2003 - 2008, Sport Suspension vs Regular Suspension - Shared Components ?

[jborchel]

What components make up the suspension system and which ones are shared by both suspensions. I am going to rebuild a system on a Z4 that I buy and would like to know which components, if any, are shared. My problem is that I've discovered that in looking for a car about 2/3rds to 3/4ths of the used cars are with the Sports Suspension feature. I plan to soften the ride with shock and maybe spring changes so if the other components of the suspension system are the same then my field of eligible cars is much larger. Also, if a buyer specified S704 M Sports Suspension did the car automatically come with 18" wheels? And, what about components like control arms, bushings, etc.? Are they different?

[dbarton62]

To my knowledge, springs, shocks and anti sway bars are the only items that were different suspension wise as part of the M package.
I think the package gave you the sport button and the 18" wheels/tires also.

Edit. Here you go from Wikipedia FWIW

An optional "Sport Package" included added stiffer and lower suspension, 18 inch wheels, and sport tuned electronic steering, throttle and shift parameters ("Dynamic Driving Control").^[

[jborchel]

To my knowledge, springs, shocks and anti sway bars are the only items that were different suspension wise as part of the M package.
I think the package gave you the sport button and the 18" wheels/tires also.

Edit. Here you go from Wikipedia FWIW

An optional "Sport Package" included added stiffer and lower suspension, 18 inch wheels, and sport tuned electronic steering, throttle and shift parameters ("Dynamic Driving Control").^[

I believe you are right although in my search I occasionally find the 17" S332 "BMW LA wheel turbine styling 106" wheel. I talked to a BMW specialist firm tech guy yesterday and he thought I could buy a sport suspension car, change the shocks and springs, and get what I am looking for.

What about the control arms and bushings? Are they one piece or separate? If the bushing is separate then I suspect replacing just the bushing will save me a bit. Seems like these Z4s need new bushings around 90K.

[wdb]

I have M Sport suspension. I like it; it's not overly harsh, my wife and I have done multi-hour cross country drives with no fatigue or discomfort at all. The run-flats that come standard are bowling balls, switch to regular rubber (and carry a patch kit). That alone will make a big difference in harshness.

As for shared components, it might take some time but you can compare parts on realoem.com to see what is different underneath.

[jborchel]

Stopped in BMW dealer today and the parts guy was kind enough to check out suspension components for me. Most all of the M and the regular components are the same. The springs are different. I didn't check the shocks as I planned to replace those with adjustable Koni's Sport Yellow's. One problem I'm facing is the height of the springs as I'm going to look into custom springs. To keep my cost down I may have to buy a car that doesn't have the sport suspension. At least then I will have a stock spring to measure for making a softer one.

I know I'm anal about this but I am determined to complete this project.