star69me

I have a 07 550i non sport model sitting on 20's staggered 245 35 20 and 275 30 20 with stock struts and springs. And I want to bring it down a lil more and I read a thread about these fsd self damping struts that adjust accordingly to the road condition, and with my base model 550i didn't come with that sport suspension or a way to adjust the ride so I'm trying to get how I can get to. Does anyone know a where I can get the best deal or any comments on what I'm trying to do. Oh and I also read they go good with the eibach pro kit.

jtbgonesailing

KONI Sport and FSD (Frequency Selective Damping)
During a typical mile of travel down the road, the damper will move in (compression) and out (rebound) millions of times. Break that mile into one second of travel, and the number of times the damper moves (stroke) defines the operating frequency (Hertz, Hz). Controlling body roll entering a corner induces relatively few strokes of the damper (low frequency), while chattering over broken pavement at highway speed results in a much higher quantity (high frequency) of very short strokes. Knowing this, damper frequency can also be used to tune handling and ride quality. Vehicle body roll control needed to aid handling occurs at a frequency of around 1Hz. Ride impact harshness is felt when damper frequency reaches approximately 10Hz.

Hit a bump without dampers, and the suspension would continue to bounce up and down uncontrollably like a bobble head doll. The damper's job is to reduce the size and/or speed of the suspension movement, preventing the never-ending bobble head scenario. We've all seen that older car going down a smooth highway with one of the rear tires visibly vibrating up and down very rapidly, which is caused by a worn-out damper that is no longer controlling the movement of the suspension. The lack of damper control allows the suspension to move uncontrolled.

The piston moving back and forth through the oil inside the damper creates the resistance needed to control (dampen) the suspension movement. How much resistance (force) develops for a given movement is determined by internal valves that control the flow of oil. Based on the force, the valves open or close to self adjust to each bump or any vehicle body roll. All dampers do this; but KONI's FSD units add a second valve system that responds to the damper's operating frequency, allowing ride and handling to be tuned more independently than with conventional dampers.

KONI's design theory for tuning dampers uses the compression (in) force to dictate the amount of axle movement and is directly linked to handling like steering response, road holding, etc. The rebound (out) force is used to control body movements (side-to-side body roll and/or pitch fore and aft) and is also directly linked to ride comfort.

KONI's traditional user-adjustable yellow Sport dampers for most applications have a fixed setting for the compression rate, but allow the user to manually adjust the amount of rebound control to tune the balance between ride comfort and handling. The FSD dampers also have a fixed compression setting, but instead of allowing the user to manually adjust the rebound, the internals of the FSD dampers automatically adjust the rate and shape of the force curve (when plotted on a graph) on the fly, responding immediately to the frequency of the damper's movement. The unique secondary valve used inside the FSD units is engineered to provide large amounts of force to control vehicle body movement at relatively low frequencies, while generating less force at the higher frequencies that affect ride quality.

Why don't you start at: tirerack.com

star69me

Ok for dummies like me this is what I want right.

johnbennett103

I had Koni FSD's on my 545, and while I did like them, they had excessive travel, and I would bottom out once in a while with mild spacers. I changed to BC coilovers with Swift springs, and now I am really happy. Spring travel is greatly reduced, and the handling is amazing with a slightly stiffer ride than stock sport springs. Go coilover, you wont regret it.

star69me

So with your setup do you feel alot of bumps or a ruff ride driving everyday or hwy driving. I go to Orlando and daytona beach alot. Will it affect my 20's? How low is the drop with these. How much did it cost if you don't mind me asking and where did you get them.
07 550i

star69me

So with your setup do you feel alot of bumps or a ruff ride driving everyday or hwy driving. I go to Orlando and daytona beach alot. Will it affect my 20's? How low is the drop with these. How much did it cost if you don't mind me asking and where did you get them.
07 550i

star69me

Hey what does "excessive travel" mean in regards to the FSD setup? And what does "spring travel" mean? Also I looked for your set up. Can the shocks be bought separate from the springs bc when I called they said the BC coilovers comes as a set. Is that how you got yours and got the springs separate? I just trying to get it right the first time. Thanks man

07 550i

johnbennett103

I would bottom out when my car was full of passengers. I think it was mainly due to my wheel spacers, but I didn't like it.

Errowen

I installed FSD's in my 2008 535i (now retired) at 80K miles, on stock springs. The OEM shocks were still functioning perfectly well, but I was seduced by the FSD science and various blog entries championing them, so I sprung for the kit (pardon pun) and had my BMW dealer install them.

The change in ride and handling, before and after, was difficult to detect in most driving situations. I did notice the FSD's were marginally "hoppier" over successions of ripples. One situation in which the difference was more apparent was long sweeping corners, like the freeway on-ramp I use every workday, and know intimately. The frequency--dependent oil passage is supposed to stay closed in steady cornering, providing greater resistance to lean. I did notice a bit less lean in the beginning of the on-ramp curve. By the middle of the curve, however, there was more lean with the FSD's than with the OEM shocks and I had to back off my usual throttle position. -- slighly embarassing and definitely unwelcome.

So overall, I think that there was a slight performance decrease with the FSD's over OEM. I certainly never told my wife what I spent on installing them.

star69me

Well that good to know. But a few others say similar stuff but they also said the didn't get the eibach pro kit springs that's is the recommended combo at first bc the felt the stock springs were good enough. But they changed the springs to the eibach now they swear by this great handling


QUOTE=Errowen;1576847]I installed FSD's in my 2008 535i (now retired) at 80K miles, on stock springs. The OEM shocks were still functioning perfectly well, but I was seduced by the FSD science and various blog entries championing them, so I sprung for the kit (pardon pun) and had my BMW dealer install them.

The change in ride and handling, before and after, was difficult to detect in most driving situations. I did notice the FSD's were marginally "hoppier" over successions of ripples. One situation in which the difference was more apparent was long sweeping corners, like the freeway on-ramp I use every workday, and know intimately. The frequency--dependent oil passage is supposed to stay closed in steady cornering, providing greater resistance to lean. I did notice a bit less lean in the beginning of the on-ramp curve. By the middle of the curve, however, there was more lean with the FSD's than with the OEM shocks and I had to back off my usual throttle position. -- slighly embarassing and definitely unwelcome.

So overall, I think that there was a slight performance decrease with the FSD's over OEM. I certainly never told my wife what I spent on installing them.[/QUOTE]