Would a brake rotor that doesn't slide on easily cause nasty scraping and knocking noises? My passenger side rear brake rotor doesn't seem to slide on nearly as easy as my driver's side one does. I have to hold each side and kind of shake each side back and forth whilst pushing it in towards the car. I know the rotor is not warped I just think the holes aren't lined up perfectly. Could I use a file or something to open up the holes a little bit? or is the bigger hole going to cause to much slack or make things worse?

Thanks

 

Ok I am going to try to open up the holes on the rotor a little bit today to see if it helps my problem... let me know if this is a bad idea for any reason.

 

I would not do that.
I would get a wire wheel and put it on a drill and run it on the lip on the axle.
I'm guessing that the rotor is not going on easy because of some rust build up on the axle.
Give that a try I'm sure that will take care of it.