I hate to beat a dead horse but I wanted to chime in on the problem several member'* seem to be having with wheel vibration. I'm going through the same thing and I've only got 22K miles. My original SE wheels/tires shook with only 13K miles on the car and my new GXP wheels/tires shake. I've had the current GXP wheels balanced two times standard and one time with the Hunter. The tech. said they were good to go but it'* still there. Feel it mostly in the seat so it'* the rears that are the culprits. The steering wheel hardly shakes a wink. I've rotated the tires around quite a bit and have finally found a decent configuration but it is still frustrating. The tires only have about 4K miles on them. They are the RSA'* which I hear can be the problem but I've heard of people replacing these with new tires with no difference. I'm not about to spend hundreds or dollars on new tires but wanted to hear any advice.

Like has been said, it puts a big damper on driving these cars on the highway. Mine shows up from 65-80. It comes and goes which is quite odd but again, seems to be normal for these cars.

The alignment hasn't been mentioned. It needs to be done by someone who understands the car and the oscillations. The settings need to be right on dead center, not just close like they do at many places so they don't have to actually fight to get the setting exact and spend time.

What size were the original tires and the new tires? On a very smooth road is there a difference between slight acceleration uphill and coasting downhill while it'* doing the vibrating? My car did that; turned out the rear toein was off from optimum setting. Service manager expect the fronts to be off but they weren't.

What were the road force amounts on the Goodyears? My Michelins were below 10 and one was 12, IIRC. I could tell where that wheel was at first. The tires seemed to soften from flexing by 20K and they weren't as sensitive then.

I have the same problem with my 2000 SSEi on brand spanking new RSA'*. Brought the tires back a couple of times to be rebalanced and rotated and I still get the same shimmey between 60 MPH and 70 MPH. The higher or lower I go and it goes away.

Now, I am no longer suspecting the tires or wheels at all because I noticed the following while on a long trip. The speed at which the shimmey was felt varied depending on whether I was driving into or with the wind direction. I would be on cruise control feeling the shimmey and as I took a turn away from driving into the wind and the shimmey became significantly less obvious. I continued and turned again even further down wind and the shimmey went away until I spend up to a higher speed. I tested this on varoius windy days and there is definately a connection.

My guess: the shimmey is the result of an aerodynamic problem with my lower front spolier. The found the spoiler to be quite loose -- I can push back on it and it receeds approx an inch before butting up against a frame behind it. I am thinking that at low speeds the spoiler doesn't vibrate beacuse of not enough wind but then at 60 to 70 MPH the wind pressure oscilates the spoiler, but higher speeads yet the spolier gets frimly pushed up against the supporting frame and it does oscilate anymore.

I haven't brought the car in yet to see if the spoiler is too loose (can't stand the thought of bringing my car to the dealer and not sure if Joe mechanic would know how firm the spoiler should be.

I am throwing this out there to see if anyone else suspect the same as I do.

I don't feel any shaking on mine. It'* got 42K miles, and I'm assuming original RSA'* on the back (I had the dealer replace the fronts).

You need to take it to a shop that can check the Lateral Force and Radial Force of the tires. If the tire has stiff spots in the rubber (most tires do), it will cause vibrations. The normal tire balance machine does not test this because it is not a balance issue.

Machines that test the Lateral and Radial Force of the tires use a steel roller that puts pressure on the tire (as if it were rolling down the road) and measures the deflection of the tire as it rolls.

If you have a very stiff spot in the tire sidewall, the tire will be balanced, but will still vibrate. When the stiff section of the tire hits the road, the side walls give less than the rest of the tire, which causes the vibration.

I ran into this problem with new RSAs that I bought a year ago. The dealer checked the balance 2 times but the vibration did not go away. They suggested that I had a drive axle balance problem. I took it to a non-dealer shop to have the drive line looked at and they checked the tires with a better machine that looked beyond just balancing. After they were done, my vibration was gone.

On the people that have some mileage on the tires..

Have your tires been rotated?

If yes.. where they rotated in the crossing method that 95% of places rotate tires?

If yes.. swap sides and try the tires rotating in the original direction. I've seen this cause an issue.

I have been struggling with this wheel vibration problem for many moons. Whenever I do get it to go away, it eventually comes back. It seems to me that there is something with the suspension or body that is making it super sensitive to wheel balance (my 92 & 93 don’t have this problem).
I was wondering if any of the guys who installed the GPX strut tower brace have noticed their cars to be more or less sensitive to wheel vibrations.
(should I be posting this on the sticky?)

Just an update on my experience with the shimmy.

I do a lot of highway driving and have continued to experiment with speed vs wind direction and still find a correlation. On my weekly religious trips back and forth from the cottage I drive on a highway that curves, significantly changing directions which has allowed me to test the magnitude of the shimmy at a constant speed but into various head winds, side winds, tail winds etc.

I still think there'* a connection. On a 'no wind' day, the shimmy occurs for me at about 65 MPH. If I am into a headwind the shimmy seems to occur at a lower speed but then no longer as I approach and exceed 65 MPH. With a tail wind I have to go closer to 71 MPH to feel the shimmy again. Slow back down to 65 with the tail wind - no shimmy. It'* when I am on cruise control and head into different wind direction that confirms it for me. I am in cruise control moving along at 65 MPG with a shimmy and as the hwy turns and I am now heading into the wind the shimmy dissapates until the hwy curves back downwind.

That'* why I still think there is an aerodynamic issues connected to the shimmy and still suspect the front air dam (that I previously referred to a front spoiler) or some orther aerodynamic issue perhaps related to the wheel well design.

Can anyone comment? Am I out to lunch on this? Has anyone else noticed that the speed at which the shimmy is found depends on head or tail wind?

I had a huge thread going about this....

http://www.bonnevilleclub.com/forum/...792&highlight=

There is a explination from the dealer in there somewhere from when I took it in. Page 2 to be exact and almost to the end

Also Motorhead had a suggestion also below my dealer explination. However I had the rear checked out and that is fine. To this day, I still have the shake between 65-80. It comes and goes.

This is actually very interesting. Have you tried tying it back somehow so it doesn't move at all, then driving again? If you can get the spoiler to be rigid, and the shimmy disappears, that very well may be your problem, and something that might be worth looking at for others.