My windshield wipers work but they go to far down and make a banging noise againsts the bottom of the windshield?

The answer to your windshield wipers making a banging noise could be a number of different reasons. It could be because they need to be replaced or it's something off track. The best way to find out the answer is either take your car to a mechanic or you could by new wiper blades and see if that works.