HEY GUYS I AM NEW HERE I GOT A 94 Z M6 WITH A AFR HEADED 383 ANYWAYS I PUT A 9" IN AND NOW I HAVE A BAD VIB. FROM 55MPH UP TO 70 OR SO IT SEEMS TO GO AWAY AFTER THAT I ALSO JUST INSTALLED A UMI ADJUSTABLE TORQUE ARM ITHINK PINION ANGLE IS SET AT -2 COULD THIS BE MY PROBLEM? WHAT SHOULD IT BE FOR STREET/STRIP APPLICATIONS? AND HOW IS THE BEST WAY TO SET THIS I HAVE BEEN TOLD SEVERAL WAYS ANY SUGGESTIONS ??????

 

You message will be a lot easier to read if you take off the caps lock Most likely it's a driveshaft problem; the stock driveshafts vibrate in that speed range. Try unbolting the driveshaft from the pinion and rotating it 180 degrees, that might help. Also you might want to verify that the driveshaft length isn't an issue. I had to use a shorter driveshaft when I went to a Moser 9" rear to keep it from bottoming out in the tranny tail. This wouldn't cause your vibration but it will be hard on your tranny.