Vibration but not from tires/wheels

I have a 2000 Chevrolet Impala. I recently purchased it in January of '06. Ever since I bought it, I have been having a problem with vibration in the ride at certain speeds (mostly around 40 MPH). I had the tires balanced AND rotated, but that didn't fix the problem. So, the tire people told me I had a bad tire and it would have to be replaced (they weren't sure which one).

Well they were brand new Firestone (I know, not the best brand) tires. The dealer had put them on just prior to selling me the car. So, I took the car back to the dealer and and they found a pulsation in the tread, and replaced the tires under their warranty. This fixed the problem for only a short time. I felt the vibration again, only about 3 days after the new tires were put on. I took it back to the dealer, also because I had noticed one of the tires was missing a wheel weight. They balanced the tires, made sure they all had weights, and then one of the mechanics rode in the car with me to make sure I didn't feel the vibration anymore. I didn't at that point.

However, the next morning, at low speeds I began to feel the vibration YET AGAIN. This time I took it back to the tire store instead of the dealer and had one of the mechanics ride in the car with me from the outset. Of course, the car wouldn't do it while the mechanic rode with me (It has been an on-and-off occurence, and it always happens when I'm in the car by myself.). But just for good measure, he balanced the tires, and made sure they all had the correct PSI. So, I went home satisfied, praying that it wouldn't occur again.

Well, sure enough, the next day, I start feeling the vibrations. This is not a subtle vibration that I'm only barely feeling; rather, it's the complete opposite. On a freshly paved and very smooth (in other cars) road, there are large waves in my drink that is sitting in the cupholder as I drive. I am very frustrated and after exhausting all my tire options, I figure something else must be causing the vibration. It still occurs right around 40 MPH and on a smooth road makes me feel like I'm going over several small speed bumps (like the ones on the side of the road) for short periods of time.

Is there any possibility that this could be a bad axle, rotor, or something else?

Please let me know your thoughts on this topic,

Driver101801

Wheel & or tire vibrations a pain for sure and sometimes difficult to find source. It could be a number of things such as..bent rim, dirt on mounting suface rim to hub, warped rotor(s), broken belt in tire or they could be seconds, (yes this can happen to new tires for any company). Not knowing the mileage I still would doubt that it was a hub bearing even at 100k or more. Alignment or worn ball joints, tie rod ends or control arm bushings. Lug nut unequally tightened (100 ft lbs for impala). Also be sure it's not the road surface and try to determine if it seems to be front or back, left or right then start with simplest remedies first...good luck on finding a solution and post what you do find.

57chevy covered just about everything i can think of except it may be a vibration in the motor at a certain RPM. check the rpm when it does it and then drop it down a gear and see if it does it at slower speed at the same rpm.

My 01 Intrigue (similar car - w body) does the same thing, except the tires seem to all be wearing more toward the driver's side. I think it might be alignment, but on my car, sometimes the vibration is in the steering wheel, while other times it feels like its coming from the back.

My money would be on either a bad tie rod or hub bearing. GM cars have a history of hub issues. The 91 Grand Prix winter beater I had did the exact same thing your car is doing, bad vibration starting at 40mph and didn't always do it. It was a right front tie rod end that was bad.

how would you check to see if these parts are bad?

OK, this issue has finally been rectified...thanks to all who posted in this thread...there were some very good suggestions.

It ended up being the tie rod ends...on the service ticket it said "found excessive play in left outer tie rod end. Recommend replacement of both tie rod ends." The service manager at the dealership told me it was going to be 331 dollars. I about crapped my pants. Luckily, someone else pointed out that the car was still under the GM certified pre-owned warranty (3-month, 3,000 miles), and would be replaced free of charge. I heaved a sigh of relief. I just barely cleared this requirement, because I had already put 2,000 miles on it in the 6 weeks since I bought it. But nonetheless they were replaced and the vibration is gone.

I love my Chevy Impala and I like it even more now that the ride is smooth as butter. Occasionally, after sitting in the driveway for extended periods of time, my tires get flat spots in them and I feel a slight hop when I first take it somewhere. But within about 5 minutes this goes away. Also, major kudos to whoever posted "does your 2000 Impala stereo suck?" thread (I think it was guenther) I got a lot of answers to the questions that I had.

Thanks again,

Driver

Richtazz, you were exactly right. Weird how tie rod ends would go out so early-my car has only 40K miles on it. I don't know how many your grand prix had, but I bet it was more than that. Anyway thanks for posting.

Driver