I have had conversations with folks that have fashioned spacers and installed them that refined the noise and shaking to almost zero. I'm going to have to put that on the modifications list for the ole SD60.
I first made a spacer out of a copper sweat fitting, figuring it could swage to shape and take the impacts without hurting the steel. quieted the machine right up. then after 4-5 mows it ejected itself, I had it zip tied around the anchor..
Then I got some thicker copper sheet, and removed the anchor, pounded the copper around it, soldered to capture, and buffed down the edges for thickness. That really did the trick, no rattle, no nothing.... though the wobble and belt flap was still there. It lasted just shy of the summer. the only way it could have come off it for the copper to be pounded into foil and fracture off at the impact points front and back.
THEN I removed the anchor again, took it to my neighbor with a welder and we built up the thickness of the anchor so it wouldn't have room to build up speed. I buffed it down to fit in the clutch slot with only a business card of space (anchor, but not bind...) so far so good, it isn't as quiet as the copper bumper, but it is quieter than OEM and the OEM >1/8" gap. it is slowly getting louder and the gap is opening. I think the steel on steel is wearing the slot in the clutch.
I'm considering throwing a turbo on the thing to see if I can liven it up. Just kidding.
I'd love to hear the mower spool up when transitioning from ankle to knee high grass
