[4banger]

I have never seen a dyno plot of this particular damper. I would love to though, being as how everyone says how great it peforms.

Originally Posted by chaos311clarity

and how about some Ohlins FPS/RCE yellows, that seems to be a fairly popular street set up... and mine lol

[4banger]

I think what Stretch ment was that we should focus the discussion on the springs that come with the dampers. We could go off on a million tangents if we were trying to determine the best spring rate for a given damper. If it will help everyone focus their opnions, lets try to stick with street driving since I think that is the inteneded use of most aftermarket coilovers.

Originally Posted by ace996

Stretch,
I believe each dyno has a listed spring-rate. How can one judge the under/overdamped-ness of a strut without taking into consideration the spring that will be used? You know, one is not independant of the other.
And most dynos show force x speed...those are CD x speed. CD can only be shown with a chosen spring rate.

I say those spring rates are too soft for track/solo. Perhaps nice street rates, though.

Be good,
TomK

[4banger]

Just wanted to say thanks to Myles for providing me with the actual spring rates for the RCE yellow springs.

[stretch]

OptimumG has some great reads pertaining to the same topic as this thread:
Untitled Document

They cite 65-70% critically damped as a good baseline for race cars just like everyone else. However, they're more specific than other sources by saying that should be the amount of low speed damping on rebound. They do say more may be required to account for sway bars during body roll.

Body roll happens at what, 3in/second? This split point will probably vary a bit from car to car, but beyond that split point, we should expect to never see beyond 70% critically damped (according to the articles).

OptimumG suggests tapering off to lower than 70% (much lower) in the high-speed region to minimize the reduction of grip from track bumps.

Originally Posted by ace996

Stretch,
I believe each dyno has a listed spring-rate. How can one judge the under/overdamped-ness of a strut without taking into consideration the spring that will be used? You know, one is not independant of the other.
And most dynos show force x speed...those are CD x speed. CD can only be shown with a chosen spring rate.

I say those spring rates are too soft for track/solo. Perhaps nice street rates, though.

Be good,
TomK

The equations do take into account the listed spring rate. If one were to change from the default spring rate, the graph would change. Obviously the images aren't interactive, though. You can use my spreadsheet to plot the change to %cd due to a change in spring rate.

[BoostJunkie]

One thing that hasn't been taken into account here is the nature of progressive springs. We are just plugging in the spring's overall rate as if it were linear. However, especially on a street car, the rates of the progressive coils are important as well, and vastly complicates things. I'm with Tom on this one, real world testing is more important than analyzing graphs and numbers, although they both have their places. The one thing that I keep thinking is, if the engineers at these large companies (Ohlins comes to mind) didn't catch the fact that their coilovers are "overdamped" how is it that we can do it so easily? I think the testing done here is not nearly as thorough as it would need to be to even come close to giving a realistic view of a damper/spring's ability. There are other variables, like oil temperature and ambient temperature (as Tom mentioned). I just don't know if we have the resources to conduct testing on the same level as these manufacturers do, nor does this Dennis Grant guy. Just my opinion, take it or leave it. It's fun to analyze this stuff but it will take a long time and a LOT more testing to get a realistic view of the big picture.

[ace996]

Originally Posted by 4banger

lets try to stick with street driving since I think that is the inteneded use of most aftermarket coilovers.

I really hope that's not true... Perhaps we drive on the street most of the time but I'd hope the need for coilovers is born from the need to set ride-height, cornerweight, and fine-tune the balance of a car driven to the edge of traction.

But if this thread is for "street" applications, then I will agree that MOST coilover applications will be overdamped. My RCE T2s with 500/400 actually felt smoother and less jarring than the stock strut/spring but if I were just using the T2s for the street, then I would have gone to 400/300 rates. I'm sure the Bilsteins...which are a softer/street based system...will also be acceptable.
And I've only heard wonderful reviews of the Ohlins.

Be good,
TomK

[stretch]

To be fair, 4banger's new calculations don't show the Ohlins to be quite as overdamped as mine did. (On the other hand, they show the stockers to be more overdamped.) Our numbers are pretty close, just not quite the same. We're currently arguing about that via e-mail.

Originally Posted by BoostJunkie

The one thing that I keep thinking is, if the engineers at these large companies (Ohlins comes to mind) didn't catch the fact that their coilovers are "overdamped" how is it that we can do it so easily? I think the testing done here is not nearly as thorough as it would need to be to even come close to giving a realistic view of a damper/spring's ability.

I don't think the companies are blind to it. I think Ohlins is a great company as are the other builders listed here, so that's not it at all. The capability is there. I think either they either deliberately aim for overdamping (the JDM mentality, something I don't particularly understand) or they choose to err on the side of overdamping (either due to manufacturing tolerances, compensation for future wear, or too few R&D revisions).

While not the same thing, do you think Brembo doesn't know drilled rotors are prone to cracking? Or how about the SPT intake throwing off the MAF calibration- that's very basic stuff, so why didn't they fix it?

[4banger]

Originally Posted by stretch

I don't think the companies are blind to it. I think Ohlins is a great company as are the other builders listed here, so that's not it at all. The capability is there. I think either they either deliberately aim for overdamping (the JDM mentality, something I don't particularly understand) or they choose to err on the side of overdamping (either due to manufacturing tolerances, compensation for future wear, or too few R&D revisions).

Considering that the stock plot looks fairly reasonable, maybe the after market companies feel that they need to give you more dampening in order to justify their products. Alot of these dampers don't look that bad on their full soft settings. Maybe the manufacturers don't really intend for their products to be used in the upper settings and just provide them as a marketing ploy.

[4banger]

Originally Posted by ace996

I really hope that's not true... Perhaps we drive on the street most of the time but I'd hope the need for coilovers is born from the need to set ride-height, cornerweight, and fine-tune the balance of a car driven to the edge of traction.

I don't see why adjusting ride height, cornerwieghting and fine tuning your suspension aren't also desirable on the street as well. Just because I don't track my car doesn't mean that I don't want it to handle well. I'm sure your average driver doesn't care about most of those benefits, but I think that the people who are into upgrading their car do car about how well their car performs on a daily basis. I just can't see many of the less expensive coilovers out their being sold as serious track upgrades.

[CGMDan]

Originally Posted by 4banger

I don't see why adjusting ride height, cornerwieghting and fine tuning your suspension aren't also desirable on the street as well. Just because I don't track my car doesn't mean that I don't want it to handle well. I'm sure your average driver doesn't care about most of those benefits, but I think that the people who are into upgrading their car do car about how well their car performs on a daily basis. I just can't see many of the less expensive coilovers out their being sold as serious track upgrades.

People on the street aren't using more than maybe 50% of the capabilities of their car. If your pushing you car hard enough that you need your car tuned to that extent, then your being a danger to everyone else.

[ace996]

Originally Posted by 4banger

I don't see why adjusting ride height, cornerwieghting and fine tuning your suspension aren't also desirable on the street as well. Just because I don't track my car doesn't mean that I don't want it to handle well. I'm sure your average driver doesn't care about most of those benefits, but I think that the people who are into upgrading their car do car about how well their car performs on a daily basis. I just can't see many of the less expensive coilovers out their being sold as serious track upgrades.

4b,
I understand what you're saying but I don't agree. I've never had a conversation with anyone that went along the lines of...
"so, I'm looking to get one or two mph more out of that off-ramp...I'm thinking of changing my springs and getting a cornerweighting with a greater emphasis on shifting weight rearward...whadda think?"
or
"I'm looking for more transitional response for lane changes on my morning commute"
or
"if I could just dial in a little more rebound, I think I'll be able to jockey for that parking space by the front door of the office"
You dig?

What I usually hear is...
"man, I just bought these expensive coilovers and they drop me like two to three inches and my car looks like so slammed but my girlfriend like hates my car now becaue she can't put on her makeup 'cus its like too bouncy...but like WTF...they're the best coilovers...I can even change settings from my remote control key-fob, that magazine or mathturbational equation says so...and BTW how do I set them up for this weekend 'cuz I'm going to the dragstrip....."

And that's the sad part.

As has been said, MOST, if not ALL, drivers will not gain any benefits of running coilovers on the street....EVER. What benefit is there by running a coilover on the street? To what end?

Taking that coilover money and putting it towards a track-school would be a much better investment.

For the street...get a set of Koni or Ohlins struts with the RCE springs..yellow or black, and call it a day...

WTF...all this for a street set-up...

Be good,
TomK

[stretch]

Street performance (for example Solo I racing, but this would go doubly for rally cars) is much more difficult than a closed track because you have to deal with more bumps and uneven surfaces. As roads get smoother, the need for a suspension disappears (until you have a totally smooth course and a go-kart with no suspension).

The beautiful thing about not being overdamped is that it helps both ride quality and performance. It's a win-win. So whatta ya say, back on topic?

[ace996]

I give you credit, man, you are tenacious with your stance...

Rally and street similar?...no, and you know this. And you cannot group Solo and street together, as the best performing STIs are far from streetable. The top TT STIs are more streetable than the Solo weapons. And the rally cars do go through a pretty dramatic suspension-transformation when they have tarmac stages...and those roads are not what we'd call "smooth"...


Back on point, yes...but I can't seem to rest with this rampant "overdamped" condition...

Pray tell, do the aforementioned dyno plots...which have been manipulated to show CD...reflect sway-bar rates? Please tell me they do...and if they do please tell me they aren't the stock bars, as onewould be quite insane to mount coilovers with stock bars and endlinks.

I suspect that the "underdamped" attitude may stem from a bit of "micro-focus"... I wonder if those graphs reflected a stiffer bar, say a Whiteline 29mm front, what they would show...just as I suspect that the spring-rates that are used are too soft for the dampers used.

The issue I see with these threads, Stretch, is that you have a certain opinion on certain applications...springs, sways, and now dampers...and you have a talent of backing up your opinions with calculations and equations, which to the inexperienced or unaware driver looking for help, is phenomenally supportive of your opinions. My issue is not that I don't respect your opinions, or right to have them or express them, in such a fashion...my issue stems from just how far from actual practice they fall, and more importantly, the lack of physical applied results/data and experience. A calculation, if proven wrong or incomplete in it's actual application, is worthless.

I am quite happy that someone is compiling a list of dynos...this may help someone who's in the market for a coilover to help them choose with more information....for example, someone who's looking for a "street" set-up may want to walk away from the Tein Flex...undoubtably a "race" coilover - and someone looking for a "race" application may dismiss the PSS9 or G4 units for being too soft and not able to handle spring-rates for the track with r-compounds - try running a 14" or 13.5" front rideheight with 300lb springs and r-comps on an autox or track with r-compounds and you will very quicky become intimate with your bumpstops or rub your tires through your hood. For those reasons, this is good. But it appears that the data is slanted and incomplete...and that is not good.

4b is asking for those who have coilovers to come forth and share their experiences...great. Let me be the first, although I do not have strut dynos...

From my post after Watkins Glen...

Well, back from Watkins Glen and the adrenal gland is empty. What an amazing track!!!
I also have a better understanding of my cars handling traits "at the limit", or as close as I could get with the given conditions...cold/rain/damp.

I'll say this twice because it bears repeating....

TarmacIIs with 600/500 rates are AWESOME!!!!
TarmacIIs with 600/500 rates are AWESOME!!!!

Really, I've never experienced such a fine handling machine...and the behavior in the rain was superb.

Here's a few vids to illustrate the results of, what I strongly consider to be, the best suspension I've ever had...

In the Wet -
YouTube - WatkinsGlen-10.14.07-Session2- BlackFlag

Dry/Damp -
YouTube - WatkinsGlen/10.14.07/3rd Session


With some audio edit...
YouTube - WatkinsBecoming


I haven't been able to sit down and crunch the numbers from my PerformanceBox (lap-timer/dynamics data-logger) but that will be next. With the poor weather, though, I believe I may need to compare Limerock next month...where I have prior logs and can do a compare.

Overall...I'd not change one thing with my suspension...not one thing. I'm so happy I went to 600/500s.

And more...

Checked the PerformanceBox data logs and was quite happy.
Here are the results of the two sessions:

Wet Session:
Fast Lap - 2:43.80secs
MaxMPH - 123.55mph
MaxLatG - 0.91

Here's the log of my 2 fastest wet laps:



Dry Session:
Fast Lap - 2:24.30secs
MaxMPH - 133.63
MaxLatG - 1.265 - on shagged/blue'd Re070s!!!! Keep in mind, this was a spike but constant/averages were just over 1g...pretty amazing for a street tire and more a testament to the suspension from Racecomp.

The log of my 2 fastest dry sessions:


Be good,
TomK

I'd say that I'm not overdamped or over sprung/bar'd with .91g in the rain or a consistant "over 1 G " on the tired stock tires.
And it sure "felt" incredible...
++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++
Here's a very experienced driver/racer/tuner's opinions on the STI's suspension...
Siegel Racing / TopSpeed Dissertation on Suspension

Here's a quick cut from it...

*** THE BEST I'VE EVER SEEN ***

We. Have. Found. It. Seriously, the way the car handled today was DRAMATICALLY unlike any Subaru I have ever driven.

Setup:
KW V3. Standard spring rates. One turn from stiff compression. One and a half rebound.
PDE front plates, stock rear top-hats.
Whiteline 27-29 front sway, stiff setting
Whiteline 22-26 rear sway, middle setting
Whiteline ALK
Carlab X-Brace in the back, M-1 chromoly subframe brace, no front strut bar.
2.6 degrees front camber, 0.1 degrees front toe-out.
1.6 degrees rear camber, 0.01 degrees rear toe-in.
Stoptech 335 BBK PFC-01 Brake pads front, Carbotech XP8 rear
Race Comp Engineering Brake Ducts
Goodyear GSCS DOT tires. 36 psi hot front 34 psi hot rear.
Sparco Pro 2000 Race seat.
Kartboy Short shifter

I have driven over 400 Subaru’s in the last 3 years. None feels ANYTHING like this car. Every other Subaru I have driven requires a bit of “man-handling” or “making it turn.” This car steers like a Vette, or a Miata. Fingertips guide the front end where to go, throttle easily controls the attitude of the car. I think I need to credit a lot of this to the M-1 front subframe brace. It does make sense that the massive loading of the lower-control-arms into to what appears to be a flexible area could contribute to the comparatively poor steering feel in most Subaru’s.

This car was eventually transitioned to the RCE-T2's and was great. Running this setup with 265/35/18 Advan Neovas was AMAZING on track. We got it dialed to the point that it felt like a Tarmac Rally car. You could make the car do anything you wanted, grip, power-off oversteer, power-on oversteer, whatever, and VERY composed while doing it. With the big Hoosiers this is by far the fastest 4-door Subaru I've driven.



Funny how our set-ups are almost identical...

Now what is more believeable.... experience or mathturbation?

Just having some fun,
TomK

[stretch]

Tom, this isn't a competition. Why are you acting like mathmatical predictions and you results are mutually exclusive? If done properly, they'll agree.

Nobody has said the RCE struts are overdamped because there is no dyno of them. We can't even begin to discuss them without that as a starting point. Perhaps the reason everyone likes the RCE T2's is because they're the only currently sold coilover setup that isn't overdamped?

You're fine with being fast. I want to know why it's fast. You have data showing you are fast but no data showing why. You showed me the ends but I care about the means. You've also obtained your ends by going brute force with immensely stiff springs (the "solid suspension" approach) and that's not really the topic of the thread. This is not a thread on springs!!! This thread is for discussion the optimal damping ratio for a given set of springs, nothing else. Please, let this thread form a useful conclusion or come back with some data that actually contributes towards finding it. Comparisons of lap times on different damper adjustments would be pretty interesting. I'd really love it if you cooperated since you have a good data logger and could contribute.

How do we know there isn't a better solution yet to be found, perhaps even one that doesn't kill daily drivability?

With a shock dyno, 4banger could predict your ideal damper settings and you could compare the times on those with your current settings. But like I said, maybe the RCE T2's are one of the few that aren't overdamped and that's why they're so fast, nobody knows! Answer THAT question for us!

I hope he posts it, but 4banger just e-mailed me a document from ChassisSim software. They modeled a Porsche 911 and had new shocks made to the software's specifications. They designed for the parameters of 50% critically damped for low speed bump and just 30% critically damped for everything else, equating to roughly equal bump and rebound. That's OUTRAGEOUSLY soft (less than half of Ohlins, above) yet it dropped 4 seconds off the car's lap time!

[DuncanG]

Here's the link for that pdf - http://www.vehicledynamics-expo.com/...y_3/nowlan.pdf
Hmm, different!

While doing the search I came across many threads on different forums each from a single-post user saying how ****-hot these guys are - .