Getting New Aod

mhjo,
1200-ish rpm (and multiples/harmonics of the number) is the magic number for rotational vibration issues. I could go into a long dissertation as to the specifics and whys, etc, but I would have to look up a bunch of stuff and don't feel the need to bore you and others. Are you "ABSOLUTELY SURE" that your engine is a 289 with a 289 crank shaft? If so, "HOW" did you come to this conclusion? I can tell you that when my brand new 1999 - 5.0 was first fired up, it had the correct 50-oz flywheel, but a 28 - oz vibration damper/harmonic balancer (not as my builder claimed) and the vibration was not very severe at all. I'm just glad that I tracked it down in the first 400-500 miles. I find it very difficult to understand how the transmission itself could be causing your vibration while parked in neutral/park. Even if the numbers on the block tell you it is a 289, there is the unfortunate possibility that at some time the engine was rebuilt using a 50-oz imbalance rotating assembly with the possible intention/assumption that it would make parts matching easier with the AOD. I am sad to say that the only way you can be 100% positive of the engine is to pull the oil pan to see/inspect the crank shaft. Trust me, I feel your pain and would really hate to see you spend the $$$$ on a new transmission to still not cure your ailment. I hate to it, but there is another, more insidious possibility that, during a down & dirty rebuild, only one or a few cylinders were over bored and fitted with mis matched pistons to get it "out the door" for quick sale. I'm sad to say that I've seen unscrupulous builders do this kind of crap before. R & R ing the oil pan is not a difficult operation, even for a "non-wrench" kind of guy.
HTH,
Gene

mhjo,
Thank you for the details of the engines history. This pretty much rules out the engine itself. Do you the actual part numbers/brands of the front damper, flex plate and torque converter, and can you post them. Also, were these actual part numbers somewhere on the parts themselves or just on the boxes/packaging? Is there any chance at all that the parts you were shipped were not what the invoice claimed? As per your initial "vibration" thread, I believe you have already tried running the engine with the accessory/fan belts removed?
Stumped,
Gene

I feel your pain. You and I have the same problem so I'm very interested to see if your AOD is really causing the problem. Please keep us posted. Below is how I described my issues on an earlier post.

Here are the car’s specs: 67, Mustang, New 5.0 Ford Crate engine, AOD and Torque converter (1800 stall) purchased from internet as “rebuilt” with trans go shift kit. 50oz dampener and 50oz flexplate.

The Problem:

1. Significant vibration starting at 60 MPH.

2. I can feel it mostly in seat of pants.

3. I would describe it as a course vibration that comes in waves.

4. It does not go away no matter how fast I drive.

5. Vibration does not go away when I shift into neutral or change when accelerating or decelerating

6. Vibration is the same in drive or overdrive at 60 MPH

What I have done to diagnose/fix it:

1. Balanced drive shaft 3 times

2. Replaced U-joints 3 times

3. Balances wheels twice

4. Replaced Wheel Bearings

5. Replaced axles

6. Replaced yoke

7. Changed Pumpkin (when I removed the 3:55 gears and replaced them with 2:79s, the vibration started coming on about 10 MPH later)

8. Changed Exhaust system

9. Ran on dyno. Felt like car was bucking on the dyno. Like the brakes were being applied on and off randomly

10. Ran car in neutral and park through various RPM ranges and could not cause vibration

11. No miss in engine

12. Ran car on jack stands with wheels off and driveshaft removed. Did not feel vibration

Possible Next Steps:

1. Replace torque converter

2. Replace Flex Plate

3. Rebuild Transmission

4. Sell car