Center bearing failed quickly on E30

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
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On Mar 25, 6:27 am, snipped-for-privacy@aol.com wrote:

Sounds like an anomalous failure to me. I would ask the shop to split the labor bill, if not pay it entirely. -- C.R. Krieger
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Since the shop didn't install the dirveshaft, they won't pay for labor to remove and reinstall it. The labor is up to me to do some weekend. At least they are willing to give me a free replacement.
Christopher
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No. You didn't put a huge amount of force on it that could damage the race, right? You didn't strike it with a hammer to get it into place? And once it was running, you didn't notice a huge amount of vibration as if the shaft was unbalanced?
It sounds to me like you got a bad one. Who did the rebuild?
Oh yes, I'll strongly recommend Mobil 1 racing grease on these things, the thick red stuff. It does not splatter, it stays in the bearing no matter what. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Scott,The rebuilt driveshaft came from some supplier in Arizona. Don't know the name. It came with a center bearing already installed on it so there was really nothing I could have screwed up. I assume that bearing was already lubed up. Didn't check.Christopher
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I am an industrial mechanic. I work with bearings all the time. Most bearings fail due to improper installation. The biggest offence is transferring the pressing-on load through the balls of the bearing. In other words if it is to be pressed on the ID of the bearing the installer will use the outer race to apply the force. This causes "Brinelling". It actually puts dimples on the races. You can feel this by rotating the outer race by hand feeling for pulses. To avoid this, a mandrel needs to contact the inner race and press on with this. If the shop does not do it this way you'll likely have the same problem again. I've seen too many people install the bearing by tapping on the outer race with a hammer.
Brinelling can also happed by impact loads to the bearing like hitting it on a hard surface.

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