2002 2.7 Vibration/Noise
 

In the last week or two I have noticed a vibration under acceleration. I have experienced this occasionally on an intermittent basis for about two years but now it deems constant. Then in the last couple days I have noticed an additional different vibration/noise while decelerating. (Sounds like a bowling ball rolling down a lane.) The frequency is speed related, not engine RPM related. I can put it in neutral and the sound/vibration does not change. Engagement of the clutch does not alter the vibration/noise either. I was thinking motor mount but it seems that would be directly RPM related. Any thoughts?

thanks

What you describe matches experiences I've had with other vehicles when a wheel bearing started to go south...

Today at lunch I drove up and down the quietest, smoothest road I could find, accelerating, decelerating, clutch, no clutch, in gear, out of gear, etc. The acceleration vibration came in around 3800 rpm and didn't get any better, and not much worse, the faster I drove. I noticed that if I applied the brakes rather hard when decelerating the vibration & noise seemed to go away or lessen greatly. Just minimal pressure on the brakes had no affect. At one point under slower speed deceleration (and 40-50 mph) it sounded like the noise you get when driving over tar seams and your tires make that rhythmic sharp-quick thumping sound but there were no tar seams......

shadrach74,
thanks for the feedback. You could be right. I've had a few 914s that had bad wheel bearings that made different noises under and off load.

Found the problem. It was the RR tire. It was a cord separation about 4" long on the very inside edge. I was driving home from work, doing various things to pinpoint the vibration when I heard a loud pop and the noise/vibration immediately stopped. I was doing about 70 and the car handled great. I was able to take an exit and pull off on a non-busy shoulder without total tire collapse.

When I acquired the car it had about 60K miles on it and a near new set of Kuhmo Exsta ASX all season tires. I told myself that I couldn't wait to wear them out so I could get more serious rubber. Since then I've put about 35K on the Kuhmos and they still have nice tread depth. I drive my Boxster daily in all weather (except ice). For everyday street driving these Kuhmos have been excellent. I just ordered another set! Just rears though.....I'm going to push the fronts a little longer.....