I had my stero system taken out of my car recently and I've come to notice something now that I dont have any stereo in the car!

This is gonna be very hard to explain....

When reversing and applying brakes as normal it does this fine, but if then change to drive then take off as normal, then apply brakes i hear this sound as if something has moved under my engine bay... but if i keep driving and braking there after there is no issues unless I then change into reverse then brake then i'll hear the same thing again (this noise happens only when braking for the 1st time moving that direction) but wont reoccur unless i change car direction and then apply brakes.

if this is confusing... ill try and explain again but hopefully you do get the idea!