I'm looking to see if anyone knows why my car rattles when I step on the brakes. As long as I'm going over 20 mph, when I press the brakes there's a big rattling sound from the rear passenger side. Hopefully someone can help me out because I don't have money to fix a BIG problem. Thank you!

 

Loose caliper?

Missing pad shims?

Missing pad springs?

Could also be bearings, worn rotors/pads, etc. The only way to know is to inspect.