Recently after having my car sit for 3 months I noticed a metallic thud sound wich can be heard in any of the two following scenarios:
-When braking only when im reverse (it only happens once for every time I depress the brake pedal). -When going from stationary in to reverse (only one thud when the car starts moving)
My vehicle is a 1990 Citroën Bx and this sound is never heard at high speeds or anytime the vehicle is not moving in reverse. The sound doesn't seem like it's coming from the transmission. I recently changed brake pads and rotors on all four wheels but the sound is still present. The sound is comparable to hitting a stationary object in sound and feedback.