Q: Knocking sound from car while driving straight and turning.

There are several reasons that may be causing a strong knocking sound from the driver’s side front wheel and this sound is likely attributed to an issue with the brakes, steering, and suspension.

• Struts/Strut Mounts - The suspension strut is attached to the vehicle by the strut mount. It reduces the sound and vibrations of the tires and stabilizes the steering system. If the struts/strut mounts have worn out, broken, or damaged a knocking sound may be heard when driving on rough roads or driving over bumps.

• Bushings/Lower Control Bushings - Bushings help to keep the vehicle properly aligned during the operation of the vehicle. If the bushings are severely worn out or broken a knocking sound may be heard as a result of metal on metal contact.

• Stabilizer Bar/Right and Left Control Arm - The right control arm and left control arm is connected by the stabilizer bar. Control arms allow the tires to go up and over bumps in the road smoothly.

• Ball Joints/Lower Ball Joint - A vehicle’s tires and wheels are attached to the suspension system by ball joints and enable the tires and wheels to turn. If the lower ball joint is severely worn out or broken a knocking sound may be heard as the vehicle makes turns.

• Bad Tires/Bad Left Tire - A knocking sound may be heard when tires go bad, if they are unbalanced or misaligned, or if there is a broken belt in one of the tires.

• Wheel Bearings - If a wheel bearing is severely worn out the wheel will not be able to spin freely. This may cause a knocking sound to be heard.

• Axles/Left front axle - The wheels of the vehicle turn on the front axle and the axle supports the weight of the vehicle. A knocking sound may be heard if the front axle is severely worn out.

• Loose Lug Nuts - Lug nuts attach the wheel to the vehicle. If the tires have recently been replaced or rotated it is possible that the lug nuts weren’t tightened to the wheel correctly. This may cause a knocking sound to be heard.

If you are hearing a knocking sound while operating the vehicle, have the brakes, steering and suspension inspected by a certified technician.