Blast from the past - SP 108

[Mobulai]

They had no splined jam nuts or hoses as well (AFAIK)

 

[Mobulai]

The service kit however came with 0 orings in it, but everything else barring a new case (lever, spring, seat, jamnut, diaphragm, cover, key and orifice)
did they have something like a rebuild/restoration kits beside service kits? Or just the concept changed over time and now we just get orings and seats?

(Orifice came wrapped in the thin paper)

 

[axxel57]

I don't think that's a Service Kit, that's an Upgrade Kit from a SP 108 to a SP 080, that's why there are no o-rings ( the orifice has one probably)......

 

[Mobulai]

I don't think that's a Service Kit, that's an Upgrade Kit from a SP 108 to a SP 080, that's why there are no o-rings ( the orifice has one probably)......

Oh that makes so much more sense, but the orifice had no oring as well

Here is what it looks like unwrapped (mext to an old one)

 

[Mobulai]

… Multi quote failed me

Here is an interesting one, from the grand daddy 108
It seems to be stainless (well stained in this rusty boi), and no gradual cone leading up to the knife edge, and a very „flat profile“ knife edge a bit similar to the g250V one

I wonder how to dress/micromesh this if needed
Also here is a NOS orifice from the service kit for it (or the 108 HP version — I can’t tell what version is what — way before my time), much closer to all the other versions

 

[parzdiver]

This is making me want to buy some old stuff just to restore it.

 

[Mobulai]

This is making me want to buy some old stuff just to restore it.

You just described most if my „free time“ since I joined Scubaboard (it was rebreathers that motivated me originally)

Madness ahead!

Every now and then I come across something that just screams „you gotta dive me“ like the 156 I have been „gifted“ (I say gifted because it is, even if I paid something for it— them things are rare; many thanks to an unnamed generous benefactor that I don’t know if he wants the attention for being a source ) or the few 109/BAs that I’m restoring alongside the countless mk10s that I actually wanna dive or the old mk19
I found and bought this kit while I was looking for parts for the 109s, so after I got myself a 108 to restore as well, and the vicious cycle continues

I wonder how long it’ll take me to get a DH

 

[halocline]

I don't think that's a Service Kit, that's an Upgrade Kit from a SP 108 to a SP 080, that's why there are no o-rings ( the orifice has one probably)......

What does the upgraded consist of? I’ll take a guess, and you can correct me. I have some 108s that have a very different lever and diaphragm, and I think the orifice is not adjustable (It’s been a while). Other 108s seem to share the diaphragm with the 109, which requires a different lever and orifice, and a different purge cover. That must be the 080 upgrade.

I’m using one of those that came with an orange exhaust tee and mouthpiece as my O2 reg, with a MK2 1st stage.

 

[Mobulai]

What does the upgraded consist of? I’ll take a guess, and you can correct me. I have some 108s that have a very different lever and diaphragm, and I think the orifice is not adjustable (It’s been a while). Other 108s seem to share the diaphragm with the 109, which requires a different lever and orifice, and a different purge cover. That must be the 080 upgrade.

I’m using one of those that came with an orange exhaust tee and mouthpiece as my O2 reg, with a MK2 1st stage.

I spent most of yesterday cleaning and tuning one of the 108s (I chose that one ad it had a blue diaphragm so it was random) that I have (mostly dressing the orifice), and successfully got it to 1.2 inH2O / 280pascal after quite a few back and forth with the orifice, micromesh, nut and all the clamps un/re installing

That was the 1st downstream 2nd I worked on, during which I scanned through some threads about 108s and also the schematics I could find
I came across some 108 and 080HP schematics but saw no (noticeable for me) difference on these
I did read something about non tunable orifices somewhere
What I did notice is, the one I was working on had a noticeably „fatter/rounder“ body than other 108s or 109s, it was more spherical

I can’t tell which is which but if that orifice wasn’t tunable I’m sure I would have had a tougher time working it is all I could say.. so that would make sense to have been the upgrade

I also noticed that I had another lever variant in a „mystery parts“ box that I got my hands on recently from a closing dive school; I was a bit „over confident“ disassembling and didn’t take pictures before, only to find the 2 lever variants next to eachother; I eventually used the one closer to the lever that came in the upgrade kit
The main difference is, one sat on the falcrum „higher“ than the other — ala curly foot lever „141“ vs older 109 ones
One was parallel to the body (or an imaginary barrel if you will), the other at almost a 45deg when aligning the feet to the housing (no poppet bo lock nut)
Edit: it did also have a curly tab lol

Edit2: what shocked me the most was the spring, apparently it used the 216 just like BA/250/… and the rest of SPs balanced lineup (I had the same issue with mixed parts on the springs with a 250v spring… not that it made a difference beyond me wasting time trying to gauge which is stiffer and a false that they were different)

 

[Mobulai]

Couldn’t let it go, I think this is the original 108 (that gets upgraded to 080 HP)?

Hi everyone, I hope to get some tips about rebuilding an old SP 108. Thanks in advance for any comments.

The reg is the non-adjustable orifice type, has old (rubber? original?) mouthpiece and exhaust tee, not too sure about the other soft parts. It scrubbed up really well but I'd to replace some things before they fall apart.

1. The diaphragm is pale blue silicon, not the standard shape - more mushroom than dome. It fits perfectly and looks in good condition. If I need to replace it can a modern SP diaphragm be used? Or maybe a NOS 109 if I can find it?

2. I think the clamp screws are metric (not 5-40 anyway). Has anyone worked out the specs? My best guess is M3 x 0.50 mm based on counting about 18 grooves in 9mm of thread.

3. Does anyone know of an available exhaust tee that will fit? The ID of the old one is approx 26mm (.87"). The flange on the reg is 30mm, stepping down to 25mm. All circular. An OEM 109 exhaust tee fits with a lot of slop but might work. An aftermarket VDH one is even more sloppy.

4a. Exhaust diaphragm Q1.
Is the exhaust diaphragm 23mm? It looks tiny but I don't want to take it out and possibly break it unless I have a replacement.

4b. Exhaust diaphragm Q2.
Should I be doing anything with the bottom (metal) exhaust diaphragm cover? It doesn't look like it unscrews, does it just protect the diaphragm?

4c. Exhaust diaphragm Q3.
Is there an easy way to change the exhaust diaphragm? My first thought is to roll up the new one like a cigar, push it through the grill, then apply equal parts patience, alcohol and cursing until it comes good.

Regards, Michael.

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