I have the exact smae issue at the moment. When acclerating hard from stationary or from low rolling speel feels like someone is banging from under my seat and passenger seat.
I dont think its the driveshaft hanger bearing, because i had it changed like 2 years ago. Plus the noise from the bearing is more hollow and quieter and its always present and low speeds.
Checked the two transmission mounts and it seems that one of them is a bit too soft.
Havent fixed it yet, still waiting to see if the symptoms will get worse and make it easier to pin point the issue.+
P.S. If you do end up dropping the tranny to change any mounts, ensure you check your rear main seal! ($80 at Maranello) Symptoms are leaking oil from where tranny meets engine.
Also inspect the driveshaft hanger bearing and flex disk.
Keep us posted.
E39 540i Sport
Last edited by Dado 540; 08-26-2011 at 10:35 PM.