Elevate the ground clearance Z4 E85

[Charllow]

Hi everyone!

I originally wrote this topic on the discussion section and I think this section is more appropriate. So I copy and paste this topic on the right section.

It can seem crazy but... I want to elevate the ground clearance of my Z4 3.0i. :evil:
I got the option M sport suspension on my Z4 and because I use my car as a daily car and with all the bumpers that are in my city it is very uncomfortable. Everytime I scratch my car on some bumpers, even if I am very slow like 5-10 km/h and even if take the bumpers in diagonal.
There are even some entrances and exits on parkings that are too much inclined that I can't take them at all.
So please don't judge me, I just want to elevate the ground clearance of few millimeters.

So my Z4 is a non M with the option M sport suspension.
The first thing that I was thinking about at a very cheap price is to change the coil springs. Because I have the M sport suspension option which lower the car of 15mm, I think I could change my M sport coil springs by the standard coil springs. This way I can have the standard ground clearance and upper my car of 15mm.
The problem about this is that I can't find the reference of the OEM standard coil spring. I searched a lot about it and I didn't find anything: even on realoem.com there is no informations about the reference of the front and rear springs.
So as an alternative I can buy aftermarket coil springs but I don't know what are the references that deal with the OEM standard coil spring. I don't know what is the stiff of the front and rear coil springs, I don't know there lengths, the diameters, the numbers of coils...

Do you know what is the reference for the standards front and rear coil springs? Or what aftermarket coil springs I can look for to answer my problem?

If you have other solutions other than change my car it would also help me a lot. Maybe coilover? Do some of you try coilovers?

Thanks a lot guys!

Edit: I found this reference: 31 33 6 757 782 which seems to correspond to the original standard z4 spring coil

 

[filipov]

Hi, I have the exact same setup and fully understand the problem. I needed about 1cm to be able to overcome the front door rail of my garage and this is what I changed:

Front:
- Thicker upper spring pad (9mm instead of 3mm) - 31331128522
- Reinforcement plate (this also helps prevent cracking of the boots) - 51717036781
- Just FYI, this also exists: 31306779671, but I've not tried it, and it's expensive.

Rear:
- Thicker rear upper spring pad from E46 xi/xd - 33531094754

With just these parts and without changing the shocks or springs I managed to increase the clearance with about 1cm, which was enough for me. And without ruining the look of the car

I am not sure if it's a good idea to mix non-sport springs with sport absorbers and vice versa - they are meant to be used together.
Hope that helps!

 

[Charllow]

Thanks a lot for your answer!!
Do you have the reference of the thicker upper spring pad (9mm instead of 3mm) ?
And is the reinforcemet plate an oem part? Or is it an option you bought to elevate the ground clearance? If so how much does it lift your car? 2-3 mm?
Thanks for your answer

 

[filipov]

Hi, all needed reference numbers are in my previous post. And all of them are OEM parts, but from E46 3-series. They are fully compatible with our Z4s though.
In the front - the thicker pad gives 6mm height and the reinforcement plate about 3-4mm more, so just about 1cm total. In the rear the pad is also about a cm thicker than the standard one.
I guess with time those rubber parts would wear and flatten a bit, but it's a good option if you need just a little bit more height. If you need more - like 1,5-2cm, maybe just swap your shocks and springs with standard ones. You would easily find someone with standard suspension that is willing to get your m-sport setup.