Koni FSD shocks on 540iT - Air Springs - Full Report & Pictures

The car is a 2000 540iT with rear air springs and factory sport suspension, 93K miles. Handling has never been a issue, has always handled amazingly well for it's size, although seemed more 'heavy' lately. The reason for wanting to install new shocks was the poor (harsh) ride quailty, particularly from the rear suspension that seems to plague every iT with the air (self leveling) suspension. Maybe in CA with good roads this is not an issue. But here in the NE with potholes, craters, terriible road patching, separating expansion joints, and just plain worn out roads, is an annoying problem.

Most manufacturers do not make (or at least list) shocks for the rear of an iT with auto level. Koni does list them, but in some literature indicates not for self leveling suspension. There are different versions for the 6 vs 8 cyl tourings, but no option for regular vs sport, although it did indicate was also for m-technic suspension. The rear shocks of an iT are mounted diagnoally. This means they do not have much travel and must be quite stiff to be effective.

Chose the Koni FSD because it looked like it should work, and wanted to take advantage of the FSD feature that would offer a smoother ride (they also worked well in our 3 series). Changing the shocks was uneventful, was pretty easy (much easier than the 3), no cursing, swearing or blood spilled while changing the shocks (just looked like I came out of a coal mine from all the brake dust).

The OEM shocks were in varied condition when removed. The rears were still very stiff, probably still like new. They did have a strange internal design that appeared to be a spring inside for the last 1" or so of extension. You needed to pull on them pretty hard to obtain the last 1" of travel (on jack stands weight of suspension is more than enough). Not sure if this 'spring' has something to do with the air springs, or is just a general design feature of that particular shock. The fronts appeared to be binding a bit, and had no gas (pressure) charge at all. When removed they did not self extend like all other BMW shocks I've worked with and presume these were shot.

The new Konis were a bit longer (piston rod) than the OEM's by about an inch. Probably because they did not make a specific sport version. For the front, no issue at all, spring was still plenty compressed. For the rear, (at full travel on jack stands) the air spring was also still in full contact with the lower support, but was just starting to lift off on one edge. There was more than enough travel in all the various height sensors, etc to accomodate the extra suspension travel.

While it certainly did not make the iT ride like a Lexus, or even that of a 5 series sedan, was still a significant improvement and would definately do it again. It's much smoother and (at least for the 10 mile test drive) always is acceptable, never irritating like it use to be. At times use to be embarrassed to have passengers when I went over bad roads. No longer. Before any road surface separation use to be greeted with a bang, now it's more like a thunk. On the 1-10 scale if the ride use to be a 3, now I would give it a 6 or 7.

If anyone else is thinking of going out tomorrow and ordering these, you may be in for bit of a wait. Believe this was last set available in the US and was told the next batch would not be produced for up to 2 months (may have been incorrect info). Remember not many iT's out there, demand is pretty low.

Feel free to PM with any questions.

The Pictures are as follows:
1) Picture of box with part #
2) Everything in the FSD kit and new self locking nuts purchased
3) OEM & Koni Rear shock comparsion (remember the OEM has another 1" of travel if you pull on it)
4) Air spring with the (gold color) Koni, car on jack stands. The gap on the bottom is not as big as it seems, there is some black metal above the rust line that is hard to see, there is a gap, but just bearly on one edge)
5) Air spring on the other side with the OEM shock.
6) Old and new front shocks
7) Reward to myself for a job well done (Yes I stole the idea)

Vey nice, I can't wait to do this modification in my wagon.\

Do you hace some pics of the wagon with new suspension?

Great write up.

Originally Posted by cbouchez

Vey nice, I can't wait to do this modification in my wagon.\

Do you hace some pics of the wagon with new suspension?

As the spings have not been changed, looks exactly the same as before (actually these pictures are before, car currently needs a bath).

Thnaks! I'm really looking forward to this mod.

You are the MAN!!!

Where did you buy the new shocks?

I've purchased FSD Koni Shocks from Tire Rack and Shox.com. There are many other suppliers as well.

That's a very nice looking touring. What are the wheels?

GREAT looking touring! And great writeup. I'm going to be putting on a new exhaust soon and my tip would look great with you wheels (what are they by the way?).



Can't see it too well, but it's chrome and looks great. If you want it, it's yours (once I get my new one). let me know.

-Chris

beautiful ride, keiths. very good write-up too! thanks for sharing. i am curious as to the ride height - no changes at all?

go wash your wagon! we'll be waiting for NEW pics...

Thanks for the writeup Keiths.

I run Konis on track and street cars and look forward to putting them on my iT Sport.

I figured there might be a problem with the sport suspension versus non-sport and was originally thinking [if available] of Koni single adjustable (rebound) yellow sport shocks / inserts to match / dampen sport springs. Sounds like from your experience with the 540iT that the FSDs are designed to work ... or you made them work with the iT?

Have to do some more research as car landed in my driveway only today.

And MAN does it need new shocks / inserts ! :lol:

Originally Posted by wagonnut

GREAT looking touring! And great writeup. I'm going to be putting on a new exhaust soon and my tip would look great with you wheels (what are they by the way?).

Can't see it too well, but it's chrome and looks great. If you want it, it's yours (once I get my new one). let me know.

-Chris

The wheels are ASA AR1's and are still available (tire rack) They do look great and are inexpensive. This was my winter tire set-up (which I sold). Actually the car is currently running on factory 16" wheels/tires. Once the tires wear out (the continentials seem to last foever), am likely to pick up a new set of 17" AR1s with new tires. Was afraid of using larger wheels due to the harsh ride, which is now fixed. Only problem with the ASA wheels is there have been many reports of clear coat failiure, which indeed happened to one of the ones I had. But they are so inexpensive ($125 each), just easy to go get another.

Chris, Let me know when that exhaust tip is available (presume it's a slip on). When I first got the car I tried to find one but with no success just gave up.

Thanks.

-Keith

Originally Posted by Jase007

Thanks for the writeup Keiths.

I run Konis on track and street cars and look forward to putting them on my iT Sport.

I figured there might be a problem with the sport suspension versus non-sport and was originally thinking [if available] of Koni single adjustable (rebound) yellow sport shocks / inserts to match / dampen sport springs. Sounds like from your experience with the 540iT that the FSDs are designed to work ... or you made them work with the iT?

Have to do some more research as car landed in my driveway only today.

And MAN does it need new shocks / inserts ! :lol:

Some more info on the touring suspension. First more than one source has told me BMW only sold about 80 sport package equipped 540iTs per year, so they are indeed rare, which is why there are are almost no shocks for it. Still not 100% sure if the FSD's are truely designed for the iT with air springs, or as like you said, I made them work (the factory rear shocks were unusual). Due to low demand suspect these are one size fits both sport & non-sport, which is why they were a bit longer. I know with Bilsteins, there is no difference in the valveing between sport and HD shocks, just the length is different. Koni does make different shocks for sport/non for more popular cars such as the 3.

The front suspension of the touring is the same as a sedan, so there are many different shocks available.

For those with rear air springs, there is no difference between the sport and non-sport. All the parts are exactly the same. What is different is the ride height SETTING. They do show different shocks (suspect sport is stiffer). This car ride height can be changed by the dealer with their computer. Some have put lowing springs in the front and had the dealer lower the rear setting to match.

You indicated wanting to get adjustable shocks. Probably not going to happen, for the rear anyway. Considered it lucky to find ANY aftermarket shock that would fit the iT.

After driving some more, the FSD's have definately helped a lot. You still know it has air suspension as you get that little extra bounce feel over larger bumps (which it had before). Some have indicated this is due to weak rear carrier mount bushings.

If considering FSD's, remember these are designed more towards comfort than a raw sport feel. The reviews (and my feeling as well), indicate while they 'seem' softer than most sport or more agressive shocks, the FSD's will actually out handle them.

Originally Posted by aw/ir02smg

beautiful ride, keiths. very good write-up too! thanks for sharing. i am curious as to the ride height - no changes at all?

go wash your wagon! we'll be waiting for NEW pics...

To be honest, I did not measure it before, but it sure looks the same. There is no reason why the ride height should change as this is determened by springs, which have not been changed. Suppose the front could be a mm higher as the Konis are pressurized and do produce a tiny upwards force (unlike high pressure Bilsteins which produce a lot of force and do raise the car).

I'm glad to hear that you used and liked the FSDs.

They do offer BOTH a cushioned ride and a degree of performance, a combo that you can not get in any other shock brand or model.

[QUOTE=KeithS as the Konis are pressurized and do produce a tiny upwards force (unlike high pressure Bilsteins which produce a lot of force and do raise the car). [/QUOTE]

Regarding the Bilsteins, the force to compress the fronts against the internal gas pressure is about 150 lbs for each front Bilstein. So that's about 300 lbs of lifting force on the front. That accounts for the higher ride ht that users experience with any spring set.

Originally Posted by KeithS

Most manufacturers do not make (or at least list) shocks for the rear of an iT with auto level. Koni does list them, but in some literature indicates not for self leveling suspension.

Hi!
I from Russia and not well know English.
I wish to buy koni for the my e39 touring. I have read your report, but have not understood — your car has self-levelling or not?

Thanks.

Yes car has self leveling (air springs). ALL US 540iT (V8) cars come with self leveling, there is no choice. It is an opton on 6-cyl tourings.

keiths, sorry for my confusion...but is ur car sport or non-sport? if non-sport, would this also work for a sport packaged one? another thing is will this set be applicable to a 528it? sorry for all the questions, but i do have one more...what springs would you suggest to lower a 528it with the FSDs?

My car has sport package and was already very low from the factory. To lower the car you can only change the front springs (just use OEM sport springs or Ebach) if you have air suspension. If you have air suspension in the back you do not change them, just reprogram the ride height (only dealer car do this).

My car rides about the height of an Eibach sprung car that is w/o Bilsteins (Bilsteins raise the car). My springs are cut down OEM sport springs.

This past weekend I drove over and along a line of the yellow metal lane markers (camel humps or road *******) with them going under the center of the car. I hit each of them tick tick tick as I moved at about 15 mph.

I was shocked that I hit/touched them. If my car rode any lower I would have done some damage.

Originally Posted by KeithS

My car has sport package and was already very low from the factory. To lower the car you can only change the front springs (just use OEM sport springs or Ebach) if you have air suspension. If you have air suspension in the back you do not change them, just reprogram the ride height (only dealer car do this).

whats the specific eibach spring you talking about? and just keep the oem shock absorbers?
i work at a dealership, exactly what should i tell the service adviser in regards to the reprogramming?

You need to have self leveling suspension (Air springs). Using the BMW computer the rear ride hight can be adjusted. Never had it done, as my car came with sport, but have heard about it. Probably can use the same shocks but if you put sport springs on the front, then you will want sport shocks on the front.

Originally Posted by KeithS

You need to have self leveling suspension (Air springs). Using the BMW computer the rear ride hight can be adjusted. Never had it done, as my car came with sport, but have heard about it. Probably can use the same shocks but if you put sport springs on the front, then you will want sport shocks on the front.

I heard the same for BMW and Mercedes, that the dealer can adjust the ht to any dimension (within the range).

Originally Posted by KeithS

You need to have self leveling suspension (Air springs). Using the BMW computer the rear ride hight can be adjusted. Never had it done, as my car came with sport, but have heard about it. Probably can use the same shocks but if you put sport springs on the front, then you will want sport shocks on the front.

what shocks would you recommend?