Suspension help needed ASAP!!

[Murt TTA/TGP]

Along with my brake problems, I also have some kind of suspension problem.  Here is how I can explain it:

Last night was the first time i have driven the car much since I have purchased it,  I drove it from MA to NY on the turnpike to the thruway then to 87.  
The car seems to have the problems similair to 1trucavaleir's post from nov 12th-- squirrely rear end.  What seems to happen is I will hit a pot hole or some kind of uneven pavement, and it almost seems like the back end is going to kick out.  The previous owner replaced the front struts with monroe sensatracks.  This cars ride was pretty scary last nite going 60 mph on the highway with it wet, I almost though I was going to lose it a few times.  :?

It also has the typical squeeky noises coming from the rear suspesion. What would be causing this "kick out" feeling from the rear of the car?  It almost seems like the car is twisting.  Is it just that the rear struts need to be replaced to compensate the new front two struts?  Or maybe the front two struts were installed improperly??  I have to do something quick, or I may not be able to get home for X-mas.  I called auto zone and they quoted me 35.99 for rear Gabriel struts and they have the special tools if needed.
Any help is greatly appreciated!
Thanks,
Murt

[90TGP]

I'm guessing a bad strut, bad strut mount. I had noises coming from my right rear strut before I replaced it.

[corvette]

I had this symptom in mine when I first got it, before I started digging into all it's problems. I did not address it first, as I had other problems bigger that needed my attention. When I got done with the brake problems, new PMIII, new brake switch, new calipers on 4 corners, new rotors on 4 corners, new pads, new line for one that leaked, rebuilt parking brake pedal assembly, and restore the cables to parking brakes (all dirty and binding), and got the thing to run and drive, this problem had dissapeared so I really believe that the handling problem was caused by a stuck caliper since I had one rear rotor that was significantly more worn and grooved than the other.
I have also seen this type of thing on my Z/28, and tracked it to a loose bushing on the track-bar, which caused the whole rear end to shift sideways under braking load. When I would come to a traffic light and brake fairly hard, it would jump sideways when I first touched the brake, and then stop straight as an arrow, I chased brakes for 3 months, then someone mentioned bushings and so I checked and found about an 1/8" play so tightend up the track bar bolts and it went away. I mention this as you really need to think a little outside the box on some of the stange problems, they are not allways obvious, especially on a car as complicated as the TGP.
THe other suggestions are on target that the other guys are giving, I'm just trying to expand the possible things to check. Also, the front strut mounts (I have not done a W body so I don't know for sure) on a lot of cars have bearings that can go bad, they only show up under unloading of the suspension and can change allignment which can cause weird steering effects also, so check there!
I have also seen where a dragging brake will cause this, when you upset the downforce on the lighter rear end and have a dragging brake, there can be some weird steering effects. Especially with the way the TGP parking brakes are designed, they can cause a dragging if not installed correctly or someone has monkeyed with the adjuster arm or you plain out just have a cobbed up piston!

The check is to lift all four corners, make sure you have nearly the same drag or lack of drag to spin the tires side to side, front will be harder since you have the tranny to rotate (do this in neutral) also, so compare side to side.

The backs should have virtually no drag and the fronts should have very little drag, basically the resistance of the tranny and maybe a little pad drag is all you should feel.

[Chris A]

the new struts in the front and old ones in back might be to blame. But i've driven TGP's with pretty dead struts before and they take corners well, not kicking out. I would check the lateral track bars for any wear. is unusual for them to wear but its possible. Like corvette said, these can cause some odd problems. If its so bad that its scary its almost got to be obvious.  In trucks, they tend to have this feeling because of the springs/shackles flexing sideways around a corner. When the suspension bounces, it allows the springs to return to center, pulling the back end around with it.

[1trucavalier]

i replaced all four of my shocks at once, and replaced the rear calipers but i am still getting the squirrelly rear end.  I have the newer rear 95 braking units but haven't installed them yet.  It has to have something to do with either the rear bushings or the rear swaybar.  I hit a pothole christmas day and now i got a bad rattle from the right  rear.  It almost sounds like the rattle from the shock pistons shields but when i replaced my shocks I didn't put it back on so now I have to find out wtf is going on with it.   You fix 5 things and 4 more things break!!!!  grrrrrrrrr! :cry:

[Chris A]

Did you do the rear strut mounts too? I've seen a couple of wbodys where the strut mounts looked ok, but when new struts were installed, mounts weren't good, still clunked. New mounts and a ok.

[1trucavalier]

covered in snow so I am gonna have to wait!