[Mountain]

Originally Posted by Msquared

As quote above, the SS 1LE spring is 3x stiffer than the front, whereas the ZLE rear spring is only 2.4x stiffer. So you could be right. But...then the non-1LE SS rear spring is even stiffer than the SS 1LE! So that seems incorrect.

Why?

[I think your point is based on an assumption in your thinking.]

Originally Posted by Msquared

Again though, I'm guessing those rears use true coilovers as opposed to the inboard/separate spring, right? So the rear spring rates are for a much higher motion ratio than either 1LE.

Correct. They do. I inserted the point as a pure "point of interest". That's simply it. i.e. "Here's what P&M did for the actual GT4 race car..."

Originally Posted by ddipaola

The SS base and 1LE rates were pulled right here off the forums. I found them hard to believe as well because they use the same suspension geometry. That seems to be the only data out there on the 1LE. I'll give the search another whirl though. I'm pretty sure it's a single-stage spring. If it was dual rate I could see the problem, but I think that's N/A here.

Here's why I believe the SS 1LE rear spring rates aren't what is stated commonly on this forum and on the one spring test someone did:
1. Eibach, long ago, stated the OE rates of the "RS", SS, SS 1LE and ZL1 cars.
Here is a post about it on Camaro6:
https://www.camaro6.com/forums/showp...78&postcount=2
2. The Eibach noted spring rate for the rear of the SS 1LE matches up with the R&D that Powell Race Parts did for the YYZ springs:
https://zzperformance.com/products/c...racing-springs
https://wildhammermotorsports.com/16...ll-race-parts/
3. The one posted spring test by a member on Camaro6, that was done a long time ago, is a bit suspect... look at the graphical output he posted for the front - he was questioned about it (think about the vehicle corner weight) and a complete answer was never posted. So, that data, I am suspicious about.
https://www.camaro6.com/forums/showthread.php?t=475647
4. It's entirely possible that GM changed something with the particular spring being used for the SS 1LE: 100%... GM used, at least for 2017 SS 1LE, the same spring in the rear as the ATS-V. It is a shorter spring than the SS and ZL1 rear springs. I personally checked this on a variety of other 2017 SS 1LE cars. I have not bothered to check any of the 2018+ SS 1LE's. We know GM messed up the front spring on the first MY of ZL1. It's entirely possible something was "adjusted" for 2018+ SS 1LE.

That is why I want to check this for myself and against a few other rear springs; so, even if one wants to scrutinize the equipment and method I have the springs checked, at least it can be comparable between several.

But why? Because I want to understand the bookend setup at which the SS 1LE is at, at least 2017 MY (my MY).

[kropscamaro16]

Originally Posted by Msquared

As quote above, the SS 1LE spring is 3x stiffer than the front, whereas the ZLE rear spring is only 2.4x stiffer. So you could be right. But...then the non-1LE SS rear spring is even stiffer than the SS 1LE! So that seems incorrect.



Again though, I'm guessing those rears use true coilovers as opposed to the inboard/separate spring, right? So the rear spring rates are for a much higher motion ratio than either 1LE.

i have a true coilovers with my mcs kit and again i run 700f/800r might upgrade to stiffer springs this year and see how the car runs but i still drive it on the streets so didnt want to go too stiff

[Msquared]

Originally Posted by Mountain

Why?

[I think your point is based on an assumption in your thinking.]

Why do I think it's incorrect that the regular SS has a stiffer rear spring than the SS 1LE? Because the 1LE as the "track option" is generally stiffer all around than the regular SS. They both have the same motion ratio (same LCA) and therefore if the SS has a higher spring rate than the 1LE, it will also have a higher rate, and that would be unexpected. The 1LE has a lower ride and therefore less compression travel, so it would also make sense that it needs a stiffer spring rate to avoid bottoming out more often than the SS.

It's not impossible that the SS actually uses a stiffer spring, but it would be a surprise. My guess is that the quote rear spring rate for the SS 1LE is not correct: I would expect it to higher, somewhere between the SS and ZLE spring rates as are the fronts. It wouldn't be hard to confirm/refute this: just compare the number of active coils and the wire diameter for the SS and SS 1LE springs. If I'm right, the 1LE will have fewer active coils, thicker wire diameter, or both. The fact that its ride height is lower right away tells us probably has fewer active coils. But...if someone can prove otherwise, I will stand corrected.

[Mountain]

Originally Posted by Msquared

Why do I think it's incorrect that the regular SS has a stiffer rear spring than the SS 1LE? Because the 1LE as the "track option" is generally stiffer all around than the regular SS. They both have the same motion ratio (same LCA) and therefore if the SS has a higher spring rate than the 1LE, it will also have a higher rate, and that would be unexpected. The 1LE has a lower ride and therefore less compression travel, so it would also make sense that it needs a stiffer spring rate to avoid bottoming out more often than the SS.

It's not impossible that the SS actually uses a stiffer spring, but it would be a surprise. My guess is that the quote rear spring rate for the SS 1LE is not correct: I would expect it to higher, somewhere between the SS and ZLE spring rates as are the fronts. It wouldn't be hard to confirm/refute this: just compare the number of active coils and the wire diameter for the SS and SS 1LE springs. If I'm right, the 1LE will have fewer active coils, thicker wire diameter, or both. The fact that its ride height is lower right away tells us probably has fewer active coils. But...if someone can prove otherwise, I will stand corrected.

Exactly what I thought you'd say.

You have to consider, SS vs SS 1LE, the design goals by GM. To which you, nor do I, completely know. We can only make a strong assumption based on what the Camaro team has commented on, the noted purpose of the trim and also in how exactly the cars are equipped and what that suggests. The two vehicle trims, SS and SS 1LE, definitely have two different criteria looking at sway bars alone; suggesting that the difference in the two isn't as simple as a "step-up" but, instead, two very distinct and differing purposes that require two different setup strategies... ​

You cant look at the SS as "PP1" and the SS 1LE as "PP2" (see what I did there). It's more like "PP1" vs "TP1"... Just like the ZL1 1LE isn't just the level up ZL1, it's a completely different vehicle strategy.

It makes total sense to me that GM could possibly go with a slightly softer spring on the SS 1LE for track use: a softer spring will be able to put down power better in more dynamic circumstances. Especially so with a high low-end-torque engine that needs to be fairly user friendly and driveable on public roads every day (where the ZL1 1LE completely diverges from on purpose).

Maybe I'm wrong and the SS 1LE springs are actually stiffer. That's the question I want to answer. Im fine being wrong. But keep in mind, we have two sources (Eibach and Powell Racing) that have results nearly identical in conclusion and one source (unknown independent shop) saying different...

Diameter and coil count are one part, but material type, material conditioning and overall free height are others.

(Considering vehicles of the same weight, same engine, same transmission and same basic suspension and chassis design)
SS = sporty everyday car directed at multi-enthusiast use:
Contact patch split = -30mm (front:rear)
Sway bar split = 450 lbs/in (front:rear)
Spring split = -440 lbs/in (front:rear)
Bar+Spring Split = 10 lb/in (front:rear)

SS 1LE = sporty everyday car directed at circuit track use:
Contact patch split = -20mm (front:rear)
Sway bar split = 569 lbs/in (front:rear)
Spring split* = -361 lb/in (front:rear)
Bar+Spring Split = 208 lb/in (front:rear)

*based on so far suggested information*

GM went to less stagger (less front:rear tire split) on the SS 1LE and also added a bunch of roll stiffness up front compared to the SS. Doing so with more of a split with sway bars (+116 front split) and less with springs (+79 front split)... So not a significant jump in global coil spring rate. Yes, the tires are sticker, but the main focus should be on how the vehicle is balanced or acts. We can't just assume "+more" and "1 level up"... Two different criteria for two different vehicle applications.

[Msquared]

Originally Posted by Mountain

We can only make a strong assumption based on what the Camaro team has commented on, the noted purpose of the trim and also in how exactly the cars are equipped and what that suggests.

I agree we can't know what they wanted for sure, but we can make strong assumptions given that the SS is the less track-oriented version and would therefore normally be set up to ride softer. This is almost universally the case for two versions of the same model car. Also, again, it rides higher and therefore needs less spring rate to avoid bottoming out. And you brought up how the cars are equipped, which is a good point: the 1LE has nearly 100lbs of extra coolers and other stuff, and therefore it would naturally be expected to have stiffer springs for the extra load just to keep the same suspension frequency (not to mention making it stiffer for track use).

Maybe I'm wrong

Ditto: I could be wrong too. But if so this would be one of the only car models in history where its track package (or any high performance handling option) would have softer springs than the regular version, and it would definitely be the first time a 1LE package did.

But keep in mind, we have two sources (Eibach and Powell Racing) that have results nearly identical in conclusion and one source (unknown independent shop) saying different...

I can't find the Eibach info outside of that thread found on this forum. The links from there don't seem to work anymore. I was never able to glean much from the Powell graphs because other than their own spring, none were labeled. However, maybe I can guess and you can confirm? There is "OEM": is that supposed to be the SS spring? And is "Brand P" supposed to be the SS 1LE spring? If so, then can I correctly infer that "Brand M" is the ZLE spring?

If those charts include the various OE spring options, then I think I see the problem. Take a look at that chart again and you'll see that:

• For the front springs, "OEM" is about 178lb and "Brand P" is about 137lb, which corresponds to the ddipaola's chart in post #1. However,
• For the rear springs, "OEM" shows about 500lb on the chart and "Brand P" shows about 450lb. Not only are those numbers significantly different than ddipaola's chart, but they are flipped in terms of which "brand" is higher.

IOW, if “OEM” is the 1LE spring set on the charts, then it is stiffer than the SS both front and rear. If “Brand P” is the 1LE spring set, then it is softer than the SS both front and rear. But either way, there is no case where the 1LE spring is stiffer in front but softer in back, or vice versa. "OEM" and "Brand P" are flipped by accident in one of their two charts. My guess is that "OEM" is really the SS 1LE spring set and "Brand P" is the SS set.

Diameter and coil count are one part, but material type, material conditioning and overall free height are others.

Nah, these springs are all made from substantially the same steel. Their modulus is the same. Free length is not pertinent to spring rate. Mean diameter of the coil is pertinent, and I left that out because I ass-umed they would be the same for SS and 1LE springs, but that should be measured instead of assumed. The whole formula for spring rate (k) is Gd^4/(8D^3*na), where G is the shear modulus, d is wire diameter, D is mean diameter of the coil, and na is the number of active coils. All we need to do is measure the wire diameter, mean diameter, and active coils of both springs and we'll know which one is stiffer. Anyone who's pulled their stock springs for upgrades could do this for us.

[Mountain]

I won't get into commenting the Powell charts too much, as the description talks about the "OEM" spring and the "Brand M", but the other springs are supposed to be aftermarket lowering springs.

You are right that the coils are most likely going to be the same material and conditioning.

The ZL1 coupe rear springs and SS coupe rear springs have the same diameter, number of coils and free height. They differ in coil diameter: the ZL1 coil diameter is actually a touch less than the SS coil diameter. Both have consistent coil diameters. They are pure linear springs it seems.

>The SS rear spring should be a little stiffer than the ZL1 rear spring.

However, the SS 1LE rear spring is not as directly comparable: the diameter tapers from starting at the same diameter as the ZL1/SS rear spring to a larger one, the spring has one less coil, but the same free height, and the coil diameter is progressive (although overall larger than the SS and ZL1).

>The SS 1LE spring should be stiffer than the ZL1 and SS rear springs, but is a progressive spring.

[kropscamaro16]

Originally Posted by Mountain

I won't get into commenting the Powell charts too much, as the description talks about the "OEM" spring and the "Brand M", but the other springs are supposed to be aftermarket lowering springs.

You are right that the coils are most likely going to be the same material and conditioning.

The ZL1 coupe rear springs and SS coupe rear springs have the same diameter, number of coils and free height. They differ in coil diameter: the ZL1 coil diameter is actually a touch less than the SS coil diameter. Both have consistent coil diameters. They are pure linear springs it seems.

>The SS rear spring should be a little stiffer than the ZL1 rear spring.

However, the SS 1LE rear spring is not as directly comparable: the diameter tapers from starting at the same diameter as the ZL1/SS rear spring to a larger one, the spring has one less coil, but the same free height, and the coil diameter is progressive (although overall larger than the SS and ZL1).

>The SS 1LE spring should be stiffer than the ZL1 and SS rear springs, but is a progressive spring.

haha that powell chart is color coded btw if that helps

[Msquared]

Originally Posted by Mountain

I won't get into commenting the Powell charts too much, as the description talks about the "OEM" spring and the "Brand M", but the other springs are supposed to be aftermarket lowering springs.

Okay, so maybe I'm missing it, but if we don't know what springs are what on the Powell charts, then it can't serve as a reference for this discussion, can it?

The ZL1 coupe rear springs and SS coupe rear springs have the same diameter, number of coils and free height. They differ in coil diameter: the ZL1 coil diameter is actually a touch less than the SS coil diameter. Both have consistent coil diameters. They are pure linear springs it seems.

>The SS rear spring should be a little stiffer than the ZL1 rear spring.

If the SS coil's mean diameter (D) is larger than that of the ZL1 spring and all else is equal between the two, then it is softer than the ZL1 spring, not stiffer.

However, the SS 1LE rear spring is not as directly comparable: the diameter tapers from starting at the same diameter as the ZL1/SS rear spring to a larger one, the spring has one less coil, but the same free height, and the coil diameter is progressive (although overall larger than the SS and ZL1).

>The SS 1LE spring should be stiffer than the ZL1 and SS rear springs, but is a progressive spring.

The mean diameter does change for the SS 1LE rear spring. Strange. Not sure why they'd make them that way. But that doesn't make it progressive, and when F1FTY tested them they proved to be linear at 539lb/in. One less coil may or may not make up for the increased mean diameter: without exact measurements it'd be hard to say. Also, we don't know the wire diameter I guess, compared to the regular SS spring. So...I don't know.

I did think of one reason that the SS 1LE spring might actually be softer than the plain SS spring: the presence of MRC damping on the 1LE. Chevy may have actually wanted a little more movement in order to have more control over the handling balance with the dampers back there. Maybe. I've seen inferences that the rear spring rate for the SS non-1LE but with MRC is different. Lots of factors to consider!

[kropscamaro16]

Originally Posted by Msquared

Okay, so maybe I'm missing it, but if we don't know what springs are what on the Powell charts, then it can't serve as a reference for this discussion, can it?


If the SS coil's mean diameter (D) is larger than that of the ZL1 spring and all else is equal between the two, then it is softer than the ZL1 spring, not stiffer.


The mean diameter does change for the SS 1LE rear spring. Strange. Not sure why they'd make them that way. But that doesn't make it progressive, and when F1FTY tested them they proved to be linear at 539lb/in. One less coil may or may not make up for the increased mean diameter: without exact measurements it'd be hard to say. Also, we don't know the wire diameter I guess, compared to the regular SS spring. So...I don't know.

I did think of one reason that the SS 1LE spring might actually be softer than the plain SS spring: the presence of MRC damping on the 1LE. Chevy may have actually wanted a little more movement in order to have more control over the handling balance with the dampers back there. Maybe. I've seen inferences that the rear spring rate for the SS non-1LE but with MRC is different. Lots of factors to consider!

lol i know which ones are which

[Msquared]

Originally Posted by kropscamaro16

lol i know which ones are which

All we really need to know is whether any of them are the regular SS springs and/or the SS 1LE springs.

[Mountain]

Originally Posted by Msquared

Okay, so maybe I'm missing it, but if we don't know what springs are what on the Powell charts, then it can't serve as a reference for this discussion, can it?


If the SS coil's mean diameter (D) is larger than that of the ZL1 spring and all else is equal between the two, then it is softer than the ZL1 spring, not stiffer.


The mean diameter does change for the SS 1LE rear spring. Strange. Not sure why they'd make them that way. But that doesn't make it progressive, and when F1FTY tested them they proved to be linear at 539lb/in. One less coil may or may not make up for the increased mean diameter: without exact measurements it'd be hard to say. Also, we don't know the wire diameter I guess, compared to the regular SS spring. So...I don't know.

I did think of one reason that the SS 1LE spring might actually be softer than the plain SS spring: the presence of MRC damping on the 1LE. Chevy may have actually wanted a little more movement in order to have more control over the handling balance with the dampers back there. Maybe. I've seen inferences that the rear spring rate for the SS non-1LE but with MRC is different. Lots of factors to consider!

Re-read what I wrote

I have the three springs now. Just trying to lock down a place to have them tested.

[Mountain]

Originally Posted by kropscamaro16

haha that powell chart is color coded btw if that helps

Noticed that.

Between that and the published comments…

[Msquared]

Originally Posted by Mountain

Re-read what I wrote

You wrote "...the ZL1 coil diameter is actually a touch less than the SS coil diameter." That means the ZL1 spring is stiffer since all the other parameters that affect spring rate are identical.

On the SS 1LE spring, I guess when you wrote "...the diameter tapers from starting at the same diameter as the ZL1/SS rear spring to a larger one," you were referring to the wire diameter (d)? I assumed otherwise, because it's really rare and expensive to make a spring that way and I can't really see a good reason to do that. But okay, if that's the case, and considering that stiffness is a function of d^4 and that there is also one less coil, that almost guarantees that the SS 1LE spring is stiffer than the regular SS spring. Obviously measurements could still say otherwise, but I wouldn't bet on it.

BTW, even a progressive wire diameter doesn't really guarantee a progressive spring rate. It's only progressive if the softer portions of the spring actually collapse into coil bind through the car's suspension travel. I doubt that happens in this case, but again, without measuring it's impossible to know for sure. Again I noted that F1FTY measured them and found them to be linear.

I would be very interested in your findings if you are able to actually measure the various OE springs.

[kropscamaro16]

they used my old oem springs to testfit and i sent him my old afe springs are orange aka orange line