Many individual components make up the steering and suspension system on your BMW E46. The suspension alone includes shock absorbers, all kinds of joints and bushings, and of course — the control arms.
The control arm consists of two main components — the control arm bushing and the ball joints — that will inevitably wear out and require replacement. This guide tells you everything there is to know about a BMW E46 control arm, from the issues you’ll face as they start to wear out to how you can go about replacing one yourself.
What Is a Control Arm?
The control arm is the component that connects the wheel assembly to the chassis of the car. As you can imagine, they are vital as they allow the wheels to move up and down in tune with the road’s surface.
Over its near-decade-long production run, the BMW E46 models were manufactured with three different kinds of control arms. One was specific to the M3, while the other two were used on the standard range. Of the two used on the non-M BMW E46 models, one was made from stainless steel and the other from aluminum. It’s worth noting that only a handful of early production cars were equipped with the steel control arms, and if you own an E46, it likely features an aluminum control arm.
The E46 M3 also uses an aluminum control arm that’s largely similar to the standard E46 control arm. If you raise your car and look at the control arm, you’ll find that it’s connected to the steering knuckle and subframe using ball joints, while a bushing connects it to the body. It’s these two components that are most prone to failure from wear and tear. The likelihood of the control arm itself failing is low as it’s a solid piece of aluminum designed to last several thousand miles.
How Do I Know If My BMW E46 Control Arm Is Failing?
Since the control arms play such an essential role in the normal handling of your car, any faults with it will become immediately apparent. However, these symptoms may also be caused by other issues in the steering or suspension system. So, the only way to confirm a control arm issue is to visually inspect the part and check for signs of wear or damage.
Nevertheless, if you experience the following issues while driving, there might be a problem with your E46 control arm:
Uneven Tire Wear
When the control arm bushing wears out, it can cause the wheel it’s connected to tilt on its axis. This changes the normal alignment of the wheel, causing additional wear on one edge of the tire. Before replacing the bushings, rule out the possibility of this being just a wheel alignment and balancing issue.
Steering Issues
When the bushings or ball joints wear out, it can cause multiple immediately apparent issues in the driver’s seat. If the wheel loses alignment from a loose bushing, it could cause the car to veer to one side.
Another symptom you’ll notice is vibration in the steering wheel. The ball joint that connects the control arm to the wheel is not supposed to move very freely. As it wears out, it can cause the wheel to wobble, which translates to the steering wheel. This is a tell-tale sign that your E46 control arm needs some attention.
Loud Noise
If you hear a loud thud around the wheel when you go over a large bump or into a pothole, it could stem from a control arm issue. When the ball bearings are worn out excessively, they can pop around in their socket, causing this loud noise.
How Long Do BMW E46 Control Arms Last?
Control arm components typically last well over 50,000 miles, but this figure is primarily affected by the kind of driving conditions the car is subject to. If you ensure that you go past every speed bump, pothole, or rough patch of road, as smoothly as possible, you could even get twice as much mileage from a pair of E46 control arms. Similarly, going through a large pothole at speed or a front-end collision will cause damage to the part.
We recommend visually inspecting the ball bearings, bushings, and control arms when you service your car. Control arm issues only amplify with time, so it’s best to have them addressed as soon as you start noticing any significant symptoms.
How Do I Change an E46 Control Arm?
Changing your E46 control arm is a relatively straightforward process you can do yourself if you can jack your car up and have the right tools. The process is the same across all BMW E46 models, including the M3.
For this job you’ll need the following:
- 15 mm wrench/socket
- 16 mm wrench/socket
- 18 mm wrench/socket
- 19 mm wrench/socket
- 21 mm wrench/socket
- 5 mm Allen key
- 6 mm Allen key
- Ball joint tool
- A pry bar
- Hammer
- A Control arm or Control Arm Kit
Step 1 – Securely Lift the Car
Whether you’re jacking the car up on stands, or you’re using a lift, it’s imperative that you do so safely. Not only will you be spending some time under the car for this job, but you’ll be whacking things with a hammer, prying stuff off with a pry bar, and more. The last thing you need is unstable above your head.
Step 2 – Remove the Stiffening Brace
Your E46 comes with a metal brace that protects the subframe. It’s held in place by 8 16 mm bolts. You’ll need to remove those in order to access the control arm bushings.
Step 3 – Remove the Adaptive Headlights Linkage
There’s a small linkage bolted to your control arm whose purpose is to track the control arm’s length of travel. It’s held in place by a 13 mm bolt. You’ll need to remove it before proceeding.
Step 4 – Undo the Steering Knuckle Ball Joint
The control arm is held in place by two ball joints and a bushing in the rear. There are several ways you can go about removing a control arm, but starting with the steering knuckle ball joint seems to be the most efficient one. Undo the ball joint nut and use your ball joint separator to remove the stud from the knuckle.
In case you don’t have this tool, you can also use a hammer. However, be careful not to hit the wheel speed sensor that is right next to the ball joint stud. In fact, do yourself a favor and remove it before you start swinging the hammer anywhere near it.
Step 5 – Undo the Other Ball Joint
This one is going to be the difficult one to remove. They’ve used a long stud that tapers as it goes through the subframe. To make things worse, the space where the bolt eventually appears is extremely crowded thanks to a massive engine mount that’s in the way. You’ll need a 21 mm wrench, or a ratchet — whatever you can fit in there. Undo the nut and work the control arm until the stud drops free.
Step 6 – Undo the Bushing
The last step is to undo the two 15 mm bolts that hold the bushing end of the control arm in place.
If you’re reusing the bushing, you’ll need to get a claw to extract it. Otherwise, installing a completely new control arm kit is the reverse of the removal. Just keep in mind that when installing the nut, you’ll need to lock the studs in place using the Allen keys.
Get Your BMW E46 Control Arm Now!
Ultimately, the control arm lets you steer your car and allows the wheels to travel smoothly over bumps and other road imperfections, keeping you as comfortable as possible. Without them in working order, you’d be in a world of trouble.
At Bimmers.com, you can get your hands on individual control arm components or entire E46 control arm kits that will let you swap the faulty one on your car. And you won’t have to worry about reliability as we’ve stocked genuine OEM BMW parts. Simply head to the shop section, input your car’s data, and search for the part you need!
