Driveshaft removal and replacement introduced vibration

[trsbmw]

My car was just at the dealer where I asked my mechanic to check out what seemed to be some oil leakage around the area of the diff input flange. He decided to replace some seals, which necessitated the removal of the driveshaft. After he got it all buttoned back up, I left the dealer, and anything above 50 mph caused a loud rumbling and vibration from the center / rear of the car. I took it back immediately, he immediately removed the exhaust to gain a view to the driveshaft, hoisted the car up with me in it to spin the wheels to 70 mph. He could not see any obvious movement, and he even showed me the paint marks he put on the driveshaft / diff flange prior to removal to ensure exact replacement position.

Anyway, he decided to order a new driveshaft. I also suggested replacing the center support bearing, but he did not agree since there was no play in it, and the car only has 11k miles.

Any ideas? Similar experiences?

[JCz04Bimmer]

The rubber in number 8 above can become fatigued over time and, if the tech was pulling on the old driveshaft to remove it, it is possible that the mount was damaged. That said, driveshafts can be finicky.

Slightly related, when I was installing my short shifter, I noticed a ring of rust on the driveshaft. The only explanation I have is that the STOCK shifter was contacting the rotating driveshaft and scraping it in precisely the same spot. It dug into it by 1mm at most so it's a non-issue but it's something that you may want to look at. that is, make sure your shifter isn't making contact with the driveshaft!

[trsbmw]

#8 is the center support bearing, which I suggested to replace. Plus, it only has 11k miles on it which is not much IMO.

[JCz04Bimmer]

Originally Posted by trsbmw

#8 is the center support bearing, which I suggested to replace. Plus, it only has 11k miles on it which is not much IMO.

Right. But... the tech is the one who may have put improper stress on the piece while removing and installing everything. At 11k miles replacement would indeed seem unusual -- and likely blamed on some sort of error and not the integrity of the part -- thus requiring some wrangling on the part of the dealership to get their costs covered. Since a new shaft has been ordered, you'll know soon enough because it is certainly possible that the driveshaft is out of balance. If that is the case, though, I'd argue that all bearings (and perhaps all supports) should be replaced as the vibration may have done damage.

...I'm assuming that at the dealership they've followed all torque specs as I'd imagine that'd effect the balance of the shaft.

[trsbmw]

The driveshaft was replaced this morning, the vibration is gone, but the noise is still there. My mechanic escalated to BMW's version of second level support, and they recommended differential replacement. Now I have to wait another 2 weeks (maybe longer because of the volcano) for shipment from Germany....

The silver lining in this cloud is that at least they have me in a new Z4 (e89) loaner car.. The weather has been excellent for top down driving...