are mainsprings not able to be repaired and/or straightened?

Generally speaking, it's not worth trying. Mainsprings are not typically expensive items, and having it perfectly flat is important - if it's not it will cause drag on the inside of the barrel, and that drag will prevent the barrel from turning as freely as it should.

Worn barrels can also cause problems, in particular if there are any ridges or grooves inside the barrel - again places where the spring can get snagged.

Cheers, Al

JimInOz · May 1, 2020

The barrel, as noted, was a contender for replacement so I found a donor in much better condition, fitted a new generic mainspring and re-assembled the movement.

After running overnight to settle down I gave it a check on the time grapher at full wind. It now has a respectable trace (for an ancient Seiko).
Dial up was much the same, but running at +4s/d.

Next step will be finishing off the case and getting it all back together.

jaguar11 · May 2, 2020

Another enjoyable read! Looking forward to the next instalment. Thank you.

JimInOz · May 4, 2020

Well here we are.
Dial and hands fitted and the movement put in the nice cleaned/lubed case.

Closeup for you V. How's that crystal?

😁

Eve · May 4, 2020

JimInOz
Well here we are.
Dial and hands fitted and the movement put in the nice cleaned/lubed case.

Closeup for you V. How's that crystal?

😁

What crystal?! I think you forgot to install one 😗
😁👍

snkn1959 · May 4, 2020

Awesome posting~!

On My Bench - Seiko 6309-7040

JimInOz

JimInOz

JimInOz

JimInOz

jsducote

Archer

Archer

JimInOz

jaguar11

JimInOz

Eve

snkn1959

Similar threads

On My Bench - Vostok Rescue

Seiko 6309-7040 Turtle

I am overwhelmed with what is on my bench ...

On My Bench - Waltham Automatic Problem Child

On My Bench - Seiko 7005-8062

On My Bench - Seiko 7549-7010 Deconstructed