Opinion on sport springs

Gauthier

Newbie
Belgian Zeds
Joined
Nov 25, 2025
Points
3
Model of Z
'98 z3 1.9 m44
I am planning to install Koni Yellow dampers, but I would also like to lower the car slightly, cause it sits quite high on standard suspension, espaecially in the rear. I think 30 mm is too much, and in my opinion it would create a bit too much rear camber. That is why I am looking for sport springs.

They are quite rare here in Belgium, but I have found a set. I still have a few questions about them. Does it matter whether they come from a 2.2, 2.8 or 3.0 model, since I would be fitting them to a 1.9? And most importantly: what about their condition? Here are the photos (the 2 springs on the right in the first picture and the 2 springs in the middle on the second picture).

The seller says it is only surface rust. My plan would be to sand them down, remove the rust and treat them with Brunox, which works as a rust converter and primer. After that I would apply primer and then 2K black paint. However, I want to be sure that they are still worth saving and that they will not break after a few hundred kilometres.
 

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Just my opinion but I would suspect the 6 cylinder engine weighs more than a 4 cylinder so spring rates are going to be different.
 
They are all the same. 1.9 also came in Sport version with same springs. I had mine soda blasted and powder coated ..no issues.
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They are all the same. 1.9 also came in Sport version with same springs. I had mine soda blasted and powder coated ..no issues.
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It is nearly impossible to tell spring rates without putting the spring on a test rig.

This video explains what you are doing. Stiffer springs reduce the time period between oscilations, so the car will return to equilibrium more quickly, but it will do so by accelerating the body's vertical movement more than a softer spring. This is why you need stiffer dampers with harder springs. Stiffer dampers are harsher. Everything is a compromise.

 
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