BMW Drivetrain Vibration Under Load – Acceleration
This answer is applicable for many BMWs in addition to the one listed below.
car year: 1999
car model: 323i
When doing a strong but not overly aggressive acceleration from a stop I notice a slight driveline vibration sound and can feel it somewhat on the auto transmission lever. Once acceleration is removed and at a highway speed there is no apparent vibration heard or felt. Passenger in right seat or rear seats can not identify a location other than the area of the automatic transmission console area. Car has 138,000 single owner miles and has never been in any accident or had any mechanical failures. What would be your recommended DIY troubleshooting decision tree?
Your symptoms point to either a weak center bearing or a weak driveshaft coupler flex disc (guibo). Either one of these will cause the vibration under load that you described. The rubber in both of these assemblies can be weak enough to cause the vibration, but can still appear OK visually. Obviously, any cracks in the rubber are reason for replacement as well. Since you have to drop the driveshaft to do either of these, we would suggest doing both at the same time. You will also need the gaskets and hardware for the muffler system, as this must be dropped in order to access the driveshaft (earlier models require the catalytic converter to be removed).