2019-2024 Volvo XC40 Steering Knuckle: Diagnosing Noises, TSBs, and Replacement Costs

Symptoms of a Failing Steering Knuckle Assembly

A steering knuckle is a robust component that typically only fails from a significant impact, like hitting a curb or a deep pothole, or from severe corrosion. More often, the symptoms you notice are caused by the failure of parts connected to the knuckle, such as the wheel bearing or ball joint. Distinguishing between these can save you from a misdiagnosis.

Noises

• Grinding, Humming, or Roaring: A constant grinding or humming noise that changes pitch with vehicle speed (but not engine RPM) and gets louder when turning is a classic sign of a worn wheel bearing, which is pressed into or bolted onto the knuckle.
• Clicking, Popping, or Clunking: A sharp clicking or popping sound, especially during low-speed turns like pulling into a parking spot, often points to a failing CV joint (on the axle shaft) or a worn ball joint. However, on the XC40, this specific noise is frequently caused by a known issue with the upper strut bearing (see TSB section below).
• Squealing When Turning: This can sometimes indicate a bent knuckle or dust shield rubbing against the brake rotor, but it's more commonly a brake or power steering issue.

Handling and Steering Issues

• Vehicle Pulling to One Side: If the knuckle is bent from an impact, it can throw off the suspension geometry (camber and caster angles), causing the vehicle to pull to one side. This pull will persist even after a wheel alignment if the knuckle itself is the problem.
• Shaky or Vibrating Steering Wheel: While this can have many causes, a failing wheel bearing attached to the knuckle is a primary suspect. A bent knuckle can also cause a wobble that is felt in the steering wheel.
• Crooked Steering Wheel: If you have to hold the steering wheel off-center to drive straight, it's a sign of an alignment problem, which could be caused by a damaged knuckle.

Visual Signs

• Uneven Tire Wear: A bent knuckle will cause the tire on that corner to wear out quickly on its inner or outer edge.
• Visible Damage: After a collision or severe pothole strike, a visual inspection may reveal a crack, bend, or heavy corrosion on the knuckle itself.

Known Issues, TSBs, and Recalls for 2019-2024 Volvo XC40

While the steering knuckle itself is not a common failure point, there are related issues specific to this generation of XC40 that owners should be aware of.

Technical Service Bulletins (TSBs)

• TSB TJ36512.2.0 - Upper Front Suspension Creaking/Knocking Noise: This is the most significant known issue related to the front suspension. Owners report a creaking, knocking, or popping sound when turning the steering wheel at low speeds. The cause is a faulty upper strut bearing, not the knuckle. The fix involves replacing the upper bearing. Many owners have had this repair performed under warranty.
• TSB TJ36424.1.1 - Vibrations in Steering Wheel Above 60 mph: This bulletin addresses high-speed vibrations that could be mistaken for a wheel bearing or knuckle issue. The cause is often related to tire balance or other driveline components.

Recalls

As of mid-2024, there are no recalls issued by the NHTSA for the steering knuckle assembly on the 2019-2024 Volvo XC40. Recalls for this vehicle have focused on software issues, brake control modules, and turn signals. Always check your vehicle's VIN on the NHTSA website for any open recalls.

Buying a Used 2019-2024 XC40 Steering Knuckle Assembly

Since a new OEM knuckle can be expensive, a used OEM part from a reputable recycler is an excellent value. The knuckle is a durable part, so a used one is often just as good as new, provided you check a few key things.

Compatibility Check: The Most Important Step

While some sellers specify this part for All-Wheel Drive (AWD) models, other parts catalogs show it fits both AWD (T5) and Front-Wheel Drive (FWD) (T4) gasoline models. Always provide the seller with your vehicle's VIN to confirm an exact match before purchasing.

Physical Inspection

• Check for Cracks or Bends: Inspect the entire part for any signs of cracking, especially around the mounting points for the ball joint and tie rod. Look down the length of the part to spot any subtle bends from an impact.
• Inspect Mounting Holes: The tapered holes for the ball joint and tie rod should be perfectly round. If they are worn into an oval shape, the knuckle is junk.
• Check the Wheel Bearing: The main reason to consider mileage on a used knuckle is the condition of the included wheel bearing. Spin the bearing by hand. It should be smooth and silent. Any roughness, grinding, or noise means the bearing is bad and will need to be replaced—a job that requires a hydraulic press and adds significant cost.
• Look for Corrosion: On cars from the salt belt, the wheel hub can rust and seize into the knuckle, making it nearly impossible to remove. A part from a southern or western state will likely be in better condition.

Mileage and Value

The knuckle itself isn't a mileage-sensitive part, but the wheel bearing is. A wheel bearing can start to show wear around 70,000-100,000 miles, but impact can cause it to fail much sooner. A used knuckle from a low-mileage (under 50,000 miles) donor vehicle is ideal, as the original wheel bearing likely has plenty of life left.

Cost Comparison

Prices can vary by location and supplier, but this gives a general idea of the cost for a single front-left steering knuckle assembly.

Replacement Guide & Special Procedures

Replacing a steering knuckle is a complex and labor-intensive job that is not recommended for beginners. It involves disassembling most of the front suspension and brakes. It requires specialized tools, including ball joint separators and a torque wrench capable of high values.

Key Steps & Torque Specs

1. The vehicle is lifted and the wheel is removed.
2. The brake caliper, caliper bracket, and rotor are removed and the caliper is hung securely to avoid straining the brake hose.
3. The axle nut is removed, and the axle shaft (CV shaft) is pushed out of the wheel hub.
4. The tie rod end, lower ball joint, and strut bolts are disconnected from the knuckle.
5. The old knuckle is removed, and the new one is installed by reversing the procedure.
6. A four-wheel alignment is mandatory after replacement. Skipping this step will result in poor handling and rapid tire wear.

While a full list of torque specs should be sourced from an official Volvo service manual, here are some commonly cited values:

• Wheel Lug Bolts: 140 Nm (103 lb-ft)
• Front Strut-to-Knuckle Bolts: ~90 Nm (66 lb-ft) - New bolts required.

Related Parts to Consider Replacing

Given the high labor cost, it's wise to replace other nearby wear items at the same time.

• Wheel Bearing/Hub Assembly: If you are installing a used knuckle with high mileage or the bearing feels rough, it's best to have a new bearing pressed in before installation.
• Lower Ball Joint: This is a primary pivot point and wears over time.
• Tie Rod End: Connects the steering rack to the knuckle. Check for play.
• Upper Strut Bearing: Given the known TSB for noise, if your car has higher mileage, replacing this part is a smart preventative measure.

Frequently Asked Questions (FAQ)