Pulsating / Vibration

[PawnofChaos]

2006 Grand Prix, 95,000 miles or so. I am getting a pulsating, vibration from what I think is the front end. Replaced rotors, pads and the drivers side front wheel hub/bearing. It's still there! Seems to speed up and slow down with the car. I did rotate the tires an couple months ago and don't remember if it was there prior to that. Could it be a tire out of balance. Could I have changed the wrong wheel hub/bearing? What else could be causing this? I did a quick visual of the CV boots and they look good?

Any help and advice would be greatly appreciated.

[tblake]

I would say it could be a tire out of balance, but it may also be a good idea to check your tie rod ends. Have an assistant turn your steering wheel back and forth quickly and you feel the tie rod ends for looseness.

[AutoService101]

At what speed does the vibration start at?? Sounds like it gets worse as your speed increases?? Tire balance is very good possiblity. Could also be that the tires are cupping. Feel around the tread of each tire (front tires will do). Do they feel choppy (cupping) or a wavey (feathering) feel to them?? If so you may be abale to balance if they are not to bad but if they are real bad even balancing will not fix. The other thing that can cause this would be bad strut's. Does the vehicle bounce excessively over bumps and thru dips?? With the age of your vehicle I am assuming the struts have never been replaced (most people do not replace struts because of cost!). When the get real bad the will hop over any imperfections in the road and will cause tire wear issues as stated above.....

[PawnofChaos]

I seems to be there regardless of the speed. Just gets quicker, slower with the car. Tires looked and felt fine when I rotated them. Checked again when I replaced the wheel hub and they/it seem(s) to have normal wear. I will try the tie rod check as posted. (Do I need the front end in the air for this?) Only other odd element is when cold in the monring, as it has been lately, it's less noticable at first.

Thanks for the quick replies!

[PawnofChaos]

I forgot to mention, she still rides really nice. Does not bounce over dips and bumps.

[AutoService101]

Best to check tie rods for play with front end off the ground. Can check the other wheel bearing for play on the other side (don't think this is you issue though). One other thing to try is when your driving if you let off the gas does the vibration stop?? If not put the vehicle in neutral and see if it goes away.

[PawnofChaos]

Thanks again. I have listened carefully with my foot off the accelerator and while in nuetral. The sound does not go away.

[AutoService101]

Can you feel the "Vibration" in the steering wheel, or your feet on the floor board? You say sound (you did not specify that before?) is it a whop whop type of noise? (LOL love trying to describe noises)

[PawnofChaos]

Yes, I do get some vibration in the steering wheel, but only at higher speeds. (55+) It not terribly noticable if I'm holding the steering wheel with my hand, but if I lay just one finger on the top of the wheel, you nitice the shake pretty good. As far as the sound, your right on it, it's a whop whop sound with the "o" sounding almost like a "u", as in up. It is a pulsating type of sounds that seems to increase and decrease with the wheels rpm's. That's why I had originally thought it was a wheel hub.

[AutoService101]

Steering to the left and the right while driving at higher speeds will tell you if it is a wheel bearing. The noise while typically go away (or change pitch noticably) when you go to one dierection or the other. My other thought is if the tires look good maybe you have a flat spot or a broken belt internally inside the tire. Flat spots may be hard to notice but if it is causeing a vibration good chance you can see it. If you go to balance the tires it will be more notable when the tire is spinning. Typically you will not beable to balance the bad tire. Every time you put weights on the tire it will still show out of balance. (Flat spots can be balanced out depending on how bad the tire is)
You can try and change the tires position (rotate) and see if the noise changes and vibration changes. I think you said you rotated them a couple months ago? I would still try it. Also about how many miles do your tires have and how often have you rotated them???

[tblake]

A tie rod which is bad enough to cause a vibration while driving can be diagnosed with the front on the ground, and it may make the looseness more noticable. Just have the car at idle, center the steering wheel, and have someone move the wheel back forth over center about an inch or two in both directions. Then you just reach your hand in and feel the tie rod to knuckle connection. My tie rods went bad right around 90k, and my g/f's right at about 85k, so thats about the ball park. The GM ones from the factory don't have a grease zirc, so we replaced ours with MOOG brand. I now have 150k and have not had issues since I changed mine.

If your outer tie rod ends are bad, here is a write-up I made for changing tie rod ends on a 97-03 Grand Prix. Yours will be similiar.

http://www.automotiveforums.com/vbul...d.php?t=929004

[PawnofChaos]

Don't know the mileage or life of the tires as I just purchased the car in March. I commute about 130 miles a day for work so I'm putting almost 3000 miles a month. I try to rotate them 3 times a year (every 4 months) and have rotated these once. I will take a closer look at the tires as the more I read, the more its pointing in that direction.

Thanks again for your help!!

[PawnofChaos]

Thanks TBlake!! I can check the rods prior to pulling and checking the tires. (If still necessary)

Thanks again to all for your help!

[AutoService101]

Just a side note about the tire rotations, I highly suggest rotating more often. Try evry 6,000 miles. You will get better wear from the tires and a little longer life span. Check the tread depth of your tires, do you know what a wear bar is??

This wear bar is located on every tire in each grove about every 6 to 8 inches. When the tread is flush with this bar time to throw the tire away. These wear bars are generally about 2/32 of a inch high. It is the best way to judge the life of the tire. I am wondering from front to rear how close your tires are to this bar. I would almost bet without seeing the front tires that they are pretty close (rears may be close to)
measuring at these bars gives a good idea how much wear the tires have on both the inside edge and outside edge of the tires. Is the tread on the inside even with the tread on the outside??

[BNaylor]

To the OP, what brand and model tires do you have?

Gee, I wish I could rotate my tires.