Alright everyone I really need your help because I am stumped. The car is a 95 Z28 A4 with 180k on the speedo. I'm going to list everything I've done, checked, or replaced so far.

1. Rebuilt tranny w/2500 stall 6 months ago
2. Poly tranny mount because I keep breaking rubba ones
3. New 3.42 gears, eaton carrier and axle bearings installed 6 months ago
4. I just had my stock steel DS high speed balanced with new spicer u-joints
5. just installed new powerbond harmonic balancer
6. checked flexplate to make sure counter weight was still their and it is, stall converter bolts are tight
7. motor mounts are stock but look good
8. started the engine without the serpentine belt on to see if any of the accessories might be causing this annoying vibration and this did not change a thing

Ok, here's the problem I'm getting a vibration while sitting in park or neutral that gets worse as the rpm's climb it's so bad it rattles my interior. This vibration also happens while driving it starts at 60 mph and gets worse as your speed increases it's so bad at 90 mph that you have to get out of it because the interior is rattling so bad. Now you tell me what's the use of having a Z28 if you can't go over 90 mph? Man, this driving me crazy I need your help people I love this car but lately it's been a bit of a cash cow if now what I'm saying.

I really appreciate everyone's help and longlive the Camaro!

 

I would try an aluminum (LS1) driveshaft. Do you have an aftermarket torque arm?

 

Do you think it would be the DS even though the vibration happens in park and neutral? And I have a stock torque arm with the poly mount. I talked to several mechanics in the area and they all said to unbolt the stall converter from the flexplate to try and isolate the vibration to the engine or tranny. They also told me to check the flexplate for cracks.

 

When during all of those things you listed did the vibration start? You might find a loose bolt on the torque converter, despite being a pain to do I'd start there.

 

Yesterday I unbolted the converter from the flexplate, started the engine and vibrations are gone. So does this mean that I have a converter going out on me?