LS1TXGuy

I know vibrations have been gone over on her but I did not seem to find mine when searching. I have a 99 T/A stock except lid and exhaust. I do have a poly trans mount but it was doing this before that was installed. It was broke and I figured that was part of my vibe... guess not. It seems to do it more above 50 mph and a million times worse if I get onto it. There is no certain speed range other than above 50. I really don't know how to describe it more than a vibration... no noise other than that. Please ask if you need and more info to help answer. Everyone has always been a big help here so far. So thank you in advance.

Dipstick99

I had a tire weight fall off once and it started shaking badly. Worn tires and/or low tire pressure will cause it also. When i bought my Z28 the tires were worn and it vibrated and handled poorly, especially with the traction control on. I bought new tires and it fixed it. It rides and handles great now.

Cry0

Try a tire rotation and/or new tires. My first car i had (dads old 93' mercury sable) would vibrate like crazy at around 70 mph then balance out at around 75. At that 5 mph interval my friends would feel the need to hold my dash to try to "help the car" lol. Rotating the tires helped me but in the end the car was old and i was 16 and not about to spend some 400$ i didnt have on new (poor quality) tires.