Hey,
I went out for a 70ish mile cruise last night. Mix of highway and curvy backroad miles. Overall trip was near 2 hours or so.

As I was on the highway heading back to my buddies house something in the rear of the car started making a loud grinding/rubbing noise. It only made the sound when I was off the gas pedal. I tried pushing in the clutch and taking it out of gear but it still made the same noise. As I got off the highway and started slowing down so did the noise. When I reached about 45mph or so it stopped, or got to quiet to hear. So it was related to speed and not engine rpm.

After I got off the highway it stopped making the noise. The trip to his place was just a couple miles but at slow speeds, 45mph or slower, and it never made the noise. On the trip home I did get a chance to get back up to near 70mph but only for 1/2 a mile or so. Same thing again, the noise did not return.

I am planning on putting the car up in the air when I get home in a few hours to spin/shake/test everything from the drive shaft back to the rear tires.

I was curious if anyone has experienced this before? Or if anyone had any advice on how to test or what specifically to test?

Any advice would be greatly appreciated.

 

Possibly driveshaft u-joints, ive gone through 2 driveshafts on my s4 na. When the first one went out it would make sound reletive to speed and only on decelaration with the car in gear, but when accelerating it sounded fine.
Hope this helps.