Have an unususal noise from the rear of the car (or so I thought). It sounds like a dragging brake or a vacuum leak, but is strictly MPH related (not RPM). The faster one goes, the louder it gets, and in coast or drive, and engine off or on, it stays the same.

By putting the car on a lift, and running and in gear, the sound seems to come from THE MIDDLE OF THE DRIVESHAFT, and it is LOUD! Further inspection sources it to the rear of the transmission. A GM tech who knows these cars said it sounds like the planetary gearset, but it's not. I just had the differential pinion bearing replaced, but can't understand how a once quiet tranny would cause such a noise all at once. A pan inspection showed normal wear debris and no bearing or bushing residue. The car has 86K miles and is stock and not abused.

Aside from the noise, which is rather loud at 60 MPH, everything else is as normal. I don't want to have the tranny exhumed and autopsied unless necessary and the tech suggests living with the noise...

Any ideas, suggestions, similar experiences???
Thanks.

 

Once the transmission is in 3rd gear, the whole gear train is going in the same direction, and the planetaries are not in under or over drive. The noise should go away. If it does not, then most likely it is not the planetaries.

 

Yea, I shoulda' remembered that! Will go and check it out later today. Thanks!

MRK

 

It's not the planets. Get noise in 2,3 and 4th gear. Any other ideas?

MRK