Question Scubapro MK20 swivel retainer failure questions.

[happy-diver]

 

[Still Kicking]

I bought my first Mk 20 in about 1995/96 but i think you're right about the switch to stainless steel predating that model.

 

[Eric Sedletzky]

I have never heard of brass retainers for the MK20 and frankly I would be shocked to see one. The change from brass to stainless steel was made in the MK10, which is two generations earlier than the MK20. I think the MK20 was first produced around 2000 (I'm not sure of that) so I guess it is possible that some of the very earliest ones had brass retainers. Maybe I'm wrong about the timeline.

I still have at least one MK5 that has a brass retainer but all of my MK10s have steel ones. I have (I think) one of the vdh MK5 SS retainers left and maybe someday I'll install it on that MK5, but the brass retainer looks perfectly fine to me.

I also would be very surprised to have one crack at such a low torque if there was no visible damage under inspection with a magnifying lens. But I guess it's possible. Those brass retainers worked very well when not over-torqued (or maybe damaged in some sort of impact, like a tank falling over with the reg attached) for many years. I understand the desire to change them out because if they break in use, it's catastrophic, but I think it's very rare. I sometimes use MK5s in cave diving and for those I have the SS retainers installed.

I've seen early MK5s that used just a circlip to hold the turret in place.

I bought my MK 20/ G200b in 1998.
I also just upgraded my MK5 with a new S/S bolt from Bryan.

 

[sumpguppy]

We had those made for the MK5. They will not work in later models.
@Diver Stan You'll have to scratch the surface to determine if you have a SS or brass retainer. (Actually, I hope someone has a better way.)

Edit: @Joris Vd Where did you obtain the MK10 retainers? I do not think the VDH retainer will work on anything other than a MK5

Density of typical brass – UNS C26000 is 8.53 g/cm3.

Density of typical stainless steel is 8.0 g/cm3 (304 steel).

Maybe a good scale could tell the difference?

 

[axxel57]

I have never heard of brass retainers for the MK20 and frankly I would be shocked to see one. The change from brass to stainless steel was made in the MK10, which is two generations earlier than the MK20. I think the MK20 was first produced around 2000 (I'm not sure of that) so I guess it is possible that some of the very earliest ones had brass retainers. Maybe I'm wrong about the timeline.

I still have at least one MK5 that has a brass retainer but all of my MK10s have steel ones. I have (I think) one of the vdh MK5 SS retainers left and maybe someday I'll install it on that MK5, but the brass retainer looks perfectly fine to me.

I also would be very surprised to have one crack at such a low torque if there was no visible damage under inspection with a magnifying lens. But I guess it's possible. Those brass retainers worked very well when not over-torqued (or maybe damaged in some sort of impact, like a tank falling over with the reg attached) for many years. I understand the desire to change them out because if they break in use, it's catastrophic, but I think it's very rare. I sometimes use MK5s in cave diving and for those I have the SS retainers installed.

I've seen early MK5s that used just a circlip to hold the turret in place.

I don’t want to shock you, Halo, ,but the Mk20 came in ’95 in Europe on the market, in the US one year later and the first years they used brass screws.

So the change from brass to SS was probably not implemented during the production of the MK10 (PLUS), but after it had been taken off the market in ‘96.

The brass retainer screws were used until middle 2000, what can be seen with the torque specs on the schematics, before and after the SS screws were implemented (see MK20 Schematics).

Since the Retainer Screw of the MK10 and the MK20 had the same Order Number ( so had the brass and SS screws), I guess SP just recommended to change the screws at the Services and put it on the '01 MK10 schematics.

Concerning the MK5 Retainer Screws, over the last thirty years I have seen at least three cracked MK5 Retainer Screws and one MK20 Retainer Screw.

I was on board in '96 when the MK5 swivvel of my boss’ 1st ripped off just before we were going to dive on a Tilla in the Maldives.

He was not unhappy that that did not happen fifteen minutes later…..

 

[Eric Sedletzky]

I wonder how many people mistakenly use a ft lb torque wrench instead of an inch lb wrench?
Or no torque wrench and just “snug” it up, which can mean a lot if different things depending on who’s behind the wrench.

 

[BoltSnap]

I think the MK20 was first produced around 2000 (I'm not sure of that)

I bought my first MK20 circa 1996.

 

[halocline]

Well, I learned something new today. Thanks!

 

[lexvil]

Other than the appropriateness of material it helps to remember these are all old Regs that may have been damaged by someone in the past.

 

[rhwestfall]

That is the 2-port (LP) MK-5 correct?