Well when i put the car to P to R, it makes a loud banging noise and the car moves a bit. But when the car is warmed up, it shifts smoothly?

 

The only thing keeping you car still is a 1/2 inch block of metal that jams itself to keep the car from moving. Well when you park even on a slight incline, even .01 degree, the car will roll back slightly and put all the weight on that .5 inch metal. Well when it disengages, it will cause the noise since it the car's weight is on the piece

 

Ohh, okay cuz my drive goes down quite a bit.

 

This is why I always engage the hand brake BEFORE I take my foot off the brakes when I'm parking.