I agree that steel rivets would be better than the bolts.  I am not certain of the difficulty in squeezing them, but they would provide a “press fit” where the bolts would not.  The strength would be similar in shear which is where most of the forces would be.  They would also be a lighter, important in a rotating mass.   The idea of putting something like “Proseal” in before assembly makes sense as well.  The combination should ensure that shear forces would never move it.  In the current situation it must be moving else the rivets could not loosen???

 

Bill B

Ok guys the obvious solution here is to size the holes. Most bolt shanks wont vary more than a few thousanths. The fix is to drill the holes out undersize and ream than to fit with an adjustable reamer