sycodon

Facts:

2006 V6
5 Speed
70k miles
P235/55r17 Wheels
I believe a 3.3 differential

Problem:

I have a rhythmic clunking coming from the rear end, I believe from the differential.

Symptoms:

Clunk is linked to vehicle speed, not engine RPM.

At 40mps, the clunk occurs approximately 495 times a minute. For the musically inclined, that is a series of 16th notes played at 134 BPM.

On jack stands, 2nd gear, at idle (800-900 RPM) the clunk seemed to be every 4 tire rotations or so.

The left wheel was rotating at a fraction of the speed of the right. In first gear, the left wheel was at a virtual stand still. The left wheel was more difficult to turn by hand. I recently changed the rotors in the back so that could be what's going on there.

The clunk causes a visible vibration in the rear axle/differential. Pressing a steel rod against the differential from the rear, I could feel it kick back at me slightly.

I saw no visible wobble of the draft shaft.

The clunk is loudest when accelerating and decelerating, using the engine as a brake.

After accelerating to speed, backing off the gas significantly diminishes the clunk. So when under load the sound is the loudest.

I was reminded of a record player skipping at the end of a record. I imagine a gear gradually moving out of alignment until it is force back into the original position and starting again.

I will update tomorrow with more precise information. Audio is available now, Video tomorrow night. I'll post on YouTube and provide links.

Thanks all

tx_zstang

Sounds like the differential is broken. Pull the rear end cover and pull out the broken pieces.