you noticed a knocking, rumbling noise coming out of the rear of your car
while going over bumps? Is the rear end sagging a little bit? Itís
possible that you may need to replace your rear shock mounts. A common
problem on the E30 BMW 3 Series, this tech article discusses replacement of
the rear shock mounts. In this article, we will focus on the E30, however
the E36 and E46 BMW 3 Series Models use the same shock mount, so with the
exception of a few differences, this tech article will apply to those models
first step in replacing the rear shock mounts is to remove the inner fender
liners. To do this, open the trunk and look at the taillight bulb holders,
notice the large round screw in the middle of each panel. Unscrew these and
the two taillight panels will come off. Next, look along the upper edge of
the fender liners inside the trunk, youíll see a number of metal tabs
holding them in place, carefully bend back these tabs, and remove the fender
liners. You may have a bit of trouble removing these from out under the
trunk hinges and springs, just bend the liners very carefully to get around
the hinge, and remove the whole piece at one time.
both fender liners on both sides removed, look at the shock mounts, they are
located in front of the trunk lid hinges. While the car is still on the
ground, itís a good idea to loosen the bolts. The added weight of the car
on the mount will help loosen the bolts. Loosen the two 10mm nuts on either
side, but do not remove the nuts just yet.
but do not remove the lug bolts on the rear wheels. You fill find it easier
to loosen the bolts with the car still on the ground
next step is to jack up the rear of the car. A good resource for this is
Wayneís tech article on jacking (insert
article link here) Let me take this opportunity to stress the importance of
safety while jacking. Be sure to always use good quality jack stands
whenever you are jacking any car. NEVER rely on only a jack to hold the car
up. You can inflict serious injury to yourself and your car.
in mind that this procedure is the same on both sides of the car, hence I
have written out the procedure for only one side.
the car is jacked up, remove the rear wheels and look at the rear of the
control arms where the shock absorber bolts on. In order to replace the rear
shock mounts, we will need to remove the shock absorbers.
get the shocks off, first place a floor jack under the rear control arm.
This will support the rear control arm when you have the shocks removed, and
prevent the control arm from swinging down and causing possible damage to
use a 19mm wrench or socket to loosen the lower shock absorber mounting
bolt. Do not remove the bolt just yet, just get it loose. Next, go inside
the trunk and remove the two 10mm nuts that hold the shock mount in place.
Now, go back down to the lower mounting bolt and remove it, while holding
onto the shock. Once you have the lower bolt removed, the shock/shock mount
assembly will drop down out of the perch and free of the car. Be sure that
you also remove the old gasket that seals the shock mount to the body.
to remove the shock mount from the shock, place the shock in a vise or
secure it in some other means, and loosen the 17mm nut at the top. You will
now notice that as you turn the nut, it will also turn the shock rod.
If you look at the top of the shock rod, you will see a square
indexing cut into it. Use a pair of vise-grips to secure this square. This
will secure the shock rod, and allow you to remove the nut.
the nut removed, simply slide the old mount off the top of the shock. Be
sure to keep the large washer underneath. Now slide the new shock mount over
the shock rod and place the large washer over the top of the mount and
install a new 17mm locknut. Use the same procedure of holding the shock rod,
while you tighten the nut. BMW recommends you torque the nut to 11ft/lbs.
With the nut tightened and secured to the shock rod, place a new gasket over
the top of the mount and from under the car, position it in place in the
shock perch. While holding it in place, slide the lower shock-mount bolt
through the shock and into the control arm, but do not tighten the nut. Now
go inside the trunk, and re-install the two 10mm nuts and torque them to
17ft/lbs. Once the upper nuts are torqued, you can torque the lower mounting
bolt. BMW recommends a value of between 52 and 63 ft/lbs.
the mounts in place, and everything tight, put the wheels back on and
tighten the lug bolts. Lower the car and re-tighten the lug bolts. With the
car on the ground, you can now re-install the fender liners by carefully
orienting them into position around the trunk lid hinges then bending back
the metal tabs, which hold the liners in place. The last step is to
re-install the taillight bulb holders and tighten the screw that holds them
in place. Make sure that you have these holders oriented correctly, as it is
possible to put them on backwards.
take the car out for a spin. You should notice that the rear end of the car
feels much more stable over bumps, and should be silent. After about 50
miles or so, Iíd re-check the nuts and bolts for tightness and re-adjust
Well, there you have it - it's
really not too difficult at all. If you would like
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