Is it necessary when you replace pads to replace the shims also? Only reason I ask is someone mentioned that those would need to be replaced but in all the how to threads I hadn't seen it mentioned. My brakes don't squeak and never have. Just know they are getting low and I am thinking about the future.

 

you could try re-using the old shims if they don't look worn. If you have problems with noise you might have to pull it back apart and put in new shims.