2016-2025 Tesla Model S & Model X Steering Knuckle: Noises, Issues, and Replacement Guide

Symptoms of a Failing Steering Knuckle Assembly

On the Tesla Model S and Model X, the steering knuckle is a single assembly that includes the wheel bearing and hub. Therefore, most "knuckle failures" are actually failures of the integrated wheel bearing. A bent or cracked knuckle from a severe impact is possible but less common.

1. Humming, Whirring, or Grinding Noises

The most common sign of a bad wheel bearing inside the knuckle is a noise that changes with wheel speed. It often starts as a faint hum or whirring sound that gets louder as you accelerate. The sound may change or disappear when turning, as the load shifts from one side of the bearing to the other. As the failure progresses, this can turn into a loud grinding noise.

2. Clunking or Knocking Over Bumps

A clunking or knocking sound, especially at low speeds over bumps or when turning into a driveway, can indicate excessive play in the suspension. While this is often caused by worn control arm bushings or sway bar links, a severely worn wheel bearing can also contribute to these sounds. The noise comes from the hub shifting within the worn bearing race.

3. Vibration During Acceleration

Some Model S and Model X vehicles may experience a vibration or "shudder" during hard acceleration. This is often related to the front CV axles, and Tesla has issued a technical service bulletin (SB-21-39-001) to address this by replacing the halfshafts. While not a direct failure of the knuckle, the vibration puts additional stress on the wheel bearing and is a related issue to be aware of during diagnosis.

4. Loose or Vague Steering

A worn wheel bearing can create play or looseness in the wheel assembly. This can translate to a feeling of vague or imprecise steering. The vehicle may wander slightly on the highway, requiring more steering correction from the driver.

Known Issues, TSBs, and Recalls

While the steering knuckle itself is a robust part, it is connected to other components that have been subject to investigation and service bulletins.

NHTSA Investigation into Front Suspension Links

The National Highway Traffic Safety Administration (NHTSA) conducted an investigation into front suspension fore link failures on 2015-2017 Model S and 2016-2017 Model X vehicles. The investigation found over 400 instances of these links failing, mostly at low speeds during parking maneuvers. While the investigation was closed without a formal recall, NHTSA noted that drivers were able to maintain control of the vehicle after a failure. Tesla had previously issued a service bulletin (SB-17-31-001) in 2017 to replace these links on some vehicles.

TSB for Squeaking Stabilizer Bar

Tesla issued Service Bulletin SB-20-31-001 for some 2019-2020 Model S and Model X vehicles that may have a squeak from the front stabilizer bar when driving over bumps. This is caused by improperly vulcanized bushings and is not related to the knuckle, but the noise can be confused with other suspension issues.

TSB for Halfshaft Vibration

Service Bulletin SB-21-39-001 addresses customer complaints of excessive vibration during hard acceleration on 2014-2020 Model S and Model X vehicles. The fix involves replacing both front halfshafts with updated parts. This vibration can accelerate wear on the wheel bearings within the knuckle assembly.

Vehicle and Part Number Compatibility

It is critical to get the correct steering knuckle for your specific Model S or Model X. There was a significant design change with the "Refreshed" (also known as 'Palladium' or 'Plaid') versions that began in the 2021 model year.

• 2016-2020 Models: These earlier models use a different knuckle design. Common part numbers include 1027311-00-F and 1027316-00-F.
• 2021+ Models (Refresh/Plaid): These newer models have an updated suspension and require a different knuckle. Part numbers for these vehicles often start with 14xxxx or 16xxxx, such as 1620311-00-K.

Additionally, all steering knuckles for these models are for All-Wheel Drive (AWD) vehicles only. There may also be differences between Plaid and non-Plaid performance versions on the newer models, so verifying the exact OEM part number is essential.

Buying a Used Steering Knuckle

A used OEM steering knuckle assembly can be a cost-effective and reliable alternative to a new part, especially since the knuckle itself rarely fails. The primary concern is the condition of the integrated wheel bearing.

What to Inspect

• Check for Play: With the knuckle off the car, try to wiggle the hub flange. There should be absolutely zero play or roughness. Any movement or grinding indicates a worn bearing, and the part should be rejected.
• Visual Inspection: Look for any signs of impact damage, such as cracks, deep gouges, or bends, particularly around the mounting points for the control arms and tie rod. Check for corrosion, especially if the part came from a region where roads are salted in winter.
• ABS Sensor: Ensure the wheel speed sensor is intact and the wiring is not damaged. Sometimes these are damaged during removal.
• Mileage: Ask the seller for the mileage of the donor vehicle. A wheel bearing from a low-mileage vehicle (under 80,000 miles) is a much safer bet than one from a high-mileage car. Failures become more common as mileage increases.

Why Used OEM is Often a Good Choice

Original Equipment Manufacturer (OEM) parts are designed and tested by Tesla for a perfect fit and to meet specific performance standards. A low-mileage used OEM knuckle assembly is often higher quality and more durable than a new, inexpensive aftermarket part. Aftermarket bearings may not have the same longevity or noise characteristics as the original part.

Replacement Cost Breakdown

The cost to replace a steering knuckle assembly can vary based on your location and the source of the part. An alignment is required after replacement, which adds to the total cost.

Key Torque Specs and Installation Notes

Proper torque is critical for safety and performance. Always use a torque wrench and replace any single-use nuts as specified by the manufacturer. Suspension bolts should receive their final torque with the vehicle at normal ride height to avoid pre-loading the bushings.

Frequently Asked Questions (FAQ)