ZCP springs on an '08 E90 - Report

[Richbot]

So, I sold my MCS 2-way double remote setup, because I daily this car and they were massive overkill and I wanted to do the ZCP springs anyway, so while I was in there, went back to my stock shocks and struts. Miss them already.

But the stock Sachs aluminum dampers are actually pretty trick, and good enough for the street. And I really wanted to do the ZCP springs because...racecar? I don't know. I like to fiddle, and the ride height was just that little bit too high for me. Sick of all those later cars who lucked into the ZCP option lording it over me with their inability to avoid scraping on driveways, etc.

The stock springs on my low-option, 6MT E90M are X1 front, X2 rear codes. The number of windings and spring wire thickness were identical to the X6 and X5 springs I ordered, new, for my car. Part numbers:


X6 front: 31332283563
X5 rear: 33532283569

Higher-option ZCP cars come with the X7 front and X5 rear. It seems anything stiffer than that is relatively rare, at least from what I've found for sale.

I installed new rubber top and bottom pads front and rear, and my rear lower rubbers were SMASHED, at least 3mm shorter than a new lower rubber. 75,000 mile X2 spring with a new lower rubber thingie was almost exactly 10mm taller than X5 rear spring with a new lower rubber thingie.

The change in ride height was as follows:

8mm front left, 9mm front right
6mm rear left, 6mm rear right

The car toed out a little in front, which I zeroed out, and made no difference on the toe plates in the rear, maybe just a whiff more toe-in.

I also installed Dinan front fixed camber plates at the same time, which ate some of the front drop as they add about 6mm to the stack height. This yielded 2.2 degrees both sides (up from 1.4-1.6 depending on how much nitrogen I had in the MCS canisters). Rear camber is unchanged at -1.8, though maybe a touch closer to 1.9 than it was before, as the gauge would sometimes waffle between 1.7 and 1.8 on the stock springs.

Driving wise, no difference really, biggest difference is probably from the stock shocks. And of course, without the pimp dampers on the car, the car is exhibiting a handling trait I like to call "mid-corner regret" in which I wish the car still handled mid-corner bumps as well as it did on the MCS dampers, which made them disappear But rolling in the pile of money the sale earned will help me get over it.

Potatocam of the result. Wheel/tire setup is 219M 9.5" square with 275/35 and 275/40 PSS. As you can see, there is a car in this picture:

[///Mobbin]

Thanks for sharing. ZCP setup now and considering going MCS 1-way or 2-way in the near future (want to do a few more track days ZCP first). That said my car is 90% DD at the moment and was afraid I'd regret it but it sounds like you appreciated the MCS setup on the street also. Good to hear!

And sorry you are regretting the swap back but thanks for sharing your thoughts on it.

Oh, how can I check what front springs my car received, is it printed on the springs?

[Richbot]

White tag on the front, printed on the spring on the rear

I think I will regret it less when I go back to my light wheels. The MCS dampers did not care how heavy the wheel tire package was, but I have noticed a big difference on stock dampers in ride quality with lighter wheel/tire packages, probably because the stock stuff just can't develop enough force quick enough to handle the heavier wheel/tire in bump