Mk5 Questions

[redacted]

My 12/97 calls for 35 to 45 inch-pounds. I stay on the light side with the brass retainer. I don't use any loctite. If you PM me an email address, I'll send you a copy of that schematic (200kb).

 

[Zung]

The nut is very thin. You may want to grind off the chamfer of your socket, or it may slip.

Another reason I haven't started messing with mine yet; the main reason is it ain't broke.

 

[LeadTurn_SD]

The nut is very thin. You may want to grind off the chamfer of your socket, or it may slip.

Another reason I haven't started messing with mine yet; the main reason is it ain't broke.

Thanks, it may make life easier if I "sacrifice" a socket for the Mk5.

I did notice that the turret bolt wanted to slip when I removed it, I had to be very careful when removing it. Grinding the socket down a bit sounds like a great idea.

Best wishes.

 

[LeadTurn_SD]

I had meant to ask some questions regarding shims, and forgot ("senior moment"):

In my Mk5, all 3 shims were located in the same place, at the body-end of the spring. In the Mk5 schematic, it shows the spacers on either end of the spring.

1. Does position of the shims on one end or the other of the spring make any difference??? (sees like it would not)

2. I think placing shims under the HP seat to lower IP was also mentioned?

Just curious about the relationships with shims, their position, and IP (I think I understand, but want to make sure). To date, I've only rebuilt diaphragm regs, where setting IP is simple.

Thanks.

Best wishes.

 

[aquaregia]

I was taught to put up to one on one side of the spring and up to two on the other, with no discrimination between sides of the spring. This is based purely on a single tutorial session with a tech, so take with caution.

 

[LeadTurn_SD]

I was taught to put up to one on one side of the spring and up to two on the other, with no discrimination between sides of the spring. This is based purely on a single tutorial session with a tech, so take with caution.

Thanks.

I'm guessing it does not really make a difference because the goal is to slightly increase compression (preload?) of the spring, but I'm curious since I found all 3 shims on the same side.

Best wishes.

 

[redacted]

I had meant to ask some questions regarding shims, and forgot ("senior moment"):

In my Mk5, all 3 shims were located in the same place, at the body-end of the spring. In the Mk5 schematic, it shows the spacers on either end of the spring.

1. Does position of the shims on one end or the other of the spring make any difference??? (sees like it would not)

2. I think placing shims under the HP seat to lower IP was also mentioned?

Just curious about the relationships with shims, their position, and IP (I think I understand, but want to make sure). To date, I've only rebuilt diaphragm regs, where setting IP is simple.

Thanks.

Best wishes.

Shims can be placed on either end of the spring. 3 shims max which should be no problem in your case.

Shiming under the HP seat was my idea when I wanted to lower IP below what I got with no shims installed. I cut some dime size discs from a thin sheet about the same thickness as the SP washers. It is not recommended by scubapro but it worked for an additional 5 to 10 psi drop in IP. When you remove all 3 shims, yours should be fine without any such shade-tree modifications.

 

[Couv]

Sorry I’m late to the party. Most of what I would have said has been posted, but here are a couple of other tid bits: Yes, the shims should be separated. In the case of two, one goes on each side of the spring. In the case of three, which I believe is the max recommended, I would put two on the body side and the other on the piston side of the spring. This brings us to a point I haven’t seen made. I would start with one shim-between the body and the spring (unless it brings the IP out of range.) I like to do this for a couple of reasons. 1) Because the spring is stainless steel and the body is brass, the shim affords a little protection from the spring. The piston being ss also should not be a worry. The shim may also reduce some of the harmonics issues that piston regs can have.

In a search through my memory banks, I seem to recall that the red paint on the spring is some sort of anti-corrosive. But if it’s flaking off and getting into the hp area, it's probably best to clean it all away. But I don't see how that can happen unless the person who serviced it last was fumble fingered.

I haven't tried it, but as Awap said, shim under the hp seat should lower the IP. I have sanded a bit off of an old puck seat and raised the IP.

Couv

 

[Zung]

... I like to do this for a couple of reasons. 1) Because the spring is stainless steel and the body is brass, the shim affords a little protection from the spring. The piston being ss also should not be a worry. The shim may also reduce some of the harmonics issues that piston regs can have.

Kudoo to my brother for the scientific explanation of something that's otherwise wispered at midnight according to the secret handshake protocol!

... I haven't tried it, but as Awap said, shim under the hp seat should lower the IP. I have sanded a bit off of an old puck seat and raised the IP.

Couv

Likewise, or otherwise, one single shim between the body and the seat retainer will raise the IP by a few PSI. I tried this with the blessing of Master awap Himself.

 

[oceancurrent]

Great stuff, everyone. Threads like this are the reason I am lurking around the DIY forum. Pure gold!

I have an MK5 that I rebuilt and love its simplicity. The turret bolt looks like a disaster waiting to happen, but since I haven't heard any reports of MK5 turrets jetting out, I guess it's reliable enough. I prefer a good solid ss piston any day over the flimsy TIS composites that ScubaPro packs in their MK25s. I don't believe that stuffing regs with plastic solves anything!

A question that lurks in the back of my head... Is there a way to convert an MK5 to DIN reliably? Does anyone have any experience using such a converted reg with 300 bar cylinders (in theory there shouldn't be any problem)?