I have noticed in the past few weeks that my 2016 2.3L Ecoboost Premium Mustang will make a very slight knock, in the general area of the rear passenger wheel, when I go to reverse from park and then from park to drive. The noise doesn't happen when I actually shift into the gears with the gear selector. It happens when I start to move in the direction I put it in (reverse or drive) and I only hear it then. I thought that maybe it might be because it is on a hill when I do these actions as well. I don't hear it but when I back out of my driveway and pull off on the road. Potential axle noise, brake noise or something else. I have no clue. It seems like makes the noise once it goes past a certain point because I have tried going extremely slow and it wont make the noise as soon as I put my foot on the accelerator. Any help is appreciated.

 

Might be a good move to check the tightness of the wheel lugs on the wheel making the noise.