Replacing your BMW F30's rear control arms is one of the easiest ways to restore the precise handling that it's known for. BMW prides itself on building the world's best sports sedans, and the F30 generation is no exception. However, the F30 is nearing ten years old, and many models have a significant amount of miles on them. Replacing the worn suspension bushings will help keep your sedan handling like new.
Even though the front suspension does the steering, the rear suspension plays a critical role in how the car handles. The rear suspension on the F30 uses four separate control arms, each with two rubber bushings. Harsh roads and significant mileage cause these bushings to lose their effectiveness, leading to less roll-control, numb feel, and poor response to sharp inputs. Additionally, the arms are made from stamped steel which makes an easily bendable construction. Significant pothole strikes or curb hits can damage the arms and put the wheel out of alignment.
BMW models and years applicable:
While we're completing this DIY on a BMW 328i, the job also applies to most 2-series, 3-series, and 4-series BMW F30s.
Symptoms of worn BMW F30 rear suspension bushings:
- Uneven tire wear
- Instability under braking
- A wandering feeling during cornering
- General laziness in response from the rear end
As the bushings in the rear arms wear, the rubber in them becomes significantly squishier. Also called deflection, the increased slop causes a greater variance of dynamic toe angles while driving. That can lead to a numb or slightly squirrely feeling from the rear of the car. The worn bushings will cause increased tire wear as well.
How much will it cost to replace BMW F30 rear control arms?
The Lemforder rear control arm kit has all of the pieces you need to replace every arm in the rear suspension. Also included are new aluminum bolts, nuts, and washers. The kit will run you right around $700.
How long will it take to replace BMW F30 rear control arms?
The time it takes to replace all of your rear control arms is dependent on where you live and the tools you have access to. Northern vehicles will likely have to work around some sort of corrosion. All but one of the bolts and nut used for the control arms uses an 18mm head. To be safe, put aside 60 to 90 minutes per corner.
Parts required to replace BMW F30 rear control arms:
Tools required to replace BMW F30 rear control arms:
- 17mm Socket
- 18mm Socket
- 18mm Deep Socket
- E14 Socket
- 18mm Wrench
- 18mm Offset Wrench
- Torque Wrench
- Impact Gun (Recommended)
Steps required to replace BMW F30 rear control arms:
You need to jack the car's rear into the air and remove both rear wheels to access the suspension arms. Place the car onto jack stands for safety.
Step 1: Replace toe link
The toe-link is the rear-most arm in the suspension, as well as the longest. The inner mounting bolt for these arms is eccentric used to adjust the rear suspension's toe angle. Use a sharpie or equivalent marker to mark the bolts on their washers and on the subframe to give yourself a rough idea of where the bolt needs to be when putting the suspension back together.
Use an 18mm socket to remove the nut and an E14 socket to counter-hold the bolt head.
Remove the nut and then pull out the bolt. The bolt is aluminum and one-time use, so throw it away, but save the washer. Then, use the 18mm socket to remove the bolt from the toe link's outer bushing.
Like every other bolt used for the rear arms, this bolt is aluminum and one-time use, so throw it away. Next, slide the new arm into the rear subframe before lining up the outer bushing and threading in its bolt by hand. After that, slide the inner bolt through the arm and fit the washer. Try and align the washer with the marks you made for the toe adjustment, then thread on the new nut.
Do your best to line up the toe marks before using the 18mm socket to tighten the inner nut while counter holding the bolt head with an E14 socket.
Next, use a jack to lift the brake and wheel assembly to ride height. You need to torque the bushings while the suspension is at ride height to prevent them from binding and tearing. Torque the outer bolt with an 18mm socket to 100Nm, plus another 90° of rotation. Then, torque the inner nut to 100Nm.
Step 2: Replace the trailing arm
The trailing arm connects the front of the knuckle to the front of the subframe.
Both bolt heads and nuts used to secure the trailing arm are 18mm. Use an 18mm socket and wrench to remove both of the bolts. Then remove the arm.
Fit the new arm into place and thread both of the bolts through the bushings. Thread on the nuts by hand and then raise the suspension to ride height. Counter-hold the bolt heads with an 18mm wrench and use an 18mm socket to torque the nuts to 100Nm.
Step 3: Replace the forward upper control arm
Follow the arm up to the inner pivot mounted in the subframe. Position an 18mm wrench to counter-hold the inner bolt's nut and then use an 18mm socket to loosen and remove the bolt.
After that, use an 18mm socket to remove the bolt mounting the arm to the knuckle. Pull out the old arm and put in the new one. Ensure the open-ended portion of the arm is positioned downward.
Thread in the inner pivot bolt and thread on the nut. Then, thread in the outer mounting bolt.
Use an 18mm socket to torque the inner bolt to 100Nm. Torque the outer bolt to 100Nm, plus 90°. Again, torque the bolts with the suspension at ride height.
Step 4: Replace the rear upper control arm
This is the last arm and the trickiest to replace. If you don't have an 18mm offset box wrench cut in half, now is the time to acquire that. Place the cut wrench on the nut of arm's the inner mount to counter-hold the nut. Then use an 18mm socket on a ratchet from underneath to loosen the bolt.
Next, use an 18mm socket to remove the arm's outer mounting bolt. Remove the outer bolt, then the inner.
After that, use a flat head screwdriver to remove the wire bracket from the control arm. Push in the locking tabs and release the clips. Then, pull out the old arm and fit the new one into place.
The arms are side-specific. Ensure the tapered portion of the outer bushing is facing rearward when installing the new arm. Clip the wire bracket onto the arm once you have it fit roughly into place. Install the inner pivot bolt and thread on the nut before threading in the outer mounting bolt.
Counter hold the inner nut with the cut wrench and use an 18mm socket to torque the bolt to 100Nm, at ride height. Torque the outer mounting bolt to 100Nm, plus 90° with the 18mm socket. After that, refit both wheels to the car and use a 17mm socket to torque the lug bolts to 120Nm.
BMW F30 Rear Control Arm Torque Specs:
- BMW Toe Link Inner Bolt = 100Nm or 74 ft-lbs, of torque
- BMW Toe Link Outer Bolt = 100Nm or 74 ft-lbs, of torque, plus 90°
- BMW Trailing Arm Inner and Outer Bolts = 100Nm or 74 ft-lbs, of torque
- BMW Upper Control Arm Outer Bolts = 100Nm or 74 ft-lbs, of torque, plus 90°
- BMW Upper Control Arm Inner Bolts = 100Nm or 74 ft-lbs, of torque
That's all it takes to replace the rear arms in your F30 BMW. With the new rubber bushings, the rear suspension shouldn't have any problems work as BMW designed. If you're interested in more DIYs for your BMW, you can visit bmw.fcpeuro.com and subscribe to our YouTube channel.
Owner of a flat-six swapped Impreza 2.5RS. Currently having dreams of Porsche 914s.