2016-2023 Mazda CX-9 Rear Upper Control Arm: Clunks, Tire Wear, and Replacement

Common Symptoms of a Failing CX-9 Rear Control Arm

The most common reason for this part to fail is the wear and tear of its rubber bushings. When the bushings degrade, they can no longer hold the arm securely, leading to several noticeable symptoms.

1. Clunking or Knocking Noises from the Rear

This is the most frequent complaint. You may hear a clunking, popping, or knocking sound coming from the rear of the vehicle, especially when driving over bumps, potholes, or uneven pavement. This noise is caused by the worn-out bushing allowing metal-on-metal contact between the control arm and its mounting points. Some owners describe it as sounding like a heavy object rolling around in the trunk.

2. Uneven or Accelerated Tire Wear

Worn control arm bushings allow for unwanted movement of the wheel, which throws off the vehicle's alignment. This often results in the inside edge of the rear tires wearing out much faster than the rest of the tread. If you notice this specific wear pattern, a bad rear upper control arm is a likely culprit.

3. Poor Handling and Instability

A failing control arm can make the vehicle feel loose or unstable from the rear, particularly during turns or at highway speeds. You might feel the rear end swaying or have to make more steering corrections to keep the car going straight. This happens because the worn bushings can no longer maintain the correct rear wheel geometry under load.

Known Issues, Recalls, and TSBs for 2016-2023 Mazda CX-9 Suspension

While there are no specific recalls for the rear upper control arm on the 2016-2023 Mazda CX-9, there are some related service bulletins and a history of suspension issues on prior generations worth noting.

• No Direct Recalls: As of this writing, there are no NHTSA recalls for part number TK49-28-C10 on the 2016-2023 CX-9. A major front lower control arm recall was issued for the previous generation (2007-2014) CX-9 due to corrosion issues, but this does not apply to the second-generation model.
• TSB for Rear Suspension Noise: Mazda issued a technical service bulletin (TSB) for a squeaking or creaking noise from the right rear suspension on some 2016 models. This was attributed to the rear coil spring and rubber seat, not the control arm itself, but it's a known source of rear suspension noise.
• TSB for Steering Column Noise: A TSB was issued for a creaking noise from the steering column on 2016-2023 CX-9s, caused by a loose nut. While not a suspension part, it's a noise that could be misdiagnosed.
• Forum Discussions: Owners on forums frequently discuss clunking noises from the rear suspension, with worn control arm bushings being a common diagnosis.

Buying a Used 2016-2023 CX-9 Rear Upper Control Arm: What to Check

A used OEM control arm can be an excellent value, often providing superior quality and fitment compared to a cheap aftermarket alternative. Here’s what to inspect before you buy.

Physical Inspection Checklist:

• Check the Bushings: This is the most important check. The rubber bushings at both ends should be intact. Look for any cracks, tearing, dry rot, or signs of the rubber separating from the metal sleeve. Squeeze the bushing with your fingers; it should be firm, not soft or mushy. Reject any arm with visibly damaged bushings.
• Inspect the Arm Body: Look down the length of the arm to ensure it is perfectly straight. Any bend, however slight, means the part was compromised in an accident and is unusable. Check for deep rust, cracks in the metal, or elongated bolt holes. Surface rust is normal, but deep, flaky corrosion is a red flag.
• Verify Part Number: Confirm the part is stamped or labeled with TK49-28-C10 or TK4928C10 to ensure you have the correct OEM component.

Choosing a used OEM arm is often a better choice than a low-cost aftermarket part. The original Mazda part was designed with specific rubber durometer (hardness) and materials to match the vehicle's intended ride and handling characteristics. Some cheap aftermarket bushings can fail prematurely or provide a harsher, noisier ride.

Replacement Guide and Difficulty

Replacing a rear upper control arm on a Mazda CX-9 is a manageable job for an experienced DIY mechanic with the right tools.

• Installation Difficulty: 3 out of 5
• Estimated Time: 1-1.5 hours per side
• Tools Required: Jack and jack stands, metric socket set and wrenches, breaker bar, torque wrench.

Is This a DIY Job?

This is feasible for DIYers who are comfortable working on suspension components. The main challenges are often breaking loose rusted bolts and ensuring the vehicle is safely supported on jack stands. If you are new to auto repair, this may be a job best left to a professional.

Step-by-Step Overview

1. Safely lift and support the rear of the vehicle and remove the wheel.
2. Locate the upper control arm. It connects the subframe (towards the center of the car) to the top of the wheel knuckle.
3. Use a wrench and socket to remove the outer bolt at the knuckle and the inner bolt at the subframe. These may be very tight and require a breaker bar.
4. Remove the old control arm.
5. Install the new control arm. It's often recommended to leave the bolts slightly loose until the vehicle's weight is back on the suspension.
6. Reinstall the wheel, lower the vehicle so its full weight is on the suspension, and then torque the control arm bolts to the manufacturer's specification.

Cost to Replace a Mazda CX-9 Rear Control Arm

Costs can vary significantly based on part choice and labor rates. A dealership repair will be the most expensive, while a DIY repair with a used part is the most affordable.

Frequently Asked Questions (FAQ)

Technical Details and Part Numbers

• OEM Part Numbers: TK49-28-C10, TK4928C10
• Part Description: Arm, Rear Upper Suspension
• Positions: Rear Upper Left (Driver Side), Rear Upper Right (Passenger Side)
• Fitment: 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Mazda CX-9