My 94 z28 Auto has a weird vibration coming from under the center console or behind. It used to do it at around 85-90 MPH, now I have 4.10's and it vibrates at around 70-75 MPH. Both times the vibration last only between those 5 MPH's Stated but this mean i either go 65 MPH or 80 MPH on the freeway, I cant go 70 or 75 because of the vibration. any Info would help.

 

A lot of the time the stock steel driveshafts are out of balance and when lower gears are put in it is more noticable! just search for unbalanced driveshaft and you will more then likely find out more info!

 

Same exact thing happened to me.... 90mph vibrashaft issue, after 4.10 install 75 mph vibrashaft... go here to check out the actual TSB http://www.ws6.com/shaft.htm

what i did to fix this: buy a 3" aluminum LS1 driveshaft

 

Thanks. I really Appreciate it.

 

No prob!