ORIGINAL: mstam1971
without having a dial indicator and knowing how to properly check runout,you may never really be able to see ,but if youre getting a wobble on the backplate and the nose ,might sound like something slipping on the prop drive ,,dude,,,i dont know if you have kids,,maybe one of then knocked it off the table ,and didnt say a thing... oops,,,
ORIGINAL: unit53
man,,,that could be anything from loose engine bolts or firewall to the allen bolt that secures the spinner ,off balanced prop ,bent prop stud ,off center crank failing bearings,whew,,,you got alot to check,unless its obvious,if you havent had any prop strikes or crashes,,,,its easy ,not to look for off balance/center,then all of a sudden you check,i found a off center crank on another motor,that way,ive noticed on my 50 ,,that theres a hair of endplay ,if one was to move the prop up and down,check yours.
I noticed the tip of the spinner wobbling about a quarter of an inch and the distance of the backplate to the cowling wasn't consistent either. Took the spinner off and the backplate is 100% flat/straight. Maybe the spinner screw, will check tomorrow. Never had an impact.