2016-2023 Mazda CX-9 Rear Upper Control Arm: Diagnosing Clunks and Tire Wear
This guide covers the common symptoms, replacement costs, and inspection points for a failing rear upper control arm on the second-generation Mazda CX-9.
- The most common failure symptom is a clunking noise from the rear over bumps, caused by worn rubber bushings.
- The OEM part TK49-28-C10 fits both the left and right sides, simplifying the buying process.
- A four-wheel alignment is mandatory after replacement to prevent severe tire wear and handling issues.
- When buying used, the primary focus is inspecting the rubber bushings for cracks, tears, or looseness.
Symptoms of a Failing Rear Upper Control Arm
The rear upper control arm itself is a sturdy piece of metal that rarely breaks unless damaged in a collision. The true point of failure is almost always the rubber bushings at either end. These bushings absorb vibration and allow the arm to pivot. When they wear out, they cause a range of noticeable problems.
- Clunking or Knocking Noises: This is the most common symptom. You'll hear a distinct clunk or knock from the rear of the vehicle, especially when driving over bumps, potholes, or uneven pavement. The noise comes from the metal-on-metal contact now that the rubber bushing has failed.
- Uneven Tire Wear: A worn control arm allows the wheel alignment to shift, causing the top of the tire to tilt inwards or outwards. This results in accelerated wear on the inside or outside edge of the rear tires.
- Rear End Instability: The vehicle may feel loose, unstable, or like it's 'wandering' from the rear, particularly at highway speeds or during turns. This happens because the worn bushings can no longer hold the wheel securely in its correct position.
- Vibrations: In some cases, excessive vibrations can be felt from the rear of the vehicle. This is often a secondary effect of the uneven tire wear caused by the bad control arm.
Known Issues, TSBs, and Recalls for 2016-2023 Mazda CX-9
As of this writing, there are no safety recalls issued by the National Highway Traffic Safety Administration (NHTSA) for the rear upper control arms on the 2016-2023 Mazda CX-9. Failures of this part are typically considered normal wear-and-tear rather than a manufacturing defect.
It is important not to confuse this with a recall for the front lower control arms on the previous generation (2007-2014) CX-9. That issue does not apply to this vehicle generation.
Some owners of early 2016 models reported a squeaking or creaking noise from the rear suspension, which was addressed by a Technical Service Bulletin (TSB) related to the rear coil springs and rubber insulators, not the control arms themselves. While various suspension noises can occur, widespread, premature failure of the rear upper control arm is not a documented common issue for this CX-9 generation.
Pro Tip: If you hear a clunking noise, it's important to inspect other suspension components as well. Worn sway bar end links can produce a similar sound and are also a common wear item.
Buying a Used Rear Upper Control Arm: What to Inspect
A used OEM control arm is an excellent, cost-effective option, as the original Mazda part is high quality. The metal arm itself has a very long life, so you are primarily inspecting the condition of the pre-installed rubber bushings. Here’s what to check:
- Inspect the Bushings: Look closely at the rubber bushings at both ends of the arm. The rubber should be firm and solid. Reject any arm with bushings that are cracked, torn, severely dried out, or have pieces missing.
- Check for Play: Grab the inner metal sleeve of the bushing and try to move it around inside the rubber. There should be very little to no movement. If it feels loose or sloppy, the bushing is worn out.
- Examine the Arm Body: Check the metal arm for any signs of bending, heavy scraping, or stress marks from a collision. A bent arm will make alignment impossible. Minor surface rust is usually okay, but avoid parts with deep, flaking rust that compromises the metal's strength.
- Verify Part Number: The OEM part number is TK49-28-C10. This part is interchangeable and fits both the driver (left) and passenger (right) sides, which simplifies purchasing.
Cost of Replacement: New vs. Used
Replacing a rear upper control arm is a common repair. Opting for a quality used OEM part can offer significant savings over a new part from the dealer, while often providing better longevity than a cheap aftermarket alternative.
| Part Source | Estimated Price (Per Arm) |
|---|---|
| New OEM (Dealer) | $100 - $140 |
| New Aftermarket | $70 - $175 |
| Used OEM | $35 - $65 |
| Shop Labor | $125 - $300 |
Important: A four-wheel alignment is required after replacing a control arm to ensure proper handling and prevent rapid tire wear. Factor this cost (typically $100-$200) into your budget.
Replacement Overview & Difficulty
Replacing the rear upper control arm is a moderately difficult job that a skilled DIY mechanic can perform.
- Difficulty Rating: 3 out of 5
- Estimated Time: 1-1.5 hours per side
- Tools Needed: Jack and jack stands, socket set (16mm is common), torque wrench, wheel chocks.
General Steps:
- Safely lift and support the rear of the vehicle on jack stands and chock the front wheels.
- Remove the rear wheel.
- Place a jack under the lower control arm or knuckle to support the suspension and prevent it from dropping.
- Loosen and remove the two bolts holding the upper control arm in place: one at the knuckle and one at the subframe.
- Remove the old control arm.
- Install the new control arm. Do not fully tighten the bolts yet.
- Re-install the wheel and lower the vehicle so its full weight is on the suspension.
- Torque the control arm bolts to 45 ft-lbs (61 N·m). This step is critical; tightening the bolts while the suspension is hanging can preload and destroy the new bushings.
- Torque the wheel lug nuts to 80-108 ft-lbs.
- Get a professional alignment.
Frequently Asked Questions (FAQ)
Is the rear upper control arm the same for the left and right sides?
Yes, for the 2016-2023 Mazda CX-9, the part TK49-28-C10 is used for both the rear left (driver side) and rear right (passenger side) upper positions.
Do I need an alignment after replacing this part?
Yes, an alignment is absolutely necessary. The control arm dictates the wheel's position, so replacement will alter your alignment angles. Skipping this step will lead to poor handling and destroy your tires quickly.
Can I just replace the bushings instead of the whole arm?
While technically possible, it is not recommended for most people. The bushings are pressed in and require a hydraulic press to remove and install. The labor cost at a shop to do this often exceeds the cost of a complete new arm that already includes pre-installed bushings, making a full arm replacement faster and more economical.
How long should a rear upper control arm last?
The lifespan of the bushings can vary based on road conditions and climate, but they typically last 80,000 to 120,000 miles. A Reddit user reported their 2018 CX-9 at 82,000 miles was recommended for replacement due to cracking bushings. The steel arm itself should last the life of the vehicle unless damaged.
Technical Specifications
OEM Part Numbers: TK49-28-C10 TK4928C10
Bushing Bolt Torque: 45 ft-lbs (61 N·m). Wheel Lug Nut Torque: 80-108 ft-lbs (108-147 N·m).
We Have This Part in Stock
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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