Geezy

Got a S13 hatch on Stance GR+ coilovers with the factory spring rates 8f/6r.
All after market arms. (not the cheap stuff)
Running zero preload on the springs all around. (just enough tension to keep the springs in place; hand tightened then locked down with spanners)
Dampers are set at 7 clicks.
Wheels and tires: 17x9.5 235/40

Anyway, here's the situation.

On the highway, at speed, when it comes to going over big dips or bumps... (and im not talking about little imperfections in the road.) I'm trying to describe huge variances in the road that make the car feel like its going to "jump" more or less.
Its enough to basically throw me out of my seat.

Is this normal with stiff coilover suspensions to react this way?
Is there a way to adjust the suspension around this reaction?

Tempo

regular highway speeds like 70/80? I feel completely planted to the highway. try turning the clicks to full soft if you haven't tried. I'm on PBM pro coilovers 10kg/8kg spring rate full soft daily, solid subframe risers and spl differential bushings and even on full hard i don't have that feeling, then again when i first installed my coilovers and broke them in on full hard i did have that same feeling you described. How long have you had the coilovers installed?

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Geezy

yes, regular highway speeds.
Ive had them for almost 4 years now. i havent tried them at full soft.
its kinda hard to describe the road conditions im talking about.
for example: in las vegas there's this patch of road near the airport by pass, its been there for as long as i can remember, even after the construction to "smooth and level" it out.
its a bit raised, almost ramp like.
that specific area feel like i almost catch air.
other than what im trying to describe, the car handles VERY well.
its just during those instances.

Croustibat

Most coilovers are made for tracks (or for parking lots), where you either wont get big bumps/holes or dont want to pay the kind of money needed to get a good ride, so they have no fast damping & fast rebound hydraulics.

Basically you need slow damping / rebound for corners, accelerations and braking, and fast damping/rebound for absorbing bumps and potholes. The speed refers to the speed of the coilover movement, not the speed of the car.

TL: DR ;

You can :
get the damping softer, and compromise handling;
bear with it and enjoy good handling where the road is smooth;
get expensive coilovers with separate fast damping and rebound adjusters, and enjoy smooth and damaged roads .

Dont expect miracles either, these kind of coilovers are made to handle; the difference in damping between comfort and handling is exactly double (if you need 5000N dampers for optimum comfort, you need 10.000N dampers for optimum handling - and then, they are not comfortable anymore). The result will be a car that handles, but unless you drive with a harness, you will get thrown around in the car.

e5s4y

my pbm pro's felt the same way as the op's until i added some preload

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BustedS13: anything you can hide on your person is free. junkyard law.

!Zar!

Why don't you just set it at full soft and see what happens?

It only takes like a few seconds.

Geezy

The ride isn't unbearable. Little bumps and shitty roads I can deal with. It's just in the instances which I described where the car feels like it'll jump. And I'm sure it has to deal with the speed of the dampers. And without the ability to separately adjust bound and rebound. I'll have no way to cure it. Not sure if I'm the only one that experiences this. Other than this, the ride is very comfortable and handles very well.

The ride was actually worse with preload. It became really choppy ad bouncy. Like motor cross over the knack knacks.


I'm gonna try that tonight on that patch of road and see if it makes a difference.

I was watching some touge challenge on Hot Version. And on the clips with the damper check, they would get some of the suspensions to react differently with basic adjustments without changing the factory spring rates.

Hopefully I get some results.