Changing Stock schocks for Koni FSD

Amigos, I am planning to change my non sport schocks for the Koni FSDs, which I am familiar with, will keep u guys posted!!!

I've used FSD's on 2 cars with completely different results. On our E46 328i, they worked exactly as advertised and we now have 60K miles on them. On our E39 540iT the front ones were completely toast in less than 12K miles. Car was bouncing all over, with the bump stops the only thing keeping it on the road. Koni replaced them with yellow adjustables which have been fine. My theory is they cannot stand up to the punishment of a heavy engine and associated high rate springs. The D has a heavy engine. You do the math.

Just my experience.

Keith great insight but I could not turn a 20% discount,plus I used them on my 02 mcs, I will take my chances at least there a waranty

Originally Posted by KeithS

I've used FSD's on 2 cars with completely different results. On our E46 328i, they worked exactly as advertised and we now have 60K miles on them. On our E39 540iT the front ones were completely toast in less than 12K miles. Car was bouncing all over, with the bump stops the only thing keeping it on the road. Koni replaced them with yellow adjustables which have been fine. My theory is they cannot stand up to the punishment of a heavy engine and associated high rate springs. The D has a heavy engine. You do the math.

Just my experience.

What shocks would you recommend for the Big D then? I have the sport shocks and HR sport springs.

Will have to presume you are not or intending to use run flats which need a special valving if your want to keep your kidneys (like the FSD's have). If that is the case I understand bilsteins are pretty much indestructabhle. I'm no expert, was just sharing my experience. I know many others that had the same issue with putting FSD's on their 540. Maybe it was a manufacturing or design issue which has since been fixed.

I have just emailed Mr. Lee from ITT Motion Technologies whom happen to do the FSds about this issue and I am awaiting his response

Originally Posted by KeithS

If that is the case I understand bilsteins are pretty much indestructabhle.

I ran Bilsteins on some of my Porsches and on my Saleen, zero complaints with them. I have had mixed luck with Koni products but never used the FSDs. Interesting to read the comment about Bilsteins with the indestructable rep because I have some on my truck and looks like at least one front one is in poor shape yet everyone in the truck world tells me that bilstiens will outlast the truck.

I just recently (a month ago) put KW V3s on my D. Was going to go with V2s but the guys I went through messed up the order and told me they had V3s in-house and offered them to me at the V2s price so it was a no brainier for me.

Ok amigos I got a response from Koni and here it is:


Hello Axel,



My apologies for the delay, I am traveling with limited internet access for the last 10 days.



I am sorry that the person with the 5 series had an issue but it was not related to the weight of the engine whatsoever. Although his weight guess was well intentioned, it was not well informed. The weight of the car and engine is totally carried by the springs and so long as the springs are correct to carry the weight of the engine (diesel, V8, etc.), then there will be no weight issue. You would not want to install springs for a lighter weight gas engine and expect it to carry the diesel weight. So long as you use the proper diesel springs, then these FSD dampers will be fine for your engine. This much later and far removed, I have no ability to tell why he had an issue in such a short time. Our KONI warranty rate is approx. 0.5% of our products sold so although it is a very small percentage, it is still a mechanical device that takes quite a bit of punishment from the road so sometimes mechanical things can fail internally or be damaged by external forces. Just hang onto your purchase receipt and any warranty issues will be covered.



I have copied the page for your car from the European web site where they sell this FSD kit for a wide range of engines: http://www.koni.com/index.php?id=254 You will notice that diesel is not separated out under the dampers alone but it is separated out specifically for all of the spring and damper combined kits. This reinforces that the diesel needs to have diesel specific springs but not diesel specific dampers.



Best regards,

Lee Grimes

KONI North America


And here is the link for the above Koni site as follows:

http://www.koni.com/index.php?id=254

Originally Posted by Axel61

Ok amigos I got a response from Koni and here it is:

I am sorry that the person with the 5 series had an issue but it was not related to the weight of the engine whatsoever. Although his weight guess was well intentioned, it was not well informed. The weight of the car and engine is totally carried by the springs .........

I'll disagree. A heavy engine has higher rate springs, which means the shock has to work that much harder to dampen out oscillations. I was not the only one with an issue, there were dozens, and they finally admitted to me there was some sort of problem. It may have just been a manufacturing issue (vs a design issue). That they would not tell me. It was both shocks that went bad, not just one.

@KeithS amigo it seems that you and others had some issues. Therefore, do as I did write to Koni. Thats all I can suggest. They do have a WARRANTY so use it. If not do not purchase from them if you are not satisfied with it. If it fails me then I have the email to use as my guarantee. I really dont know what to say about this, I will keep in mind your issues though, gracias!!

Yes they have a warranty, which I used and was pretty painless execpt for the fact I had to change the shocks twice in a year. I probably should add the car that wore out the FSD's was not only a V8 but has a sports supension as well. This means very high rate springs putting even more stress on the shocks.

Just be sure to keep your sales receipt and you will be fine if anything ever happens to them.

I will keep the reciept as stated, Like i have mentioned here my old 02 MCS is still running the roads of Puerto Rico the last Ime I remember although a smaller engine displacement. I believe other shocks would have the same issue of defaults, God knows anything can break at least Keith you were able to replace them than buying all over but the mere fact of changing takes a toll on ur pocket is enough to be pissed at

BTW the 02 MCS still has the SPORT SUSPENSION!!! I just added regular Koni FSDs

FSDs with stock Sport package springs work just fine on the d. I have put north of 20,000 miles on my d with FSDs and the factory Sport package with no issues other than a vastly improved ride quality.

Axel proceed with caution when considering changing out shocks without addressing springs. I would suggest replacing your springs at the same time with a spring with a higher spring rate e.g. either zsp springs, EPK's or similar. The shock/spring system is engineered to work in concert. Shocks are designed to manage the spring rates they are paired with. A shock that cannot handle the rebound and or dampening of a stiff spring will result in a bouncy ride and vice versa. I can't tell you how many people I have read about that only did one without the other only to end up paying for the install all over again to have matched springs installed. Just my $.02

Have you considered the BMW Performance suspension kit (springs and shocks together)?

So Koni does not sell an FSD for non sports package cars then another for sports?

Two points to consider on this topic. Dampers work WITH the springs not against them. In systems dynamics class (part of mech engineer curriculum), the spring force and damper force summed together (with same sign) against the external force coming from the road. External force tearing up shocks, not the springs. I follow the koni guy's point at least. KeithS, i'm not saying you're wrong, just goes against what i was taught. Please don't take offense.


Second point is spring rate and damping rate are relatively sized together by the damping ratio. So, i agree with cssnms on the dual change out.

http://en.wikipedia.org/wiki/Damping

Go to the spring-mass-damper portion of the link. It is down a little from the top.

Originally Posted by Snipe656

So Koni does not sell an FSD for non sports package cars then another for sports?

One size fits all (same Koni part #) as regards FSDs for Sport vs. non-Sport edition E90s.

Originally Posted by anE934fun

One size fits all (same Koni part #) as regards FSDs for Sport vs. non-Sport edition E90s.

But then based on prior comments in this thread they are not one size fits all but instead for sports springs?

Originally Posted by Snipe656

But then based on prior comments in this thread they are not one size fits all but instead for sports springs?

I am not sure I understand your question. The fittings on the FSDs that enable the damper to be mounted to the suspension on the E90 are the same regardless whether you have a Sport package or not (hence my comment about 1 Koni part number). You can fit Koni FSDs to your E90 whether you have the Sport package or not. Stated another way, there is no exclusion for FSDs for non-Sport package E90s. There is an exclusion for FSDs for AWD-equipped E90s.

Originally Posted by anE934fun

I am not sure I understand your question. The fittings on the FSDs that enable the damper to be mounted to the suspension on the E90 are the same regardless whether you have a Sport package or not (hence my comment about 1 Koni part number). You can fit Koni FSDs to your E90 whether you have the Sport package or not. Stated another way, there is no exclusion for FSDs for non-Sport package E90s. There is an exclusion for FSDs for AWD-equipped E90s.

This:

Originally Posted by cssnms

Axel proceed with caution when considering changing out shocks without addressing springs. I would suggest replacing your springs at the same time with a spring with a higher spring rate e.g. either zsp springs, EPK's or similar. The shock/spring system is engineered to work in concert. Shocks are designed to manage the spring rates they are paired with. A shock that cannot handle the rebound and or dampening of a stiff spring will result in a bouncy ride and vice versa. I can't tell you how many people I have read about that only did one without the other only to end up paying for the install all over again to have matched springs installed. Just my $.02

Have you considered the BMW Performance suspension kit (springs and shocks together)?

Is that not saying that the FSDs are not engineered to work correctly with non-sport springs? Meaning sure they can bolt in there but will not ride/handle correctly because the FSD is designed to work with a "tighter" spring.

Originally Posted by anE934fun

One size fits all (same Koni part #) as regards FSDs for Sport vs. non-Sport edition E90s.

Well that maybe what the manufacturer says, but in reality one shock does not fit all spring rates.

Originally Posted by Snipe656

This:




Is that not saying that the FSDs are not engineered to work correctly with non-sport springs? Meaning sure they can bolt in there but will not ride/handle correctly because the FSD is designed to work with a "tighter" spring.

One size does NOT fit all, it never has when it comes to performance suspension systems. Koni might tell you otherwise, but they are in the business of selling shocks. Personally, if it were me, I would buy a shock and spring that are designed/engineered to be paired with one another.

How are the suspensions setup on these cars anyway? Do you end up removing the springs to replace the "dampners" anyway?