Mk5 Questions

[ams511]

I appologize for not linking this to an existing thread but I am on a different computer and I cannot find the appropriate thread.

I finished rebuilding my first MK-5 last night and wanted to rebuild a few more. However I am running into some problems.

1. The two mk5s I disassembled seemed to have the steel turrent nuts. What size socket removes them? Does the same socket work on the brass ones also?

2. Yokes. I am using the Scubatools yoke socket and extender and am finding that the socket does not fit the older nuts well and that the extension is too thick to fit through the holes of the early and middle mk-5 yokes.

3. Yoke nuts. Some of the nuts will not take a cone filter. I realize I can get the disk filters from Trident but is there a reason Scubapro changed these yoke nuts?

I would appreciate any suggestions, especially off the shelf ones as a do not have a work shop. Thank you all for your help.

 

[elan]

The socket for the turret nut is the same. I do not remember the size now - not at home but important thing is to find one without round over edges on the inside otherwise it slips. Or you can always buy one from Herman he has a proper socket that works well.

I can look up the size when Im back home.
Cannot answer the yoke questions as mine are all DIN

 

[herman]

I can answer 1 and 2.

1: It is a 11/16 and yes it does....now that said, most sockets have a slight bevel on the end to make getting the socket on easier, all well and good if you have a lot of nut to grab on to, the problem is, that nut is very thin. So much so that on some sockets, the bevel is almost as wide as the nut face. If the nut is the least bit tight or corroded you stand a good chance of rounding it over, the SS less so than the brass but you can round over either. I suggest you only use a 6 point socket, you will get the maximum socket to nut contact that way. You can use a 3/8-24 bolt or a reg vise tool to hold the turrent when you loosen or tighten that nut.

2. The socket should fit the older yoke nuts but there is very little room at the bottom of the socket on any of them. SP did a poor job of design on that one spot. Sockets have to be machined a lot to get them to fit. The socket entender will not fit through the hole on any yoke except the latest 9/16 one. There is just not enough room in the older designs to pass the socket though. If you are the gotta torque it type and have the older yokes, you have to use a crowsfoot and likely it will need to be modified to work around the yoke. If you are not picky about torque (I am not) then there are other options such as a large wrench with the throat ground out or a large adjustable wrench or a machined down socket and a pull bar.

I know some will disagree but torque is not that critical on the yoke nut. The seal is done by an oring so any torque in excess of seating the nut is just to keep it from coming loose. Being a brass to brass connection the main thing is NOT to over torque it, as long as it's plenty snug with a reasonable sized wrench it will be fine.

---------- Post added March 19th, 2013 at 07:07 PM ----------

 

[Zung]

3. SP started with the flat filter, then improved the design with the conical one which offers more surface area, therefore better flow and filtering.

 

[halocline]

The big problem with the early yokes is getting a 1/4" drive 1" (or 25mm) socket. No way can you get a 3/8" drive extension through the yoke-screw hole. Unless you're willing to buy a special socket and then use a 1/4"-3/8" adapter for a torque wrench, just a big adjustable open end wrench. I agree with Herman that the torque spec is not that critical. You're probably going to over torque it; apparently some studies have shown that the human tendency when estimating torque is to over tighten. It's probably not a big problem on the yoke nut.

On the turret retainer it is, more so with the brass ones. Are you sure that what you have is not chromed brass? It's not that easy to see the difference. I haven't messed with too many of the early small-yoke MK5s, but every single one I've seen had the chromed brass turret retainer, except for the really early ones that used a circlip to hold the turret in place.

The flat filters aren't considered as good, but so what. Use decent tanks with decent quality fills and you don't even need a filter.

 

[redacted]

I made my own 1", 1/4 inch drive yoke nut socket. I started with a 1/2 inch drive socket and cut it down with a dremel too to fit inside the yoke. I the took and ole 1/4 inch drive socket and cut it to fit inside the 1/2" drive opening. A little JB Weld and it was good to go. Ugly but works.

 

[herman]

What do you "gotta torque it" guys think about something like this? This thread got me to thinking about torquing the old 3/8 and 7/16 yoke nuts and after an hour or so in the shop this is what I came up with. It uses a 1/2 drive 6 point socket and a 1/4 to 1/2 adapter. A standard 1/4 extension will pass through the older/smaller 3/8 yoke with a little room to spare. With a 1/4 drive torque wrench or a 3/8 to 1/4 adapter and a 3/8 torque wrench you guys could torque the older MK-5s to your hearts content....works on MK-2 also. If there is interest I would bet it will show up in a tool catalog soon.

 

[redacted]

Yours is a lot prettier than mine.

I used to have a picture in the photo gallery but can't seem to find any of my pics any more. Oh well.

 

[Zung]

Brilliant! Add it to herman's must have toolkit.

 

[ams511]

Is the MK-5 turrent bolt the same size as in the MK-10 and 20?

---------- Post added March 21st, 2013 at 03:46 PM ----------

What do you "gotta torque it" guys think about something like this? This thread got me to thinking about torquing the old 3/8 and 7/16 yoke nuts and after an hour or so in the shop this is what I came up with. It uses a 1/2 drive 6 point socket and a 1/4 to 1/2 adapter. A standard 1/4 extension will pass through the older/smaller 3/8 yoke with a little room to spare. With a 1/4 drive torque wrench or a 3/8 to 1/4 adapter and a 3/8 torque wrench you guys could torque the older MK-5s to your hearts content....works on MK-2 also. If there is interest I would bet it will show up in a tool catalog soon.

Herman I am not sure I would buy one of these because I already have the scuba tools yoke socket and a 1/4" extension. What I would need is an adapter to use the scuba tools socket with the extension. Now if I did not already purchase the scuba tools socket or if this thing was cheap enough I would buy it.