Popping sound only in reverse

[SnakeyesTx]

I keep forgetting to post this since its more of an annoyance than anything but ever since I bought the 39, I noticed a popping noise in the front end when I'm in reverse and moving. It generally happens within the first 3 to 5 feet of backing up. It doesn't jerk the wheel, but the noise can be felt like someone kicked the front end of the car and you feel the impact just a little.

I took the covers off the strut mount bushings and they look really reallly healthy but then again, its only the top I can see. Where else should I be investigating?

(Edit : I think the sound is on the driver's side)

[Ferret]

With the windows down and moving the car around slowly do you hear any rattling from the front wheels?

The E39 is prone to getting **** stuck down between the brake discs and the heat shield. The heat shield itself may be in contact with the brake disc allowing free forwards motion, but chatters on reverse.

Stick your head under the front end of the car and ping the heat shields with your fingers, see if they snap back against the discs!