I have a 94 LT1 m6 and recently replaced the opti, plugs, and wires. I noticed I have a slight vibration at idle and when I'm driving. I'm going to check my u joints because the shaking is mainly when I'm decelerating or driving at a constant speed. I noticed the harmonic balancer seems to have a very slight wobble. I started it without the balancer and the hub seemed to look true. I'm not sure what the wobble could be as the balancer only goes on one way. Did my balancer somehow get messed up when it was off the car or when I pulled it off? Thanks.

 

sounds more like a miss than the balancer. like maybe one of your wires isn't pressed on all the way. But I guess if anything could screw up your balancer, it would be if you pulled it off with a claw, potentially screwing up the rubber ring near the inside. I don't think that would cause vibrations though.

 

It's not a balancer, but a damper and it's a two-piece. The two are insulated with a rubber strip. It's possible the outside ring is not centered correctly and that may be where you are seeing the wobble. And it may be a miss. You can unplug each injector plug one at a time and see if the idle changes. Once you unplug one where the idle doesn't change then you know you have a miss. Also, start the car in the dark and look under the hood and see if there is any spark jumping from the plug wires and/or coil wire.

 

it should have ZERO "wobble". You may have damaged it when removing it for Opti or it just has aged and the rubber deteriorates. FYI its a "damper" not a "balancer" It is neutral balanced

Make a mark from hub to outside edge and drive for awhile....does the mark still line up with inside to outside edge?...if not the outside part of the damper is moving

also since you replaced opti & wires you could have:

a plug wire not all the way on
bad plug wire
bad opti
plug wire arc (especially if using the factory heat shield boots on plug wires)