MPS, Rebuilding the MPS Options

[Ron914]

Hello to all who have helped me with this project . @emerygt350 ,@TJB/914, @Superhawk996 , @ChrisFoley , @rjames , @MDTerp
I am in the middle of rebuilding my MPS and have a couple of comments and questions .
First when I opened up the unit I found the most difficult job was removing the rivets holding the two halves together.
When I removed the retainer plate to take out the old diaphragm it was in two pieces .

I needed to take two measurements since I was replacing the stop screw , I needed to measure the the stop screw protrusion into the housing . The instruction sheet sent to me by a member had the measurements he must have made when rebuilding his MPS . His stop screw protrusion was 1.97mm and mine only measured 1.72mm.
His inner/outer screw assembly depth in the old diaphragm measured 6.51mm .
Here's one of my questions ?
when I measured mine I got two measurements depth to inner/outer screw assembly was 4.03
and depth to the washer outside the inner/outer screw assembly was 5.46mm.
Again there is a difference and since mine was never accessed before (epoxy over screw was not disturbed) is the difference in measurements ok and which measurement should I use I will try to attach a photo or two to help with my question.
this one .

I have not touched either of these measurements yet and awaiting any help/comments.
I think it's this one to the washer on diaphragm .

[rjames]

Crazy that it could hold vacuum at all!

[Superhawk996]

Crazy that it could hold vacuum at all!

Mine did the same thing. It’s my belief that they don’t actually fracture into two pieces until you crack the case open.

I think it’s basically a giant stress crack but it’s not fully fractured. Thus the partial leakage.

Because there is the partial leak it basically prevents the diaphragm from moving anywhere near full travel - thus limiting further stress on the diaphragm when it’s assembled.

Then when the case is pulled open, it lets go all the way around. I can’t prove that but like you, seems to me if the whole thing was literally in two pieces it wouldn’t even hold the partial vacuum.