[DWR]

Originally Posted by Mik325tds

Your point about unsprung masses is important though. Even the phone on the seat might excite differently then my 150 pounds of weight in the seat. I'm slowly coming to the conclusion that the benefit of the new shocks is not in the amplitude of acceleration of sprung masses rather than the sound it makes when I drive over harsh bumps.

Good observation. Typically, it is lack of control/damping in unsprung weight that makes noise.

[Mik325tds]

Originally Posted by TDIwyse

This is starting to look interesting.

Curious, if you're sampling at 1kHz, how many sample points do you have for one "bump"? To get to the frequencies where the FSD is supposed to be doing its "stuff" it looks like you would need to be able to resolve frequencies below 10 Hz.

http://www.koni.com/car-racing/techn...fsd-principlel

Indeed. Looking at the data more closely it appears the time stamps are not uniformly continuous. Many times you get two per millisecond but sometimes there's nothing for up to 40 ms. The bump from 74.15 to 74.3 has 33 samples, which equates to a sample rate of 220 Hz or an average distance of 4.5ms between samples.
Looks like we don't have enough samples to resolve 10Hz in a FFT using 32 samples per window.

Also, for my data analysis I have used only one column for time and then tried to line up the data of the second log with the first one. Now, with the time being not equidistant I rendered the second data set unusable. Start over.

[Persian Whisperjet]

After reading the thought views here and considering the lousy DC streets, I'm heading for for a set of Koni FSDs. The good people at Tuner Motorsports say the kit with springs will lower the car (base sedan) 25-30mm, but I can also just order the shocks for no lowering. They also advise they do not offer the shock/strut mount kits.

Question:

- If roads are iffy how much am I giving away by lowering the car 25-30mm?

- How important is the shock/strut mount kit?

[Yozh]

Couple of things for ya.
If your roads are "iffy" you may wish to reconsider lowering the car for a simple reason not to be bottoming out or hitting things. The question is also what is the spring rate of the new spring set you are considering. From my research when I was looking around, a lot of manufacturers have not maintained proper ratio in rates between from to rear.

On the mount kit question, all depends on what is your mileage. Most people choose to replace some components as you are already taking things apart and it's easy to do. At the very least a front upper mount would be the recommended. You can also upgrade from the spongy factory rear upper strut mounts to Monroe.

[Thecastle]

I wouldn't lower it, reducing suspension travel is rarely a way to improve ride quality.

When I did my koni fsd install, I replaced all of my mounts, strut bearings, and on he front the bump stops. May as well as the labor is the same to replace them now. Replacing them later requires removing the suspension. It's a lot of labor to remove the front struts again to replace the strut bearings. I had 35k miles on my car when I redid the suspension. I had the sports suspension on my car, and the original shocks did a bad job of handling sharp impacts, and felt way under damped when hitting big dips at high speeds like road/bridge transitions. You'd hit it and the car would bounce up and down a couple of times after the hit. The koni fsd eliminated nearly all this bad behavior. I think the fsd's ride very well, and have better damping than the stock, but probably could have gone a bit further,

On my rears I'm swapping to the Monroe mounts. I went with stock but still find the rear to be bouncy on big hits. Swapping the rear upper strut mounts is actually fairly easy, and it will allow me to check the health of the rear shocks. I've got about 16k miles on mine.

Would also recommend replacing the rear sub frame bushings too on these cars, they weave out pretty quick.

[Persian Whisperjet]

Can anyone share the PN for the Monroe upper strut mount or suggest a source? Thanks.

[gavronm]

Originally Posted by Persian Whisperjet

Can anyone share the PN for the Monroe upper strut mount or suggest a source? Thanks.

http://www.e90post.com/forums/showthread.php?t=1145344

[9mmkungfu]

Doing some of these next week - FSDs with Monroe mounts and new front strut mounts/bearings.

[Persian Whisperjet]

Originally Posted by 9mmkungfu

Doing some of these next week - FSDs with Monroe mounts and new front strut mounts/bearings.

That is exactly what I got minus the new front strut mounts. I drive down two blocks of cobblestone streets in Georgetown every day picking up my daughter at school and the FSDs are unflappable.

[9mmkungfu]

Originally Posted by Persian Whisperjet

That is exactly what I got minus the new front strut mounts. I drive down two blocks of cobblestone streets in Georgetown every day picking up my daughter at school and the FSDs are unflappable.

I am familiar with those streets, lol. Good deal. I'm looking for that balance of comfort and performance and it seems like these have made most of you all pretty happy.

[robnitro]

How have the fsd been in terms of paint? A while back i recall koni had issues with paint peeling off, leaving rust to build up.

[9mmkungfu]

Originally Posted by robnitro

How have the fsd been in terms of paint? A while back i recall koni had issues with paint peeling off, leaving rust to build up.

I think this issue still exists but the others that have had them on for a while now would know better.

I read a post where a member sprayed on two coats of clear and it held up well. I plan to do the same.

[TDIwyse]

Originally Posted by 9mmkungfu

I think this issue still exists but the others that have had them on for a while now would know better....

Over 2 years and 2 winters on salted midwest roads on my FSD's and the paint on mine are good and I do not see rusting.

[Asonchadwick]

I have the sport suspension amd get headlight shake on bad roads, i bought me the bilstien b6 10 ways and just putting then on the rear was better still working in the fronts though.

[Adieu]

Originally Posted by Tucson335d

I have the sport suspension amd get headlight shake on bad roads, i bought me the bilstien b6 10 ways and just putting then on the rear was better still working in the fronts though.

Headight shake CAN also be from the "self-levelling sensor" beng loose (looks like a tiny miniature of a sway bar with electronics atrached to your driverr side front lower control arm)

[Asonchadwick]

Originally Posted by Adieu

Headight shake CAN also be from the "self-levelling sensor" beng loose (looks like a tiny miniature of a sway bar with electronics atrached to your driverr side front lower control arm)

Thank you, the rod is securely attached, I wish I could video it but it doesn't come out on camera very well to see.

[Adieu]

Are you sure your driver side front suspension has nothing loose? Perhaps something not torqued down, perhaps a blown ball joint or bushing on the LCA...

Because if your headlights shake w/ self levelling and the sensor isn't loose, that essentially means your driver's side LCA is shaking