Hey guyz,
I have a GP Tjet 1400cc 125PS Sporting.
From day 1 I had replaced the original springs with Eibach red ones, approx. 3 cm lowering, but kept the original struts.
From my understanding the struts should be then all the time on some small percentage of their stroke distance, since lowered spring was installed.
However I had never problem with my ride, it was comfortable and somewhat tight on high turns etc.

However now, after 140K kilometers, I decided to change the struts, normal ones not coilovers or adjustable, to keep the Eibach springs still on.
I replaced the original struts with a Koni (orange) STR.T performance package, which were supposed to be aprox. 50% tighter than the original, and also have a shorter stroke cylinder distance and would allow them to be 100% not in pressure in stable state.

Now after chanings, while the whole suspension feels strong and new (new top mounts also front and back), the only problem I have and I cannot understand where its coming from is that even in good and well maintained roads (to the human eye) I feel like the rear of the car is bounching up n down, like if my suspension is scanning the road for the slightest anomaly and the rear of the car acts as the wheels run on a road with "waves".
It gets a whole lot uglier when I am on a turn with high speed eg. 120 km/h.

Anyone has any idea? are these struts so much stronger and tighter and its transfering all the anomalies on the rear? Is it maybe alignment issue? (i did not perform alignment after replacing the struts and topmounts)

I am pleased to receive your experience guyz, as i am already 2 weeks with the new struts and already searching to sell them and buy the original ones again.

Thank you

Strange..

Are the original stock wishbones still good.
They can have a weird effect.

Important question: have you replaced all four shocks ??

Your being asked 'if' you have also changed the rear shocks..we know you changed the rear top mounts...IF I have read your post correctly. BUT tbh I though the years were simply a direct bolt in bolt out job.
Uneven spring weights etc will cause driving/suspension experiences...

Hi guyz,

Sorry for so late reply, I had completely forgot about this post.
yes I had changed all struts + topmounts. After so many months, just before 2 weeks I contacted Koni here in Greece, and they sent me to one of their workshops. I told them I cant stand this anymore and I wanted them to refund me, and they said it was too strange for this usual setup eibachs red+koni orange to behave like this.

As a result, we took out the rear struts, and 99% because of incorrect installation(struts were torqued to topmounts with high torque electrical tool, while this is forbidden to protect the internals of the struts), the rear left strut was completely stuck. No movement at all.
So Koni replaced my both rear struts, inside of warrantee period, for free.

Now the vehicle is better than I wanted it to be. a good amount of comfort ride, and very good sportif suspension when needed.

So who overtorqued the mount?

I changed the struts+mounts while I had the car scheduled for its maintenance service.
So I had the service done from a local service center of Fiat-Lancia-AlfaRomeo (it was not the official dealership, but an authorised Fiat service center) which I had put my trust over the last 3 years now.
However this event proved the center unworthy, since not only he overtorqued the struts on the mounts and destroyed them, but also did not install correct all the essential small accessories came in the package such as the bump stops, plastic roller discs etc. which means he didnt even open up the manual of my fresh new Koni kit.

Not only it could end up destroying my kit prematurely, as it actually did, but not installing the bump stops at all can cause serious damage on the strut or even puncture it's top cover (imagine that while being in your favorite mountain roads pushing the car)

Glad to say that I learned from this event, so everyone changing struts, better do it yourselves reading the manual or have it installed by professionals.

And thanks for the update BTW ...