[Herakles]

So much info our there, looking for a refresh- If otherwise completely stock car, would the Koni FSD or Bilstein (sport for stock spring?) would be better? Im leaning to FSD after a tire rack article I read-

[Jeff@TopGearSolutions]

I've read on more then a few occasions people don't like the bumpy aspect of the FSD on this platform. Of course, everyone and their sensitivity will be different. Koni FSD otherwise are a great choice but so are the Bilstein.

I'd honestly recommend just going with the Koni yellow. They are cheaper then FSD and they will allow you to adjust so basically you can be exactly where you want to be on ride stiffness.

I'd love to hear what aspect of the FSD you read brought you to your conclusion so far?

[Herakles]

Originally Posted by Jeff@TopGearSolutions

I've read on more then a few occasions people don't like the bumpy aspect of the FSD on this platform. Of course, everyone and their sensitivity will be different. Koni FSD otherwise are a great choice but so are the Bilstein.

I'd honestly recommend just going with the Koni yellow. They are cheaper then FSD and they will allow you to adjust so basically you can be exactly where you want to be on ride stiffness.

I'd love to hear what aspect of the FSD you read brought you to your conclusion so far?

Hi Jeff!
SO i was data mining, and came across a great read on tire rack- they did a nice test of the yellow, billys, and FSD- and I CANT FIND THE DAMN ARTICLE!!!

[matteblue3er]

Originally Posted by Herakles

So much info our there, looking for a refresh- If otherwise completely stock car, would the Koni FSD or Bilstein (sport for stock spring?) would be better? Im leaning to FSD after a tire rack article I read-

xDrive sport suspension is the same as non-sport.

Do not use Koni FSDs with stock xDrive springs....ride is bouncy. The ONLY springs that should be used with FSDs are oem RWD sport suspension springs.

Koni Yellows should also not be used with xDrive springs.

The only shocks you can use with stock xDrive springs are Bilstein B4 or B6. B4 is OEM equivalent. B6 slightly stiffer than stock/B4.

B8 is only for use with aftermarket lowering springs.

[Jeff@TopGearSolutions]

Originally Posted by Herakles

Hi Jeff!
SO i was data mining, and came across a great read on tire rack- they did a nice test of the yellow, billys, and FSD- and I CANT FIND THE DAMN ARTICLE!!!

Originally Posted by matteblue3er

xDrive sport suspension is the same as non-sport.

Do not use Koni FSDs with stock xDrive springs....ride is bouncy. The ONLY springs that should be used with FSDs are oem RWD sport suspension springs.

Koni Yellows should also not be used with xDrive springs.

The only shocks you can use with stock xDrive springs are Bilstein B4 or B6. B4 is OEM equivalent. B6 slightly stiffer than stock/B4.

B8 is only for use with aftermarket lowering springs.

Good catch. I already know the FSD were bouncy therefore I never recommend them, even on the RWD I've heard some complaints. That's why I usually at least recommend Koni Yellow.

I agree on the bilstein b4 or b6 given the above.

[bman5150]

Love my Bilstein HDs with stock springs. Ride is actually better than with OEM shocks/struts and yet handling is same or better. This is my second set of Bilstein HDs on a vehicle and I'm really happy with them.

[boro92]

I have billy b8 on stock xdrive springs. Ride is firmer and rebound is much better - there is even enough rebound to keep the rear inside wheel lifted when trail braking in a corner at the track install on the front was difficult due to the shorter shock body, but I welcome the additional travel up front with the b8. EVEN still, I have had the b8 bottom out a few times. No doubt the b6 or any other standard length shock (yellow, fsd et al) would be meeting the front bump stops often. Fwiw the roads are crap here. The car with these shocks is no longer floaty, and no longer sways about and wallows with quick steering inputs. The car just settles and remains settled when loading it up. The weight transfer is much more controlled and you really can drive it harder with confidence.

[miker2013]

Originally Posted by boro92

I have billy b8 on stock xdrive springs. Ride is firmer and rebound is much better - there is even enough rebound to keep the rear inside wheel lifted when trail braking in a corner at the track install on the front was difficult due to the shorter shock body, but I welcome the additional travel up front with the b8. EVEN still, I have had the b8 bottom out a few times. No doubt the b6 or any other standard length shock (yellow, fsd et al) would be meeting the front bump stops often. Fwiw the roads are crap here. The car with these shocks is no longer floaty, and no longer sways about and wallows with quick steering inputs. The car just settles and remains settled when loading it up. The weight transfer is much more controlled and you really can drive it harder with confidence.

so u can run stock xdrive springs with b8? what do u think is a better setup for a daily driver who wants to get rid of a bit of the sway and floaty softness of stock xdrive suspension and doesn't mind a little more firmness, assuming stock springs are kept? b8 or hd?

[boro92]

Both B8 and HD will accomplish exactly what you are seeking.
The car drives great with the shocks on the road course as well.
Both B8 and HD have identical valving. Both will ride firmer and more controlled over stock. The only difference is that B8's have a shorter shock body - allowing for a shorter spring and yet still retain adequate levels of bump travel. For stock springs, it makes more sense to go with HD unless you are looking to control some of the droop - but by the sounds of it, you are doing this for street purposes. With that in mind, I would not play around with the droop and keep the factory settings. HD's will allow you to maintain factory setup.

[Herakles]

Awesome, thanks everyone- so sounds like stock Xdrive set up gets Bistein HDs..

[bman5150]

You will love them. I still do. Great option for street use and maintaining a comfortable ride.

[miker2013]

so assuming i go with the hd on my stock xdrive springs, anything else i should change at the same time? what about camber plates? as much as i want to firm the ride and get rid of floatiness, i also want to quicken the steering up too as much as i can

[boro92]

Camber plates will add nvh if u get ones that do away with the bushing. However, it is precisely these types of camber plates which would bring the greatest handling benefit. If you are rwd and primarily street driven, you will benefit more from m3 arms or tension strut bushings without affecting tire wear as camber plates would

[NiNeTyOne]

The FSD's are bouncy out of the box for about 3 days, and then they are great.

I would not match them with the OE springs as they are not suited. The Eibach Pro springs are a really good match. I've done the yellows on other cars and was not impressed with how fast they clapped out, same with the HD's.

The better upgrade from all this is the Ohlins Road and track dampers with the Eibach ERS springs. You're at about $2k for those though. They are as good as you'll get without spending $4500 or more. Benefit of the Ohlins are they are rebuildable.

[NiNeTyOne]

Originally Posted by matteblue3er

The ONLY springs that should be used with FSDs are oem RWD sport suspension springs.

This is absolutely false. The Eibach Pro Springs are rate matched to the FSD's, Koni and Eibach worked together on the package.

They do not sell the Pro Springs for all the xDrive cars in the US, but you can get them out of Germany, which is typically cheaper, even with shipping. I got the properly matched Eibach Pro springs out of Germany for $190 plus $60 shipping and had them in 10 days.

The FSD's have been on the car for 10k miles and handle amazing. The drop is 1.33" front and 1.25" rear.

You can also take those rates (148lbs/in in the front and 479lbs/in for the rear for the e91) and replace them with Eibach's ERS springs which are Linear coils and gain you some additional room for a wider tire. Those springs are VERY good, and again, can be rate matched to the FSD damper.

Performance Shock at Sears Point/Sonoma Raceway can get any of these for you. They are very good and work with some of the top racing programs in the country.

[matteblue3er]

Originally Posted by NiNeTyOne

This is absolutely false. The Eibach Pro Springs are rate matched to the FSD's, Koni and Eibach worked together on the package.

They do not sell the Pro Springs for all the xDrive cars in the US, but you can get them out of Germany, which is typically cheaper, even with shipping. I got the properly matched Eibach Pro springs out of Germany for $190 plus $60 shipping and had them in 10 days.

The FSD's have been on the car for 10k miles and handle amazing. The drop is 1.33" front and 1.25" rear.

You can also take those rates (148lbs/in in the front and 479lbs/in for the rear for the e91) and replace them with Eibach's ERS springs which are Linear coils and gain you some additional room for a wider tire. Those springs are VERY good, and again, can be rate matched to the FSD damper.

Performance Shock at Sears Point/Sonoma Raceway can get any of these for you. They are very good and work with some of the top racing programs in the country.

Do you have a reference from Koni or some other source that can verify this?

Every install of Koni FSDs and lowering springs I have installed or ridden in has been sub par. I've driven new and borken in setups. Everyone's idea of "works" is subjective and personally, I don't think they work WELL together.

[Jeff@TopGearSolutions]

Originally Posted by matteblue3er

Do you have a reference from Koni or some other source that can verify this?

Every install of Koni FSDs and lowering springs I have installed or ridden in has been sub par. I've driven new and borken in setups. Everyone's idea of "works" is subjective and personally, I don't think they work WELL together.

That's the problem with any suspension recommendation or feedback. What works for you could be way off to someone else.

[matteblue3er]

Yes very true. I also feel that if there was collaboration involved it would be more agressively marketed as a matched pair and/or sold as a cup kit

[NiNeTyOne]

Originally Posted by matteblue3er

Every install of Koni FSDs and lowering springs I have installed or ridden in has been sub par. I've driven new and borken in setups. Everyone's idea of "works" is subjective and personally, I don't think they work WELL together.

I've been in motorsports for nearly 20 years, have run at every major track in the US, placed in the top 10 at Daytona, setup quarter million dollar Porsche's, highly tuned road cars of most Germna marques, and when I do suspension on a car I work with one of two shops, or directly with either Ohlins or Koni in Europe. In the US, PSI in Sonoma is the best in the business.

When I set up the e91 with FSD's while awaiting the DFV Ohlins that will fit the xDrive front, I spoke directly to Koni engineers in Holland. The Eibach E10-20-014-10-22 kit for the e91 is rate matched. The e90 and e92 will have their own part numbers in Germany. The kits for xDrive cars are, as far as I know, still not sold in the US (though this may have changed), so you have to order the correct springs from Germany or the UK. Contact Eibach's UK distributor as they know their stuff.

Tests using stock springs is the only test data I have seen. These indicate the FSD's out perform the old damper tech at a similar price point.

They do not feel as stiff, and there a reason for that if you ever take one apart, but they control body roll very well and do exactly what a good damper should, which is keep the tire in contact with the road.

[NiNeTyOne]

Originally Posted by matteblue3er

Yes very true. I also feel that if there was collaboration involved it would be more agressively marketed as a matched pair and/or sold as a cup kit

It is in Europe. Here you can get it for the non-xDrive cars.

Lack of availability is the fault of Eibach, as they only sell combos they can directly test here in California. They lack xDrive car access. So no kits here.

You can buy them all day in Germany just like the non-xDrive cars here.

Here's the non-xDrive kit:

linky

[butanmist]

I avg 100k commercial miles a year, my car is my office/shop. I did not need my xi lower as mud/snow/etc in the West is no joke so I have kept stock height. For my first 100k went with the stock xi "sport" suspension, at end of second 100k (184K today) all on FSD with stock springs. I run 235 tires instead of 225s on 17s to deal with the on/off road issues I subject my car to. Can't speak to the the other types but I have been informed that as one of the last e90s off the line in 2011 my stock shock/struts were B6s. My two bits is the FSDs are better if you have crap roads/conditions and so far have lasted better.

[NiNeTyOne]

Originally Posted by butanmist

I avg 100k commercial miles a year, my car is my office/shop. I did not need my xi lower as mud/snow/etc in the West is no joke so I have kept stock height. For my first 100k went with the stock xi "sport" suspension, at end of second 100k (184K today) all on FSD with stock springs. I run 235 tires instead of 225s on 17s to deal with the on/off road issues I subject my car to. Can't speak to the the other types but I have been informed that as one of the last e90s off the line in 2011 my stock shock/struts were B6s. My two bits is the FSDs are better if you have crap roads/conditions and so far have lasted better.

Crap roads=pretty much anywhere in North America, the way we've been neglecting infrastructure.

I would agree as the B6's are essentially 30 year old damper technology, where the FSD's are the direct result of co-development with MacLaren F1 during their MP4-23 program. It's a big step forward in damper design.

Here's an old PDF from when they were initially released

..and an old article from Racecar Engineering: http://www.racecar-engineering.com/a...koni-dampers/#

While they are not adjustable like the Ohlins DFV R&T's, you can put them on Xdrive cars. Mine are now well north of 10k miles and they are still performing as well as the week they were installed. I have absolutely no idea what people mean by them being "bumpy." They are very, very well mannered, and they do an extraordinary job of reducing body roll for a damper when paired with decent springs like the Eibach's. Honestly, I'm pretty confident I'd be faster around the track on these than any of the Bilsteins.

You do want to be sure to replace the upper rear strut bushings with high durometer poly as they really need to be locked down to work optimally. I had OE rubber bushings for the first 500 miles and swapped them for Strongflex yellow, and it made them behave even better in the back.