Just trying to get the rotor on the hub, can't seem to do it. I've cleaned all of the corrosion off of it, but can't get it to seat in the last 3mm. I have no idea why, as I can't seem to find where it is hanging up on. Anyone that can help, please do.

 

Single piston front rotors, if that helps.

 

get a caliper (the one that measures..) measure the hub size and the interal size on the rotor and if is wrong, check part numbers to make sure its for your model of car..

 

or you can use some lugnuts to press it on, but I'd use mort2002's method first.