STEERING WHEEL SHAKING  OVER BUMPS?

This is usually one of two problems, either your thrust rod bushings need to be replaced, or your front shocks are leaking.

To determine if your shocks are bad, raise each wheel , one at a time, and visually inspect the shock inside of the spring. You will need to raise the bump stop and dust cover, which are the foam and plastic pieces inside the spring. After raising these items up the shaft of the shock, you may see an oily film surrounding the opening the shaft comes out of. If the shock is very bad, you will have wet oily stains running all the way down the housing.

If your shocks appear to be dry, check your thrust rod bushings for more ideas on your shake.

There are very few occasions when it is advised to replace one shock absorber alone. You should always change both units on the same axle, or you may get some weird handling. Very low mileage cars are the exception, but then , that would be a warranty repair, and you would not be here.

BMW's use strut assemblies, with replaceable inserts, this version of a shock absorber is often referred to as a strut, or insert.

Replacing the front shocks
Raise and support the vehicle, remove the front wheels, you can do one at a time if it is more convenient.

The following applies to almost every model of BMW, except the E36, E39 and E38

Remove the brake hose from its support on the strut, and remove the caliper, most cars have a pair of 19mm bolts holding the caliper to the bracket, there is no need to remove the clip on front of the caliper if your car has one, or the 7mm Allen bolts that the caliper slides on, by removing the 19 mm bolts, the caliper can be removed complete with pads, use wire or string to tie the caliper up out of the way, in a manner that relieves pressure from the rubber brake line. Do not let the caliper hang, this can kink or tear the rubber line leading to brake failure.

Next, remove the 5 or 6 mm bolt holding the rotor onto the hub, then remove the rotor. The rotor does not have to be removed, but removing it reduces the weight of the strut considerably, and you have to lift it later.

Now, remove the 5 mm Allen bolt holding the ABS sensor into the back of the strut housing (if you have ABS), after removing the bolt, you can remove the sensor by twisting, and pulling at the same time, don't just try to lever it out, twisting it back and forth, will usually allow it to come out easily.

Now remove the top nut from the sway bar link.

If you are working on the left front, you will need to remove the brake lining sensor harness from its retainer on the strut.

Now remove the 3 bolts in the bottom of the housing, this plate contains the ball joints from the control arms, and unbolting it from the bottom of the strut saves risking damage to the ball joint boots by removing them directly.

Now you are ready to remove the strut assembly, undo 2 of the 3 nuts holding the strut into the car, these nuts are located under the hood, at the top of the strut tower. Now, while holding the spring, remove the 3rd nut. The strut will drop, but not fall out of the car. Now you will need to push down the plate at the bottom of the strut, which will allow you to bring the bottom of the strut housing out of the wheel well, use some care doing this, the assembly is somewhat heavy and you do not want to chip the paint on the lip of your wheel opening.

With the assembly out of the car, use a suitable compressor to compress the spring. You must do this, the spring is under quite a lot of tension, and if it is not compressed before undoing the top nut, serious injury and damage is an almost certainty. I have seen these struts throw the top mount more than 100 feet, so use caution.

With the spring suitably compressed, remove the nut at the top of the shock, Now pay attention to what order you remove parts, there are often more than one washer on the top of the strut and these must be put in the same position when assembling the unit. Remove the top mount and the spring, then the bump stop and dust cover. If your foam bump stop is deteriorating, or missing, it must be replaced, failure to do so may cause damage to the new shock. This bump stop prevents the shock from completely bottoming out on a hard bump. The dust cover is equally important, it prevents the build up of debris around the sealing surface of the shock.

Now that you have the bare strut housing you will need to remove the large locking nut at the top. This is easiest if you lock the strut in a vice, use a ballpein hammer to gently tap around the top of the housing, to shock loose the nut. Now use a large pair of pliers, or a large pipe wrench to remove the nut, pull the insert out of the housing, and install the new one. It is good practice to tip a small amount of oil into the housing before installing the new shock. Use ATF or a light engine oil, you cannot put in too much, any excess will be forced out by the insert when you install it, though this will make a nice mess of your work area.

Before inserting the shock into the housing, make sure your top mount will go over the top of the shock. BMW has a habit of changing the diameter of the top of the shaft in the shock, so everything will fit together until you find the last piece will not go on.

The new insert should come with new nuts, use the new nuts to install the insert in the housing.

If your shock has been leaking badly, your rubber bumper at the bottom of the spring will be swollen and unusable. In this case it is best to replace it. If you are stuck and cannot get another one, cut the ring, and shorten it to fit, then glue it in place on the housing.

Assembly is pretty straight forward, make sure the main nut holding the strut into the housing is as tight as you possibly can. Place the lower rubber mount on the housing, then the bump stop and dust cover, the spring is next, followed by the top mount. Make sure you put any washers back in the same order they come out. Do up the top nut until it is tight, you will know when it is tight by the fact that the shaft will no longer turn, the top nut is self locking and does not need to be done up extremely tight, in fact, it is possible to snap the top off of the strut.

After the assembly is back in the car, remember to step on the brake pedal a couple of times before starting the car, this will close the front brakes back down onto the rotor, or you may find yourself moving with little or no brakes on the first application.