Ok.. let us know how it turns out. Chryslertech may have called it.

 

i too have the same with my 99 sts.... almost a mirror to your story...... and too have spent big to try to correct...... at this point i have learned to live with it. i will say that there are times that it is not there the shimmy and times it is. mine starts at 66 mph, and seems to go away at 77 mph..... you know i might add that it seems more like a vibration, in that if it were front end problem i shouldfeel it in the steering wheel, and if problem were rear i should feel it in the seat......

my arms are still up in the air on this one....??????? so hopin maybe someone might have some answers.........

wheel bearing??? i really havent had these checked. maybe that will be next.....

please, lets keep the forum posted on this one.........

rickyd

also need to mention.... the vibration is more pronounced when i give er a little gas in that cruising speed, 66 to 77 mph. and seems to go away when i am off gas.........

фото крупным планом

 

Check you rotors and pads for uneven wear; possibly warped rotor(s). I would also check the front bearings and ball joints.

 

Are the Pac rotors balanced? Some cars use small, spring like balance weights that can be seen by looking down in between the rotor surface. If they are, and one of these has gone awol, that could be the problem. I've never looked to see if they are or aren't. What do you say Chrysler Tech?

 

I have never seen "spring like balance weights". The rotors should be balanced.

 

They are in the air pockets like he says. Not that I like them but I have seen them over the years.

 

Did you get her fixed TMJ? I was reading back over the posts and it sounds like a "rotating mass" type of vibration. I've noticed at my local tire shop, the balance machine hardly gets to a significant speed before it shuts off and gives(what it thinks) the wheel weight calculation. I wish that it would really get them going, like say 65-75mph. I had a high speed vibration once in my Pac and I had to have the tires balanced 3 times before it finally went away.

 

Okay..... new rim did not do the trick. Vibration still there, was getting a little worse. So I took it to a driveline specialist. After driving it with me, we decided to replace the passenger side halfshaft. The tech said occasionally due to the long length of this side halfshaft that they can get the slightest tweak to them, or slightly get imbalanced over time. After replacement of the halfshaft, vibration in the steering wheel was cut by 90%. I still occasionally get a small shudder in the wheel, but the shimmy is completely gone and the rumbling noise I was experiencing is almost completely gone. I just went on a 400 mile trip in the Pacifica and was pleased with the improvement.

Now if only I could get rid of that last 10 percent of the vibration.....

 

You have described the same exact symptoms that I am now noticing. Keep in mind, before replacing the passenger side halfshaft, the vibration was so much I could see the steering wheel shaking up and down and at certain speeds I had a noticeable shimmy in the steering wheel. Also was experiencing a rumbling noise as soon as the car got above 60 mph. Now those symptoms are gone except for the slight vibration of the steering wheel that comes and goes at the same speeds that you mention. This to me appears to be a resonance issue. Don't know how much people know about vibration, but everything has a resonant frequency or a frequency that they are most inclined to vibrate at. If that frequency falls in the same area as an imbalance frequency (one times turn speed), or a misalignment frequency (two times turn speed) they will be excited (or increased) to higher levels. This also explains why the vibration comes and goes. RPM, different contacting surfaces, temperature leading to expansion, these are all things that could change the resonant frequency.

The only way to correct for a resonant frequency is to either change the frequency at which the item vibrates by adding mass or increasing stiffness or by removing the source of vibration. I know that this might not make a lot of sense, but I guess what I am trying to say is that finding and correcting the final source of vibration may be very difficult.

As you are saying, I am thinking that i am just going to have to live with it.

I am considering replacing my brake rotors. The front end has been inspected by multiple mechanics who can find no fault with it. Possibly hubs, bearings? I also wonder if it could be something in the steering. Not sure I am appreciating any info passed on here.

 

You know I have definitely considered this possibility, but if there was warpage I would feel it when I stepped on the brakes right? If there was an imbalance in the rotors, would I feel it when I stepped on the brakes also?