CS Suspension Specifics

[Celestion]

I have compiled a list of M4 CS-specific suspension components.

M4 CS Springs/dampers:

• M4 CS/ZCP w/DCT or Sunroof Front Spring - 31337857356
• M4 CS/ZCP w/Sunroof Rear Spring - 33537857312
• M4 CS/ZCP Front Damper Left - 31318008627
• M4 CS/ZCP Front Damper Right - 31318008628
• M4 CS/non-ZCP Front Sway - 31352284760
• M4 CS/ZCP Rear Sway - 33557853266

M3 CS Springs (all other parts are shared with the M4 CS):

• M3 CS/non-ZCP Front Spring (DCT): 31337847701*
• M3 CS/non-ZCP Front Spring (6MT): 31337847700**
• M3 CS/non-ZCP Rear Spring: 33537847710*

*Note: Oddly, these spring part numbers are also used in the regular M3. Given how unlikely this seems, it is possible that the BMW spring table is incorrect. I will check their spring table periodically to see if these part numbers change. Feel free to check these on your own as well. To do so, you will need the last 7 digits of an M3 CS vin (5K99072).

**Note: Although the 6MT M3 CS does not actually exist, BMW's spring table will allow you to configure a 6MT version of the M3 CS and will even provide you with an appropriate part number.

Source:
All part numbers are directly from the BMW part catalog.

To view the part catalog, use these logon credentials.
User name: eu111111
Password: bmwetk1

[domino_z]

or another way of looking at it

zcp hardware identical to cs

[Celestion]

Originally Posted by domino_z

or another way of looking at it

zcp hardware identical to cs

Not quite. The CS uses the non-ZCP front sway bar and unique front and rear springs.

[RalphyBMW]

What about the springs?

[Celestion]

Originally Posted by RalphyBMW

What about the springs?

See updated first post.

[Délid'f]

thanks for your contribution, very interesting !

[CanAutM3]

Very interesting. Thanks for sharing.

It says that the CS has a "parts bin" suspension with no unique hardware. What I read out of this, assuming that the CP with sunroof spring are stiffer and that the non-CP front sway bar is softer, is that they softened the front and stiffened the rear even more for improved front-end grip.

[CanAutM3]

Originally Posted by domino_z

or another way of looking at it

zcp hardware identical to cs

Re-read the OP, it depends how the CP is configured (DCT/6MT and CF/Sun roof) and the non-CP front sway-bar.

[domino_z]

Originally Posted by CanAutM3

Re-read the OP, it depends how the CP is configured (DCT/6MT and CF/Sun roof) and the non-CP front sway-bar.

Looks like I have cs springs then

Explains the firmness

[CanAutM3]

Originally Posted by domino_z

Looks like I have cs springs then

Explains the firmness

You might have the CS springs, but it results in a different tune for your heavier chassis (I assume you have the sun roof, since you say you have the CS springs).

A softer suspension usually results in increased grip. Softening the front relative to the rear will improve front-end grip. According to the published spring rates, they had already done that to some extent with the CP.

[Celestion]

Originally Posted by Délid'f

thanks for your contribution, very interesting !

No problem! I figured I would share my research. I’m deciding between going the CS parts bin route vs. buying the Tractive EDC damper kit. I’m leaning towards the latter.

[mechanic75]

Originally Posted by Celestion

No problem! I figured I would share my research. I’m deciding between going the CS parts bin route vs. buying the Tractive EDC damper kit. I’m leaning towards the latter.

Jeez from what I have read of Tractive this isn't even a debate..!

[IcebergM4]

Originally Posted by Celestion

Not quite. The CS uses the non-ZCP front sway bar and unique front and rear springs.

I have an F82 ZCP with sunroof AND 6MT, so does this mean all I need is the non-ZCP sway bar?

[Celestion]

Originally Posted by mechanic75

Jeez from what I have read of Tractive this isn't even a debate..!

Totally agree from a performance perspective. Not sure how the wife will feel about dropping $5k though... 50/50 on being able to persuade her.

[Celestion]

Originally Posted by Iceberg4

I have an F82 ZCP with sunroof AND 6MT, so does this mean all I need is the non-ZCP sway bar?

Yes I think so. You’ll also need to code your car of course. There is also the possibility that the M3 CS will end up having different springs than the M4 CS, but I don’t think this is likely.

[CanAutM3]

Originally Posted by Celestion

Yes I think so. You’ll also need to code your car of course. There is also the possibility that the M3 CS will end up having different springs than the M4 CS, but I don’t think this is likely.

IIRC, in the video interview with the BMW AG M3/4 product manager, he did say that the M3 CS had different hardware due the different weight of the car. If they go through the trouble of fine tuning spring rates based on DCT and sun roof, it is fair to assume they would fine tune between sedan and coupe. Particularly considering that the weight difference between the M3CS and M4CS is likely greater than the difference between the CP M3 and M4 because the M3CS has slightly less weight reduction than the M4CS.

[tke743]

Originally Posted by CanAutM3

IIRC, in the video interview with the BMW AG M3/4 product manager, he did say that the M3 CS had different hardware due the different weight of the car. If they go through the trouble of fine tuning spring rates based on DCT and sun roof, it is fair to assume they would fine tune between sedan and coupe. Particularly considering that the weight difference between the M3CS and M4CS is likely greater than the difference between the CP M3 and M4 because the M3CS has slightly less weight reduction than the M4CS.

We'll know in a few months when RealOEM shows the new parts for the M3CS. Note: None of the springs are orderable from the dealer. I asked.

[Wills2]

And where does the MP HAS fit into all this? I have a non CP with MP HAS, it's all very confusing as the MP HAS is an option to "improve" the CP and CS as well as the civic M3.

Why would you order the CS springs when the MP HAS is available as an upgrade for all of the models (GTS excluded)

[CanAutM3]

Originally Posted by Wills2

And where does the MP HAS fit into all this? I have a non CP with MP HAS, it's all very confusing as the MP HAS is an option to "improve" the CP and CS as well as the civic M3.

Why would you order the CS springs when the MP HAS is available as an upgrade for all of the models (GTS excluded)

I plan on installing the MP HAS on my CS

[Wills2]

Originally Posted by CanAutM3

I plan on installing the MP HAS on my CS

Indeed! Not sure why people would want to fit CS springs to their car though as per the OP, just fit the MP HAS regardless of model.

Have you ordered your car? SMB or LRG...

[CanAutM3]

Originally Posted by Wills2

Indeed! Not sure why people would want to fit CS springs to their car though as per the OP, just fit the MP HAS regardless of model.

Have you ordered your car? SMB or LRG...

I have deposit down since February 2017, it's taking forever to release these on this side of the Atlantic

In Canada, order books for the M3CS, which is a 2018MY, have been opened for just a few week. The order books for the M4CS, which will only start as a 2019MY, are not yet open.

I am pretty much set on LRG.

[Celestion]

Originally Posted by CanAutM3

I plan on installing the MP HAS on my CS

If you wanted a better-handling, faster, and more affordable car, you could opt for a non-ZCP F8x, get the Tractive suspension for ~$5k including install, and flash the CS tune for $700....

Is the CS really worth the extra $30k? I think not, given that you could get a base 992 (i.e. an actual sports cars) for only a little more... just trying to give you an alternative perspective.