My 126 ('91 300SE) kinda chewed up my new rubber doughnuts that hold the end of the front swaybar to the upper control arm.
I noticed the sway bar shaft was pretty rough under the old doughnuts I removed. I really didn't clean up the bar, I assumed the new doughnuts would stick to it. However, it seems the new ones are chaffing on the rough bar, and getting reamed out.
They look pretty rough and have a lot of powder, and groan loud after 4k miles.

So, should one clean and sand the bar to make it smooth, or was it intended to be rough so the rubber would adhere rather than slide on it? It looks like rust build up, but maybe it was always intentionally rough. I assume I should not use lube of any kind, except maybe the rubber slide lubricant that dries up after an hour or so?

oh, everything else is in good shape - ball joints, control arm inner bearings, etc.

Tks,
S=Class