Where to find parts for SP 109/156 regs?

[VTscubaDAN]

1) I've always appreciated the design and durability of the older SP's so I recently took the leap and purchased a MK5/109 combo from ebay. I've spent much of my days since searching the threads and google for any info about these regs like service manuals, owners manuals, spec sheets, rebuild instructions, etc. I've founds lots of folks who say how much they love their regs, but haven't been able to find manuals for them or sources for parts beyond the o-rings, poppets, etc. I'd like to upgrade this 109 to the 156 balanced adjustable which I understand I can basically do with the G250 kit, but I haven't found a kit with the lighter spring included. Is there a better way (like a source for the original BA upgrade that I've heard legends of around here)? Are there any good sources for SP internal parts online or do I have to track down a local SP shop to order the parts? Has anyone found a good tutorial for doing the BA conversion? If anyone has service manuals for the older units in pdf, I'd appreciate a link to it.

2) At the other end of the hose is the MK5. After all of the reports I've read about this setup being the easiest breathing reg ever, I was a little disappointed when I tested this one. The flow is low even after adjusting the 2nd to the point of nearly freeflowing, yet when I breathe off the 2nd, it feels like a gun with too heavy a trigger-pull followed by having to suck harder to increase the air flow (shallow breaths are like breathing through a straw, but a large, forced breath delivers a larger gust of air. Is this normal for these regulators? My sense is that the MK5 is sending a consistent IP, but that it's something in the 109 that makes breathing awkward. I can't see how to lower the cracking pressure any further as the adjustment knob is turned out to it's stop on the one side and the adjustment plug on the inlet port is turned to the edge of free flow. My understanding is that this is as easy as I can mechanically make it breathe with the current configuration.

My experience has been with a ScubaMax XR2002 2nd for the last 8 years which tends to push air when I breathe rather than making me pull it, so maybe my expectation is skewed? On the otherhand, I can see where this would greatly lower my air consumption for dives where I'm not exerting myself (shallow breathing).

Does anyone have enough experience with these to effectively describe what the "breathing experience" should feel like?

Thanks for your help in advance!

 

[Scared Silly]

This auction is from the former owners of ScubaTools Pete Wolfinger. They are cleaning out the shop and lots of ScubaPro stuff for sale. You might find what you need from them.

bigfoot-daisy | eBay

 

[ams511]

Welcome to SB Dan. You may have better luck with your question about parts if you have the mods move your post to the DIY repair section.

As for the breathing, the 109/156 does not have any venturi, so you will not get the air being forced into your mouth sensation.

 

[halocline]

As for the breathing, the 109/156 does not have any venturi, so you will not get the air being forced into your mouth sensation.

It does have venturi assist, just not an adjustable vane like the later 2nd stages. But I agree that you don't get the overload feeling that some newer regs can give you.

The only thing that's normal for a properly working MK5/109 is smooth easy breathing, so something is definitely wrong with the OP's. The schematics are easy to find; in fact I'll try to attach them to this message. The Vance Harlow book has excellent chapters on rebuilding balanced piston first and barrel poppet 2nd stages, so I'd recommend that.

As far as the conversion to balanced/adjustable, if you can find a NOS rebuild kit for the G250 it will have the poppet and balance chamber. You'll have to get the spring separately, but any decent SP dealer will have one, and I suspect you'd be able to convince one to sell it to you. In fact, there's a SP dealer here on scubaboard named beaverdivers who is CONSTANTLY pitching his products and touting what a FANTASTIC dealer he is, so maybe he'll be a good guy and sell you the parts you need without the B.S.

The current kits have only seals and o-rings, so you'd need to buy a poppet, balance chamber, and spring separately, but it still shouldn't be too much.

 

[Wolfie]

As ams said, DIY forum, there is a lot of info regarding this specific reg and some die hard members that will give you all the info you need. When they run out of parts they whittle their own.
Good luck

 

[ams511]

Dan your first step should be to check the IP of the MK-5. it should be 135 +/- 10. Alternatively you can mount the second stage on you Scuba Max first to see if it is the first or second stage giving you the problem. My guess from what you describe is the second stage is that the level height is not set correctly. You need to inhale strongly before the diaphragm engages the lever then you get a blast of air. Get the Harlow book and read up the threads in the DIY section.

 

[Zung]

Like halo said, a working 109 gives a "smooth easy breathing". Regarding yours, don't worry, I'm sure it's only in need of a good service. Been there, my 1st impression with the 109 was exactly like yours: I had to suck like hell to get any air at all. After servicing it, it was completely transformed.

My advise is: rebuild your as is, enjoy it, and take the time to find the parts to upgrade it to the BA level. No rush, there's not a lot of difference between the two, the upgrade is just a nice to have item.

 

[VTscubaDAN]

Thank you for the quick response all. Should I just repost in the DIY forum, or is there a procedure to have this moved? And thanks Halo for the pdf's!

Btw, can anyone tell me the performance difference between the old blue poppet for the BA and the newer S-Wing? Does it swirl the air more as it comes in?

I think the lever geometry may be off as AMS suggested (thank you). I took AMS's advice and played mix-n-match with the 1sts and 2nds. The 109 breathes a little better on the newer 1st, but still has a lot of takeup before a distinct, mechanical crack. I don't have an IP gauge (yet) or a manometer, so I can't quantify my experience, but I'll take these with me to the LDS the next time I need a fill and see if they can at least benchmark them for me.

---------- Post Merged at 10:54 PM ---------- Previous Post was at 09:42 PM ----------

After deciding that I would have to get a new lever anyway, I figured I wouldn't have much to lose by modifying this one. I found another post around here that said the 109 should purge within 1/16 to 1/8 " depression by the diaphragm. Mine was easily 1/4" or a little more which appears to have been causing the long takeup I was describing earlier. I bent the forks of the lever up to make up the difference and now it's cracking much closer to how I would expect it should. I think the remaining roughness is lack of a progressing curve to the forks due to my crude bending. I have to think that the correct lever with a factory bend would smooth out the crack profile. I may strip it down again and try a more precise method of shaping the lever to save this one.

I'd still love to know what effect the various poppet designs have on the regulator if anyone has experience with them, thanks!

 

[Zung]

The major difference between the old blue poppets and the current ones is the seat: it's replaceable in the current ones, and fixed in the old ones, so the whole poppet had to be replaced. Performance wise, it's hard to tell a difference.

You didn't say if your reg. has been serviced or not, so I assume it's in an "unknown" state. In such a case, the steps should be, and in this order:

1. A thorough test according to couv's commandments
2. A full service, including the replacement of both seats
3. Test again

This should fix most of the common problems, the most common ones being engraved seats, and crud impairing the movement of various parts. You only bend the lever or, worse, file the openings of the barrel, as a last resort, if all of the above fail.

Out of my dozen or so 109/156/G250, only one had a lever problem that I fixed by swapping. I never had to bend any one at all.

 

[VTscubaDAN]

Thanks all. I replaced the lever and updated the poppet/spring assembly to the balanced configuration. Breathes like a champ now. The lever was out of shape previously, causing my problems.