Tom's Corner Garage: Banging Noise from the Front End

This weekly feature for Edmunds Daily about car repair and maintenance is written by Tom Torbjornsen, the popular host of America's Car Show on satellite radio.

Dear Tom,
I own a 2002 Pontiac Grand Am. There was a banging noise in the front end whenever I drove over a speed bump, so I had the front bearing plates replaced. I hoped this would solve the problem but it still makes the same noise. Could the struts be bad?
Sammy from LA

Sammy asks a question that can only be answered with a complete front-end inspection.
It could be the struts, and a host of other things. Get it into a shop for inspection and diagnosis. The "hit and miss" approach to solving automotive problems wastes a lot of time and money.

Below is an illustration of his car's front suspension.

Sammy already had numbers 10, 11 and 7 replaced to no avail.

There are several possible problems that would cause the banging noise:

• Worn lower control arm bushings cracking and banging (#4)
• Broken strut flexing (#6)
• Bad lower ball joints cracking in steering knuckle (#2)
• Broken spring flexing (#8)
• Broken sway bar cracking (#12)
• Worn sway bar links flexing (#15)
• Crushed sway bar insulator bushings banging on the underside of the vehicle (#14)

The only way to determine what component is bad or worn is to get the vehicle up on a lift and properly inspect all these parts.

Other conditions that can cause a banging noise when going over a bump:

• Loose wheel
• Loose brake caliper
• "Body flex" caused by a broken weld or body panel
• Loose body-to-frame bolts
• Broken engine or transmission mounts

Take a ride with your tech so they can better pinpoint the noise. That way you don't get surprise repair bills for unnecessary work. A test drive ensures everyone is on the same page and focused on the same concern.

On a side note, people often wonder if bad wheel alignment can cause noises such as banging. The answer is NO. Wheel alignment only affects how the tires wear and how the vehicle handles while driving. Maladjusted wheel alignment will not cause a mechanical noise. Something has to be worn or broken to cause this sound.

A final word: After replacing the part that is the culprit, make sure the front end is realigned or the tires will wear out prematurely.

'Til next time...Keep Rollin'

Posted by

Ron Montoya October 21, 2009, 11:00 AM

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