[devioushaikuzero]

Well, I was able to score OE M-Sport style springs and struts for the front at a good price. I have m-sport springs on the rear with Bilstein B6's still. The Bilstein's are hot fucking garbage. I gotta redo the rear again. I am going to order Koni's this weekend. So much time and money wasted on the wrong parts.

[devioushaikuzero]

Originally Posted by B50AteYourRide

Really curious to see how you like the Koni Special Actives.
I came close to buying them for my wife's car several years ago, but ended up with Bilstein. Not bad, but they were a bit stiff for her. It was a 2008 Audi A3 S Line. Poor car ended up in the hands of a completely incompetent mechanic and I just ended up selling it.

Seems like competent german car mechanics are a rarity unless you like extortion.

[casualDIYer]

Originally Posted by devioushaikuzero

Hello bimmerpost,

Now, when I drive, the car is super bouncy. It feels oversprung. It sort of makes the ride unpleasant. I want to understand why. When you drive over a bump or small, but short, elevation change, your stomach drops and it feels very intense.

In general, performance dampers slow down the rate in which the chassis will travel when encountering undulations in the road surface. For example, a car goes into a turn, the suspension will compress slowly but it will also decompresses slowly, hence the feeling of being 'sucked' onto the road. As wonderful as that sounds, it's not ideal for lots of little bumps that require the suspension to react quickly. What's going on in your car is the rear reacts slowly to common bumps found on city streets while the front reacts quickly, thus turning the rear of the car into a pivot and worsening the jumpiness of the car.

As mentioned by others, installing the B4 damper in the rear (similar to BMW's Sach's OE damper) will help as it will even out the bumpiness by allowing the front and rear of the car to react similarly to road imperfections. Alternatively, you could install a B6 in the front but it is advised the springs also be changed out. As mentioned, performance dampers tend to slow the rate at which the springs will compress/decompress but there are limits. The thick steel coil of a spring is able to do a lot more work than the damper. Using a spring that provides less resistance to up/down forces means more work is transferred to the damper, prematurely wearing it out. You could just swap to the B6 alone but without a spring change, longevity between fails could be shortened significantly.

If you are wondering if there is a 'perfect' suspension that works in all situations, there might be, but it will cost significantly more than a pair of dampers or springs.

[devioushaikuzero]

I did m-sport springs and struts in front. I did m-sport springs in rear with bilstein b6s. Will Koni Special Active be ok to replace the rear b6s? Or should I return those and get b4s?

Or should i just replace the front with b6s and use the new springs? Then, sell the new m-sport struts?

Or should I replace all with Koni Special Active and sell the rear b6s and front m-sport OEM?

[E90lova]

Originally Posted by casualDIYer

In general, performance dampers slow down the rate in which the chassis will travel when encountering undulations in the road surface. For example, a car goes into a turn, the suspension will compress slowly but it will also decompresses slowly, hence the feeling of being 'sucked' onto the road. As wonderful as that sounds, it's not ideal for lots of little bumps that require the suspension to react quickly. What's going on in your car is the rear reacts slowly to common bumps found on city streets while the front reacts quickly, thus turning the rear of the car into a pivot and worsening the jumpiness of the car.

As mentioned by others, installing the B4 damper in the rear (similar to BMW's Sach's OE damper) will help as it will even out the bumpiness by allowing the front and rear of the car to react similarly to road imperfections. Alternatively, you could install a B6 in the front but it is advised the springs also be changed out. As mentioned, performance dampers tend to slow the rate at which the springs will compress/decompress but there are limits. The thick steel coil of a spring is able to do a lot more work than the damper. Using a spring that provides less resistance to up/down forces means more work is transferred to the damper, prematurely wearing it out. You could just swap to the B6 alone but without a spring change, longevity between fails could be shortened significantly.

If you are wondering if there is a 'perfect' suspension that works in all situations, there might be, but it will cost significantly more than a pair of dampers or springs.

Just so you know Sachs does a way better job at dampening that crappy Bilstein. I have tons of use with both brands. Honestly I'd rather get stock Sach than B6 or B8s. I did this with my Volvo as well and love the Sachs stock strut much better than the B8 or B6s I had on the same car.

[Polo08816]

Originally Posted by E90lova

Just so you know Sachs does a way better job at dampening that crappy Bilstein. I have tons of use with both brands. Honestly I'd rather get stock Sach than B6 or B8s. I did this with my Volvo as well and love the Sachs stock strut much better than the B8 or B6s I had on the same car.

I don't think B6 or B8s are designed to be used with stock spring rates.

[devioushaikuzero]

Originally Posted by Polo08816

I don't think B6 or B8s are designed to be used with stock spring rates.

B6's are very much intended for stock springs. B8's are the same hardware, just shortened, to accept aftermarket lowering springs.

[Polo08816]

Originally Posted by devioushaikuzero

B6's are very much intended for stock springs. B8's are the same hardware, just shortened, to accept aftermarket lowering springs.

Clearly they were not...

Originally Posted by devioushaikuzero

Well, I was able to score OE M-Sport style springs and struts for the front at a good price. I have m-sport springs on the rear with Bilstein B6's still. The Bilstein's are hot fucking garbage. I gotta redo the rear again. I am going to order Koni's this weekend. So much time and money wasted on the wrong parts.

I don't think the factory Sport/M-Sport (RWD) spring rate is suited for Bilstein B6/B8 struts/shocks.

I currently have the M Performance Suspension on my 335i RWD and I wouldn't be surprised if the B6/B8s are more suited for the M Performance suspension spring rates which are higher than the Sport/M Sport.

[devioushaikuzero]

According to this, by FCPEuro, b6's are designed for OEM springs:

But since BMW likes to make 423213413423 variations of everything, I could see that being off.

[Polo08816]

Originally Posted by devioushaikuzero

According to this, by FCPEuro, b6's are designed for OEM springs:

But since BMW likes to make 423213413423 variations of everything, I could see that being off.

So I think I ran into the problem you're experiencing on my X3 35i. I replaced the factory struts with the Bilstein B6 struts but the X3 had the factory base springs.

The ride feels exactly how you were describing. But in my haste, I overlooked the B6 saying it's designed for the S226A Sport Settings:

https://www.fcpeuro.com/products/bmw...n-bil-24197205

Well, I don't think recall the S226A Sport Settings being an option in the US for the model year of the X3. You either had to go with the base suspension or the Dynamic Handling Package.

I had my dealer (BMW of Annapolis) look into this and they were able to square me away. They found the part numbers for the springs of the S226A package which were for a car withOUT Electronic Damper Control.

Those springs get here by Tuesday/Wednesday and it'll be a few weeks before I get to install them.

[casualDIYer]

Originally Posted by E90lova

Just so you know Sachs does a way better job at dampening that crappy Bilstein. I have tons of use with both brands. Honestly I'd rather get stock Sach than B6 or B8s. I did this with my Volvo as well and love the Sachs stock strut much better than the B8 or B6s I had on the same car.

What is the Sachs equivalent of the B6? The m-sport damper?

[devioushaikuzero]

OK, maybe my car is cursed or something else is not right with it. I had replaced my front shocks and spring with OEM M-Sport. I had removed the Bilstein B6 from the rear, and replaced with Bilstein B4 matching compatibility with M-Sport Part Numbers, while using the new OEM M-Sport Springs.

Nothing actually improved. Now the rear is all over the place: lots of horizontal and diagonal sway whenever I hit an imperfection in the road. I would say that for 90% of use-cases, the B4's are worse.

I am just feeling defeated at the moment. I have spent ~$6k USD to try and fix this issue, 50% of what I paid for the car, and yet I am really doing no better then when I bought it new. I am not sure if it is a driveshaft or axle issue, or I just need to the rip the whole fucking thing out and buy street comfort coilovers, or sell it and just eat my loses ($2k in audio equipment as well).

I just don't know what to do, I am at my whit's end with this whole ordeal. Maybe the F30 chassis just isn't ever meant to be comfortable or sporty.

Any and all advice would be appreciated.

[alohasurftoad]

imo mix match hodge podge components = no bueno
bilstein(lately) = no bueno
m-sport springs = meh, almost no bueno

ideally always get the proper stuff from the start. it often means buying once and crying once, but it's cheaper in the long run and avoids the headache, inconvenience, frustration and the deflated feeling you are now experiencing.

from where you're currently at, if it were me, i would swap the whole front and rear out for the m-performance suspension kit, which includes dampers, springs, strut mounts, bumpstops, spring seats, and some nuts/bolts as well.
https://www.getbmwparts.com/oem-part...kgUGFnZQ%3D%3D

you could also do eibach pro-kit springs and koni special active dampers, however you'd need to additionally buy new strutmounts, bumpstops, rubber bits, etc.

https://www.eibachshop.com/index.php...-springs-bmw-3
+
koni special active dampers
https://www.ecstuning.com/b-koni-par...it/87451356kt/

[Polo08816]

Originally Posted by alohasurftoad

imo mix match hodge podge components = no bueno
bilstein(lately) = no bueno
m-sport springs = meh, almost no bueno

ideally always get the proper stuff from the start. it often means buying once and crying once, but it's cheaper in the long run and avoids the headache, inconvenience, frustration and the deflated feeling you are now experiencing.

from where you're currently at, if it were me, i would swap the whole front and rear out for the m-performance suspension kit, which includes dampers, springs, strut mounts, bumpstops, spring seats, and some nuts/bolts as well.
https://www.getbmwparts.com/oem-part...kgUGFnZQ%3D%3D

you could also do eibach pro-kit springs and koni special active dampers, however you'd need to additionally buy new strutmounts, bumpstops, rubber bits, etc.

https://www.eibachshop.com/index.php...-springs-bmw-3
+
koni special active dampers
https://www.ecstuning.com/b-koni-par...it/87451356kt/

I'm back on the M-Performance Suspension kit as well. Easier daily driving compared to the Ohlins.

So you'll probably want to use a wall mount spring compressor for the M Performance suspension kit.

Most strut compressors won't be able to compress the springs enough to get the nut on the M Performance strut shaft. The M Performance struts are pre-charged in a way that makes them appear to retract into the strut body.

[E90lova]

Originally Posted by devioushaikuzero

According to this, by FCPEuro, b6's are designed for OEM springs:

But since BMW likes to make 423213413423 variations of everything, I could see that being off.

For my past Audi H&R recommended I use their lowering springs with B6s instead of B8s. Weird but true.

[cfm56d7b]

Reducing suspension dynamics (a broad topic) to a few items:

- With the exception of a few proven options, mixing shocks and springs not designed to work together isn’t a good idea. One proven option is Koni Special Active and Eibach Pro springs

- Most adjustable coilovers do not provide independent compression and rebound controls (what everyone would perhaps want given the opportunity) because of higher costs

- KW V3 coilovers do provide the above but lower suspension too much for some tastes. Compromises.

- Coilovers also allow changing the suspension height at any time after initial installation.

For precise suspension tuning, cost being no object, and lowered suspension being within an acceptable range, KW V3 coilovers are about half the $6K price.

If the suspension tuning goals are more complex, coilovers represent the optimum alternative.

[Polo08816]

Originally Posted by cfm56d7b

Reducing suspension dynamics (a broad topic) to a few items:

- With the exception of a few proven options, mixing shocks and springs not designed to work together isn’t a good idea. One proven option is Koni Special Active and Eibach Pro springs

- Most adjustable coilovers do not provide independent compression and rebound controls (what everyone would perhaps want given the opportunity) because of higher costs

- KW V3 coilovers do provide the above but lower suspension too much for some tastes. Compromises.

- Coilovers also allow changing the suspension height at any time after initial installation.

For precise suspension tuning, cost being no object, and lowered suspension being within an acceptable range, KW V3 coilovers are about half the $6K price.

If the suspension tuning goals are more complex, coilovers represent the optimum alternative.

I would say that if the car is RWD and you're looking at spring/shock/strut options, just go with the BMW M Performance Suspension kit.

It's guaranteed to work especially with the minor drop and the factory sway bar endlinks. Also, the kit comes with all the other hardware you need for the install such as strut top mounts, bolts/nuts, etc.

[devioushaikuzero]

Thanks for the amazing advice, guys.

So I have taken it to a local motorsports shop that specializes in BMW. I had them investigate and diagnose. They are declaring that "Rear Subframe Bushings" need to be replaced. Parts are only $200, but they say 6.2 hours of labor. I am not terribly familiar with this issue. Though, if memory serves, this has been a documented issue with this platform.

They also had declared that fixing the bushings is paramount to further fixing the suspension problem.

Any further advice would be greatly appreciated.

[devioushaikuzero]

Originally Posted by Polo08816

I would say that if the car is RWD and you're looking at spring/shock/strut options, just go with the BMW M Performance Suspension kit.

It's guaranteed to work especially with the minor drop and the factory sway bar endlinks. Also, the kit comes with all the other hardware you need for the install such as strut top mounts, bolts/nuts, etc.

So from getbmwparts, do I need only the $1k kit or do I need the $1,865.76 that includes kit and springs for cars w/o m-sport.

[alohasurftoad]

Originally Posted by devioushaikuzero

So from getbmwparts, do I need only the $1k kit or do I need the $1,865.76 that includes kit and springs for cars w/o m-sport.

i'd fix the rear subframe bushings 1st, then reassess the path you desire to take

you also need to determine if you have the 704 sportline/m-sport suspension. if you have it, then you don't need sways because it comes with sways. if your car is a base model w/base suspension, it doesn't have sways. if you don't have sways, should you get them? that is the question...

i didn't realize the $905.xx price is for dampers(front struts/rear shocks)+strutmounts etc, only. since they offer it, it implies you can use the m-performance dampers with the m-sport springs, which you already have, if you desire.

or you can do m-performance dampers+springs=$1387.xx

or everything for $1865.xx if you don't have sways and want them. keep in mind, suspension installs are not cheap and swaybars are even more because you have to drop the rear subframe. i suppose you could install sways at the same time they fix the rear subframe bushings to save a bit of labor cost.

while m-performance products will surely work, i'm admittedly going to be a hypocrite here and suggest reconsidering, a proven mix/match option with the Koni SA/Eibach Pro-Kit setup. if you don't have sways, i'm fairly confident there are better options than the sportline/m-sport sways.

i'll hit up johnung as he may have better/different thoughts on this.

btw, the m-performance is a very good setup. i have it myself and paid $$$$bank years ago. at present, value wise, i feel it is slightly expensive with everything ala carte and a generation old.
.

[devioushaikuzero]

I have the sportline package. So, I believe i have the sways. Do you think the bushings need to be replaced? Or would I better use the labor for suspension?


Here is the car:
https://bimmer.work/vin/ffbc9f780aab...9e82daf606e5c/

I will get part numbers tomorrow.

[alohasurftoad]

Originally Posted by devioushaikuzero

I have the sportline package. So, I believe i have the sways. Do you think the bushings need to be replaced? Or would I better use the labor for suspension?
Here is the car:
https://bimmer.work/vin/ffbc9f780aab...9e82daf606e5c/
I will get part numbers tomorrow.

if possible, get a 2nd opinion on the bushings. if they need replacing i'd probably go ahead and do it.

i don't see 704 which is the m-sport suspension that occurred on some sportline packages. you can visually check for them