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I've got a weird issue that I've been trying to narrow down on my 99 SSE. When you drive down the road (worse in the morning) you will get a overall shake in the car and gets worse when on a rougher road. Car has new motor/trans mounts, new subframe mounts, new alinment, new Kohmo ZR rated tires, and had them rebalanced three times but the issue still persists. No bent rims or anything. But when you hit a certain speed or hit ruff parts of the road it gets worse too.
Here's the weird part, if you switch the ride mode from performance to touring the shaking almost disappears instantly. Is it possible the electronic struts are bad in the front? Cause the car handles really good and there's no front end bounce and the struts are in really good shape. If you bounce the car when stationary it test's fine. I've got a long trip coming up and I'd love to figure this issue out

To be honest, CCR diagnosis rarely comes up because you don't find many that still function and replacement struts are impossible to find.

Just guessing here. It could be something else springy, like control arm bushings or coil springs have weakened to the point where they oscillate with a resulting resonant frequency when the struts are in Performance, and Touring interrupts the harmonic. Or one or more struts don't work in that mode anymore.

Do you use a tech2 to diagnose it? I've checked all the bushings and such and nothing seems to be bad. I wonder if one strut in the front end has failed cause part of the shaking is in the wheel. What happens when you try to unplug both front struts and drive it? Does it default to touring mode?

My truck used to get a shake at a certain speed and it turned out to be a failing hub. may want to jack up each front wheel individually by the control arm and see if there is any excessive play.

Was the shake present before the new tires?
Unless your mechanic is not very knowledgeable and thinks that it is OK to not balance a tire to zero, then the tires are probably balanced by now.
What I mean by balancing to zero is that the numbers on the machine when the balance is finished should be 00 and 00.
I had a vibration in the front end and the mechanic swore that it is perfectly OK to balance a tire to .75 ounces---meaning the tire needs another .75 ounce weight added.
Knowing that he's wrong, I insisted he spend the extra 30 seconds and finish balancing the tire.
Makes me wish I had my own dynamic balancing machine--since it is so easy to do .

If not, then one of your tires may be defective--perhaps a slipped belt or a tire that is out of round.
You can balance a defective tire from now until doomsday and it still won't be ok---even though the tire IS balanced.
The mechanic will have to look at the tire as it spins on the balancing machine and watch for any up/down movement at the tread area of the tire.
He probably already checked for lateral play, since he said the wheels are straight.
To isolate this as a tire problem, you would have the front tires moved to the rear and vice versa.
If you still feel a vibration but now it's felt in the seat, instead of the wheel, it's your tires.

If you still have the vibration in the wheel then it could still be a defective tire or but it may very well be a front end problem.
Bad control arm bushings are often overlooked when mechanics check the front end.
A few years back, I took my car to 3 different shops--with all of them swearing that everything was fine--until I took a look myself and found bad control arm bushings.
A more remote possibility is that one of the front hubs is slightly bent, causing the tire to wobble as you drive.

You can have someone else drive the car, while another person drives you around so you can watch the wheels turn and see if anything looks abnormal.
The less safe option is to support the car by the frame and watch the wheels turn.
A lift is really the best option but most of us don't happen to have a lift at home ;-)

I do all my own mechanical work as I worked as a gm tech for 15 years. The tires were off my modded regal Gs and they were fine on that car. I had a place mount the tires and balance them, then went back and had them balanced again with me their and everything balanced out to zero fine. Like I said in the first post its something related to the performance/touring ride control, since when I switch modes the problem goes

monte0 wrote:I do all my own mechanical work as I worked as a gm tech for 15 years. The tires were off my modded regal Gs and they were fine on that car. I had a place mount the tires and balance them, then went back and had them balanced again with me their and everything balanced out to zero fine. Like I said in the first post its something related to the performance/touring ride control, since when I switch modes the problem goes

Only trying to give you ideas as to what to look at.

I do appreciate it, sorry if it came of wrong

No problem.
The CCR struts are an oddball type of strut--but sound like a rather nice feature. Too bad it was sort of a short-lived experiment.
I don't have a service manual for a year which includes the CCR feature, but I've read that they pass an electrical current through the strut fluid to change the effective viscosity.
If this is true, then perhaps when they're in the lower viscosity mode the fluid is bypassing some worn internal seals.

Hope you get it sorted out soon.

Thanks for the info. Today it started doing something different though, when you drive if you switch modes the shake is still their in either mode but the suspension is still changing. Only thing I did was replace the lower dogbone for the trans. So far I've replace all the trans mounts and one engine ( realized last night I miss a motor mount on the rear side). And found one other thing that might be it, the passenger side cv axle isn't ripped but is seeping grease out from under the clamp. I'm wondering if the axle is causing some of the shake?

I'm going to try and replace the cv axle this weekend and see if the shake goes away hopefully

Ended up replacing the CV shaft and that fixed the issue

Glad you got is sorted out.
Thanks for posting the solution!