Q: Knocking noise underneath car.

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When driving my car, I hear a knocking noise coming from underneath, usually worse at slower speeds (45mph or lower). When I accelerate, the noise dissipates but will return when I'm coasting or on the brake. It makes this noise when I'm going straight and when I'm making left hand turns, but not as much when I'm turning right. It sounded like it could be a tire problem with the windows down (although I was told its something to do with the axel), and it comes from the front drivers side of the car. It also makes the steering wheel shake a little bit.

My car has 100000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. Diagnosing the exact source of a vibration or noise is typically only possible through an onsite inspection. However, after reading the symptoms you’re describing, the two possible suspects may include the wheel bearings or the CV joints. Both components can cause steering wheel vibration at speeds and can also cause knocking sounds as the wheels turn. Here at YourMechanic, we can have a technician come to your home or office to inspect and diagnose this noise issue for you, and make or suggest the necessary repairs.

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