Options for ECS struts and other concerns

**2fnloud** · 02-05-2012, 08:16 AM

I was asked to bring this out of the PM system and make a thread for all to see, so here it is directly pasted from the PM that I sent to DG.

DG,

Thank you for the reply,

I am definitely looking for more than "cosmetic lowering". On the flip side I am not looking for what Rakuny is trying to accomplish.

Brief story:

I happen to have a 1994 Stealth R/T TT Hennessey tuned stage 5 3s, The Hennessey part is cool, but I know that he barely scratched the tip of the iceberg in unlocking a 3S's potential. So combine that part of the car's history with the fact that the car only has 30,xxx original miles....I have a BEAUTIFUL example of the 3S platform.

My Goal: As I improve the car's performance, be it engine, suspension, breaks. Is to keep every function that the car came with. For example right now the car has the HKS D2 exhaust. In doing this the Active Exhaust was removed. My solution when I add my Stillen D/P is to also install an electronic cut off valvethat is wired to the A/E switch, thus bringing back the A/E feature of the car.

For what it is worth, 3S gatherings are probably the only events that I will track the car.

So now understanding my car and my goals, you can see that a non-ECS strut is not an option for me.

I would be willing to corner weight my car, honestly had to read up on what that was exactly, My assumption was correct on how you weigh it, just had no clue how you compensated for it, still kind of confused. Are you slightly raising / lowering the height of the C/O lspring perch to shift the weight around? That was the impression that I got after reading the article.

Also in your reply about OD of the shock matching Bilstein or Koni, do that make a insert that is compatible with the 3S ECS system?

Finally, you mention of the upper spring perch, I am not following. Granted all my research at this point is what others have done vs. what I have done, so if I tore into the project I would probably know what you are referring to.

Anyways the information shared on the website Stealth316 He made no reference to having issues with his "upper spring perch. The only thing I see that he didn't do but should of, was to install helper springs to keep the C/O sleeve system in a load while the car is the air be it on a hoist or from extreme cornering. Is there anything else that was over looked that you see?

My other concern is the spring rates that he listed for the GC springs that he used and what he plans on using. With my limited understanding, and I do mean limited, I was under the impression that there is a balance between a struts bound and rebound rate and the spring that is mounted to the strut.

At what spring rate does the spring become too high for a ECS strut properly dampen? or is my understanding flawed?

Again thank you for your insight.

DG · 02-05-2012, 09:00 AM

Corner weighing: what you are doing is changing how much load is carried by each tire by changing the amount of spring preload on each corner - effectively, you are changing how hard each spring is pushing up on that corner of the car. This is done to attempt to ensure, as much as possible, that dynamic weight transfer affects the car equally in either direction. On a car whose CG is offset, either front/back or left/right, you can't get there from here, but you can at least prevent (or reduce) the amount of fore/aft change that happens with left/right load and vice versa.

More info here: Autocross to Win (DGs Autocross Secrets) - Corner Weights

Aftermarket shocks compatible with ECS: almost certainly not - at least, not off the shelf. The ECS shocks are basically single-adjustable, rebound bleeds with a motor attached to the adjuster. The motor is synchronized to the adjuster so that it can set the shocks on full hard, full soft, or an intermediate setting. It really is a VERY simple system.

In theory, either a Koni or a Bilstein (fitted with their new adjustable shaft) or even an Ohlins or Penske for that matter, could be adapted to the ECS. You'd have to see just how much the rotor turned the adjuster for each setting, and you'd need some sort of adaptor made to fit the motor drive interface to the aftermarket adjuster interface. Then you have to tune the adjuster itself to produce the forces that you want at the settings where the motor is going to turn it.

Doable? Yes. Feasible? That's a lot of engineering for a super-niche product. You won't be able to sell any because it will be super expensive and people balk at paying money for suspension (that's how Megan, JIC, Buddy Club, Tein etc stay in business - people will happily buy shit if it is cheap shit) You won't get a shock manufacturer to step up and build it for the same reason. So you'll have to do it yourself....

I wouldn't do it, myself. But then I also understand that the 3S is a GT car, not a race car, so I'm less inclined to go down that rabbit hole.

The normal reason for fitting stiffer springs is that the tires are so sticky that lateral G capability is much higher than the car was designed for. Accordingly, the resultant roll angles get much larger and that drags the suspension around with it and pries the tire contact patch off the ground. Along with this, race cars are usually so low to the ground that there isn't much room for suspension travel so stiffer springs are needed to keep the chassis off the track surface.

Neither of these apply to a street car, even a street car that sees track use, assuming it keeps the street tires. You just aren't going to generate race car levels of lateral G, nor are you going to be an inch off the ground, so you don't need race car natural frequencies. Keep in mind that it is the rare street car that can hit 1.0 lateral G. My race car would see 1.7G peaks and could sustain 1.35-1.37. You aren't in that business and never will be - so don't worry about it.

Keep in mind too that the OEMs design the car to work both with a 155lb driver and a couple of gallons of gas, all the way up to four American passengers with a full tank of gas and a load of luggage (I wonder if there is an SAE standard for a typical max passenger load?) The car will be optimized for a specific case but needs to be acceptable over that entire range - that's like a 1000lb weight swing, with the according changes in location of CG. That useful range is why the cars sit so high unloaded, and why more modern cars have fenders that hide the gaps when unloaded. If you choose to optimize for a more specific case, you do so at the expense of some of this operating range.

That same wide operating range is what makes the ECS option such a good one - as long as you keep the changes reasonable, the ECS will still work reasonably well. The more extreme you get, the more likely you are that the design envelopes for car and ECS will diverge.

The upper spring perch on OEM cars is usually designed to fit a pigtail spring, so there is a rubber (or steel) spring socket that fits a pigtail. Race car standard springs are ground flat, so now you have to fit a flat surface into a non-flat receptacle. Depending on the actual design of the spring perch, this may or may not be a big deal. I haven't disassembled one (I have ECS, so no need) so I don't know specifics. But I've done enough cars to know that fitting the coilover sleeve is the easy part, it is the upper perch where the devil lurks.

Similarly, I've never dynoed an ECS shock so I don't know the specific rates for which its operating envelope will cover. I have studied the Mitsu docs on how it works, so I know it is a rebound-only system (Mitsu publishes typical shock dyno curves at each setting, but with no units)

My honest advice to you, given the nature of your car and how you intend on using it, is to keep the OEM ECS and use a decent quality lowering spring like an Eibach or an H&R to compensate for wheel gap. Then, if the thing is still rolling too much on the track, pick up a slightly thicker front roll bar and install it for track days, and call it a day.

That's my plan. I have no need nor desire to go down the coilover route.

If I didn't have ECS, I'd do Bilsteins, which makes doing coilovers trivially simple in the rear (with the one caveat of the upper spring perch) and maybe in the front if I really felt like burning money for no real reason.

And if I felt like racing the car.... I'd go lie down until the feeling went away. There are far better choices for a race car than a 3S.

DG

**J. Fast** · 02-05-2012, 10:44 AM

The front ECS strut has a 5" diameter spring that's offset. There's a pocket that locks the spring in place and keeps it from rotating or escaping the perch. A bilstein spring, GC or whatever, doesnt have that so you need to modify the perch to ensure the spring is in full contact 360 degrees at both ends. It's imperitave the force is equally distibuted at the upper and lower perch. Additionally, you have to ensure it can't escape. That's what it means to modify the perch: cut and weld, dissasemble and have perches machined, or fab something up on your own.

If you're sticking with the ECS and are doing a spring ONLY change you can use something like this as a guideline for selecting a spring. I't a Claude Rouelle Spring and Dampener Tech Tip.

http://www.optimumg.com/OptimumGWebS...Tech_Tip_1.pdf

DG · 02-05-2012, 11:53 AM

**B-Man** · 02-05-2012, 12:36 PM

Originally Posted by DG

And if I felt like racing the car.... I'd go lie down until the feeling went away. There are far better choices for a race car than a 3S.

DG

Curious what you'd race instead of a 3S in the same price range.

Originally Posted by DG

And I have one of those from an SAE seminar, doesn't mean I retained any of it :P

I know you know what you're doing. I've used your site many times in the past couple years, but you seriously take all the fun out of owning a car :P

DG · 02-05-2012, 01:08 PM

Curious what you'd race instead of a 3S in the same price range.

Formula Ford. Older Formula Atlantic. Spec Racer Ford. Spec Miata. Anything NASCAR.

but you seriously take all the fun out of owning a car

Would you play golf with a hockey stick?

Would you play baseball with a tennis racket?

Would you go bowling with a curling stone?

Let me tell you, from experience, it is way, WAY more fun to show up at a gunfight with a gun than to try and hammer a knife into a gun. You go faster, sooner, and spend a tiny fraction of the money.

My DSM, at the point when I sold it, was a teensy tiny bit faster than an C5 Z06 Corvette in aggregate, and in the right circumstances (rain) could hammer the living daylights out of it. To get it there, I spent probably three times as much money as I would have spent had I just bought a Z06 and been done with it AND I would have won more races.

Let me put it this way - I would have had every bit as much fun and spent as much money had I bought three Z06 Corvettes and set two of them ON FIRE as I did hammering that DSM into a race car.

And a 2G DSM is a MUCH better starting point for a race car than a 3S, by virtue of a much better suspension, starting off much lighter, and having cheaper (read: less expensive) parts overall. That is, of course, two slightly different flavours of "turd"....

If you want to spend money and time on a 3S because you like the car and you want to see how far you can take it... hey man, knock yourself out. People soup up lawnmowers fer crissakes, who am I to throw rocks at you for the 3S. But if your intent is to go racing so you can WIN, then you need to get over the "platform loyalty" thing and go looking for simple, cheap, popular, and fast.

Race cars are TOOLS, not fetish objects. They are ultimately disposable. If you are not in a position where you can light it on fire and walk away, then it isn't a race car.

I got caught where my "fame" (small "f". Really small "f") was tied too closely to the platform. All my sponsors were DSM guys, and I could not afford to walk away from them. So I had no choice but to turd polish like a madman to keep up with (and ultimately defeat) the M3s and S4s and Supras that were the big dogs in my series. I wanted nothing more than to jump into an M3...

I would spare all y'all that if I could.

DG

**B-Man** · 02-05-2012, 01:27 PM

Originally Posted by DG

Formula Ford. Older Formula Atlantic. Spec Racer Ford. Spec Miata. Anything NASCAR.

Would you play golf with a hockey stick? Yes

Would you play baseball with a tennis racket? Yes

Would you go bowling with a curling stone? OMFG Yes

Let me tell you, from experience, it is way, WAY more fun to show up at a gunfight with a gun than to try and hammer a knife into a gun. You go faster, sooner, and spend a tiny fraction of the money.

My DSM, at the point when I sold it, was a teensy tiny bit faster than an C5 Z06 Corvette in aggregate, and in the right circumstances (rain) could hammer the living daylights out of it. To get it there, I spent probably three times as much money as I would have spent had I just bought a Z06 and been done with it AND I would have won more races.

Let me put it this way - I would have had every bit as much fun and spent as much money had I bought three Z06 Corvettes and set two of them ON FIRE as I did hammering that DSM into a race car.

And a 2G DSM is a MUCH better starting point for a race car than a 3S, by virtue of a much better suspension, starting off much lighter, and having cheaper (read: less expensive) parts overall. That is, of course, two slightly different flavours of "turd"....

If you want to spend money and time on a 3S because you like the car and you want to see how far you can take it... hey man, knock yourself out. People soup up lawnmowers fer crissakes, who am I to throw rocks at you for the 3S. But if your intent is to go racing so you can WIN, then you need to get over the "platform loyalty" thing and go looking for simple, cheap, popular, and fast.

Race cars are TOOLS, not fetish objects. They are ultimately disposable. If you are not in a position where you can light it on fire and walk away, then it isn't a race car.

I got caught where my "fame" (small "f". Really small "f") was tied too closely to the platform. All my sponsors were DSM guys, and I could not afford to walk away from them. So I had no choice but to turd polish like a madman to keep up with (and ultimately defeat) the M3s and S4s and Supras that were the big dogs in my series. I wanted nothing more than to jump into an M3...

I would spare all y'all that if I could.

DG

Aha! I got you to say it.

I think that's what most people need to see. Find a setup that fits your car/needs. All of this work you're talking about is to get that last 10% out of a car. I'd much rather spend the $1200 on 'crap' and enjoy the car at it's 80%. I'm not trying to beat Z06s or win series (although that would be nice). I think most of the people here are in the same boat.

I find my car to be more of a learning exercise, and I want to make the mistakes like buying shit suspension to get a feel for what's good and bad.

My car actually is pretty disposable

Remember people, we're all free to have our own opinions

Alright, I'm off my soapbox. I'll let the two suspension threads go uninterrupted.

DG · 02-05-2012, 01:40 PM

I'd much rather spend the $1200 on 'crap' and enjoy the car at it's 80%.

The big problem with suspension is that we aren't talking about the difference between an 80% solution at the low end and a 99% solution at the high end.

The "crap" that is JIC, Tein etc etc is actually much WORSE than a straight up OEM replacement shock.

It's not like it is with, say, turbos, where you can do 13G and get a nice little upgrade without a lot of tradeoffs, as an intermediate step to the GT50000 Disco Rutabaga or whatever the hot single turbo is these days. Crap, when I talk suspension, really is CRAP.

If you want a simple upgrade, a set of OEM replacement shocks - by virtue of being newer and so not worn - plus a set of lowering springs, will do the job.

Want something a little better? Use the OEM replacement Bilsteins, with the OEM spring adapters they ship with, and a set of lowering springs.

Want coilovers so you can do corner weighting? Now you're going to start down the rabbit hole. Now you do OEM shocks with the GC sleeves and worry about the upper spring mounts - or you do Bilsteins with the Bilstein sleeves (which may require a new snap ring groove) - and you worry about the upper spring mounts.

Still not good enough? Retrofit ECS (and figure out the spring mounts) or start a Bilstein take-apart conversion (and figure out the spring mounts) etc etc etc.

There is no real off-the-shelf, buy-it-as-a-kit, intermediate-upgrade option.

DG