Suspension Gurus, please chime in.

[ATK_Designs]

I'm experiencing extremely stiff and bouncy on my rear suspension. This is on the aftermarket Coilover systems. The brand shall remain nameless until I get it resolved, but they're pretty reputable.


Here are some quick information.

Monotube Design.
18 ways damping adjustable.
Right height adjustable.
12Kg/mm front and 8Kg/mm rear (100% stiffer in the front and 28% stiffer in the rear)

The rear suspension is the 2 pieces design (springs and shocks are separated).

Rear shocks have adjustable collar (see attached pic - Furthest one to th eback).

During installation, I noticed the the rear shocks are higher than OEM. Right now, at the rear has 6 (out of 18) damping seting and 1.25" lowered, the car is very stiff and very bouncy.

The front is okay, smooth and not bouncy at all (1.5" lowered and at 3/18 damping setting).

Now my questions are:

1. Is the stiffness and bounciness in the rear caused by the springs or the shocks?
2. Could it be that the shock is initially set to be higher than OEM, which caused to compress a whole lot more when the car is on the ground, thus, not much vertical/damping movement, causing a negative effect?
3. If 2 is the reason for the harsh ride, should I lower the shocks body to OEM's height (FYI: this will not affect ride's height as the springs are on a separate location)? I know that these are valved to the rates of the springs, would that be changing the valving/damping of the shocks?

Thanks

Attached pics is a generic pics for reference only. It is NOT my coilover.

Notice that the front is one piece coilover and the rear has the shocks and springs separate.