Need a little help diagnosing a random vibration in my 08 TL. Everything seems fine up to about 50mph then a slight vibration begins to cycle through the car. It isn't severe but annoying. Becomes more pronounced at higher speeds but never to the point it shakes the wheel - more like it makes the the car 'quiver'. Feels like its moving from the front to the rear and then back again - goes away and then comes back. Isn't engine speed/load dependent, tires only have 5k on them (rebalance didn't change it), alignment good (realignment didn't change), car has 39K.

Thought it might be the road surface but a recent trip to the coast gave me an extended distance of new pavement to try varied gear/speed combos - stays the same - actually you can feel it better the smoother the road.

Any help is greatly appreciated.

 

Probably tire balance as the TL wheel/tires are a bear to get perfect. After about 5 different tries with 2 shops had them done on a Hunter Road Force unit and they have been fine for over 2 years.

http://www.gsp9700.com/pub/search/findgsp9700.cfm