Koni FSDs on a 1 series

[Revelate]

Some of you may be aware that Koni includes a restriction for the BMW 1 series application of their FSD shocks (p/n 2100 4036)

FSD kit must be used with stock height suspension

Forum posts from the past few years suggest that most people have good results with FSDs and lowering springs, so I called Koni to ask why they include the warning.

Here is the Koni technician's response (in my words):
The module in the FSD adjusts by reacting to sharp, high speed travel (such as a pothole) with reduced damping to absorb better, and inversely increases damping during low speed travel (braking, cornering) to improve handling.

Some vehicles are more prone to actively using the bump stops to supplement the springs under normal conditions, rather than as a "last resort" measure in extreme situations.

In vehicles that regularly rely on the bump stops, the FSD module can be easily confused when compression reaches the bump stop. It may sense the impact as sharp enough to react in the same manner as a pothole and lower the damping force, which is exactly the opposite of what you want to happen under heavy compression. The result is that the car will feel underdamped and will bounce hard off the bump stops.

He couldn't speak specifically to the BMW 1 series application, but the warning generally means that the manufacturer has designed the stock suspension to rely on the bump stops during normal operation, and the FSD shocks will simply not function properly.

I am slowly acquiring the parts for my spring suspension upgrade project and I really want FSDs for their Jekyll & Hyde operation. My compromise to include them in my plan is to go with BMW PS springs (less overall lowering than the originally planned Eibachs) and BMW PS bump stops (1/2" less material), and get the Dinan rear upper shock mount kit (10mm additional travel).

My hope is that these adjustments will reduce the reliance on the bump stops for normal operation and allow the FSDs to do their job.

I'm probably not going to be finished until June, but will update this thread with the results, and my impressions. I'm also interested to know what others have experienced (good or bad) with the Koni FSDs in whatever application you chose.

[timhatimay]

I had considered and researched the FSD shocks during my suspension upgrade, but ultimately ended up with the full performance suspension. Unless your absolutely set on the FSD, have you considered the BMW PS shocks instead? They should be properly tuned for the performance springs rates, and on my car have a good mix of performance and road comfort (with more emphasis on performance). I would assume the FSD may be a bit less aggressive than the PS, but that may not necessarily be a bad thing depending on your goals. Utilizing the shorter bump stops and shock mounts will be a help though. I felt they made a big difference in the suspension travel and crashing over large bumps. I really like the Dinan shock mounts on the rear of my car, and they made a big improvement in comfort and consistency. I think there were also some that use E46 (or maybe another older BMW) bump stops as they were shorter, so you may look into that, since the PS stops may be hard to come by without the whole kit. Hope this helps.

Tim

[opvaulet]

I had FSD's and the same bump stops as the BMW PS...namely those from the Z8 (front) and E91 (rear). A gentler riding set up than stock Msport. Also used the Dinan rear shock mounts.

[GaryS]

I have PS springs/bump stops, FSDs and Dinan rear shock mounts. I think the FSDs and PS springs match perfectly for a daily driver. On the tracks at Summit Point, I never hit any sharp bumps, so the selective damping stays firm and only loosens slightly in some corners to keep rubber on the road. On streets, the ride is great at all times but it feels firm and sporty in corners and very stable in lane changes. Over some big bumps, there can be one or two very small bounces - enough to keep me from calling the FSDs perfect, but not enough to make any practical difference.

I should mention, I also have M3 front arms and swaybar and M3 rear subframe bushings. I added the rear subframe bushings after the other parts because with the stiffer springs installed, the back end of my car was bouncing 1-2" over bumps. The M3 rear subframe bushings cured that and added just the right amount of road feel and a ton of stability. You probably want to avoid the extra cost like I did, but I strongly recommend including M3 rear subframe bushings to anyone who installs sportier springs.

[1fastbmw]

I recently installed Koni FSD's and BMW Performance Springs and I'm very happy with the way things turned out. As GaryS I also have all the M3 components and bushings with Dinan Shock Mounts and I do think these components help with the overall feel and travel. I used the E85 Z4s Bump Stops, my full review is below.


31331096099, fronts, each (so order 2)
33536788905, rears, each (so order 2)



http://www.1addicts.com/forums/showt...&highlight=lsd

[Revelate]

I obviously didn't read through enough threads to find others with the same, or similar, configurations. I'm also glad I'm not alone; I thought this was going to be an experiment but it sounds like it's a pretty well known solution for "performance oriented" owners not trying to slam the car on H&Rs or coilovers. I like the lowered look as much as the next guy, but I much prefer the handling improvement without a harsh ride and scraping over everything. My BMW Performance front bumper with CF splitters will thank me.

I have the M3 front control arms and E93 front sway bar on my list already, they are going on for sure. The only part I'm trying to avoid is the rear subframe bushings because of the labor. I don't have the tools, nor the space, nor the confidence to pull off something like that.

I'm staging the installation for maximum installation efficiency, and to feel the differences after each step.

Phase 1: Replace RFTs and OEM style 264 wheels - Michelin Pilot Super Sports (225/255) being installed next Wednesday on Breyton GTS-Rs (18" stock widths, 7.5F 8.5R).

Phase 2: M3 front sway bar - Easy access, easy installation, no adjustments necessary.

Phase 3: M3 front control arms - Bolt-in replacements, nothing difficult to move/remove, just need a 2 wheel alignment.

Phase 4: Suspension - Koni FSDs, BMW PS springs, Dinan rear shock mounts. And a 4 wheel alignment.

Phase 5 (if still unsatisfied): M3 rear subframe bushings.

As for the bump stops, I wasn't aware there were so many options. If I read opvaulet's post correctly, the BMW PS bump stops are actually "borrowed" from the Z8 and E91, so I could just go with whichever is cheaper, or more available.

1fastbmw, I hadn't heard of using the E85 Z4 bump stops before, what was your rationale behind those?

[Revelate]

Originally Posted by timhatimay

I had considered and researched the FSD shocks during my suspension upgrade, but ultimately ended up with the full performance suspension. Unless your absolutely set on the FSD, have you considered the BMW PS shocks instead? They should be properly tuned for the performance springs rates, and on my car have a good mix of performance and road comfort (with more emphasis on performance). I would assume the FSD may be a bit less aggressive than the PS, but that may not necessarily be a bad thing depending on your goals. Utilizing the shorter bump stops and shock mounts will be a help though. I felt they made a big difference in the suspension travel and crashing over large bumps. I really like the Dinan shock mounts on the rear of my car, and they made a big improvement in comfort and consistency. I think there were also some that use E46 (or maybe another older BMW) bump stops as they were shorter, so you may look into that, since the PS stops may be hard to come by without the whole kit. Hope this helps.

Tim

For some reason I have the feeling that the full BMW PS suspension kit is like a v1.1 upgrade, whereas something like the FSD/spring combo would be v2.0. I am really unhappy with the stock suspension for both handling and ride quality, so I'm trying to get away from whatever crack BMW was smoking when they approved the final design. Call it a mental roadblock.

[MastaMind]

Originally Posted by Revelate

I obviously didn't read through enough threads to find others with the same, or similar, configurations. I'm also glad I'm not alone; I thought this was going to be an experiment but it sounds like it's a pretty well known solution for "performance oriented" owners not trying to slam the car on H&Rs or coilovers. I like the lowered look as much as the next guy, but I much prefer the handling improvement without a harsh ride and scraping over everything. My BMW Performance front bumper with CF splitters will thank me.

I have the M3 front control arms and E93 front sway bar on my list already, they are going on for sure. The only part I'm trying to avoid is the rear subframe bushings because of the labor. I don't have the tools, nor the space, nor the confidence to pull off something like that.

I'm staging the installation for maximum installation efficiency, and to feel the differences after each step.

Phase 1: Replace RFTs and OEM style 264 wheels - Michelin Pilot Super Sports (225/255) being installed next Wednesday on Breyton GTS-Rs (18" stock widths, 7.5F 8.5R).

Phase 2: M3 front sway bar - Easy access, easy installation, no adjustments necessary.

Phase 3: M3 front control arms - Bolt-in replacements, nothing difficult to move/remove, just need a 2 wheel alignment.

Phase 4: Suspension - Koni FSDs, BMW PS springs, Dinan rear shock mounts. And a 4 wheel alignment.

Phase 5 (if still unsatisfied): M3 rear subframe bushings.

As for the bump stops, I wasn't aware there were so many options. If I read opvaulet's post correctly, the BMW PS bump stops are actually "borrowed" from the Z8 and E91, so I could just go with whichever is cheaper, or more available.

1fastbmw, I hadn't heard of using the E85 Z4 bump stops before, what was your rationale behind those?

I wouldn't avoid getting the rear subframe bushings installed. Yes, it's expensive if you don't do it yourself, but the end result is worth it. No matter what you do, the rear of the car will not feel planted without them. They truly make a huge difference that's immediately noticeable.

[Bimmer-Bob]

The BMW Performance bump stops are available separately. I almost ordered them but cancelled my order because my Bilstein PSS9's are built with internal bump stops. I don't have the part numbers anymore, but you can get them from the guys at Tischer. Interestingly, I remember the rear bump stops were the same p/n as those found on certain Euro-spec E91 (Touring) models. Strange. I never ran the p/n's for the fronts on RealOEM.

Slight threadjack, but for the guys who paid to have the rear subframe bushings installed, can you share what your costs were? I'd like to do this eventually and would like a ballpark figure to budget for. Thanks.

[timhatimay]

Originally Posted by Revelate

For some reason I have the feeling that the full BMW PS suspension kit is like a v1.1 upgrade, whereas something like the FSD/spring combo would be v2.0. I am really unhappy with the stock suspension for both handling and ride quality, so I'm trying to get away from whatever crack BMW was smoking when they approved the final design. Call it a mental roadblock.

I think they put the crack-pipe down during the PS design. I believe its probably a little more aggressive than the FSD and less aggressive than the yellow for most driving. I could be wrong though. Despite the roundel the PS is quite a significant upgrade, and makes a big difference! Either way I'm sure you'll be happy. The M3 front links are also a great mod, but my suggestion is save up and do it all at once! That way you save some money on the alignment. Plus it will be easier for you to install once you are already deep inside the wheel wells with tools. You won't be able to determine the improvement made solely by each modification, but it will save some time, effort, and money.

I did my mods in a similar fashion, but did the first 2.5 phases together. Eventually I got better tires, so I'll save the extra .5. I think you have a good plan but...Once you do phase 1-2 you will be hooked and looking to install the springs and shocks!

Good luck!

Tim

[ulrichd]

I've been running the Eibach/FSD combo with the M3 front swaybar upgrade for two years and I am very happy with the result. It's a nice even 3/4" drop, not as much as springs alone oddly, with great ride and handling characteristics. I wouldn't use it on the track but it suits my needs perfectly as I only wanted a subtle drop with minimal ride tade-off.

Before that I had FSD shocks paired with H-Sport springs on my 03 Cooper S. I ran that for 5 years.

[GaryS]

Originally Posted by timhatimay

I think they put the crack-pipe down during the PS design. I believe its probably a little more aggressive than the FSD and less aggressive than the yellow for most driving.

It's hard to compare because Yellows are adjustable and FSDs self-adjust. I'm pretty sure Yellows set to medium are firmer than PS dampers. The softest setting might be softer than PS shocks, I'm not sure.

FSDs are very different. They adjust themselves from much softer than Yellows in reaction to bumps and texture to firmer than Yellows in reaction to braking and turns. It seems most people either love them or hate them.

[Hind]

I too am weeks from ordering the FSD/ eibach combo for my car. I have subscribed to this thread, look forward to more posts. I want something with close to the current comfort now, that i can take to autocross on the weekend.

[ulrichd]

Originally Posted by Hind

I too am weeks from ordering the FSD/ eibach combo for my car. I have subscribed to this thread, look forward to more posts. I want something with close to the current comfort now, that i can take to autocross on the weekend.

You won't be able to run in the stock classes with suspension mods. It's been a while for me but I believe that will put you in SP- Street Prepared. If you are going to do this might as well add the e93 front swaybar which will really help turn-in.

[Hind]

Originally Posted by ulrichd

You won't be able to run in the stock classes with suspension mods. It's been a while for me but I believe that will put you in SP- Street Prepared. If you are going to do this might as well add the e93 front swaybar which will really help turn-in.

I dont really care about my class, I just go for fun... I have an e93 front sway now, and its great!

[timhatimay]

Shocks and front sway bar are legal instock class. I believe with springs you would then be STU unless you have other modifications.

[Revelate]

There are quite a few posts on this thread from owners using FSDs. I need your help. I'm struggling with the following:

The Interwebs (mainly BMW, VW and Mazda forums) contain anecdotal evidence that the spring perch on the front FSD shocks is placed so that the OE ride height, if used with stock springs, is actually higher by 1/4" to 1/2". I've also seen pictures of 135 owners with FSDs and PS springs that appear to have no lowering effect over a standard M-Sport. This also suggests that the ~10mm lowering of the PS springs is effectively keeping the right height stock by offsetting the FSD perch.

My M-Sport suspension is just a little "baha" for my tastes, but I am not trying to lower the car significantly. I don't want tucked wheels, just no gap. 1/2" to 5/8" would be perfect, but I'm worried that I will need more lowering from the springs to offset the FSDs and still be 1/2" lower than where I started.

Would anyone care to measure their ride height with FSDs and comment on what springs you're running as well? Measurement should be taken from the center of the wheel cap to the edge of the fender to avoid any variations for ground level, wheel/tire size, etc.

Here is mine for reference (stock M-Sport)

F/L - 13 5/8" (34.6cm)
F/R - 13 5/8" (34.6cm)
R/L - 13 5/8" (34.6cm)
R/R - 13 7/8" (35.2cm)

[thez99]

I wouldnt mind hearing about this as well, however wasnt it touched on earlier that the FSD's are specifically made for our car's stock ride height and if you add a drop with the fsd's there could be issues? I dont remember the exact problems that came from it, something about the bumpstops bottoming out or something

[Revelate]

Originally Posted by thez99

I wouldnt mind hearing about this as well, however wasnt it touched on earlier that the FSD's are specifically made for our car's stock ride height and if you add a drop with the fsd's there could be issues? I dont remember the exact problems that came from it, something about the bumpstops bottoming out or something

I spoke with two Koni techs who basically said the FSD shocks don't care what the ride height is, as long as they don't regularly hit the bump stops under normal driving conditions, as this action will trigger the "soft" setting inadvertently.

Their warning is based on the assumption that a 1 series owner may replace the shocks and nothing else. With soft springs and the large OEM bump stops, that could pose a problem for the FSDs. My intent is to use the Z8 bump stops which are much shorter, and the Dinan rear shock tower mounts for extra travel. My expectation is that those improvements will allow me to get a ~1/2" drop without negatively impacting the FSD operation.

My real concern now is that I may not get enough lowering out of the PS springs if the FSDs actually increase ride height. Barring any new information that challenges my knowledge and assumptions, I'm going to try the Eibach springs... they're only $250. If it doesn't meet my expectations, I can swap them out for the PS springs with a minimum investment loss by selling the Eibach springs in "barely used condition".

Still interested in seeing other's measurements (the car that is ).

[thez99]

Originally Posted by Revelate

I spoke with two Koni techs who basically said the FSD shocks don't care what the ride height is, as long as they don't regularly hit the bump stops under normal driving conditions, as this action will trigger the "soft" setting inadvertently.

Their warning is based on the assumption that a 1 series owner may replace the shocks and nothing else. With soft springs and the large OEM bump stops, that could pose a problem for the FSDs. My intent is to use the Z8 bump stops which are much shorter, and the Dinan rear shock tower mounts for extra travel. My expectation is that those improvements will allow me to get a ~1/2" drop without negatively impacting the FSD operation.

My real concern now is that I may not get enough lowering out of the PS springs if the FSDs actually increase ride height. Barring any new information that challenges my knowledge and assumptions, I'm going to try the Eibach springs... they're only $250. If it doesn't meet my expectations, I can swap them out for the PS springs with a minimum investment loss by selling the Eibach springs in "barely used condition".

Still interested in seeing other's measurements (the car that is ).

So the only way to make it so they dont hit the bump stops often is to replace yours with a z8? Plus, wtf do I get those??

Also, I wouldnt recommend the eibachs for this car, they rake in the front. I am considering the H&R oe sports. Should lower the car about 1/3-.5" with the fsd's im figuring, and its a consistent drop.

[Hind]

Originally Posted by thez99

So the only way to make it so they dont hit the bump stops often is to replace yours with a z8? Plus, wtf do I get those??

Also, I wouldnt recommend the eibachs for this car, they rake in the front. I am considering the H&R oe sports. Should lower the car about 1/3-.5" with the fsd's im figuring, and its a consistent drop.

Ive never seen rake from the eibachs on a 1series, the spring drop is even on all 4.

I've have seen rake on many H&R spring setups. This is the reason I plan on getting Eibach.

[thez99]

Originally Posted by Hind

Ive never seen rake from the eibachs on a 1series, the spring drop is even on all 4.

I've have seen rake on many H&R spring setups. This is the reason I plan on getting Eibach.

Um, well go search around a bit here, see what some of the ppl with eibachs are saying bout their setup. The front sits atleast .3" lower than the rear, no good in my book. And no, the H&R oe sports are a level .75" front and back.