[paco29toy]

I recently got my 2013 328i and the caliper had some rust. Any one has seen this on their f30?

Any recommendations on how to clean them up other than use some sand paper and spray paint them?

[Whistlefist]

I would clean them with sandpaper/scotchbrite pads, or if its an option, disassemble and sand blast them. Then you can paint them.

Also, you might just try and look for replacements on eBay if you don't feel like going through the work. I just looked and they seem to be going for around 100-150 or so for the pair depending on quality.

Here is a pair for 135 that look like they are in great condition and possibly come with a set of pads as well:
http://www.ebay.com/itm/BMW-F30-REAR...FYzBSU&vxp=mtr

[paco29toy]

I might just clean them as you recommended. It will be my first small project on the car. Thanks for the suggestions!

[JamRWS6]

I'd start with a good iron dissolving wheel cleaner like Sonax first to see if that will take it off. Judging by the pattern of rust it looks to be possibly surface contamination from the pad sweeping a rusty rotor. Good luck