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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
hydronaut
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Mistral rebuild

Wed Jun 29, 2016 5:23 pm

Picked up a mid 70s mistral at a scuba swap for 100 Canadian. Is is great shape with a few dings and little of the label coming off. It actually breathes well but the hoses and duckbill are shot. Thought it would be a good entry into the double hose foray.

Familiar with rebuilding most single hose usd regulators.

What internals should I start with replacing?

Thanks.


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Greg Barlow
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Re: Mistral rebuild

Wed Jun 29, 2016 5:40 pm

A good rule of thumb is to plan on replacing anything that is not made of metal. With most of the single stage USD regs, you can polish the face of the HP assembly. Polish the surface only enough to remove all visible traces of the impression from the volcano orifice. I suggest using 400 grit wet/dry paper on a perfectly flat surface, and using a figure 8 pattern. When the impression is gone, I suggest a final polish using 600 grit paper.

The VDH Mistral rebuild kits are an excellent purchase. You will also need a new diaphragm, along with the hose assembly parts. Again, VDH has absolutely everything you need to make your reg better than new.

Greg Barlow
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Herman
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Re: Mistral rebuild

Wed Jun 29, 2016 7:11 pm

I would add to the list a band clamp and a duckbill eliminator (DBE). The "C" clips are a pain to remove and install, esp without special tools. The DBE works better than a duckbill, is easier to install, makes hose installation and removal a lot easier and is not that much more. Also, hose clamps are not a bad idea.
I suspect you meant mid-60s Mistral, they were not made in the 70s and all USD double hoses were discontinued in 72.

I tend to use finer sandpaper -800-1000 (you can find it in auto supply stores) than Greg and do it wet. A plate of glass, a flat glazed ceramic tile or a scrap of stone counter top work well for flat surface to lap on.
Herman

hydronaut
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Re: Mistral rebuild

Wed Jun 29, 2016 8:21 pm

Yes mid-60s DW. Was typing on my phone when I posted.

Plastic hose clamps where already on it. Will place an order for the parts and dive it. It was cheap and a good way to start the double hose collection. Not that concerned about the condition as I intend on diving and not displaying it.

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Herman
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Re: Mistral rebuild

Wed Jun 29, 2016 9:36 pm

Plastic hose clamps were standard but there are 2 versions. It's not uncommon for the older version to be brittle so if it has those then I would def replace them. It's easy to tell the difference, The newer ones have a screw and nut, the older ones had just a screw threaded into plastic. Wire ties work well too if you don't mind it not looking original.
Herman

hydronaut
Skin Diver
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First Name: Andrew

Re: Mistral rebuild

Thu Jun 30, 2016 7:37 am

Image

Image

It's the ones with the screw. Looks really good/clean on the inside but l am assuming somebody dropped the things during a service at one point in time. Small dent in the edge. Diaphragm seats fine and it goes together okay.

Any suggestion ho to straighten? I plan on ditching the clips anyway.


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swimjim
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Re: Mistral rebuild

Thu Jun 30, 2016 10:47 pm

The can itself looks straight. As long as everything seals you should be good to go. I might massage it a little with a hammer and a punch. If the can is out of round(I doubt that in this case) you can do this.............https://vimeo.com/55484797 .

Jim

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Herman
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Re: Mistral rebuild

Fri Jul 01, 2016 6:45 am

Neat press Jim, might have to make one myself.
I would suggest a hardwood or hard plastic dowel instead of a metal punch to straighten the cans, they are much less likely to leave marks in the metal. They are not as effective but do less damage to the surface.
Herman

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Greg Barlow
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Re: Mistral rebuild

Fri Jul 01, 2016 3:11 pm

Excellent video, Jim. Thanks for creating it.

Greg
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TomcatPC
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Location: Toledo Ohio

Re: Mistral rebuild

Fri Jul 01, 2016 4:48 pm

The only thing I know about the Mistral is:
1. Even I was able to put one back together (with expert help and support).
2 They are great fun to dive with.
3. I really love mine!!
Mark

hydronaut
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Re: Mistral rebuild

Mon Jul 04, 2016 5:09 pm

Herman wrote:Neat press Jim, might have to make one myself.
I would suggest a hardwood or hard plastic dowel instead of a metal punch to straighten the cans, they are much less likely to leave marks in the metal. They are not as effective but do less damage to the surface.
Brass punch did the job.

ImageImage


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antique diver
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Re: Mistral rebuild

Mon Jul 04, 2016 5:29 pm

Nice job, Hydronaut!
With a clamp ring installed you probably won't see any evidence of the original damage.
The older I get the better I was.

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ScubaLawyer
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Re: Mistral rebuild

Mon Jul 04, 2016 6:11 pm

Hydronaut, excellent job! I love it when a plan comes together! I do not have an original Mistral. I do have a modern one but there is no comparison. I keep looking for one to rebuild but they either get bid up beyond what I'm willing to pay or the few garage sale finds I've made have been in FUBAR condition. I'll keep looking. In the meantime, congrats on your rebuild progress. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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