dab4133

I was hearing a noise from the rear of my 84 AT. It was speed sensitive, and sounded like a click or rattle. I inspected the cv joints and went ahead and replaced them. Test drive, and the noise is still there. Could it be torque tube bearings going bad? Wheel bearings would have a constant whine or howl, wouldn't they? My sound is almost like a tin can rattle. Thanx - Dave

fbarnhill

Hi,
I read somewhere that the rear wheel bearings can make a clicking sound.

Good luck,
Frank Barnhill
79 Euro

Bill Ball

In an AT, the TT shaft is spinning any time the engine is on, in gear or not, at engine RPM speed. So, TT bearing noise is closely related to engine speed.

If this is related to road speed, then rear axles or perhaps differential gears.

Bearing noises vary with side load. So, when you turn, the noise usually changes dramatically.

Give us any more clues as to how regular the noise is and anything that affects it.

SharkSkin

When was the last time you torqued your lug nuts? Also, what year car, AT/MT, etc?

dab4133

Yes Bill, the noise is related to road speed, not engine rpm. There is no change in the noise when turning. The faster I drive down the road, the loudness and frequency of the rattle/click becomes more pronounced. Dave A. - I will torque my lug nuts to see if that solves anything. Thanx

Dave B.
1984 928S AT

ROG100

Shot in the dark - On my 82 I went through all the scenarios that you are looking at.
Conclusion - non of them - it was the O2 mileage recorder down under the cover next to the passenger seat. It always sounded like it was from the back of the car. If the 84 has it fitted disconnect the wiring harness and see if that makes a difference.
Long shot but worth a try.

PS: Are you getting rain in Amarillo - if so keep sending it my way

dab4133

Roger- I unplugged the 02 mileage recorder (cooper wire wrapped device next to the amp?) and still have noise. I guess I will start researching differential and rear axle troubleshooting this weekend and see if I can get some results. Rain? I have heard tell of that substance in the tales of the village elders, but have never seen it myself - seriously, we have been fighting wildfires up here for the past 2 months. No real rain since last Oct. Bad mocha.
Dave B.
1984 928S AT

Bill Ball

Pull the rear wheels and check the brake hardware including things like the backing plates. You might find somehting loose or bent hitting the rotor.

You might jack up and carefully support the rear and run the car in 1st gear while listening for the noise at the rear. Something like a long 3/4" heater hose with one end held to your ear and the other end poked around the rear can help a lot to locate the noise source.

dab4133

Yes Virginia there is a Santa Claus I jacked up the rear end and removed both wheels to inspect for anything loose or interfering with the rotors, etc. Everything checked out OK, so I went ahead and put wheels back on, coated the studs with anti-seize and torqued them down to manual specs (96 ft/lbs) Test drove it and - noise is completely gone Thanx to all for your comments and suggestions - A quick, free fix every blue moon is good for the soul. To Dave A. - Thanks for the input. I have visited your site and plan to redo my fuse/relay panel next. That stabilant sounds amazing - I would never attempt to redo this panel without your excellent write-up. Thanx again to all.

Dave B.
1984 928S AT

dab4133

Amendment to my previous post - while replacing the cv joints was neither quick or free, I had already inspected them and both had boots in bad shape. Needed to be serviced anyway, so I am that much further ahead in this process of bringing this shark back into decent shape

Dave B.
1984 928S AT

Bill Ball

Good that Dave and you caught this!

SharkSkin

Good, glad to hear it Dave!

NC928S4

This description sounds very close to what I am experiencing. When the car is cold everything sounds normal. After 15-20 minutes when accelerating around a right turn a rattle is heard. Almost like a tin can rattling then tipping over and no more noise. As things warm up the same noises can be heard on any accelerating turn. Revving the engine at a stand still past 3300rpm can generate the rattle but not the can tipping over.

There were some signs of heat shields with vibrational contact with the frame from a previous encounter of someone hitting something on the road like a rock or animal but we pried the metal back with only marginal reduction in rattle if any.

From what I've read my problem sounds like a TT bearing. Any comments are welcome.

Black Sea RD

NC928S4,

The noises could be:

1. The rear flex plates that are attached to the torque converter are starting to come apart. The two plates are riveted together and the rivets can loosen with time causing a sound like what you are describing.

2. The TT vibration dampener has come apart from it's rubber holders and the heavy steel weight in the TT is now moving around and vibrating against the TT.

3. TT bearings are completely gone and making the noise.

If it is your drive line that is making this noise, my informed guesses are in the order I wrote them.

Hope that helps,

NC928S4

Item #2 sounds like it. We noticed some "interesting" modifications when changing the ATF and filter. Thanks for narrowing down the suspects.