PJB

My car has a bad vibration and clunking sometimes when decelerating (coming to a stop). It seems to shake the whole back of the car.

Im not positive of the exact source of it but its definately in the drivetrain.
Ive got an AOD and 4.10 gears in the rearend.

I removed the weight thing that bolts to the differential housing and got rid of it because I remember reading it was pretty much useless with nonstock gears.

I had the problem Im having even beforeremoving that thing though.

I never have a problem when accelerating or driving normally (without stopping).

What could be the cause of the noise/vibration/clunk?

mattdel

give a little more detail about the speed of the car and what you are doing when it happens.

ie; the car vibrates after i let off the gas, from 40-20, then when i stop it clunks.

PJB

It happens pretty much any time Im slowing down at any speed when coming to a stop really.
Foot off the gas, sometimes on the brakes.

mattdel

well, to start with, i'd put the vibration dampner back on. its not a counterweight, its a dampner.

then i'd take a look into bad ujoints.

WhiteWindsor

Sounds like it could be the pinion gear. Grab the driveshaft in the rear next to pinion gear and see it there is any play, it could be something as simple as needing to tighten your pinion bolt. After i changed the gears in one of my mustangs it did the same thing. I could push and pull the ds back and forth. When i had pressure on it, like accelerating, i did not notice it, but when i took that pressure off, de-accelerating, the noise would be there.

PJB

I just realized it was in the box of front end parts I gave away. Ill have to get another one.

PJB

Ill have to check that when I get a chance. I just cleaned up from putting on a tranny cooler and Im taking it to a tranny shop tomorrow to put in a shift kit and stall converter.

blahman20

If you have a miss during idle it will vibrate at higher speeds when slowing down...but if it isn't a miss look at ball joints maybe.

PJB

Today I had a stall converter and shift kit installed and when driving home from the tranny shop I noticed the clunk and vibration seem to have disappeared.
Maybe something was loose like the driveshaft or a mount. The shop doesnt do rearends and didnt touch it. They took it for a ride and didnt notice anything weird.

mattdel

odd..

i normally tell the customers when i find something loose or wrong.