2022-2025 BMW iX Front Knee & Steering Knuckle: Failure Sounds and Replacement Guide

Symptoms of a Failing Front Knee or Wheel Bearing

Failure of the front knee assembly is uncommon unless caused by a significant impact, like hitting a deep pothole or curb. More often, the symptoms drivers notice are from the integrated wheel bearing reaching the end of its service life. Because the wheel bearing is pressed into the knuckle, the entire assembly is typically replaced. Watch for these warning signs:

• Grinding or Scraping Noises at Low Speeds: Owners report hearing a distinct "scraping," "grinding," or "crunching" noise that is most apparent during low-speed maneuvers like parking or making a U-turn. This sound can often be felt through the steering wheel.
• Clunking or Knocking Over Bumps: A metallic "clunk" or "knock" when driving over bumps or uneven road surfaces can indicate a worn ball joint where the control arms attach to the knuckle.
• Humming or Whining Noise: A steady hum or whine that changes pitch or intensity with vehicle speed, especially when turning, is a classic sign of a worn wheel bearing. The noise may disappear or get louder when you steer one way or the other.
• Vague or Loose Steering: If the steering feels less precise or if you notice excessive play in the steering wheel, it could be due to wear in the knuckle's connection points.
• Uneven Tire Wear: A bent knuckle, even slightly, will alter the car's alignment and cause rapid, uneven wear on the inside or outside edge of the front tires.

Known Issues, TSBs, and Recalls

As of mid-2024, there are no specific recalls or widespread Technical Service Bulletins (TSBs) from BMW or the NHTSA concerning the front knee/knuckle assembly or wheel bearings on the 2022-2025 BMW iX. Most owner complaints are isolated incidents, with some forum members reporting creaking sounds that were resolved by a dealer replacing a faulty ball joint under warranty.

Several recalls do exist for the iX platform for issues related to software, the high-voltage battery system, and cruise control activation, but none directly involve the suspension knuckles.

Buying a Used Knee / Steering Knuckle Assembly

A recycled OEM knee assembly is an excellent, cost-effective alternative to a new dealer part, especially since quality aftermarket options for the iX are not yet available. Because the knuckle itself is a solid piece of metal, failure from wear is rare; damage is almost always from collision or impact. The integrated wheel bearing is the primary wear item.

Inspection Checklist:

• Check for Cracks: Carefully inspect the entire part, especially around the mounting bosses for the strut, control arms, and brake caliper. Look for any hairline cracks or signs of stress, which would indicate it was removed from a vehicle with significant collision damage.
• Spin the Wheel Hub: The used assembly should include the wheel bearing and hub. Grip the hub and spin it by hand. It should rotate smoothly and silently. Any roughness, grinding, or clicking noise means the integrated bearing is bad, and you should not purchase the part.
• Examine Mounting Surfaces: Ensure all mounting surfaces and bolt holes are clean and free of damage or stripped threads.
• Verify Part Numbers: The left and right side knuckles are different parts. Confirm you are buying the correct one for your needs:
  • Right (Passenger Side): 31-10-6-890-574
  • Left (Driver Side): 31-10-6-890-573

Mileage Considerations

For a newer vehicle like the iX, mileage on a used part is less of a concern for the knuckle itself. However, it is a factor for the integrated wheel bearing. A part from a low-mileage vehicle (under 50,000 miles) is ideal. One forum user reported a ball joint issue at around 25,000 miles, while another mentioned a noise starting around 47,000 miles, suggesting that wear can begin in this range. Given the vehicle's heavy weight, a bearing from a higher-mileage donor vehicle carries more risk.

Replacement Cost Breakdown

Replacing the front knee assembly is a labor-intensive job. The following is an estimated cost breakdown. Prices can vary based on your location and the specific labor rates of your chosen repair shop.

Replacement Procedure Overview

This is an advanced repair that is not recommended for DIY mechanics without significant suspension work experience and the proper tools. The vehicle's high-voltage system also requires caution.

Key Steps & Torque Specs

1. Safely lift and support the vehicle and remove the front wheel.
2. Remove the brake caliper and rotor, and hang the caliper securely to avoid straining the brake line.
3. Disconnect the ABS wheel speed sensor from the knuckle.
4. Separate the steering tie rod end from the knuckle arm using a ball joint separator.
5. Disconnect the upper and lower control arms from the knuckle.
6. Remove the large axle nut and push the drive axle out from the wheel hub.
7. Unbolt the knuckle from the bottom of the strut assembly.
8. Installation is the reverse of removal, using all new nuts and bolts.

Related Parts to Inspect

While the knuckle is removed, it is the perfect time to inspect related components for wear:

• Control Arms: Check the bushings for cracks or tearing and the ball joints for any play.
• Tie Rod Ends: Check for any looseness or play in the joint.
• Sway Bar End Links: These are a common source of clunking noises and should be checked for looseness.
• Strut Assembly: Look for any signs of fluid leaks from the damper.

Frequently Asked Questions