U.S. Divers metal second stage flutter

[finflipper49]

Hi, I bought a U.S. divers metal second stage reg. to swap out my glacia second stage. I rebuilt with new exhaust tee, LP seat, o-ring and diaphram. It came with a grey diaphram which is thicker than the new black one. This is attatched to an Aqualung titan cone shaped first stage which based on the IP guage is working perfectly but when I breathe off the second stage it doesn't seem to breathe smooth when I take a deep breath. When I try the grey diaphram it flutters bad when I exhale. The cracking preasure seems good when I put in water "mouth side up". Free flows before it reaches mouth piece. I planned to have the whole thing serviced but if it is just a simple adjustment I may not need to. My glacia second stage worked fine. Any thoughts would be greatly appreciated.

 

[Fishpie]

Exhaust diaphragm "flutter" on exhale is common when dry.....goes away under water.
however....
If it's the main inhalation diaphragm that's making a noise then you probably have to adjust the lever height.
You say that the new diaphragm is thinner and this may be the problem.
Does the 2nd stage rattle if you shake it when pressurized?
If it does you can adjust the lever higher so it will just touch the diaphragm.....
Unscrew the volcano oriface nut.
Block the square seat body (from turning when you do the next step) by wedging a small flathead screwdriver next to it.
LOOSEN the lever nut a SMALL amount, try 1/8 to 1/4 turn.
Too much and there'll be a slight freeflow, too little and it'll still rattle.

 

[Paladin]

With the front cover off and the reg pressurized, run a flat straight edge, like a ruler, across the rim. The bottom of the flat surface should just touch the tip of the lever without causing air flow.

As far as diaphragm flutter when breathing dry, it isn't anything to worry about. Like Fishpie said, it goes away underwater. Underwater, the water has a damping effect that isn't present in dry air.