Seiko 6138-0040 ‘Bullhead’

It’s easy to see why Seikos 6138-0040 is nicknamed the Bullhead. It’s one of Seikos more iconic vintage chronographs and a model I love working on. This particular example came in for a spruce up and service recently.

Seiko 6138-0040 Bullhead

The owner is a man who knows what he wants and sent these parts along with it, a sample case along with a NOS bezel, crystal, crown, stem and seals. It certainly makes my job a lot easier when they arrive as fully prepared as this one!

Seiko 6138-0040 Bullhead

A quick look at the back shows it has a production date of November 1975, almost 40 years ago from the date of this post.

Seiko 6138-0040 Bullhead

I remove the back and the movement looks to be in reasonable shape, everything appears in place and undamaged.

Seiko 6138-0040 Bullhead

Once I’d removed the rotor and autowind mechanism the movement could be uncased.

Seiko 6138-0040 Bullhead

The dial and handset look pretty good but the owner wants the lume renewed and the missing white paint on the minute hand touching back in.

Seiko 6138-0040 Bullhead

I always remove the old lume before removing the dial as the safest place to hold it is when it’s firmly attached to the movement. Any stray particles getting where they shouldn’t doesn’t matter a bit as everything gets stripped and cleaned anyway. It’s always a tense time when scraping old lume off a pristine dial, one slip and it’s curtains! Twelve to two are done in this shot….

Seiko 6138-0040 Bullhead

….and the rest are removed here.

Seiko 6138-0040 Bullhead

The hands are also done and the damaged minute hand paint is touched back in to give it time to dry before reluming.

Seiko 6138-0040 Bullhead

With the lume stripping done the watch stripping continues, I won’t bore you with the descriptions as I’m sure you’re getting familiar with the insides of these now 🙂

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

I turned the movement over and tackled the chronograph layer and motion work next.

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Soon it was fully stripped and ready for cleaning and inspection.

Seiko 6138-0040 Bullhead

There’s a lot of components in one of these 🙂

Seiko 6138-0040 Bullhead

Whilst the parts were whizzing through my vintage cleaning machine I turned my attention to the case. This was rebuilt with the sample body, NOS bezel and crystal, NOS seals and the original caseback.

Seiko 6138-0040 Bullhead

Very smart it looked too.

Seiko 6138-0040 Bullhead

The NOS stem was trimmed and fitted to the NOS crown.

Seiko 6138-0040 Bullhead

The pushers were stripped and cleaned, as usual the old seals were as hard as iron….

Seiko 6138-0040 Bullhead

….so the new seals were fitted….

Seiko 6138-0040 Bullhead

….and the crown and pushers greased and fitted to the case. The owner wanted it as watertight as possible as it had been susceptible to moisture ingress in the past, hardly surprising with the old rock hard seals.

Seiko 6138-0040 Bullhead

To this end the watch was given a 6bar leak test which it successfully passed. This is the best way to test a chrono case as there’s no movement to keep the pushers or crown in place, any weak points and the case will pressurise and blow the pushers and crown straight back out!

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Although I’d never advocate swimming whilst wearing a vintage timepiece, it’s nice to know that the daily routines of washing your hands, car, dishes or whatever aren’t going to be a problem for this watch.

Seiko 6138-0040 Bullhead

With the inspection carried out everything appeared to be in great shape so the rebuild began.

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

When I get to this point I normally wind the power on and roughly adjust and time the watch, however with the calibre 6138 the top barrel bearing is carried in the dial side chronograph plate so this needs refitting first.

Seiko 6138-0040 Bullhead

So the movement is turned over and the chrono work replaced….

Seiko 6138-0040 Bullhead

…and the top plate fitted.

Seiko 6138-0040 Bullhead

Now the movement can be turned over and the power wound on.

Seiko 6138-0040 Bullhead

With the timing adjustments roughly done the rebuild continues.

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

With the dial back on I tackled the reluming. I mixed up some powder and started to apply to the batons.

Seiko 6138-0040 Bullhead

The hands were next.

Seiko 6138-0040 Bullhead

The whole lot was left to dry overnight then a second coat was applied to ensure it had maximum glow.

Seiko 6138-0040 Bullhead

The hands were refitted next….

Seiko 6138-0040 Bullhead

….the movement was recased….

Seiko 6138-0040 Bullhead

….and another vintage example of Seikos finest was ready for a few more years sterling service 🙂 ! I do love the Bullhead range, very distinctive watches especially when on their original bracelets.

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

Seiko 6138-0040 Bullhead

 

 

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