THERE IS A METAL CLUNKING NOISE COMING FROM THE ...
2001 SAAB 9-3
November, 9, 2012 AT 6:19 PM
There is a metal clunking noise coming from the middle underneath my car. The noise becomes more frequent the faster I drive and stops completely whenever I step onto the brakes. The noise is irregular to the turning of the wheels and becomes more noticeable when I step very lightly onto the brakes and gets louder as I keep depressing the brakes slowly, until there is one last loud clunk and the noise stops, only to resume when I lift off the brakes. I have also noticed with the car completely off and in park (automatic) it makes a very similar clunking noise once when the brakes are depressed a good amount. The type of sound makes me think a caliper is loose, but at the same time the noise seems to come from the middle and not from any specific wheel. I have had strut mounts replaced and a control arm for other suspension noises, but I am fairly confident this is a problem with the brake system as the noise is only gone with the brakes in use.
Start by having the brake system inspected. A noise like you described should be pretty easy to locate. Some of the more common things are a loose brake pad, a loose caliper mounting bolt, and a deteriorated caliper mounting bushing. A loose pad is typically caused by a missing or rusted anti-rattle clip or a loose caliper that is able to move around. There can also be grooves worn into the mount the pads sit on but that will usually cause a clicking noise when applying the brakes.
Loose pads normally get quiet as soon as you press the brake pedal. With deteriorated bushings, the caliper should make one clunk too as soon as you press the pedal. Don't overlook a chunk of metal rusted away on the inside of the brake rotor. You may not hear or feel that at higher speeds.