"Planetary gearset noise".. Ideas or suggestions?

[emarkay]

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. 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.

[Iron1384]

I just bought a 2000 Trans Am WS.6 6-speed, and I think my car has the same thing. I had the car inspected by different dealer than where I bought it, and they didn't report anything wrong. I haven't narrowed down where the noise is coming from, but it definately sounds like it is coming from below the car and not the engine bay. It's just a constant "howl" that increases with speed. It is noticeable around 50 mph, and gets louder the faster I go....

[Iron1384]

The other day my car started making horrible, loud metallic rubbing noises when moving in neutral or when engine braking. Took it to a dealer, and the rear differential is totally messed up. The driveshaft was wiggling where it meets the differential, and most of the diff oil had leaked out. Gonna cost at least $1,500 to replace the entire rear axel. All this after 2 separate dealers did a safety inspection before i bought it two weeks ago....if only one of those loser mechanics had tried to wiggle the driveshaft and noticed that it was loose...

[Wesman]

The other day my car started making horrible, loud metallic rubbing noises when moving in neutral or when engine braking. Took it to a dealer, and the rear differential is totally messed up. The driveshaft was wiggling where it meets the differential, and most of the diff oil had leaked out. Gonna cost at least $1,500 to replace the entire rear axel. All this after 2 separate dealers did a safety inspection before i bought it two weeks ago....if only one of those loser mechanics had tried to wiggle the driveshaft and noticed that it was loose...

I don't know your financial details or anything, but if it was me I'd tell the dealer to take tht $1500 and stuff it. For about a few hundred dollars more you can get a complete 12 bolt rear, ready to bolt in and go. Even with a minimal amount of mechanical skills, you could do it yourself. And it will be much stronger than any rebuilt 10 bolt would ever be. Just figured I'd suggest that for you in case you might want to go that route instead ;)