@mitu thanks once more for your response.
The only stand-alone emulator that i am using is Amiberry, all the others are lr-ports.
In some way i am forced to use only lr-ports, because i am addicted to retro-achievements :)
In my first year of RetroPie i used two PS3-SixAxxis Pads, because i allready had them. They have nor umble at all, so the topic was not relevant for me.
Since 2013 i am using 8BitDo SN30Pro-Pads constantly.
I started 100s of PSX- and -DC Games over the years, but these pads never rumbled at all.
Since yesterday, "Tokyo Extreme Racer 1" for the DC brings the pad on fire :D
But it is the only game doing this.
My guess: these Pads are able to rumble (everyone knows that) but seems highly incompatible to RA-FF-Functions.
With a Ratio of 1:500 it works ;D
I could imagine that as soon as i buy a more popular pad (XBOX, Switch, ...) it will rumble all the time.