deadsexyii

09 Base MN6 LS3. I've got a recurring vibration that happens when approaching 80 mph. Happens around 78-80. Around 85 it's shaking so bad that both front fenders are visibly moving/shaking. I've had both front's road force balanced. Jacked up both sides and spun the rims. Visibly inspected, do not detect any symptoms of out of round tire or bent rim. Also had it aligned at the same time the fronts were balanced. Not sure where do go next? Thoughts/ideas? Thank you.

extrapilot

Vibration issues seem to be the norm around hear.
There was a poster that had the same problems and had the tire rebalanced with the road force machine with very low numbers.
He wound up trying a simpler spin type balancing job and cured him of all vibrations.
Worth a try....

Mike's LS3

Wheel bearing? Bad Rotor?

Also, did you encounter the vibration after the wheel balance? Spinning tires on the car will not detect a slightly bent rim, it needs to go on a machine.

I bent a rim, but visually was fine. Threw it on a balancer and it was off.

I had a vibration/humming noise at 80 mph from a bent rim.

Jmartin97850

I had a similar problem with my 08 Base MN6 (22k miles) earlier this summer. Took it to the coast and it had a weird harmonic feel and a vibration that started at 70mph (original GY run flats). Took the left sides in for balancing when I changed my oil. The back was fine, but the front was way out of balance. More weight and the weights moved about 90 degrees. Thought all was well until a trip to Vegas. No harmonic, but a noticeable vibration started at 85mph. I was thinking wheel bearing. Upon return I jacked it up and spun the tire. It appeared out of round. I removed the tire for a visual inspection. . The inside was noticeably more worn on one side than the other. i put new Michelin PSS (non run flat) on the front about a month ago. Problem seems to be solved.

rpmextra

-a brake rotor will cause a vibration only when braking not normal driving unless cracked or something.
-in 15yrs working as a tech I have yet to solve a vibration with a wheel bearing (unless it was falling off)
-I would say either bad balance or bad tires. Also make sure the tpms isn't broken and flapping around inside the tire.