91GTSTANGKID

Have a 2005 GT and every time i get to 50-55 mph i get a bad vibration and as soon as i get to 56 mph it goes away. Then you can slightly feel it at 80 mph. I don't even know where to start with what could be causing it

SpartaPerformance

Sounds like a wheel balance problem, I'ld start there

JIM5.0

Sounds like you have mud in your tires!

http://www.youtube.com/watch?v=nYJEyToSRtE

91GTSTANGKID

haha im thinking pilot bearing. Tires got balanced and wheel bearings are good and thats the last thing i can think of

08Steeda

Has it been lowered? Pinion or Camber angle on the Drive Shaft. I just went through the same thing with my 08 GT.

Waiting for my new Adjustable Panhard Bar.

stand behind the vehicle and look at both rear tires. See if you can tell if one tire sticks out further than the other in realtion to the body/fender. I never noticed it until I had a Blue Collar Performance install my D-Specs.

Something to look at anyhow.

91GTSTANGKID

At this time the car wasn't lowered at all. I just lowered it yesterday myself and the rear seems to be fine.

Lifter583

get your tires "Road Force" balanced...I had mine done on a regular spin and they gave vibration...the Road Force found what regular spin wont.

Nuke

+1 on the RoadForce balance. It will identify tire and wheel problems that a standard balance will attempt to balance out (and fail). After the balance, then go from there.

Also, if you have aftermarket wheels, be sure the clips on any of the wheel studs are removed. They were installed on some of the studs during assembly and are unneccessary. They prevent aftermarket wheels from sitting flush.