Anyone tried the new Koni FSD struts?

[sgt brad]

I just installed them on my 996 with eibach springs and sways. The car is about an inch lower but feels almost the same as before as far as dynamics go. It's as if the struts are slightly softer than stock and the springs progressively firmer. If you want a better ride height, but want the car to ride essentially like stock then I would recommend them. There was no transformation of the car like in my boxster when I switched to biksteins and hr bars and springs. I hope that helped.

[911monty]

Originally Posted by sgt brad

I just installed them on my 996 with eibach springs and sways. The car is about an inch lower but feels almost the same as before as far as dynamics go. It's as if the struts are slightly softer than stock and the springs progressively firmer. If you want a better ride height, but want the car to ride essentially like stock then I would recommend them. There was no transformation of the car like in my boxster when I switched to biksteins and hr bars and springs. I hope that helped.

Thanks! All input is appreciated. What was your decision driver? I see these FSDs are highly thought of on the Renlist. Also your comments tend to mirror the Tire Rack test concerning the slalom, Where they initially thought the car too soft and comfy until they timed them and they outperformed the Sport on the soft setting. I think the explanation was the FSD maintained tire contact much better.

[jakeru]

Here is the shock dyno plot for my two rear 986 Koni sports. (I believe set to minimum rebound setting.)


The purpose of the dyno run (performed by Koni) was to verify that both sides matched before they sent my repalcements. This was the replacement set Koni shipped which I still need to install in the car. The set I initially got and returned were quite uneven in low speed compression damping (even without a shock dyno, it was blatantly obvious to me that one side compressed about 3x as fast as the other given an approximately equal force... which is definitely not the hot ticket as on konis only the rebound adjusts so you'd be stuck with screwed up shock valving and poor handling characteristics!)

I'd be interested to hear what the above plots looks like (in terms of the "kinked" shape, etc) for someone really into suspension tuning who is really up in interpreting these things. (Although comparing against similar Koni FSD plots for the 986 rear, if they could be obtained by anyone else somehow, would be very interesting to see!)

I take my suspension setup seriously as I have an interest in autocross racing and any serious competitor there knows the importance of good shocks. (In stock class, shocks are one of the few things that are allowed to be modified.) I trophied at SCCA Solo nationals a few years ago in a "lowly" VW. (But it was rocking custom-valved, double adjustable Konis front and rear.) I hate to say it but the lowly VW can still run circles around my 986 at lower speeds. (At higher speed, the aerodynamics of course favor the Boxster.) So I've got some more work to do on my fairly high-mileage 986 to bring it up to my performance expectations for what a Porsche should do. (The front suspension rebuild was already a huge improvement, but I'm really looking forward to getting the rear Koni spots on there.) For many years, I've admired watching Boxsters with the mesmerizing and amazingly neutral looking handling dynamics dodging autocross course cones at speed.

[911monty]

Jakeru looks like a very well matched set of shocks. I'm certainly no shock expert, those guys are magicians, anyone that can design a suspension for a stadium truck that can launch 20 feet in the air and land on level ground like a butterfly with sore feet really knows their stuff. What I do see from the chart is that these shocks are very linear. The compression is linear in the slow speed until the transition to high speed where it firms up just prior to valve pack opening and is divergent in the high speed circuit. I see what you mean by not being as divergent as one would expect. In fact I would have expected the initial response curve to be much steeper. These are definitely on the full soft setting based on the rebound slope (no knee). It would have been really useful if they had made a few plots with a couple adjustments to the firmness setting. Guess that's for the experts.

[sgt brad]

I went the fsd route because the bilsteins and hr setup on the boxster was too stiff for my wife and lowered the the car too much. I also don't track my car so I was not interested in pss9 and the additional expense. I had Komi sports on my old 914 and had hoped they would be a good choice.

I appear to be a bit of a guinea pig on the 996 as most renlisters running fsd are 993s. My feelings are that the eibach and fsd combo is a little soft. But then again it still rides well and doesn't crash over rough roads. It certainly doesn't handle worse than stock, the ride height looks much better, and my wife still rides with me!

[911monty]

Originally Posted by sgt brad

I went the fsd route because the bilsteins and hr setup on the boxster was too stiff for my wife and lowered the the car too much. I also don't track my car so I was not interested in pss9 and the additional expense. I had Komi sports on my old 914 and had hoped they would be a good choice.

I appear to be a bit of a guinea pig on the 996 as most renlisters running fsd are 993s. My feelings are that the eibach and fsd combo is a little soft. But then again it still rides well and doesn't crash over rough roads. It certainly doesn't handle worse than stock, the ride height looks much better, and my wife still rides with me!

Thanks for that feedback. Sounds like what I'm looking for.

[911monty]

Well Koni didn't come through with Dyno results. They did send the following. No clue what it means though..

Monty,
Thank you for contacting us here at KONI NA. Unfortunately, I do not have Force v. Velocity graphs readily available for each of the dampers offered. I can however provide the factory specs at which the shock are tested to for quality control.

Tested at .33m/sec (13in/sec)

Front FSD- 8745 1328
Compression – 350N
Rebound – 1350N

Rear FSD – 8745 1329
Compression – 900N
Rebound – 1650N

Sports
Front – 8741 1573sport
Compression – 500N
Rebound – 1250N

Rear – 8740 1574sport
Compression – 1050N
Rebound – 1550N




Mason O’Hara
Technical Sales Represenative
KONI - an ITT company

1961A International Way Hebron, KY 41048
(859) 586-4100, (859) 488-0324 mason.ohara@itt.com
KONI NA | Home www.koniracing.com www.konirv.com

[jakeru]

These specs don't show how digressive the shocks are, but basically what I'm getting is that the Koni FSDs are lighter in compression (especially at front) and firmer in rebound than the sports are when set at full soft setting (which is where Koni measures their specs, as I understand it). If the sports were adjusted firmer, I expect their rebound rate would first match, and then exceed, the FSD's rebound damping.

The specs Koni provided for the rear sports match the dyno plots I posted for mine - look at the far right end of the graph (highest speed measured is where Koni checks their specs, apparently).

[911monty]

And that all makes sense. Since this test is at the high frequency 13ft/sec, this is where the valve on the FSD is wide open and providing the least resistance. This is what would be happening over say a speed bump. This allows the spring to compress while transferring the least amount of upward force/lift to the chassis. The info that is missing is what is the force at the low frequency setting? I think I read somewhere the FSD is actually stiffer than the Sport (full soft) in the low frequency travel.

[snotrag]

Seeing as this thread comes up top of Google when you search for "Boxster Koni FSD", I thought I'd add that in the end I went ahead and ordered them, in the post currently. I'llet you know how I get on once they are fitted.

[911monty]

Originally Posted by snotrag

Seeing as this thread comes up top of Google when you search for "Boxster Koni FSD", I thought I'd add that in the end I went ahead and ordered them, in the post currently. I'llet you know how I get on once they are fitted.

Too funny! I pulled this up yesterday thinking about closing or at least adding to the thread I started, but felt I wanted a little more time to evaluate. I installed these FSDs ~1k ago. I just had the alignment done. Unfortunately a comparison to the stock system is limited due to my stock driver side shock was shot. Good news is all other suspension components were in good shape so no major changes there. What I can say is I am extremely happy with them. Broken pavement no longer jars the suspension, bumps and potholes are now soaked up and have a soft and "plush" feel. Turn entry is immediate and much firmer with hardly almost no body roll. Uneven pavement in the corner no longer unsettles the car, the failed front shock could have contributed to this though. Bottom line is if you're a dedicated racer and have to have your ski boots buckled so tight they hurt, then these are not for you. However if you want increased comfort and are tired of gritting your teeth when driving onto a bridge but don't want to give up any handling, then I wholeheartedly recommend these shocks. I am impressed so far.

edit: I have a close friend that has a 2001 S with 107k that is meticulous with maint. He has the Bilstein sports w/ HR springs. I have driven tis car multiple times. My feeling is the FSDs give up very little if any to the Sports handling wise but I feel are actually superior to the Sports on turn entry. Remember this is the low speed circuit where the FSDs have the firmer valving.

Details are: 98 base w/M030 sways front and rear. Michelin Pilot SS. Alignment specs: Front- Camber 0.3 deg, Caster 7.7, Toe 0.03 in. Rear- Camber -1.7 Toe 0.10 in

[snotrag]

That's very reassuring to hear! I also have all new coffin arms, tuning forks, top mounts etc to go on at the same time so I'm expecting a dramatic change - it's currently feeling very worn out!

[911monty]

Originally Posted by snotrag

That's very reassuring to hear! I also have all new coffin arms, tuning forks, top mounts etc to go on at the same time so I'm expecting a dramatic change - it's currently feeling very worn out!

I had replaced my rear upper control arms (tuning forks) several thousand miles ago, I did replace new Bump stops, bearing plates and boots. My lower control arms were good. To do the fronts I only removed the calipers, rotors and top strut mount. Rears I disconnected the control arms at the camber and toe adjustment points. As an FYI the paint on the strut body was so thick on the rear they would not slide into the hub carrier. On reassembly I loosely assembled the control arms then carefully jacked the hub carrier up onto the strut.
Will be interesting to hear your thoughts! Gives us older car owners the ability to have a similar effect to the expensive PASM on the later cars. I really like mine. Now if StevedOX would weigh in with the track perspective......