Scubapro MKV Red Spring

[jacked_72]

I just picked a NOS red spring assembly package for the SP MKV. In it is a little note saying that with the red painted springs, two washers (the term it uses) must (which is underlined) be used and refers to Engineering Bulletin #35.

I'm wondering if they were optional with the non red springs and if the red springs had some different sort of tension that required the use of the shims to get the correct IP.

Does anyone know? I've probably gone through 5 or 6 MKV regs and I have not found one yet that had two shims. Most have one, some have had none, but none have had two.

 

[redacted]

I suspect the washers were used to dampen any sound as well as set IP. So, use them if you need them. I usually run my IP in my Mk5s on the low side (125 to 130) so most of mine us 0 or 1 washer (IP shim).

 

[Couv]

I've heard two unconfirmed and only slightly plausible stories about the "red spring."

1. The red coating is an anti-corrosive.
2. The red coating is an anti-ice coating.

So now, you've piqued my interest. I'd like to see this

Engineering Bulletin #35. ​

Calling Zung, Luis H, or DA to chime in with the real story.

Couv

 

[jacked_72]

I can't help with Engineering Bulletin #35, but here's the note in the kit. The spring is painted and most of the paint is already coming off, so I don't know that either theory could be correct as they would require the paint to actually stick. The washers, not shims, are .011 in thickness. My wild guess is that the spring is shorter than the originals. How thick are the shims generally on the MK5?

edit: I took a closer look at the spring and only one half of it is painted. It is painted as if you stood it up on an end and sprayed it from the top--just one side gets painted. The other side has no paint.

second edit: As I looked at the picture, I noticed it was addressed "Dear Customer." How ironic. Scubapro won't even admit it has customers now. Just distributors. And good luck buying a regulator part today, Mr. Customer, off of Scubapro.

 

[mahjong]

I was once told by a technician that red springs belong to the MK10, and that they were painted red precisely for this reason. Have no idea how true this is. Could the additional shims be necessary to allow an MK10 spring to fit inside an MK5? Just a wild guess. I never measured them, not to mention internally, but the MK5 does "look" a tiny fraction longer than an MK10.

I've heard two unconfirmed and only slightly plausible stories about the "red spring."

1. The red coating is an anti-corrosive.
2. The red coating is an anti-ice coating.

So now, you've piqued my interest. I'd like to see this

Engineering Bulletin #35. ​

Calling Zung, Luis H, or DA to chime in with the real story.

Couv

 

[redacted]

I was once told by a technician that red springs belong to the MK10, and that they were painted red precisely for this reason. Have no idea how true this is. Could the additional shims be necessary to allow an MK10 spring to fit inside an MK5? Just a wild guess. I never measured them, not to mention internally, but the MK5 does "look" a tiny fraction longer than an MK10.

Since the piston head surface areas are about a factor of 2 different, the strength of the springs should be also.

 

[Zung]

I don't have the EB #35, but one thing I know for sure: Master awap is always right.
Once upon a time, there was an unfortunate leak from one of the holy few who passed the SP midnight secret handshake ritual, and it goes like this:
"The reason given for the minimum two shim requirement was to eliminate resonance from metal to metal contact between the piston and spring and the body in the MK 5, Mk 10 and Mk 15."

Another possible explanation is they had a batch of known weak springs, so they sprayed them red and recommended an extra shim. Cheaper than throwing them away.

Most of my MK5's are low on IP because of the Trident seats, so I use all 3 shims.

 

[redacted]

Hey, I'm just making an educated guess. I have some Mk5s with just a trace of red left on them and I just target my desired (low spec) IP. The Mk20 washers are too large for the Mk5/Mk10.

 

[halocline]

I thought the MK20 washers would be the same as the MK5, but the MK10 ones would be smaller; just like the piston head o-ring. I don't seer how you could confuse a MK5 and MK10 spring. While I've never compared them side by side, the pistons are very different diameters.

 

[redacted]

Picture is worth 1000 words. Mk25 - Mk10 - Mk5