Check out this thread:
http://forums.bimmerforums.com/forum....php?t=1235885
Just read the response excerpt from TiMM:
"The fault is due to the lock-up clutch within the torque-converter. The clutch is normally only locked (engaged) when cruising in 4th and 5th gear. It is used to reduce losses in the torque-converter, without the lock-up clutch, the pump and turbine 'slip' in respect to each other when cruising, this reduces fuel-economy. When the lock-up clutch engages it mechanically locks the pump and turbine so no energy is wasted.
The way the lock-up clutch is controlled is more complicated in the later models, instead of a simple ON/OFF control, the clutch can be proportionally engaged to reduce converter losses. It is during this proportional phase that the shudder occurs. The shudder is the same sort of shudder you can get from an oil-contaminated manual clutch.
What you will find is that you can drive around the problem by using Sport or manual modes. This is because the lock-up clutch is controlled differently in those modes. The shudder also goes away when heavier throttle is applied, this is because the lock-up clutch is fully disengaged to provide torque-multiplication (which is the torque-converters main task)."
Bookmarks