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While replacing your driveshaft flex disc, you may find that you have to disassemble the rear part of the driveshaft. If so, this would be an excellent time to inspect and/or replace your rear driveshaft bearing. The bearing supports the rear part of the driveshaft, right before it connects to the rear differential. Although I haven't found this part to be too terribly worn on the cars that I've inspected, it's a wise idea to replace it while you have access to it. A worn bearing will generate strange vibrations that you will be able to feel in the cockpit, and may also increase the amount of "gear noise" you hear while driving.
Replacement of this bearing requires removal of the driveshaft flex disc. For more information on this, see our Pelican Technical Article on Replacing the 3-Series Driveshaft Guibo / Flex Disc. Read that article for instructions on how to disconnect and drop down the driveshaft.
With the Guibo removed, you should have removed the driveshaft tunnel support brace (Figure 1 and Figure 2), and also have loosened up the bracket that holds the rear driveshaft bearing (Figure 3). Mark the center driveshaft and the rear driveshaft - they are a balanced assembly and need to be put back together in the same location in order to avoid vibration later on. The large clamp that secures the middle driveshaft to the rear needs to be loosened (Figure 4). I found it difficult to fit a normal wrench on this clamp, so I used a plumber's wrench for a better grip. It's a little cludgy, but it worked the best out of any tool I tried. Loosen up the clamp (Figure 5) so that the center driveshaft can be removed. With the clamp loosened, you should be able to pull on the center driveshaft and remove it from the rear driveshaft (Figure 6). Figure 7 shows the driveshafts disconnected. If the driveshaft will be hanging like this for an extended period of time, make sure that you support it with some wire or a jack stand.
The new bearing is shown in Figure 8. I also like to replace support components when performing a job - you would hate to have a part fail because you were too cheap to replace the one dollar circlip that holds it in. The picture shows the bearing/support (sold as an assembly), the front and rear support plates, and a new circlip.
Begin by removing the driveshaft clamp from the splined end. Then remove the large circlip using a pair of circlip removal pliers, or a pair of needle-nose pliers. Wear eye protection for sure here, as these can fly off if you're not careful. Pull the large support cup away from the bearing (Figure 9). You should not be able to remove the entire bearing and support bracket assembly.
On the backside, use a pair of pliers to remove the back support plate (Figure 10). Then tap in the new one, being careful to align it in the same orientation (flat side goes to the bearing). Tap it all the way onto the driveshaft so that it mates flush with the end. This piece will spin around with the driveshaft when the car is moving.
Now, place the new bearing assembly on the shaft. It should be a snug fit and the bearing should spin freely. Do not grease this bearing as you insert it - you don't want it to spin on the shaft itself. Attach the new support cup, and insert the new large circlip into it's groove on the driveshaft (Figure 11). Reinsert the driveshaft clamp onto the splines (Figure 12), and then reattach the center driveshaft, lining up the marks you previously made on the two driveshafts (Figure 13). Clamp down and tighten the driveshaft clamp.
Figure 14 shows the new driveshaft bearing reinstalled. Refer to the flex disc article for instructions on how to reconnect the flex disc. When tightening the rear driveshaft bearing to the chassis, push the bearing all the way towards the front of the car.
Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.