So, I was driving my 2007 C4S tiptronic this morning. After about 2 minutes into the drive, at about 35 mph, I suddenly heard a very loud sound (from my car) that sounded like "metal scraping metal". Like the sound of a dozen forks screeching against a chalkboard.

After about 10 seconds into the sound, I slowed down to about 10 mph. The sound lessened as I decreased my speed (still pretty loud though). Then, after about 25 seconds from the time the sound began (and still rolling at 10 mph looking for a suitable place to turnout), the sound disappeared immediately.

After the sound disappeared, I found a place to pull my car over. I inspected the car and looked underneath. Nothing out of the ordinary. This entire day, and some 50 miles driving since this morning, I have not heard any unusual noises from the car. I cannot duplicate anything. The car is driving fine.

I am truly at a loss as to what happened. I could not tell exactly where on the car the sound was coming from. For a second, I thought maybe my tailpipes were dragging on the street (THATS how loud the sound was). My best guess is that a foreign object (i.e. rock) got stuck somewhere in the wheelbase. Still cant be sure though.

Thoughts? This one puzzles me.

 

I'm guessing everybody else will be puzzled just like you are since you don't have any more specifics. Could be a rock got lodged in the brakes. Could be a major mechanical issue with the diffs or tranny. Who knows without further info.

 

I had this happen to me a couple of weeks ago while driving on a newly paved road with excess loose gravel. Sounded like metal finger nails on a chalkboard. I immediately stopped and then proceeded forward, backward while applying the brakes to dislodge the stones. It worked ! And I had to do this several times as new asphalt gravel (which is very sticky) would get lodged in the calipers. A real PITA.......Porsche service tech said that no harm was done because the material used in the brake calipers is much harder than any stone.

 

Had a similar thing happen, was a stone between the disc brake and the disc inner guard.... Just backed up and all was fine.

Matt

 

I concur....stone in the brake/disc area. Be happy...could have been much worse.

 

Much worse with PCCB's if it was a stone.