1992 525i SE (auto), 215k miles. I replaced my prop-shaft (driveshaft) donut coupling when I bought this car 3 years ago. Recently, my friendly local mechanic (GM franchise) replaced the shaft's centre bearing as the housing had fractured. After he did the work, there is a quite harsh vibration - from about the centre of the car - under load from a standstill, like when you give it some throttle. I thought he must have failed to tighten the centre bearing housing bolts, so I gave it back to him. He has checked all the fastenings that could be involved and everything is tight. Any ideas?
Rod