I put a rebuilt driveshaft on my E30 about six months ago.  I pre-
loaded the center bearing (which came pre-installed on the new rebuilt
driveshaft) and torqued everything as listed in the Bentley manual.

Have probably put less than 1,000 miles on the car since then with no
extreme driving conditions.  Now the center bearing is squealing
loudly, usually around 30mph, but the noise is intermittent.  Most
noticable when the car is cold, but usually stops after things are
warmed up.

A mechanic put the car on a lift, put in gear, and the center bearing
was confirmed to be the source of the noise, which he described as
sounding like a whale call.

The shop that sold me the driveshaft has a one year warranty on it and
will replace it free, but of course that means a few hours of labor
for me to take the old one out, etc.

Before I go through this routine again, I was curious if there was
anything left out of the Bentley manual or some mistake that is easy
to make which would quickly destroy your center bearing?

Thanks,
Christopher