Joints with rigidbody and gravity

[rosostolato]

I have a part with a hydraulic cylinder in swing. When unity is not running, the cylinder case moves synced with the cylinder itself, but when unity runs and physics start to work, it loses its sync.

It's hard to explain in text, so here is a gif of what is happening:

As you can see, the swinging cylinder is using rigidbody with hinge joint because I need it to respond to gravitiy, it needs to extend and retract the piston automatically when is forced by gravtity.

So my question is: is there a way to work with joints and gravity to make a "swingable rocker hinge"?