Hi guys im new here obviously i just got my bonneville GXP three days ago its a dark grey 2005, it has 59k on it. i was driving home from the dealership and noticed a weird vibration at 35 mph. once u go over 35 it stopped. The one thing i noticed as i tried to reproduce it, was that it only happened when the sun roof was open. I dunno what it is maybe the sound of the wind coming in but the whole car vibrated for a second or two any ideas?

I dont think wind would have any effect unless your rollin at a Buck and a half. Several GXP members have reported bad front wheel bearings sooner than your mileage. I would check them and the sway bar bushings. At 43k miles, my wheel bearings are still good but my bushings are trashed. Frustrating that critical yet inexpensive parts wear out so quickly on this $40k sedan. No wonder Obama'* running the company now...........

JHUDSPE2 - Next time you are driving before you open the sunroof crack all four windows and see if it stops. My car has done this as welll as some of the other cars I have owned especially Chryslers. It is some weird pressure thing that happens with many of the newer cars because everything is so tight and sealed. I tell you I don't have this problem with my '72 Olds Cutlass!! HA HA HA!

Take to heart the advice from Venom as well.

I had a Firebird that I could only stand to drive with both windows down (or at least with the pass side down partly which looks wierd). Something with the aerodynamics, but the wind would actually buffet you and make the seat belt slap back and forth.

One thing about rotating parts - they tend to do it in multiples of the speed. Try it at 70 mph and see what happens.

Oh yeah, one more thing. When you are going 35, put a little pressure on the gas and a little pressure on the brake (meaning maintain your speed). Changing the tension on the drivetrain may help narrow down any vibration.

A good point, we've had a few engine mounts break on the GXP'* also. You can check this parked as well. Have someone hold the brake peddle firmly down, (and the Parking brake on for safety) and lightly depress the accelerator in gear while you view the engine from the side of the car. Never let your wife help with this procedure.......

Haaaah - They hold grudges we don't even have a clue exist!

Yep, my engine mount was trash before I hit 60k.

I had the same problem with my 05 GXP, The wind breaker bar that pops up when you open the sunroof was stuck in the down position. I had to manually lift it and grease it up a little.

Got the same thing--when sunroof is fully open push the sunroof shade back an inch or two! See if that it?