Weird suspension problem, need some pointers.
 

Basically i just rebuilt and revalved (according to my spring rates) my Bilsteins not long ago, I put them on with my Eibach linear race springs. (Front 250.600.800, rear 250.600.900. Those are 2.5" ID, 6" length and 800/900 spring rates) I also have my ground control coilover sleeves, so just like any other coilover, i can adjust the height with a turn of the collar. Also, bump stops been cut but they are still there.

So now the problem, even though the ground to fender height is the same in the rear (only rear), but they are not the same when i measure the threads. They are off by a lot. On top of that, i found that the ride is way bouncy and not as stiff as before. But i should be pretty stiff at 800/900 spring rates. Those might be two separate problems though.

All i did was rebuilt and revalved the Bilsteins and put everything back together exactly the same way as before with the same springs. What could be wrong?

I love driving the car, and having a stiff suspension, is very disappointing and frustrating now. Please help me out~

Who did the shock rebuild?

Are you sure the shocks are working properly after the rebuild? Did they do a shock dyno graph to show you their work?

Bilsteins of America, Poway Cali~

Springs support the vehicle, the damper is generally not supposed to support the car as far as height setup. So your height issue is probably spring or mount related.

Swap the springs from side to side, nothing else, only the spring. If the height issue follows, then it’s the spring. Variances of 10-15mm could be the car. More than that would probally be an issue. I would start by disconnecting any sway bars, and then swapping spring form side to side and see what happens.

If the car is “bouncy” that usually means not enough rebound force. This means that as the spring decompresses, the damper isn’t controlling that movement properly. Are the dampers adjustable? What is your rebound set to? If they are adjustable, increase your rebound force. If they are not, did they revalve them to the same spec they were before?

Bilstein did revalve according to my spring rates which are f800 and r900.

i did a typical jounce test on all 4 corners, definitely not have that f800 and r900 feeling. i can push down fairly easily on all 4 corners but it used to be barely moving.

and i can also say that it definitely not the struts problem since when i push down, it doesn't have that bouncy movement.

Do you agree that i am having a spring problem? have the springs are deteriorated? i have these springs for almost 10 years now.

So maybe i will just order some new Hyperco springs, but maybe i will do 7" or 8" this time instead of 6".

Or send all my Eibach back to Ground Control and let them test them. But then i will have my car on jack stands till the springs come back. Which i think it will be at least couple weeks.

Or should i just get the exact same Eibach linear race springs from Ground Control and save the hassle.

Is it possible it was much harder before because the car was sitting on the bump stops (too low, no real travel)?

My last question still stands, are these adjustable dampers, if so, what’s the rebound at?

Ten years, depending on the spring, may or may not have degraded to the point where they are failing. If you are getting a real difference of height (more than 15mm per side), and you don’t want to try swapping the spring from side to side, replacing them with new springs may solve the problem.

It may be that at this point the springs are old and no longer holding the same rate as they once did. You are blowing through the spring travel and getting into the bump stop, bouncing the car off them. That would explain the bounce and the height difference in that one spring is worse than the other. The ride would be total shit though. You would have to have a bump stop that compressed enough to have enough force to push the car back up, But normally your rebound forces would control this, so not totally sure. Brings me back to my first question, are these adjustable, and what’s your rebound at?

All of this is total guessing. Only way to tell is to start testing. At ten years old, replacing the springs, and checking your travel would be a good start. There are some easy to do tests listed on different websites to show if you are getting into your bump stops, if you are, adjust accordingly.

I’m not really sure if Ground control has specific setups for cars, or if they just let people build whatever they want, but you may want to call them as well. If this is one of their setups, I would assume they have some insight that may help.

pm'd~

These are not adjustable dampers. The struts are valved according to my spring rates at Bilstein.

Performance Shock told me to do the zip tie test to see if i am riding on bump stop. Even though i wasn't, car still feels soft.

Definitely frustrating:\

Have you tried running different springs?

How old are the springs? If they're old, maybe they're at the point where they sag or as some people like to say the springs are "tired."

That's what i said to Performance Shock, but they kinda don't think so.

Yah i have 2x 700 springs available in the same diameter i can try. But yah have to pull everything out. Might worth a try though.

I guess after i put those on then set with the exact same height, push down on the fenders and be able to tell if the springs are sagging or degraded.