I installed hotchkis springs on a few months ago, waited a few weeks for the springs to settle and got an alignment. But now when I drive the car on the highway and change lanes or hit a bump at speed the rear end seems unstable/skittish/not planted. Any ideas, I will probably throw the stock springs back on and see it helps. Any help would be appreciated.

 

did you put the rear springs in correctly??

you must reuse both rubber mounts....the cone mount that hangs from the top, just hangs up there, nothing fastens it, there are just clips that 'sorta' hold it in place...

the bottom rubber mount fits a certain way and the springs are CUT a certain way to where the bottom of the spring "must" mate up correctly with the notched step in the spring bucket.

see here:


you can check this with a flash light and mirror by looking through the cut out section of the spring bucket thats inboard...

in this pic, you can see both rubber pieces if you look close:

-J

 

Do you hear a popping sound? Your endlinks might be bad

 

That won't matter, its just noise.

Did you install sways ? Swaybar setting can do that, alignment setting, and blown bushings can all cause this.

 

IMO, I'd take the car to another alignment shop and see where your set right now.

 

I'm with Gsedan, your alignment is probably off. I have taken my car in and had it set wrong; so it happens.

 

+1 on getting alignment checked first.

I did however notice a floaty feeling with my Hotchkis springs at highway speeds much like what the 2003-2004 owners complained about.

What year Z do you have? If it's 2004.5+ then your rear shocks are valved for a stiffer rear spring.

Stock spring rates
Front: 314lbs
Rear: 427lbs

Hotchkis springs
Front: 340lbs
Rear: 330lbs

 

before you put the stocks back on check the alignment again. does the front end feel fine?

 

Feels like rear toe is off to me~~

 

it does...........however he states he got an alignment already??? i guess assuming it was done right????

OP, can you post your alignment sheet from the alignment you got??

the other thing that would cause this would be the front translink bushing being out...

This one:
https://my350z.com/forum/brakes-and-...ight=translink

-J

 

Unless it was damping related every instance of instabilty I have ever had could be traced to alignment.

Remember, to many people let shops send them away with imprefect alignments. I have learned to NEVER trust them, equipment doesn't get taken off the car until I have seen the after specs and signed off on them.

 

yeah that was probably very stupid of me to not get the alignment specs after they were done. My car is 2004, and I checked the installation on the springs. Maybe I'll have another shop check the alignment out and see if it truly is within spec.
Thanks for all the help guys, i didn't have a more prompt reply because I busy studying midterms but I really appreciate the input. And I will keep you posted

 

let us know if you ever figure it out.