2015-2019 Lincoln MKC Rear Upper Control Arm: Diagnosing Clunks, Tire Wear, and the FWD vs. AWD Trap

Symptoms of a Failing Rear Upper Control Arm

A failing rear upper control arm typically fails in its bushings—the rubber insulators at the mounting points. When these bushings wear out, crack, or collapse, they allow excessive movement, leading to several distinct symptoms.

• Clunking or Knocking Noises: This is the most common symptom. You may hear a clunk, pop, or knock from the rear of the vehicle, especially when driving over bumps, potholes, or uneven pavement. The noise is caused by the metal components of the arm making contact with the frame or knuckle as the worn bushing fails to absorb the impact.
• Uneven Rear Tire Wear: A worn control arm allows the wheel's alignment, specifically the camber angle, to shift out of specification. This typically causes accelerated wear on the inside or outside edge of the rear tires.
• Rear-End Instability: The vehicle's rear end may feel loose, unstable, or like it's wandering, particularly at highway speeds or during cornering. This is due to the unwanted movement of the wheel assembly that the worn bushings can no longer control.
• Vibrations: In some cases, excessive vibrations can be felt from the rear of the vehicle as the worn bushings are no longer able to dampen road imperfections effectively.

Known Issues, TSBs, and Recalls

TSB for Rear Suspension Clunking Noise

It is important to note that while a clunking noise is a primary symptom of a bad control arm, it is not the only possible cause. Ford issued Technical Service Bulletin (TSB) SSM 46495 for some 2015-2017 Lincoln MKC and Ford Escape models that exhibit a rattle or clunking noise from the rear suspension over bumps. This TSB identifies the rear shock absorbers as the potential source of the noise, noting that faulty shocks may compress several inches before providing resistance. Before replacing the control arms for a clunking noise, it is wise to also inspect the rear shocks as a possible, and potentially more likely, culprit per this TSB.

Recalls

As of mid-2024, there are no specific recalls for the rear upper control arms on the 2015-2019 Lincoln MKC. However, there is a major safety recall (NHTSA ID: 23S28) for a fire risk related to the battery monitor sensor, and owners are advised to park their vehicles outside until the repair is completed. Always check for the latest recall information using your vehicle's VIN on the NHTSA website.

Compatibility: The FWD vs. AWD Difference

The rear suspension geometry is different between FWD and AWD models to accommodate the rear differential and drive axles on AWD versions. This means the control arms have a different shape and/or length.

• Front-Wheel Drive (FWD) Models: Use OEM part number EJ7Z-5500-C. Multiple Ford parts catalogs explicitly state this part is for vehicles "Without AWD".
• All-Wheel Drive (AWD) Models: Use a different part number. While a single definitive number is elusive, aftermarket kits and dealer catalogs confirm a unique part is required for AWD models. Do NOT attempt to install the FWD arm (EJ7Z-5500-C) on an AWD vehicle.

The left and right side arms are identical for this application. The same part number is used for both rear upper positions.

Buying a Used 2015-2019 MKC Rear Upper Control Arm

A used OEM control arm can be an excellent value, often providing better material quality than a cheap aftermarket alternative. However, careful inspection is key, as the bushings are the primary failure point.

What to Inspect:

1. Check the Bushings: This is the most critical check. The rubber bushings at both mounting points should be intact. Look for any signs of cracking, tearing, dry rot, or separation from the metal sleeve. The rubber should not look collapsed or squashed.
2. Inspect the Arm Body: Check the metal arm for any signs of bending, cracks, or significant impact damage. While these arms are robust, an arm from a vehicle in a major collision could be compromised.
3. Surface Corrosion: Light surface rust on the cast iron or steel is normal, especially for parts from northern climates. However, avoid any part with deep, flaking rust that compromises the structural integrity of the arm.
4. Verify Drivetrain Compatibility: Before purchasing, confirm the donor vehicle's drivetrain (FWD or AWD). If you are unsure, ask the seller to verify the OEM part number stamped on the arm. Cross-reference this with the known FWD part number (EJ7Z-5500-C) to ensure you are buying the correct version for your MKC.

Replacement Overview & Difficulty

Replacing the rear upper control arm is a moderately difficult job that a skilled DIY mechanic can perform. A wheel alignment is mandatory after the repair is complete.

• Difficulty: 3 out of 5
• Tools Required: Jack and jack stands, socket set, torque wrench, breaker bar.
• Procedure Summary: The vehicle must be safely raised and supported. After removing the wheel, support the knuckle/lower control arm with a floor jack to take tension off the suspension. Unbolt the control arm from its two mounting points on the subframe and the single mounting point on the top of the wheel knuckle. Install the new arm and torque all fasteners to specification.
• Critical Final Step: A four-wheel alignment is required after replacing a control arm. Skipping this step will result in poor handling and rapid tire wear.

Cost Comparison

Prices can vary based on location and supplier. The following is an estimated breakdown of costs:

Frequently Asked Questions (FAQ)