Reviews: SAT Variable Velocity Device Piston


1 Customer Review
Location: Z2-168

Displaying 1 to 1 (of 1 reviews)

by Greg I. on 2014-07-27 13:39:24
"The VVD piston actually works pretty good.
Good to have if you visit different fields that have different FPS rules.

But this VVD has a serious flaw... the piston shaft is made of very cheap plastic.
As mentioned in a Facebook comment, it will crack if you use a heavy (140 and up) spring.
In my case the cylinder was severely scratched up and the sector gear lost 2 teeth.
Seems that for $65 it would have a better piston shaft... if not aluminum.

What I did:
If you are mechanically inclined, you can take the VVD and mount it on an aluminum piston.

The actual piston head can be removed from the adjustable valve, but its not easy.
Remove the cheap plastic piston shaft.
You'll need 2 pair of small vice-grips, one to grip the piston flange and the other to grip
the value(be careful not to crush the valve).
The piston head flange will get grip marks, it's unavoidable, but you can genitally file the marks
smooth without messing up the o-ring seal.
Separate the piston head from the valve...ccw. I think they used lock-tight as it's hard to turn...

Once separated you can see that the value has a key that you will need to incorporate into
the aluminum piston.
You most likely will need to ream the aluminum piston hole just a bit so the valve will fit, and
file a notch to accept the values key(keeps it from spinning when adjusting).

I have purchased 3 or 4 of these over the past year, transplanting all of them to aluminum
piston shafts... and they work great now.

In one of my M4s I use a 150 spring(upgraded gears and gear box)with the VVD..., when
the valve is closed, I get about 460 fps (.20 g BBs).
Each setting down seems to reduce the FPS by about 20-25 fps.
This gives this M4 a real good range of FPS for the various fields to go to.

Of course, if all this sounds like it's too much, you can get a QD gear box. APS has a decent hybrid
and Matrix has a nice one also..., I own both.

Displaying 1 to 1 (of 1 reviews)