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Well, I finally located somebody to take a hard look at my vibration Friday (Craigslist is your friend). He spun the wheels up while keeping them on the car with an old-style balancer. I'm surely thinking this would solve the infamous vibration problem with these cars as he will be able to balance the entire rotating mass. He spun the rear wheels both up to 100 mph roughly and the fender was as smooth as glass (they go by feel of your fender--old school) and his 'vibration meter' barely registered a tick. So, the rear is good to go and I can rule that out (which is odd because I feel the vibration in the seat and floorboards).

Now it's time for the fronts. I'm guessing these will be super-smooth like the rears and I'll be heading on my way shortly, still without an answer to this problem. I had to put the car in drive to spin the fronts for him and starting at about 44 mph, the fenders/dash/everything started shaking like a wet poodle and continued on up into the 70's. Ah-hah! Now, we're getting somewhere! Nope. He could not improve it any it was so severe and finally we had to stop trying. Jacked up the left side and the shake comes in at the low 40 mph-range, just like the right. He then took the front wheel and stuck it on the rear to see if it shook back there but it was smooth as glass.

So, my question is, what on this car could be causing this? Should I seriously take a look at GM's control arm "fix?"

What has been replaced to date:

New tires that have been balanced over and over on a road-force machine and are fine.
New rotors and pads all the way around.
New tie-rod ends.
New front-right half-shaft.
On-car balancing

What's next? Wheel bearings? I don't feel any play in the wheels when I jack up the car and move them around. I am determined to fix this problem but it seems to be almost impossible.

I would be curious to see if anybody else with this problem gets the 'shakes' like this when their drive wheels are off the ground (make sure to completely stop your wheels with the brake pedal before putting it into park!). It was an eye-opening experience for me. Shook much worse off the ground since the tires cannot absorb any of the vibration I'm assuming.

Thanks...

VERY INTERESTING! Thank you for the info.

Rotors and wheel bearings were my next step. I have already replaced both cv axles. Sometimes I have wondered if the vibration originates in the transmission and not the suspension. If I understand what you wrote, it seems when the load is removed from the wheels the front end shakes even more? I think this would suggest that linkages and bushings are not the problem, and that the problem is in the rotating mass of the drivetrain. So wheel bearings and cv axles and then the tranny itself. Gearheads, what components of the transmission could theoreticly cause vibration like this. My idea is if there is play in a rotating component of the trans, it would be transfered through the axles and steering linkages to the steering wheel and resonate through the unibody through the trans mounts. What do you think? I know nothing of transmission internals so I ask!

This very common problem has got to be solved! My shaking has gotton so bad it has me wondering about the stability of the vehicle at highway speeds.

harrydunn wrote:So, my question is, what on this car could be causing this? Should I seriously take a look at GM's control arm "fix?"

My dealer replaced both control arms trying to fix the vibration in my 02, but it didn't help any. Does that shop have a vibration analyzer?

When we had our transmission rebuilt, the vibration went away.
Don't know why. We had that vibration for 5 or more years.

ROD

If I understand what you wrote, it seems when the load is removed from the wheels the front end shakes even more?

Yes, it was horrible. The dash was even shaking and I could see the mechanic's hand on the top of the fender bouncing all over the place. It was nuts. I don't get any dash shake when driving, just feel it in the floor boards and seat. I too feel this a transmission problem perhaps now. I had it up on ramps today checking things out. Engine and transmission mounts look good. I remember an '86 Cougar I owned that would shake everytime the car would hit about 40 miles per hour. Turns out both of the motor mounts were busted and the shaking occured when the torque converter in the transmission would lock up. Could this be something similar?

My dealer replaced both control arms trying to fix the vibration in my 02, but it didn't help any. Does that shop have a vibration analyzer?

The analyzer I'm referring to is part of the on-car balancer he was using. You stick the 'vibration analyzer' under the control arm, just as close as you can get to actually touching the control arm. Any movement will cause his the control arm to touch the analyzer and get a reading. He barely got any reading at all on the rears but he said the front-right went to almost 50% up the meter!!!

I've gotta ask... Does it seem like your vibration comes and goes at times? Like it can start off heavy and change to lighter and sometimes comes back again? I mean on different trips AND on the same trip. Like it could change every 5 minutes, or it could change every 5 days. Is it random or is it persistant?

Joshua--

It is better and times, worse at times...but it's always there. Just about when you think you can perhaps live with it, it's worse the next day when you hit the highway. Very peculiar problem.

Exactly how mine is then.

Mine will some days be THIS CLOSE to being completely gone, and then the very next trip it'll be jaw rattling.

If you get this figured out, you will be my hero. My car has pretty much had it since I got it. I've learned to live with it, as things I've had fixed/checked never did it. I didn't go as in depth as you have though.

Like others have said, I'd almost have to agree something in the tranny or something mechanical that doesn't involve the suspension or the wheels themselves... Especially as it seems to come and go 'with the weather' as I've said 100x before.

x3 Sometimes its fine other times its aweful. Sometimes it comes and goes like waves pulsing through the vehicle.

TenGHz, did you ever replace the wheel bearings? I can't remember who but I think someone with the problem has. That is my best guess at fixing this but there is no play in them.

Does anyone have a cross-section or parts breakdown illustration for our tranny? It would be interesting to see its guts. If it were the tranny though you would think there would be more occurances in all models.

I may just put mine up on jackstands and run the wheels for a bit and see if it will shake. If it does shake then it might be interesting to do the same with the wheels and rotors removed. I would like to crawl under there while the wheels are turning but that might be a bit dangerous.

I had the front passenger side wheel bearing replaced not too long ago. No change. It, of course, doesn't mean that the driver's side isn't the problem...... *sigh*

TenGHz wrote:I had the front passenger side wheel bearing replaced not too long ago. No change. It, of course, doesn't mean that the driver's side isn't the problem...... *sigh*

When the dealer replaced the driver's side on mine it didn't make any difference. The bearing was bad, making noise when turning left at speeds around 50mph. I made a comment to my service adviser that maybe this will help with the vibration. His comment to that was "I doubt it", it obviously didn't help either.

Yeah, I didn't figure that was the issue. I've seriously just learned to live with it, as most of the time it's not too bad.

But, if harrydunn (crap can't remember your real name!) gets this figured out, then I'll be glad to follow his steps.

My steps are probably close to being finished unfortunately. Not sure where else to look. I've spent way too much money on it to not have it fixed (roughly $1,100)--money that could go towards another car. It's paid for with low miles so it may be time to concede defeat, sell it at a reasonable price and move on. I've had fun modifying it and I've tried hard to fix this vibration, so I could at least feel good about those two things if I decide to let her go.

--Mark

Thanks for posting your name to refresh my memory.

I'd be sad to see your car go, not that that matters much to you! I have always liked your SE. Too bad something so stupid would make you want to think of trading it. I can't blame you though.

Well guys, I'm going to give it one more shot. I don't know if this guy can fix it but I sure do like his enthusiasm! His family owns several tire shops in Mid-Missouri and they have a good reputation. I've been avoiding the larger stores like his because they seem to want to just get you in and out as quickly as possible. I was glad to hear his response to my e-mail. If he can fix it, he'll get all of my business from now on. Of course, there is the part of me that has a pretty good feeling that I'll leave without it fixed too. Friday at 8 am--I'll keep you posted.


His reply:

I would love to take a look at the vehicle and it's vibration problem! We enjoy a challenge and we recently bought some new equipment that will assist in proper wheel balance on newer vibration prone suspensions. Please call ahead for an appointment with Bruce my service manager, so we can allow enough time to properly view your vehicles vibration concern. Thanks for the opportunity. I'm reasonably certain we can fix your issue
Scott

I wish you the best.

If you sell (which I hope you don't have to. I'd hate to say goodbye to my bonne), I'll take your GXP rims!

I just got finished switching tires/wheels with my 94 GP. I only switched the front cause I don't have enough jacks/stands to hold the prix up and the larger diameter bonnie tires won't fit on it. I put the GP wheels on the front of the bonnie and the difference is HUGE!!! I have absolutely NO vibration in the steering wheel. I have a tiny bit resonating through the unibody but it isn't bad. I assume that is from the rear wheels/tires which are still on it. I am going to go check the tire PSI on the GP wheels to check if they are low (they have been sitting for months). But this suggests that the problem lies in the wheels or tires. Since so many have replaced the tires I am betting wheels. Now I am going out to put it on jackstands with no rotors and see if it vibrates.

If a car is up on a rack or on jackstands with the front wheels hanging, does that affect how the moving parts work?
Is it better also to support under the A-arm so that the wheels are up in position they normally are in vertically?

well I didn't bother running it without wheels. I just don't have the ability to do it safely. I agree that the suspension should be in the same position but I can't think of a good way to do it without killing myself. I tried jacking the car up on the a arm once like I did on my GP. I took a jack to the face as the car fell off of it - not fun. I am going to try and get the body shop that "fixed" my car to recheck the wheels to make sure they are straight and in balance. Then I will take in the tires and have them balanced. I have a question for harrydunn: When you had the wheels balanced, did the problem go away for a little while and then come back? just wondering