Thanks Lou! So that shaking comes from turbulence hitting elevator?

Also i noticed in general, that extended speedbrakes makes plane much more sensitive in roll. Looks as it should be. is that right?

And is there any bank angle restriction when turning with speedbrakes extended? I noticed that if i try to descend on A\P, with spdbrakes.(especially in 727) In turns (using HDG HOLD mode) it dangerously drops the nose! It turns with high bank angle, and it looks like lack of lift and it drops the nose down to  -10, -20  :o So i quit using A\P and speedbrakes together.
Did you had some rules about that?