Alignment? Wheel Bearing? Warped Rotor? Something completely different?

[IBCoupe]

This will be lengthy; for that I am sorry.

I took my '08 Altima Coupe 3.5SE (CVT) in for maintenance (oil, filter, fluid checks, tire rotation, etc) almost exactly 3,000 miles ago. With the amount of driving I do, that's roughly a month-and-a-half ago.

I didn't notice anything particular about the car when I brought it in. I asked them to switch to synthetic oil. Also, the tires in the back were the Bridgestone tires that came on the rear of the car when I bought it ten months ago with 18,600 on the odo. On the front were the Cooper tires that I put on at about 27,000 miles in late winter/early Spring. The car now has nearly 43,000 miles,with the Bridgestones on the front and the Coopers on the rear.

After the maintenance, the engine generally ran smoother (to the point where engine-braking was noticeably less effective), and so it might have been the decrease in engine noise and vibration that allowed me to begin to perceive the problem: I was getting a vibration accompanied by a vibrating noise at certain speeds, and still am.

The noise comes, and, from my vantage in the driver's seat, seems to be coming from my right, though it just may be my perception from sitting on the left. It only becomes apparent at speeds above 35 mph, and peaks at 55 mph, but then drops off almost instantly. It is all but unnoticeable between the speeds of 60 and 75 mph, but it returns loudly above 75 mph. It changes in pitch in relation to wheel speed, not engine revs. The physical vibration associated with it is detectable at times in the steering wheel, the shift knob, the gas pedal, and occasionally the driver's seat. I haven't noticed any change in vibration in the brake pedal that would be associated with the change in pitch of the noise, but I don't normally have my foot on the brake.

A visual inspection shortly after the maintenance revealed that the plastic cover inside the wheel well, between the wheel and the oil filter was broken in multiple places. I bought a replacement part from the dealer and installed it myself, but the noise remained.

Coworkers suggested that I have my tires balanced, and that removed 90% of the vibration in each of the locations, but the noise remained. On a lengthy drive after the balancing, I decided to try my hand at a scientific experiment and learn if it was brake-related. So, instead of my normal practice of down-shifting to decelerate, I left the transmission in D and used the brakes, at times heavily, in the name of science.

Subsequently, the noise and vibration worsened, but it still behaved in the same way at the same speeds. There are competing theories:

My roommate suspects that the car needs to be aligned. I have my doubts; the car drives perfectly straight, and it seems odd that an alignment would cause a noise that comes and goes like that.

Based on my very limited knowledge of noise (and what could be reproduced in the Car Talk noise archives), it seems to me that the noise is coming from either a bad wheel bearing or a warped rotor, but the same thing about the noise confounds me there, too. One of my original thoughts was a sticky caliper, but I don't know enough about it to remain firm to it.

Any ideas?

[jwerty1]

feel the inside and outside edges of the tire, is it smooth, or is it not?i would think it's not a wheel bearing unless the vehicle has been potholed hardsounds like tire noise, which may have occured from alignment wear while the tires were on the reari've noticed after the break in of these cars, the rear alignment becomes skewed and the tires will become choppy, creating a noise and vibrationif the tires are not smooth, replace them, align the car, and see if your vibration still existsunless a rotor is very, very bad it will not create a driving vibration, rotors will most noticeably create a vibration on braking, noises occur from rotors mostly when glazed from alot of high speed brakinganyhoo, check/replace tires, align car, if still not solved, have front rotors turned, should be solved by then, if not, have a dealer check the wheel bearings

[IBCoupe]

Thanks for the reply, mate.

I'll run my hands over them later today when I actually get outside to the car, but here's an update from last week that I had yet to post:

I took the car in, and ended up having to do some brake service, which didn't, as you might expect, solve the problem. They also rotated the tires again for me, and that actually made the problem worse.

Before, where the vibration peaked at about 55 mph, it now peaks at about 46-47, drops off a little, and peaks again at 55. The rest of the symptoms are the same. The tires did spend about 3000 miles on the back wheels, so it might be consistent with your theory, but is that enough time to make that kind of change?

Does this information confirm your diagnosis?

[thephishh]

What ended up being the problem? I have the same issue with my wife's car. The mechanic said it is probably the calipers.

[IBCoupe]

Was a wheel bearing. That was the first one that went; almost a year ago, another one went. Since then, no issues.