Project E36 323is: Building the Poor Man's M3, Part 6: Tales of a Guibo: What The Hell is That Vibration?
Not too long after we finished installing our Turner Motorsports Power Package 1 update with aFe intake and Jim Conforti tune, our 323is developed a vibration under acceleration in 2nd gear. The vibration would only occur between 3,000-4,000 RPM, and it was limited to just second gear under heavy acceleration. After a few more days, however, the vibration was noticeable in all gears, and through the entire RPM range. Things were getting serious.
In order to diagnose our problem, we had to first get the car in the air and check the usual suspects: wheel bearings, axles, tires and wheel balance. Everything looked fine upon initial inspection, but after some internet forum research we came across many E36 owners who've had similar problems, and it usually came down to either the Guibo (flex disk) or the center support bearing for the driveshaft.