2012-2019 Porsche 911 (991) Rear Upper Control Arm: Clunks, Tire Wear, and Replacement Guide
This guide covers the common failure symptoms, inspection tips for used parts, and replacement costs for the rear upper control arms on the 2012-2019 Porsche 911 (991 generation).
- The most common failure is the rubber bushing, leading to clunking noises, unstable handling, and uneven tire wear.
- A four-wheel alignment is mandatory after replacement to prevent unsafe handling and rapid tire damage.
- This part does not fit GT3 or GT3 RS models, which use a different suspension design.
- When buying used, prioritize inspecting the rubber bushings for cracks and ensuring the arm itself is not bent.
Symptoms of a Failing Rear Upper Control Arm
Failure of a rear upper control arm on the 991-generation Porsche 911 is almost always due to worn-out rubber bushings. The metal arm itself is very durable, but the rubber deteriorates over time from heat, stress, and environmental exposure. When the bushings fail, they allow for excessive movement, leading to several noticeable symptoms.
- Clunking or Knocking Noises: The most common symptom is a clunking, knocking, or banging sound from the rear of the car, especially when driving over bumps, potholes, or uneven road surfaces. This sound is caused by the metal part of the control arm making contact with other suspension components as the worn bushing fails to provide adequate cushioning.
- Unstable Steering and Wandering: A worn control arm can make the car feel unstable or loose, particularly at higher speeds. You might feel the rear of the car 'wandering' or find yourself making constant small steering corrections to keep the car straight. This is because the worn bushings can no longer hold the rear wheel in its correct alignment.
- Uneven Tire Wear: A bad control arm bushing will cause a change in the rear wheel's alignment, typically affecting camber (the vertical tilt of the wheel). This results in accelerated and uneven tire wear, most often on the inner or outer edges of the tire tread.
- Vibrations: While less common for a rear arm failure, vibrations can sometimes be felt through the seat or floor of the car. This is a result of the wheel assembly moving erratically due to the worn bushings.
Compatibility Warning: These standard control arms do not fit Porsche 911 GT3 or GT3 RS models. GT models use different suspension geometry and often feature solid spherical bearings (monoballs) instead of rubber bushings for increased precision, making the parts incompatible. 🎬 Watch: A detailed breakdown of 991 suspension components and geometry. The part number for the GT3 arm is different (e.g., 99133106180).
Buying a Used Rear Upper Control Arm: What to Check
A used OEM control arm is an excellent alternative to expensive new parts, as the arm itself rarely fails. The key is to carefully inspect the condition of the bushings and the arm's structural integrity.
- Inspect the Bushings: This is the most critical check. Look for any signs of cracking, tearing, or deterioration in the rubber bushings at each end of the arm. The rubber should be firm and free of major cracks or splits. If the rubber is severely perished or missing chunks, the part should be rejected.
- Check for Bends and Cracks: Visually inspect the entire length of the aluminum control arm. Look for any signs of bending, stress marks, or cracks. An arm that is not perfectly straight is a sign of damage from a collision or severe impact and must not be used.
- Examine Mounting Points: Check the areas where the bolts pass through. Ensure they are not oval-shaped or deformed, which could indicate they were loose or subjected to extreme forces.
- Verify Part Numbers: Confirm the part number on the arm matches the required OEM number for your vehicle. The primary part number is 9P1505237B, which supersedes the older number 99133106104. These arms are typically identical for the left and right sides.
Pro Tip: When purchasing a used control arm assembly from a recycler, ask about the donor vehicle's mileage. An arm from a lower-mileage car (e.g., under 50,000 miles) is likely to have bushings with significantly more life left than one from a high-mileage vehicle.
Cost Comparison: New vs. Used
Replacing a rear upper control arm involves the cost of the part and labor for installation and alignment. Here is a general cost breakdown:
| Part Type | Estimated Cost (per arm) |
|---|---|
| New OEM (Porsche) | $240 - $280 |
| New Aftermarket | $150 - $250 |
| Used OEM | $75 - $150 |
| Shop Labor (Installation) | $150 - $300 (per side) |
| Shop Labor (Wheel Alignment) | $200 - $350 |
Note: A four-wheel alignment is mandatory after replacing any control arm to ensure proper handling and prevent tire wear.
Replacement Overview & Difficulty
- Difficulty Rating: 3 out of 5
- Estimated Time: 1.5 - 2.5 hours per side, plus alignment time.
- DIY Feasible: Yes, for experienced mechanics with the right tools.
The replacement process involves safely raising and supporting the vehicle, removing the rear wheel, and unbolting the control arm from the subframe and the wheel carrier. Access to the bolts can be tight. Porsche specifies that all suspension nuts and bolts are single-use, torque-to-yield hardware and should be replaced whenever they are removed. The final torque must be applied with the suspension loaded to its normal ride height to prevent binding the new bushings.
🎬 See this step-by-step walkthrough of the rear control arm replacement.Important: Failure to perform a four-wheel alignment after installation will result in poor handling, vehicle instability, and rapid tire destruction. It is recommended to mark the position of any alignment-related eccentric bolts before removal to get the alignment close enough to safely drive to a shop.
Frequently Asked Questions (FAQ)
Do I need to replace both rear upper control arms at the same time?
It is highly recommended. Since the rubber bushings wear out with age and mileage, if one side has failed, the other side is likely not far behind. Replacing them in pairs ensures balanced handling and saves you from having to pay for a second alignment job in the near future.
Is a wheel alignment always necessary after replacing a control arm?
Yes, absolutely. The rear upper control arms are a key part of the suspension geometry that determines the wheel's alignment angles (camber and toe). Replacing an arm will alter these settings. Driving without a proper alignment will cause poor handling and destroy your tires quickly.
Can I just replace the bushings instead of the whole control arm?
While it is technically possible to press out the old bushings and press in new ones, it requires specialized hydraulic press tools. For most DIY mechanics and even many shops, replacing the entire control arm assembly is faster, easier, and ensures all components are new and properly fitted.
Are there any recalls for the 2012-2019 Porsche 911 suspension?
My research found no specific NHTSA recalls for the rear upper control arms on the 2012-2019 Porsche 911. Failures are typically considered normal wear and tear.
Helpful Videos
Technical Specifications
OEM Part Numbers: 9P1505237B 9P1-505-237-B 99133106104
Material: Aluminum alloy. Bushings: Rubber. Location: Rear Suspension, Upper Position. Fits both left and right sides.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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