My 25 year old classic DF has a "freewheel" (inside the rear cog stack) which screws on to the rear hub. The clearance in the freewheel bearings is set by a stack of shims. My shim stack is about .002 too thick, which makes the bearing races wobble slightly under certain load conditions and in certain gear combinations. This produces an annoying clunk/clank noise in sync with the pedaling (but varies depending on gear) which I can sometimes feel in the drivetrain..
The noise is particularly loud when cold and/or when I first start off, but it seems to diminish with miles (as it warms up?). I have no idea how a freehub or freewheel on a delta trike axle works, but....
Hal