[NiNeTyOne]

Originally Posted by Speleochig

The "old" Koni FSDs have somewhere between 5 and 10k miles, which can hardly be described as old in their normal lifespan. My question was not concerning the old and new, as I don't care since they're both quite new. My question is about the difference between FSDs and Sports. How different are they really?

Anyway, I'll probably get the Sports for the front, just not rushing to do it unless it's a safety issue.

Totally different damper circuit design. The sports are essentially 50 year old tech, the FSD was designed in conjunction with MacLaren's F1 team and it's a very modern design.

Mine now have 20k+ miles on them and they remain stellar matched with Eibach Pro springs.

More here

[dleccord]

Originally Posted by mweisdorfer

Go with the Koni Yellow, and up your profile of tire by 5mm. With the Koni Yellow, you can adjust the stiffness etc.

But increasing stiffness will cause micro bounce, no?

[NiNeTyOne]

Originally Posted by dleccord

But increasing stiffness will cause micro bounce, no?

Stiff does not equate with better. My fastest times at Daytona, high 1:53's, have been in very compliant cars. It's not about stiff, it's about contact patch.

[mweisdorfer]

Originally Posted by dleccord

But increasing stiffness will cause micro bounce, no?

Perhaps. That's the magic of the adjustable shock. You can move it from soft to ultra stiff. Your choice

[feuer]

Originally Posted by NiNeTyOne

Stiff does not equate with better. My fastest times at Daytona, high 1:53's, have been in very compliant cars. It's not about stiff, it's about contact patch.

For stiff suspension you need stickier tires. If your tires can provide sufficient mechanical grip you are better off with softer suspension.

[The Nightman]

Originally Posted by NiNeTyOne

Your experience sounds like you under sprung the dampers. If you get the correct spring rates, and also get the links on the sways correct this should not be an issue.

In Seattle we live in a city wide construction zone and our streets are worse than a bad neighborhood in Newark (I used to live in Manhattan). Properly sprung and properly matched with the correct durometer bumps, they are great dampers.

Suspension is a system, too few people treat it that way.

Thanks for the feedback. I'm in the market for new dampers to match my Sport D5/D4 springs and while I was initially set on the Bilstein B4s, the FSDs seem to be the way to go. The road conditions here aren't great either and I've had poor experiences with stiffer cupkits on my prior cars. It does come at a premium, however, as a set of B4s cost $275 compared to $630 for the FSDs.

The Sport springs' spring rate (145/460) is very similar to the Eibach Pro Kit (148/456) so the FSDs should be a good match? Which bumpstops are you running?

Spring rates: http://www.e90post.com/forums/showthread.php?t=235797

[NiNeTyOne]

Originally Posted by mweisdorfer

Perhaps. That's the magic of the adjustable shock. You can move it from soft to ultra stiff. Your choice

Originally Posted by feuer

For stiff suspension you need stickier tires. If your tires can provide sufficient mechanical grip you are better off with softer suspension.

These are both over simplifications. Adjustable shocks like the ones you are discussing here are extremely limited when you don't have a bypass circuit like DFV or FSD. The main problem is you really need to have both high speed and low speed damping for both rebound and compression, but that comes with a big cost. Single adjustable mototube dampers are, by design, a big compromise.

Both DFV and FSD were developed to address this issue without needing to spend $8000+ on dampers, and require complex setup by the end user. Did it succeed? Well, I would say Ohlins did a better job than Koni, but they had different objectives, and price points. For the target application the FSD's are very good with the right springs, and I would argue they need more rate than your OE or even sport springs deliver.

As for the other comment, you can't just slap sticky tires on an over damped and under sprung car and get better performance. In fact, I would ask; sticky by what measure? My Michelin Cup N1 and N2 slicks are harder compound than any street car will ever see or need. Hell, sidewall stiffness is a bigger factor than "stickiness." So are bump stops and how you tune them for initial engagement. With a street car these factors can be all over the map depending on what tyres you chose. Tyre pressure is also a MAJOR factor.

My experience on track is too stiff is usually an indication of an over damped and under sprung car. On so many street cars I've driven that's paired with oversized swaybars which further complicate and mask the real handling issues.

I often dial dampers to full soft and disconnect swaybars to establish a baseline, spring rate being my first consideration when setting up a car.

My fastest ever lap at Daytona was in a car damped softer than I'd ever had it before, with slightly higher rate springs than I would have expected, and since then I have always erred towards a under damping and nailing spring rate first and foremost. The tires wore far better, I had more lateral grip, and the corner speeds came right up by more than a couple kph, which was a huge deal. The speeds I was able to carry out of turn 6 and through 10/11 were the highest I'd ever done, which translates into more speed for the next 6000 feet out of T6, and 6800 feet out of T11. If you can carry a couple kph more off the corner in just those two corners you obliterate previous lap times.

Stiff as it has been characterized, is not fast.

[NiNeTyOne]

Originally Posted by freedomfries

Thanks for the feedback. I'm in the market for new dampers to match my Sport D5/D4 springs and while I was initially set on the Bilstein B4s, the FSDs seem to be the way to go. The road conditions here aren't great either and I've had poor experiences with stiffer cupkits on my prior cars. It does come at a premium, however, as a set of B4s cost $275 compared to $630 for the FSDs.

The Sport springs' spring rate (145/460) is very similar to the Eibach Pro Kit (148/456) so the FSDs should be a good match? Which bumpstops are you running?

Spring rates: http://www.e90post.com/forums/showthread.php?t=235797

All these springs are progressive so it's hard to say what the rate REALLY is. That's likely effective rate. It's one of the reasons I like the DFV over FSD, you can go to ERS springs and dial that much more precisely. But on xDrive your options are limited so...

I have the Eibach Pro springs with the FSD's, as does Dan. He's RWD, and I am xDrive.

You need bumps set up to engage after about .55-.6" of compression and very progressive engagement. If you put a linear potentiometer on your dampers and measure the travel, you'd be surprised how narrow the range of motion is under normal driving. I've forgotten which I have, but I'd like earlier engagement on the bumps as I have mentioned in the past. Koni makes shims that are 2.5mm thick for tuning bump stop engagement, you can get them from PSI.

Don't forget to get yourself longer end links as well. Despite not being noted as a requirement, they make a big difference in the swaybar's initial rate.

You want that to be correct.

Originally Posted by NiNeTyOne

Your experience sounds like you under sprung the dampers. If you get the correct spring rates, and also get the links on the sways correct this should not be an issue.

This makes no sense...how can you "under spring" the damper when the dampers themselves are listed as OE replacements? In Koni sales literature they specify Pro-kit springs can be paired with these dampers as well, but even those have the same spring rates as stock.

Are you running these on some top secret/higher sprung pro-kits that no one else knows about?

Also, have any experience with other suspension setups on this platform by chance to compare/contrast? I respect your knowledge/experience with other platforms on the track, but not exactly apples-to-apples when considering the topic of the thread in question.

Originally Posted by NiNeTyOne

you can't just slap sticky tires on an over damped and under sprung car and get better performance.

Even a Nissan Leaf can hit almost ~1G on the skidpad with just a swap to race tires:
https://www.caranddriver.com/feature...-a-911-feature

You can't tell me that wouldn't provide "better performance" in every conceivable metric on a performance scale; over damped, under sprung, or otherwise.

[feuer]

Originally Posted by NiNeTyOne

As for the other comment, you can't just slap sticky tires on an over damped and under sprung car and get better performance.

Originally Posted by FCobra94

Even a Nissan Leaf can hit almost ~1G on the skidpad with just a swap to race tires:
https://www.caranddriver.com/feature...-a-911-feature

You can't tell me that wouldn't provide "better performance" in every conceivable metric on a performance scale; over damped, under sprung, or otherwise.

That is what I meant. In Auto X they have official classes that allow semi-slick or slick tires with completely OEM suspension in competition. True, side wall stiffness, tire pressure, tire heat are also factors but if tire is not able to adhere to pavement due to inappropriately setup suspension none of those are much relevant. Don't forget alignment settings.....

[Dan Bilzerian]

Originally Posted by feuer

Don't forget alignment settings.....

Lol and we all know you do your own alignments!

[NiNeTyOne]

Originally Posted by FCobra94

This makes no sense...how can you "under spring" the damper when the dampers themselves are listed as OE replacements? In Koni sales literature they specify Pro-kit springs can be paired with these dampers as well, but even those have the same spring rates as stock.

Are you running these on some top secret/higher sprung pro-kits that no one else knows about?

Also, have any experience with other suspension setups on this platform by chance to compare/contrast? I respect your knowledge/experience with other platforms on the track, but not exactly apples-to-apples when considering the topic of the thread in question.

Why be a douche instead of just asking the question?

No.

If you put them on a dyno, the damping rates are slightly higher than the OE damper, so by using the pro, or the OE springs, they are slightly under sprung.

[NiNeTyOne]

Originally Posted by FCobra94

Even a Nissan Leaf can hit almost ~1G on the skidpad with just a swap to race tires:
https://www.caranddriver.com/feature...-a-911-feature

You can't tell me that wouldn't provide "better performance" in every conceivable metric on a performance scale; over damped, under sprung, or otherwise.

Do whatever you want to your car on a skidpad, that's not the street (or the track for that matter). On a skidpad you're fully on the bump stops dude.

Come down to Daytona and flip any lap time under 1:59 dead and I'll start listening to you rant. Shave off another 5 seconds a lap and you'll be near my average time on a clear track. Maybe then I might actually care about your opinion.

[DrRobert]

Now who’s being a douche?

[Cloud9blue]

Originally Posted by NiNeTyOne

These are both over simplifications. Adjustable shocks like the ones you are discussing here are extremely limited when you don't have a bypass circuit like DFV or FSD. The main problem is you really need to have both high speed and low speed damping for both rebound and compression, but that comes with a big cost. Single adjustable mototube dampers are, by design, a big compromise.

Both DFV and FSD were developed to address this issue without needing to spend $8000+ on dampers, and require complex setup by the end user. Did it succeed? Well, I would say Ohlins did a better job than Koni, but they had different objectives, and price points. For the target application the FSD's are very good with the right springs, and I would argue they need more rate than your OE or even sport springs deliver.

As for the other comment, you can't just slap sticky tires on an over damped and under sprung car and get better performance. In fact, I would ask; sticky by what measure? My Michelin Cup N1 and N2 slicks are harder compound than any street car will ever see or need. Hell, sidewall stiffness is a bigger factor than "stickiness." So are bump stops and how you tune them for initial engagement. With a street car these factors can be all over the map depending on what tyres you chose. Tyre pressure is also a MAJOR factor.

My experience on track is too stiff is usually an indication of an over damped and under sprung car. On so many street cars I've driven that's paired with oversized swaybars which further complicate and mask the real handling issues.

I often dial dampers to full soft and disconnect swaybars to establish a baseline, spring rate being my first consideration when setting up a car.

My fastest ever lap at Daytona was in a car damped softer than I'd ever had it before, with slightly higher rate springs than I would have expected, and since then I have always erred towards a under damping and nailing spring rate first and foremost. The tires wore far better, I had more lateral grip, and the corner speeds came right up by more than a couple kph, which was a huge deal. The speeds I was able to carry out of turn 6 and through 10/11 were the highest I'd ever done, which translates into more speed for the next 6000 feet out of T6, and 6800 feet out of T11. If you can carry a couple kph more off the corner in just those two corners you obliterate previous lap times.

Stiff as it has been characterized, is not fast.

DFV, FSD... whatever the marketing ppl call it these days... they are just shocks with digressive valve...

anyway, there are a lot more to suspension setup than just spring and damping rate. With a macpherson strut front end like ours, a higher spring rate might reduce the suspension compression on the outer tires, and retain a more favorable camber angle and tire contact size.

[NiNeTyOne]

Originally Posted by Cloud9blue

anyway, there are a lot more to suspension setup than just spring and damping rate.

Yes, but that's where it starts. I've only been doing this for 20 odd years, but I'm not going to take 300 pages to explain how to setup a car here.

We could go into all sorts of things from how to shim the bumps to how setup is an evolutionary process where you tweak everything from rake to tire pressures to preload, etc.. How many people are running thermal sensors on the strut bodies so they know when the data they are collecting is valid? See where I'm going here?

This is a big subject and a forum isn't the best place to get into it under ideal circumstances. Reality is most people will never do the work to get their chassis tuned, let alone their dampers, and they do stupid s#!t that screws up their setup without ever knowing.

Something like an FSD or the Ohlins R&T's (for those willing to do some extra work) are far better for most than a single adjustable monotube design that hasn't changed much since 1959. For 90% of drivers they provide better damping, and a better contact patch under almost all conditions, especially if you haven't gotten the rest of the setup right. That's why FSD's are in my DD and not a set of TTX's. It's a daily.

[Cloud9blue]

Originally Posted by NiNeTyOne

Yes, but that's where it starts. I've only been doing this for 20 odd years, but I'm not going to take 300 pages to explain how to setup a car here.

We could go into all sorts of things from how to shim the bumps to how setup is an evolutionary process where you tweak everything from rake to tire pressures to preload, etc.. How many people are running thermal sensors on the strut bodies so they know when the data they are collecting is valid? See where I'm going here?

This is a big subject and a forum isn't the best place to get into it under ideal circumstances. Reality is most people will never do the work to get their chassis tuned, let alone their dampers, and they do stupid s#!t that screws up their setup without ever knowing.

Something like an FSD or the Ohlins R&T's (for those willing to do some extra work) are far better for most than a single adjustable monotube design that hasn't changed much since 1959. For 90% of drivers they provide better damping, and a better contact patch under almost all conditions, especially if you haven't gotten the rest of the setup right. That's why FSD's are in my DD and not a set of TTX's. It's a daily.

Plenty of entry level monotubes out there have the same digressive valves like the FSD and ohlins r&t. Heck, even the twin tube Koni based shocks on my TCK DA coilovers are digressive too. They ride heck a lot better than my stock and BMW PS setup as long as you dont hit the bumpstocks (by then the solid bearings comes into play, in a not so good way)

So I disagree that fsd are the best setup for most people, if that's what you are saying. They seems to be too underdamped(not enough low speed damping) like the stock zsp shocks from all the reports I have been reading since the late 2000s.

[NiNeTyOne]

Originally Posted by Cloud9blue

Plenty of entry level monotubes out there have the same digressive valves like the FSD and ohlins r&t. Heck, even the twin tube Koni based shocks on my TCK DA coilovers are digressive too. They ride heck a lot better than my stock and BMW PS setup as long as you dont hit the bumpstocks (by then the solid bearings comes into play, in a not so good way)

So I disagree that fsd are the best setup for most people, if that's what you are saying. They seems to be too underdamped (not enough low speed damping) like the stock zsp shocks from all the reports I have been reading since the late 2000s.

Your contention that entry level digressive valving is in any way similar to the DFV technology integrated into Ohlins R&T is flat wrong, the way they work is completely different.

Ohlins DFV is more of a parallel circuit. 3 paths. Bleed, shim stack or DFV. Shims handle low/medium speed. Piston blowoff handles high speed. DFV handles ultra high speed simultaneously.

Take one apart & then look at how they perform on a shock dyno some time, they are very different animals, both in design and in function.

Digressive valving in street applications work great IF the streets / pavement are smooth or you are going fast. This can be true even on poor pavement if you are fast. However the ride will deteriorate on poor pavement at slow speeds due to over-damping.

The ability to handle both situations is really where the Ohlins R&T's shine, and why I have said previously that they got it right, where Koni missed the mark a bit. Different price points, different objectives. If the R&T were available for xDrive cars they would be on mine, no question.

For the daily grocery-getter, the FSD's do a fantastic job. A number of people who have driven my car with this setup and remarked at how composed and stable the car feels, and how predictable it handles when pressed hard. Better still, the car is not upset by expansion joints and pot holes don't send you to the dentist to get your fillings redone. These are very good drivers with lots of track experience, so I'd say that there's growing consensus that if you get the spring/damper/link setup correct with FSD's they can be great for a daily driver that's not going to see track duty.

I have also driven cars that have the wrong links and cars that have the correct links on the front bar, and too short of a front link gives the impression of an under damped shock. Short links reduce the initial bar rate. If this was a race car the whole setup would be wildly different, but it's not, it's a daily driver I use in a city that's been a non-stop construction war zone for going on a decade..

Also note that the rear dampers are matched to fairly low rate springs on the OE bushed rear subframe as higher rates are problematic with an overly compliant rear subframe. To do much more in terms of improving the back end, you need to lock down the subframe as they do on the M3 (where they use solid bushings (maybe one of the biggest things you can do to get the car in a state where it can be improved further)). As soon as you do this the rear spring rates jump by 70% (400 vs 686 for rear rates), which means the rear damper valving totally changes. Few people understand how big a factor those rear subframe bushings are and how they factor into suspension dynamics.

As soon as you do this you're into all sorts of other costs, because your rear dampers are now not a part of the standard kit you get from Koni/Bilstein/Ohlins, and you're into a total ala carte situation with springs as well.

If I lived in a place where the asphalt was billiard table smooth, I'd have chosen differently, but few have that luxury, and some of us are just not THAT motivated for a car that's essentially one step past utilitarian.

[cvc 22349a]

Originally Posted by NiNeTyOne

Your experience sounds like you under sprung the dampers. If you get the correct spring rates, and also get the links on the sways correct this should not be an issue.

In Seattle we live in a city wide construction zone and our streets are worse than a bad neighborhood in Newark (I used to live in Manhattan). Properly sprung and properly matched with the correct durometer bumps, they are great dampers.

Suspension is a system, too few people treat it that way.

OE Sport springs?
Glad they work for you

[Dan Bilzerian]

Originally Posted by DrRobert

Now who’s being a douche?

Being blunt and being a douche are different.

[feuer]

Originally Posted by Dan Bilzerian

Being blunt and being a douche are different.

Blunt? I don't think so! More of a show off. 2min hot lap on Daytona in GT3 are intermediate. I would not brag about that time.