unstable on dips - long plea for help
 

To my 993 brethren, especially those who have suspension insight, Like Bill V. and others:

My 95 has suddenly developed a weird suspension flaw, so much that I am hesitant driving it like I have in the past.
Over swells or dips in the road, the car will squirm, for lack of a better description.
Other than the squirm, I noticed the left rear is 1/2 inch lower than the left rear.
The front L/R is equal.
I am fortunate enough to have a BendPak midrise lift, and have inspected but found nothing amiss.

Car history - Had the car over 10 years, so pretty comfortable with the history, and how it drove in the past.
Approximately 6 years ago, I installed Koni FSD and 033 springs. Made new sway bar links.
Great driving after the upgrades......until now.

Test so far:
Thought the rear springs might have rotated in the seats.
Removed the rear, all looked as installed.
Springs same height, shocks responded to body weight the same.
With the springs removed, I cycled the suspension, all seemed to move freely.

After re-installation, back to symptoms above.
I pride myself on being able to tackle any issue....but I am at a loss this time,.

How does it corner? Does it squirm at the apex also?
suspect rubber parts in the suspension. When you renewed the shocks & springs did you also replace control arms, strut mount bushings, steering toe ends, rear links, etc?
<edit> and sway bar links, they really take a beating and get loose quick. It’s easy to take sway bars off and see / feel difference

Corners well, seems normal, until undulations are encountered.
Sharp bumps dont appear to cause any problem.

Removed swaybar and links yesterday while removing rear springs and shocks.

Need some clarification. First off, the springs rotating would change nothing. They are machined top/bottom flat so not like an ellipse where they would greatly change pressure by rotation?

Second, "I noticed the left rear is 1/2 inch lower than the left rear" :confused:

Correct. Roughly 25.5 lip of fender rt, 25 on left.

and the springs rotating is a concern for the 033 springs and Koni fsd. At full droop springs are a little loose.

the top mount is molded with a ramped groove. If the springs rotate, they will change the position on that groove.

At least the theory as I understand it.

Correct? No., Ok So we went from the same corner being 1/2" lower than itself to left rear being 1/2" lower than left right.

Um, ok, so would you say after 6 years of driving the springs are still in a good orientation or did one side manage itself in an orientation to raise that corner ride height by 1/2" ?

There I go, reading and typing too fast.

Upon disassembly yesterday, the springs as relates to the mounts were correctly positioned.

Reassembled correctly, installed and the 1/2 inch and squirm is still there.

What about replacement links and bushings? Is everything else original?
25 years is a lot to ask for 1990's rubber, even of Porsche origin.

Something is loose and it''s hard to tell in a static environment, These cars take massive forces so just ragging on the links by hand won't reveal anything.

how does it drive without the sway bars? you'll get more body roll in corners but does the squirm go away?

Tell us about your engine mounts.

/

Engine mounts.

I also suspected it might be that. Original mounts replaced with RS style mounts.

No change for the squirm.

It may seem obvious but did you check that the adjustable collars on the struts haven't moved and are essentially equivalent side to side?

Can you post an image of your KT Toe adjuster eccentrics? For example:

https://cimg6.ibsrv.net/gimg/rennlis...ea2c6faf94.jpg

https://cimg7.ibsrv.net/gimg/rennlis...cc52b83ae.jpeg



https://cimg5.ibsrv.net/gimg/rennlis...8456d70c7.jpeg

Earlier question about the collars. Both front appear secure and unchanged from the original install.