BMW cars use a MacPherson strut front suspension which has a lower control arm shaped like an L on both sides. This control arm has two ball joints, an inner joint which connects to the chassis and an outer joint which connects to the wheel hub. At the rear there is a bushing in a metal bracket which connects the rear end of the L to the chassis.
If either of the ball joints develops slop, or the bushing wears out there will be slop in the handling, as well as shaking under braking and turning, and possibly a throbbing of the steering wheel at speed.
This article covers the basics of replacing these worn components.
Begin by removing hubcaps (if equipped) and loosening lug bolts on both front wheels.
Jack the front of the car up and support both sides with jack stands.
Remove front wheels and set aside.
Remove the nut that holds the sway bar drop link to the control arm, as well as the two bolts that secure the rear control arm bushing brackets to the chassis.
Loosen the nut that holds the outer ball joint to the wheel hub. Followed by the inner ball joint nut. The two ball joints will most likely stick as they have a tapered surface. To release these surfaces either knock them down with a punch, or use a ball joint splitter tool.
Install the new control arms and torque the nuts fully.
The control arm bushings require a bit more work. First get the steel brackets from your old arms. If you cannot pull the bushing off the old control arm drill between the bushing and the stem of the control arm in several places and then twist the old bushing off.
Using a hacksaw cut through the steel ring of the old bushing being careful to not cut into the steel bracket. Remove the bushing from the bracket by bending the steel ring in on itself then using a hammer it is possible to knock the old bushing out of the bracket.
Align the marks on the bushings with those on the bracket and press into place using a shop press or a vice. This is difficult to do, and you might consider having a shop press the bushings into place for a nominal fee.
Otherwise using a vice and some peices of scrap metal press until the bushing is centered in the bracket.
When installing the bushings you must work quickly, the bushings will begin to stick to the control arm, and the car should be fully assembled and sitting on its wheels when this occurs.
To facilitate this heat the bushings in hot water, then remove the bushing lubricate it with laundry detergent and then push and wiggle it into place. This can be made easier by using a large gear puller to press the bushings into place. However it can be done manually, and I prefer to do so.
Once both bushings are in place and the brackets bolted into place reinstall both wheels and lower the car. Allow the car to sit for the bushings to stick in place.
