Koni Yellow Settings

[NotaHybrid]

I'd be making a phone call to cancel an order right now if I had done that

 

[kcbrown]

Just don't be that guy that is lying because he is too scared to embrace a mistake. You must embrace The Stupid.

But ... it burns!

 

[rextang]

So far, I've had no reason to go beyond +1.5 turns front and +1.25 turns rear relative to full soft even for track days. I'm still on the OE springs. More than one instructor has commented that the car is composed at those settings (and with the rest of the setup).

With the wheel & tire upgrade (that hasn't seen track time yet), I expect I might increase those settings a little.

For the street, it depends. With my wife present and a lot of driving on rough pavement expected, about +3/8 and +1/8 turn. Alone, anywhere from +3/4 & +1/2 to +1 & +3/4.


Norm

Thanks Norm. I run Koni yellows on stock springs in my '11GT and the "wife" settings you recommend work perfectly for me on Michigan roads. I ran the rear stiffer than the fronts for almost a year and was starting to hate it.

 

[cm581978]

I swear, Ive been playing with the settings every other day. I tend to either go full soft on all four corners or slightly stiffen up the rear shocks.

 

[sheizasosay]

Word of the day: critical damping.

 

[claudermilk]

OK, I had to go hit teh Google for a while on that one. As the South Park kids would say: "I learned something today"

It seems that is what we are all striving for, but having to do it by experimenting & using the ever-so-accurate butt dyno.

I think I'll try attacking settings from the opposite end next time around--start at full soft and work my way up.

 

[kcbrown]

Word of the day: critical damping.

How does one achieve critical damping (or, rather, a desired percentage of it) other than via a shock dyno? Seems to me there's far too much going on in the suspension for anyone other than a complete expert to be able to dial in dampers with any real degree of precision.

 

[csamsh]

How does one achieve critical damping (or, rather, a desired percentage of it) other than via a shock dyno? Seems to me there's far too much going on in the suspension for anyone other than a complete expert to be able to dial in dampers with any real degree of precision.

It's not as hard as you'd figure. Start on soft and work your way up depending on the transitional response the car has. The Neil Roberts book has a fantastic section on making shocks adjustments, complete with table of cause/effect.

Couple things to consider...you have to be systematic, and only make one change (front or rear) at a time. Also, without a good racing seat, adjusting shocks becomes exponentially more difficult. All of these adjustments rely on your ass. If it's held in place, good. If not, good luck.

 

[kcbrown]

It's not as hard as you'd figure. Start on soft and work your way up depending on the transitional response the car has. The Neil Roberts book has a fantastic section on making shocks adjustments, complete with table of cause/effect.

Couple things to consider...you have to be systematic, and only make one change (front or rear) at a time. Also, without a good racing seat, adjusting shocks becomes exponentially more difficult. All of these adjustments rely on your ass. If it's held in place, good. If not, good luck.

How do you ensure that the damping is the same left to right?

How do you get the damping to, say, 65% of critical as opposed to, say, 90% of it?

Are such differences really going to be obvious even when your posterior is secure in the seat?

 

[dontlifttoshift]

You can't.

Why would you want it that soft?

Yes......even if its not you can tell when they are wrong. Run back to back on full soft and full stiff.

 

[Renesis07]

1.5 Front/ 1.25 back is what I run all the time. Car handles great and doesn't lose much ride quality on the streets IMO. Little rough over potholes and whatnot but I do my best to ricer swerve around those.... lol

 

[kcbrown]

You can't.

Why would you want it that soft?

Because this: http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_3.pdf


Among other things.

Overdamping (damping greater than critical) means your suspension never gets a chance to return to steady state. It also unnecessarily stiffens the ride. In rebound, it means that your suspension will not be able to extend quickly enough to maintain optimal contact with the surface.


A properly tuned suspension should, I expect, feel both soft and responsive. Soft because when the transmissibility is minimized, it generally means the suspension is following the road surface perfectly -- feeling the surface means some of the movement from surface irregularities is being transmitted to you, which means that there is greater variability of force at the wheels than there would be if you didn't feel those irregularities (since the force transient you feel from the movement is representative of a force transient that the suspension is transmitting back to the road, and force transients represent variations in available grip, since available grip is a function of the downforce on the tires). Responsive because it will reach a new steady state as quickly as possible.

My car is primarily a daily driver, but I drive it on the track as well. I want excellent ride and excellent handling. A low-speed damping coefficient of around 0.7 in rebound looks like it will yield that.


A very good thread on the subject of damping is here: http://www.iwsti.com/forums/gd-susp...analysis-ohlins-tein-ground-control-more.html

Yes......even if its not you can tell when they are wrong. Run back to back on full soft and full stiff.

Well, sure, you can (or should be able to) tell the difference between those, but the question is how you tell that you've achieved the optimal damping coefficient.

 

[SoundGuyDave]

Well, sure, you can (or should be able to) tell the difference between those, but the question is how you tell that you've achieved the optimal damping coefficient.

First off, you need to define "optimal." This can either be objective or subjective...

Optimal damping for handling can objectively be defined by net lap time.
Optimal damping for ride quality can subjectively be defined by driver's comfort.
Optimal damping for a dual-purpose car will, I think, NECESSARILY be subjective.

So, how do you tell? On track, keep tweaking until ANY adjustment yields slower lap times. On the street, keep tweaking until you've turned your corner-carver into a Cadillac Fleetwood. Dual-purpose car? It's a compromise by definition, so find the middle ground you're happiest with, and call it a day.

Note that even with subjective testing on track, driver preference plays into things. One driver will prefer a looser car, another will prefer a tighter car. Different settings will achieve the net lowest lap time for each driver. Clear as mud, right?

 

[sheizasosay]

How does one achieve critical damping (or, rather, a desired percentage of it) other than via a shock dyno? Seems to me there's far too much going on in the suspension for anyone other than a complete expert to be able to dial in dampers with any real degree of precision.

I don't try to achieve it. I just tune my dampers to the point where the car reacts the way I want. If critical damping happens I wouldn't even know it. I can guess and estimate if I'm over-dampened by the way the car handles. If I'm over-dampened, the car will lose traction in transitions and then gain it back if it has enough time. Could be while breaking or at turn-in. Over-dampened rears will make the tell wag on hard break zones because it's basically holding the tires off the pavement as the nose plants (forward weight transfer). If it's under-dampened I think the ride kinda feels scary. Scary in relation to the way the car feels when it had more dampening in the same transition/same speed/same track...etc.

I just tune my dampers to go around the track as fast as I can AND as comfortable as I can at the limits. I just dropped that word because it is more like an *awareness* type deal for me or a goal and a reminder that over-damping and under-damping are a result of being away from critical damping.

EDIT- the "I don't try to achieve it" is not exactly accurate. I try to achieve it without trying to achieve it. That probably doesn't make sense.

 

[kcbrown]

First off, you need to define "optimal." This can either be objective or subjective...

Optimal damping for handling can objectively be defined by net lap time.
Optimal damping for ride quality can subjectively be defined by driver's comfort.
Optimal damping for a dual-purpose car will, I think, NECESSARILY be subjective.

So, how do you tell? On track, keep tweaking until ANY adjustment yields slower lap times. On the street, keep tweaking until you've turned your corner-carver into a Cadillac Fleetwood. Dual-purpose car? It's a compromise by definition, so find the middle ground you're happiest with, and call it a day.

Note that even with subjective testing on track, driver preference plays into things. One driver will prefer a looser car, another will prefer a tighter car. Different settings will achieve the net lowest lap time for each driver. Clear as mud, right?

Heh. Yep.

Of course, the problem with using lap times as a metric for tweaking is that it presumes that the amount of difference the changes make exceeds the natural variability in the lap times. For someone like me, that natural variability is going to be quite large, on the order of a second or so per lap at a track like Laguna Seca. Consistent lap times can only occur if you do everything the same every time, something that I have trouble doing (as I learned at my track event at Laguna Seca, something I have yet to do a writeup on. The upshot is that the consistency problems I have there in real life are identical to the ones I have in Gran Turismo). Only then, I expect, will anything but the largest changes become apparent.

At an HPDE, it's even worse, because chances are you're contending with traffic, and that will introduce even more variability.


In essence, I don't see any reasonable way to achieve such a thing on the basis of lap times until the driver is really good and has more or less exclusive access to a track.


Also, based on what I've been reading about damping, I'm no longer sure that the compromise between handling and ride comfort is as great as has been claimed. As I said, the most effective (and controllable, I should think) suspension with respect to maintaining a corner is going to be the one that keeps the tires planted on the road while minimizing the amount of tire-to-pavement force variation due to bumps. Such a thing would of necessity result in maximum ride quality (smoothness of the chassis over bumps), as any force variation that is transmitted to the chassis must originate from or generate force variations between the tires and the pavement.

It may be that steering responsiveness is a compromise for that, but I would think that would be determined primarily by spring rates than by dampers. As long as the transition time from one steady state to another is minimized (as it would be with a damping coefficient in the range I'm thinking of here), then steering responsiveness should be maximized as well.

 

[SoundGuyDave]

Heh. Yep.

Of course, the problem with using lap times as a metric for tweaking is that it presumes that the amount of difference the changes make exceeds the natural variability in the lap times. For someone like me, that natural variability is going to be quite large, on the order of a second or so per lap at a track like Laguna Seca. Consistent lap times can only occur if you do everything the same every time, something that I have trouble doing (as I learned at my track event at Laguna Seca, something I have yet to do a writeup on. The upshot is that the consistency problems I have there in real life are identical to the ones I have in Gran Turismo). Only then, I expect, will anything but the largest changes become apparent.

And therein lies the rub. If you have clean laps to look at, and you're getting a one-second (or more) variability in lap time, then IMO worrying about achieving critical damping is akin to obsessing over the shade of red that you're painting the barn while it's on fire... Remember the mantra: Fix the driver first, THEN start working on the car once you have idenitified one specific thing about the chassis that is genuinely holding back the driver...

At an HPDE, it's even worse, because chances are you're contending with traffic, and that will introduce even more variability.

In essence, I don't see any reasonable way to achieve such a thing on the basis of lap times until the driver is really good and has more or less exclusive access to a track.

Yes, for an overall lap time, you are correct. However with any good data acquisition setup, you'll be able to define and look at sector times, which are arguably just as good. Even in a 20-minute session, you should be able to find 3-4 instances of a "good" run through any given corner or set of corners, and that can be used as the comparison basis for between-session tweaking.

Also, based on what I've been reading about damping, I'm no longer sure that the compromise between handling and ride comfort is as great as has been claimed. As I said, the most effective (and controllable, I should think) suspension with respect to maintaining a corner is going to be the one that keeps the tires planted on the road while minimizing the amount of tire-to-pavement force variation due to bumps. Such a thing would of necessity result in maximum ride quality (smoothness of the chassis over bumps), as any force variation that is transmitted to the chassis must originate from or generate force variations between the tires and the pavement.

Not necessarily. The essence of "ride quality" is isolation between the driver and the pavement. The essence of "maximum effort" is the elimination of that isolation. In a Caddy Fleetwood, the car just floats over the bumps, and when turning-in, will spend quite a bit of energy rolling over, all of which isolates the driver from the bumps and g-forces, or at least slows the onset. On a 996 (or fill in your favorite hyper-tuned supercar) though, you can practically feel the grain of the asphalt in your butt, and when you turn-in, it is IMMEDIATE, and you feel all of it.

It may be that steering responsiveness is a compromise for that, but I would think that would be determined primarily by spring rates than by dampers. As long as the transition time from one steady state to another is minimized (as it would be with a damping coefficient in the range I'm thinking of here), then steering responsiveness should be maximized as well.

Possible, but that same responsiveness is primarily (I think) created by the rate of loading in the transition between straight-line and turned. That has nothing to do with springs, and everything to do with dampers. A softly-sprung car is not, by definition, impossible to turn crisply. High damper forces will delay the roll, effectively stiffening up the wheel rate until it bleeds down and steady-state is achieved. The forces acting on the chassis as it begins to turn haven't changed. It's still F=MA. What HAS changed is the instantaneous loading of the suspension under the car, and that's governed by the dampers.

Bottom line, though, is that I think worrying about achieving critical damping, while desirable, is shooting for that last 1/2% of performance, when the first 35% hasn't been achieved, at least at this point. Even with a "pro driver" in the seat, if the AS% and geometry issues aren't fixed first (for example), the absolute perfect damper rates could be lost in the "noise." At least in comparison to "close enough," anyway.

Regarding the driver: Honestly, for anything beyond the absolute basics, until you can get within a 1/10th or two per mile of track, any changes you make are going to be masked by driver error. I'm not saying they're not worth studying, but the focus still needs to be on the driver at that level.

 

[kcbrown]

And therein lies the rub. If you have clean laps to look at, and you're getting a one-second (or more) variability in lap time, then IMO worrying about achieving critical damping is akin to obsessing over the shade of red that you're painting the barn while it's on fire... Remember the mantra: Fix the driver first, THEN start working on the car once you have idenitified one specific thing about the chassis that is genuinely holding back the driver...

And this makes me wonder if I might be better off just putting on camber plates. But as I mentioned elsewhere, I don't want to touch that part of the suspension twice. If I put on camber plates, then I have financial reason to put on coilovers at the same time, as otherwise I wind up, in essence, paying for the installation labor twice.

That's basically why I'm asking about critical damping here. I want to set up the suspension right the first time.

Yes, for an overall lap time, you are correct. However with any good data acquisition setup, you'll be able to define and look at sector times, which are arguably just as good. Even in a 20-minute session, you should be able to find 3-4 instances of a "good" run through any given corner or set of corners, and that can be used as the comparison basis for between-session tweaking.

Okay, that makes sense in the context of a consistent driver.

Not necessarily. The essence of "ride quality" is isolation between the driver and the pavement.

Yes, but that translates directly to isolation between the chassis and the variations in the pavement.

The most desirable behavior of a suspension in a corner that has bumps is for the suspension to maintain a steady cornering force in the corner, right? That's basically why we don't like suspensions that skip all over the place when they encounter bumps: they make the car unpredictable and difficult to control while in cornering, and that reduces confidence. Conversely, we like suspensions that keep the cornering grip steady even in the presence of bumps.

Available cornering grip is a direct function of the contact force between the tires and the surface. Variation of that of necessity gets you variation in available cornering grip, and when that falls below the demand, the end result is that the tires temporarily slide over the surface until the necessary contact force is restored. That is exactly what happens when the suspension "skips" over bumps.


Now think the physics of this all the way through. A bump that's felt by the driver is one that is transmitted to the driver through the chassis, which means that a transient force is transmitted from the suspension to the chassis, and from the chassis to the driver. But every force has an equal and opposite reaction. A force that is transmitted to the chassis by the suspension has an opposite force that is transmitted to the ground. But a transient force that is transmitted to the ground by the suspension is a variation in the contact force between the tire and the surface, which is exactly the thing you want to minimize in order to maximize cornering stability.

Thus, it follows that since the most effective suspension in a corner is one that will minimize variations in the contact force between the tires and the surface that arise from surface variations, such a suspension must also be the most comfortable one. Isolation of the passenger from the bumps comes as a natural side effect of this.

Possible, but that same responsiveness is primarily (I think) created by the rate of loading in the transition between straight-line and turned. That has nothing to do with springs, and everything to do with dampers.

Well, it's both. The shorter the amount of suspension travel necessary to transition from one steady state (e.g., straight line) to another (e.g., mid-corner), the less time it will take for the transition to occur. Time in the transition is responsiveness.

A softly-sprung car is not, by definition, impossible to turn crisply. High damper forces will delay the roll, effectively stiffening up the wheel rate until it bleeds down and steady-state is achieved.

Of course. But that comes at the expense of the suspension's ability to keep the tire contact forces constant. Which is to say, you may have to overdamp the suspension in order to achieve sufficient crispness of turn-in.

Bottom line, though, is that I think worrying about achieving critical damping, while desirable, is shooting for that last 1/2% of performance, when the first 35% hasn't been achieved, at least at this point. Even with a "pro driver" in the seat, if the AS% and geometry issues aren't fixed first (for example), the absolute perfect damper rates could be lost in the "noise." At least in comparison to "close enough," anyway.

I don't doubt it. I just want to somehow set up the suspension properly from the beginning so that there will be no question that it's the driver, and not the car, that's screwing up.

Regarding the driver: Honestly, for anything beyond the absolute basics, until you can get within a 1/10th or two per mile of track, any changes you make are going to be masked by driver error. I'm not saying they're not worth studying, but the focus still needs to be on the driver at that level.

I completely agree. As I said, were it not for the financial angle, I'd just be throwing camber plates on the car and otherwise not messing with it. But inasmuch as I need camber plates, and I would like to address some ride quality issues at the same time, I think it's time for me to go with coilovers. And I think I've figured out the spring rates I want to use for this: 250 lb/in in front, and 325 lb/in in rear, while keeping the ride height the same as stock (in order to avoid changing the suspension geometry).

 

[SoundGuyDave]

I think we're getting into that forest vs. trees thing here...

Lets take a look at two cars, one focused on ride quality, and the other on crisp responsiveness...

"In this corner, weighing in at three metric assloads, we have the Cadillac Fleetwood, beloved of the Florida sandal-and-black-dress-socks crowd, and renowned for it's ability to float over parking berms and even small animals at speed without distracting it's blue-haired pilot from attempting to peer myopically over the dashboard at an uncertain and scary world!"

"And in this corner, still weighing in at wayyyyy-too-much, is the BMW M3, the gold standard for sporty tin-top, championed by the yuppie country-club set, and the butt of many jokes revolving around roses and thorns. This is the Ultimate Driving Machine, just ask any of the middle-aged men who wear perforated driving gloves while braving the streets between their McMansions and Starbucks!"

The Caddy has a suspension best compared to a marshmallow, has travel for days, but answers helm commands in time periods best measured with a calendar.

The BMW has a suspension that is crisp at turn-in, sets very quickly, does NOT have a lot of travel, and on a buckboard road can cause the occupants to suffer kidney failure.

By any standard, the Fleetwood is a comfortable car to ride in, potholes, pavement cracks and pedestrians be damned. By the same standard, the BMW has a ROUGH ride, where you feel every surface imperfection in the road right in your spine.

If we assume that the designers of both vehicles A) know the spring rates to be used and B) can calculate "critical damping," then we have a problem, since the characteristics of the two cars are radically different. IMO, it's one of the following:

1) Either the gangsters in Detroit or the engineers in Bavaria are unable to use a calculator and got the math wrong. Very unlikely.
2) "Responsiveness" and "Comfort" are diametrically opposed goals requiring radically different damper tuning. Very likely.
3) "Critical damping" isn't so critical. Possible.

If we define critical damping as simple control over the springs, to prevent excess vehicle oscillation after suspension jounce or rebound, then neither car really meets that definition. With the Caddy, the damn thing could be parked and still gently bobbing from a pothole four miles ago. The M3's suspension feels, in contrast, almost like it's not there. Is one underdamped, and the other overdamped? Probably. The real essence of the question becomes: Why? I'll still submit that underdamped suspension tuning delivers a nice cushy ride, but substandard handling capability. Overdamped, by comparison, rides hard, but corners crisply.

Your point about springs is well taken, I may add. Yes, given that force remains the same, the higher spring rate will "take a set" more quickly. I'll also go as far as to say that the higher spring rate MAY also contribute to more NVH, and thus lessen the "ride quality." However, there is a wealth of anecdotal evidence (which I generally discount) that higher spring rates with better dampers yield a net increase in ride quality over the stock setup on our S197s, however since "ride quality" is still only nebulously defined, that is subject to far too much interpretation to hold as proof of concept.

Speaking of somebody who HAS rebound-adjustable dampers, that little knob does make one HELL of a difference to both lap times and lack of bloody urine. I have found that my track settings are miserable on the street, and my street settings are so bad on track that "pathetic" would be too kind a word. Note that this is with rebound-adjustability only. I can only imagine (and drool over) what kind of control you would have with triples, where you can completely control the low-speed circuit, AND have some control over the high-speed circuit as well...

I think your plan of going directly to coil-overs is the right one. You can simply and easily (cheaply!) play with spring rates, and if you get triples, you can play with damper curves to your heart's content. Either way, I think you'll find you'll need very different settings to really carve corners and to have a nice, cushy ride.

So, what are you waiting for???

Oh, and driver mod: Seat time is everything. The more comfortable you are out on track, and the more experience you have, the less you have to think about what you're doing, and the more consistent you become. THAT is where changes made to the car will show up. Basics, like getting enough negative camber are not about going faster necessarily, you're going to do that anyway as you accumulate experience, but are about protecting the tires. In your case, doing camber and swapping the dampers out will accomplish the same thing. Get the camber you need, find a good compromise setting on the dampers, and then LEAVE THEM ALONE!! Resist the urge to touch them unless and until you can say with complete honestly that you are driving beyond the capability of the suspension tuning to support. Then prove it to yourself by ripping off a string of laps where each sector is consistent in time. THEN tune and assess the validity of the change.

Data acquisition is key to this stuff! It's dead-nuts simple to whip up a graph of velocity vs. distance. If you're consistent, the lines from multiple laps will overlap, since you're passing the same point on each lap at the same speeds. If you have a sag on the line in some area for a given lap (passing, being passed or a mistake), it's safe to say that it should be back up to snuff after the next braking zone when you're back up to speed. Once you're getting close on the velocity/distance graph, OR if you're scratching your head as to why it's not close, you can start looking at LatG vs. distance, and LonG vs. distance, and start analyzing where you ARE inconsistent. If you REALLY want to start improving once you have some sort of foundation, pull your "best lap" and "theoretical best lap" and start comparing. TBL essentially looks at all the laps in the session on a sector-by-sector basis, and constructs a hypothetical lap based on your best performance in each sector. This is particularly handy for reinforcing to yourself that yes, you CAN take corner "X" at velocity "Y" and make it stick, because you already did it!

Don't bother with lap times or data acquisition, though, until you have figured out that whole pesky "outside-inside-outside" thing and have pretty consistent (deep!) braking points. Lap times and data are great for refining, but you have to have the basics down first. Oh, and run video at the same time. NOTHING is more frustrating that looking at the data and realizing that you just cut 2/10ths out of a corner but not knowing how you did it.... Ask me how I know... And no, the resolution (GPS position) on most data systems is NOT close enough to judge the difference between turn-in points that are 2' or so apart, particularly in different sessions or on different days. That's up to net lap times and the video camera.

 

[csamsh]

[/thread]

 

[kcbrown]

If we assume that the designers of both vehicles A) know the spring rates to be used and B) can calculate "critical damping," then we have a problem, since the characteristics of the two cars are radically different. IMO, it's one of the following:

1) Either the gangsters in Detroit or the engineers in Bavaria are unable to use a calculator and got the math wrong. Very unlikely.
2) "Responsiveness" and "Comfort" are diametrically opposed goals requiring radically different damper tuning. Very likely.
3) "Critical damping" isn't so critical. Possible.

I'm inclined to say that option 2 is likely to be the correct one, but only because the nature of the modern suspensions (i.e., the use of springs and dampers) is such that it necessitates such a compromise. Which is to say, you have to use some minimum spring rate when you have a given amount of suspension travel available, else you're going to be on the stops all the time (which is inherently uncomfortable, as it's an abrupt transition), and any compression damping on top of that will of necessity result in greater resistance of the suspension to bumps, and that resistance automatically translates to felt vertical acceleration in the cabin.

However, that doesn't mean that the M3 in your example is going to be overdamped! Rather, I expect that the chances are good that it's using fairly high spring rates combined with the correct amount of damping (around 0.7 of critical) in order to minimize the amount of time it takes for the suspension to take a set and to deal with bumps that come its way. Which is to say, the hardness of its suspension very likely comes from the spring rates, not the dampers.

If we define critical damping as simple control over the springs, to prevent excess vehicle oscillation after suspension jounce or rebound, then neither car really meets that definition.

Critical damping actually has a mathematical definition: http://en.wikipedia.org/wiki/Damping#Critical_damping_.28.CE.B6_.3D_1.29

It turns out that, for suspensions, you don't want your damping to be quite at the critical level. Well, okay, you certainly can, but if you do so, you'll be slowing down the suspension a little more than necessary, which will make for a harder ride as well as a potentially slower-responding suspension under certain conditions.

If you look at the graph in this, you'll see that the point in time that the suspension returns to steady state is essentially the same when at both critical damping and 0.7 of critical damping. The difference is that the 0.7 case overshoots slightly. But that it's overshooting means that it's passing through the steady state location earlier (in about half the time), which may have some advantages for dealing with variable-frequency imperfections in the road surface. It also means that you have that much less harshness while not really giving up anything in terms of suspension responsiveness.

Your point about springs is well taken, I may add. Yes, given that force remains the same, the higher spring rate will "take a set" more quickly. I'll also go as far as to say that the higher spring rate MAY also contribute to more NVH, and thus lessen the "ride quality."

Yep. I'm going to be very interested to see if the coilovers wind up giving me a better ride quality. That's one of my goals, of course.

Speaking of somebody who HAS rebound-adjustable dampers, that little knob does make one HELL of a difference to both lap times and lack of bloody urine. I have found that my track settings are miserable on the street, and my street settings are so bad on track that "pathetic" would be too kind a word. Note that this is with rebound-adjustability only. I can only imagine (and drool over) what kind of control you would have with triples, where you can completely control the low-speed circuit, AND have some control over the high-speed circuit as well...

I'm awfully tempted to go with fully controllable dampers, but not only they stratospherically expensive, they also tend to be limited in terms of their warranty. They're rebuildable, but if something breaks, you're out the money, and that's that. That's one of the reasons I'm going with the Ground Control coilovers. While they may be less expensive and some will scoff at them because they're not monotube dampers, they carry a lifetime warranty, and GC will build the coilovers to my specifications, including centering the rod extension to my chosen ride height. All other coilover systems I've seen assume you're going to be lowering the car by at least an inch, and thus fail to meet my needs. My ride height is remaining stock (I may lower about 1/4 inch just for aesthetics, but no more than that), both for practical daily driving reasons (speed bumps and steep driveways ) and for suspension geometry reasons (mainly, location of the front roll center).

I think your plan of going directly to coil-overs is the right one. You can simply and easily (cheaply!) play with spring rates, and if you get triples, you can play with damper curves to your heart's content. Either way, I think you'll find you'll need very different settings to really carve corners and to have a nice, cushy ride.

That is a real possibility.

Even so, I'll say again that I remain extremely impressed with the stock suspension. It has me scratching my head wondering what all its detractors are on about.

So, what are you waiting for???

It won't be long now! I'm going to be making that move in October. I've got two more track events coming up between now and then, and an Evolution driving school in November. The Evolution school is perfect for playing with a new suspension setup -- perfectly safe, lots of seat time, lots of variation in the types of corners one has to handle, etc. So October is the perfect time to do the upgrade. I need to find out how much lead time is going to be needed for these.

Up until now, my main question was what spring rates to run, but everything I've computed so far (total front versus rear spring rate differences and ratios, which includes the sway bars; ride frequency ratios; etc.) says that 250 in the front and 325 in the rear will get me characteristics that are a close match to what I already have, and I really like how the stock suspension behaves. Interestingly enough, I'll only get an additional 20% of roll resistance out of this setup, but twice the dive and squat resistance. With dampers that have an appropriately reduced bump rate and an appropriate amount of rebound rate (about 65% of critical!

), I anticipate the end result should be very good for both ride quality and handling.

Oh, and driver mod: Seat time is everything. The more comfortable you are out on track, and the more experience you have, the less you have to think about what you're doing, and the more consistent you become. THAT is where changes made to the car will show up.

Yep. I've already been to:

• 2 NASA events at Sonoma Raceway
• Evolution driving school (2 days)
• Simraceway driving school (at Sonoma Raceway), stages 1, 2, and 3.

I've got coming up:

• NASA at Thunderhill
• NASA at Sonoma Raceway
• Evolution driving school (2 days)
• Another Simraceway stage 3 (which is basically a big pile of track time -- 5 sessions of 25 minutes each).

And that's just this year.

Basics, like getting enough negative camber are not about going faster necessarily, you're going to do that anyway as you accumulate experience, but are about protecting the tires. In your case, doing camber and swapping the dampers out will accomplish the same thing.

I would expect to get a little more oversteer out of it too, yes? After all, you're making more use of the front tires, I'd think.

Get the camber you need, find a good compromise setting on the dampers, and then LEAVE THEM ALONE!! Resist the urge to touch them unless and until you can say with complete honestly that you are driving beyond the capability of the suspension tuning to support. Then prove it to yourself by ripping off a string of laps where each sector is consistent in time. THEN tune and assess the validity of the change.

That is exactly my plan.

And that's why I raised my question in the first place. I want to get the damper settings right the first time, so that I'm not fighting some undesirable damping characteristics of the suspension while I learn.

Don't bother with lap times or data acquisition, though, until you have figured out that whole pesky "outside-inside-outside" thing and have pretty consistent (deep!) braking points. Lap times and data are great for refining, but you have to have the basics down first. Oh, and run video at the same time. NOTHING is more frustrating that looking at the data and realizing that you just cut 2/10ths out of a corner but not knowing how you did it.... Ask me how I know... And no, the resolution (GPS position) on most data systems is NOT close enough to judge the difference between turn-in points that are 2' or so apart, particularly in different sessions or on different days. That's up to net lap times and the video camera.

I'm not sure I'll ever get to the point where my braking points are truly deep. I intentionally leave a lot on the table for a couple of reasons. The first is safety. Even with my braking being intentionally conservative, I've nearly gone off the track as a result of having my attention diverted. The second is control. If I begin my braking early, it allows me to more finely tune my speed at the turn-in point, while braking later means I have that much less to work with for fine-tuning.

But even with that, I think I should be able to gain the needed consistency with experience.