My car is a 2002 BMW 330Ci Convertible. Your car may be similar or different depending on the model.
The Lower Control Arms (LCAs) are an important suspension part that sets the position of the front wheels. Each LCA on this car has two ball joints and an end inserted into the bushing. If a play has developed at any of the ball joints, as is the case on the passenger side of my car, the wheel will have a play that can cause uneven wear of the tire (cupping) and the car pulling to the side when going over uneven roads or under braking (bump steer). It's easy to test the ball joints. Simply jack up the car so that the front wheel is off the ground. Rock the front wheel back and forth. If there is any play, there is a problem with the LCA or bushing.
Apparently the ball joints are a common problem on some model years of the E46 because a nylon lining is used for the ball joints which tends to fail at around 60K miles. Mine started having problems at around 50K miles.
The ball joints are pressed into the LCA and requires a power press to remove and install. DIYers need to replace the entire LCA assembly. LCAs need to be replaced in pairs, and alignment is needed afterward. This guide illustrates the steps for replacing LCAs. After the replacement, the car will go back to solid and firm handling, reminding us why we got these cars in the first place.
Allocate at least 4 to 5 hours for this job if you're doing this for the first time, even though it can be done in 2 to 3 hours if you're familiar with it. Then again, you wouldn't be reading this if you had done it before.
Step 0: Get a set (left and right) of Lower Control Arms. Mine are Lemförder, which I got for $336 plus taxes and shipping.
Step 1: This job is more about having the right tools and using them correctly than the procedure itself. These are the tools I bought specifically for this job.
- The pickle forks are $10 each from Pepboys. If I had to do it again, I would only need the bigger one -- it allows you to hammer on it without hitting the car's fender while trying to separate the inner ball joint.
- The KD ball joint separator, $20 from Sears, can be used to remove the outer ball joint and was probably not needed if I knew what I know now. But, it can come handy for other jobs, such as separating steering tie rods.
- The 8-lbs hammer, $24 from Lowe's, was definitely needed. Not sure if a 4-lbs hammer would also work.
- The 21mm wrench is needed to work the nut holding the inner ball joint. I got it for $7 from Pepboys. In hindsight, an 18mm wrench would also help working the outer ball joint nut.
Step 2: Put the car on 4 stands. I've done it several times, and I still find it tricky because the car is so low to the ground. First, use the jack that comes with the car to lift the car just enough so that you can slide a hydraulic jack under the car. Then lift the car by jacking on the frame reinforcement railing, after which you can put a stand to replace the car jack. When you do the other side of the car, you need to constantly check to make sure the car doesn't slip off the jack.
After the car is put on 4 stands, rock it back and forth to make sure everything is even and solid. No, the car won't fall from the rocking. If it does, it's much better that it falls now than when you're under it!
Make sure to loosen the wheel nuts first before putting the car on stands, as you'll need to take the front wheels off later on.
Step 3: Remove the plastic dust guard and the aluminum underside reinforcement. Both are easy. The only thing not obvious is the plastic retaining clip holding the dust guard to the front bumper. You'll need to pull on the center insert in order to remove the clips.
This is the step where you'll need to get under the car. After this step, you mostly work on the side of the car.
This is after the plastic guard and aluminum reinforcement brace have been removed.
Step 4: Remove the front wheel, exposing the access to the LCA ball joints and bushing. It is helpful to turn the steering wheel one way or another in order to have better access to the place you'll be working on.
Step 5: Use an 18mm socket or wrench to remove the outer ball joint nut. The ABS sensor is in the way of a socket as the nut rises. I didn't have an 18mm wrench. So I used an 18mm socket to break the nut loose and used a 19mm wrench to remove the nut completely.
Step 6: Insert a pickle fork around the outer ball joint, and start hammering. Hammer the fork in such a way as to insert it deeper. There is no point in applying any lateral force, as it's not going to help (ask me how I know). I believe you'll need a sledge hammer of at least 5 lbs. Mine is 8 lbs. Also, take out the nut completely before hammering (unlike being shown here) -- you don't want to deal with the situation where the nut is stuck and the ball joint rod rotates freely (you'd need an Allen key to hold the ball joint stud in that situation).
Make sure to wear protective eye wear when you do any hammering! Little things might fly under impact, and you don't want anything to hit your eye at high speed.
Another view of the outer ball joint (this is on the driver side), showing the ABS sensor.
An alternative is to use a ball joint separator as shown here. It's a bit tricky to use this type of separator because it doesn't go into position completely on the outer ball joint (it doesn't work at all on the inner ball joints), and you'll likely have to jack up the MacPherson strut to get enough grip. If you do use this separator, the outcome is quite spectacular, making a loud pop like a gunshot, when the ball joint rod separates. Also make sure to use protective eye wear.
Step 7: Use a 21mm wrench to loosen the inner ball joint nut on top of the frame cross member. You will need to use a rubber mallet to hammer on the wrench to break it loose. I used the pickle fork itself to transfer the force as shown here. Once the nut is turning, you'll have to use a lot of patience to remove it because there isn't much room at all, probably about 30 degrees before you have to reseat the wrench.
This is the view of the inner ball joint under the cross member. After using a fork, the boot will be damaged.
Step 8: Use the longest pickle fork you have to separate the inner ball joint. Again, hit the fork with a large hammer as if to drive it deeper. Be careful not to damage the car's fender when you swing the hammer. Use the fork only after the nut has been removed completely (to avoid the situation in which the nut is stuck and the ball joint rotates freely).
This is how it looks after the inner ball joint has been separated (driver side).
Step 9: Remove the LCA bushing by undoing two bolts (16mm) so that the LCA comes off the car completely.
Step 10: If you want to remove the bushing from the LCA, a good puller would be the best, but a C-clamp like this worked for me.
Putting a bushing on the new LCA requires very advanced material -- soap! With soap, it requires very little effort. Make sure it's installed the correct way (there are two possible ways for the bushing to go on the arm).
Here are the old and new LCAs side by side.
Repeat Steps 4 to 10 above to remove the other LCA. The only difference between the two sides is when you have Xenon lights, in which case there is a leveler on the passenger-side LCA.
Step 11: Now we need to install the LCAs. In order to install the inner ball joint nut, you'll likely need to use a jack to push the inner ball joint against the frame cross member. You have to put quite a bit of the car's weight on the jack to stop the ball joint rod from rotating while you try to tighten the nut. There is no way I can put my torque wrench there, so I simply tightened the nut as much as I could. You may also need to use the jack for the outer ball joint as well.
Step 12: Install the outer ball joint and the LCA bushing. This is after the new LCA have been installed.
Repeat Step 11-12 for the other side.
Put back the aluminum reinforcement brace and the plastic guard.
Put back the front wheels.
Lower the car to the floor.
Tighten the wheel nuts.
You're done for now.
The final step is to get the alignment adjusted. I went to a local shop specializing in German cars, and it cost me $94 cash (I was quoted $130 earlier by the same shop). They told me they needed to adjust the toe-in slightly.