Had the wheel/tires checked 3 different place. Not them. Had the shop check the car out. They used some type of "vibration diagnostic" tool. Supposedly pinned it down to the around the "middle" of the car. But no answers. I do have one front caliper that I can wiggle about 3/16 of an inch on the front. My clutch (factory #3) is sometimes missing fourth gear (grinds on a slow shift). The vibration is so bad (starts at ~50) that it doesn't even make driving the car fun. It is the worst between 50 & 65, but is still bad above that. Does not inspire confidence to really run her...and I have a NOS 5177 ready to install. HELP!

 

Well, since no one else has offered any advice, I might as well chime in. I don't know much, so here it goes. First off, it sounds like your synchro is going. Some of your trans internals could be out of whack. A vibration around a certain speed means that it is a part that rotates when the car moves. It hits its resonance frequency with the vibe it at its worst. If I had to guess, I'd say you drive shaft is out of balance. Has the car ever been wrecked? Is the vibe present regardless of the gear you are in? Like I said, I don't know too much. I hope this got you looking the right direction.

 

Thanks ZZed,
No, no accident of any kind. I am gonna be a little more forceful on my next visit. It is warranty gold and I am using a cool Chevy dealer...they "ignore" all my mods. Any and all help is welcome.