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
Technical Article on Replacing the 3-Series Driveshaft Guibo / Flex Disc.
Read that article for instructions on how to disconnect and drop down the
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
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
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