I have a Vibration that starts at about 85 MPH, its not my tires, they ahve been balanced more times then I can count and ride perfect up untill about that speed.
It gets worse the faster I go, and by the time I hit 100 it feels like my car is going to shake apart.

 

prob the driveshaft unbalanced. try rotating it 180 degrees, if it doesn't work, get an LS1 aluminum shaft.

 

I am willing to bet it is your DS. I had the same problem and when I swapped it out with the 1LE all my bad vibrations went away.

 

Definately your DS.. rotate it 180 nd see if it works.. probably wont I'd start looking for a replacement.....

 

does the rotating it actually work?

 

what exactly do you guys mean by rotating the DS 180*? To put teh back in the front and front in the back??

 

You can take the shaft out of the rear yolk and spin it 180 and reinstall it. The rear U joint will fit both ways.
Sometimes this helps, sometimes not.

 

Thanks, I kinda thought it was me DS. I havent looked under my car, how do I take it apart? or is it pretty simple?

 

This is a real simple process to accomplish...

1st... Jack up car
2nd.... I like to make a kark from my u-joint to the yolk (with a marker) to make sure I turn it over 180 incase I get interupted and have to stop...Take your (8mm?) wrench and take the u-boldt that connect the rear u-Joint to the rear yolk. You may have to pry them appart gently to get them to come appart.
3rd.... Remove DS and then re-install so that the marks are on oppisite sides of each other.... ie.. flipping it 180...
4th re-install u-bolts then lower car and then hit the highway to see if it stops the vibe... this works sometimes... but not always but it's worth a shot...

Good Luck

 

This is a real simple process to accomplish...

1st... Jack up car
2nd.... I like to make a mark from my u-joint to the yolk (with a marker) to make sure I turn it over 180 incase I get interupted and have to stop...Take your (8mm?) wrench and take the u-bolt that connect the rear u-Joint to the rear yolk off. You may have to pry them appart gently to get them to come appart.
3rd.... Remove DS and then re-install so that the marks are on oppisite sides of each other.... ie.. flipping it 180...
4th.... re-install u-bolts then lower car and then hit the highway to see if it stops the vibe... this works sometimes... but not always but it's worth a shot...

Good Luck