[Snrub]

That's pretty amazing that you had the rates determined for yourself. That's gold star level forum participation.

Interesting that the rear rates are actually lower for the 1LE than for the SS.

[tecmec]

Originally Posted by F1FTY

https://flic.kr/p/SNnvV3 front

https://flic.kr/p/SNnvU1 rear

Is that MRC or not?

Also, I'm new to this, but why does the label say 188.x, when the line itself seems to average just under 180?

Sent from my Nexus 6P using Tapatalk

[glenB]

Originally Posted by 00 Trans Ram

Yeah - something is off on Eibach's site. Is N/mm right, or lb/in?

REAR
40 N/mm = 228.4 lb/in, not 121
121 N/mm = 690 lb/in, not 2691

I'm thinking that the correct rates are 40/228.4 and 121/690. This is obviously a progressive spring. Meant for comfort, not performance.

Also, I don't believe the stock spring is a straight 577 lb/in rate. It's probably progressive, too.

The stock springs are linear, front and rear, including the Performance Lowering Kit

[F1FTY]

Originally Posted by tecmec

Is that MRC or not?

Also, I'm new to this, but why does the label say 188.x, when the line itself seems to average just under 180?

Sent from my Nexus 6P using Tapatalk

Yes, the 1LE comes with MRC.

I'll ask the shop that did the test when I pick the springs up next week.

[F1FTY]

Originally Posted by Snrub

That's pretty amazing that you had the rates determined for yourself. That's gold star level forum participation.

Interesting that the rear rates are actually lower for the 1LE than for the SS.

Thanks! Sometimes if you want something done, you gotta go and do it.

It is! It does makes sense considering the rear swaybar increase. Will measure SS bars once the kit is installed for a comparison.

[glenB]

Originally Posted by F1FTY

Thanks! Sometimes if you want something done, you gotta go and do it.

It is! It does makes sense considering the rear swaybar increase. Will measure SS bars once the kit is installed for a comparison.

The C6 base had a higher spring rate and smaller bar in the rear as well Vs the C6 Z51

Swapping out the rear 1le spring should be a 1 to 1 Vs the SS since the shock is separate. The fronts unfortunately is a different story because the MRC has a different spring pad height, or so I've read.

[F1FTY]

Originally Posted by glenB

The C6 base had a higher spring rate and smaller bar in the rear as well Vs the C6 Z51

Swapping out the rear 1le spring should be a 1 to 1 Vs the SS since the shock is separate. The fronts unfortunately is a different story because the MRC has a different spring pad height, or so I've read.

Interesting how GM does that to control the rear end dynamics between a sport setup and a performance one.

I was actually thinking about that the other night. If you have a 1LE, the rear SS springs might be an upgrade for you to get a little more oversteer.

If only we had MRC valving information between FE3 and FE4.

[Eric SS]

Originally Posted by F1FTY

Interesting how GM does that to control the rear end dynamics between a sport setup and a performance one.

I was actually thinking about that the other night. If you have a 1LE, the rear SS springs might be an upgrade for you to get a little more oversteer.

If only we had MRC valving information between FE3 and FE4.

Thank you for the spring info! I'd like to see the FE3 and FE4 springs next to each other to see if they are the same height or not. I'm really waiting for someone with a non-1LE SS to buy the FE4 suspension kit and put it on their SS to see if it alters the ride height.

[F1FTY]

Originally Posted by Eric SS

Thank you for the spring info! I'd like to see the FE3 and FE4 springs next to each other to see if they are the same height or not. I'm really waiting for someone with a non-1LE SS to buy the FE4 suspension kit and put it on their SS to see if it alters the ride height.

That's coming next...

I plan on having the suspension installed this month and will do height measurements and add that information to the first post.

I'll keep updating this thread for search reasons and plan on also including swaybar sizes and rates for comparison too. Eventually, building a spreadsheet.

Also will be testing the factory SS springs from the FE3 so we have graphs to compare. Each test costs me $43, so not a biggie

[F1FTY]

Originally Posted by tecmec

Is that MRC or not?

Also, I'm new to this, but why does the label say 188.x, when the line itself seems to average just under 180?

Sent from my Nexus 6P using Tapatalk

Follow up to your second question:

The real rate on these is that center flat section. The ramp up are when the spring is being compressed to load or at coil bind and those numbers don't matter for our uses.

I've corrected the front rate down to 178 lbs/in to reflect this.

Big thanks again to RRT for getting this done and explaining the graphs to me.

[Ryephile]

Originally Posted by F1FTY

I'll be adding factory SS graphs to this post in the future

Non-MRC SS Rates: 137 lbs/in (Front) 577 lbs/in (Rear)
Eibach Rates: 160 lbs/in (Front) 121-691 lbs/in (Rear)
1LE Rates: 178 lbs/in (Front) 539 lbs/in (Rear)

Eibach rear springs must be progressive

Factory SS and 1LE are basically linear


1LE Spring Rate Front


1LE Spring Rate Rear

Absolutely fantastic! Bravo for putting forth the effort to get the stock springs actually tested!

Wow only 3" of spring linear travel. Yikes. That's probably OK for the rear given it's motion ratio, but man that's very limited stroke up front.

[TheRealJA105]

Has anyone determined the ZL1 spring rates yet to compare?

[F1FTY]

Originally Posted by TheRealJA105

Has anyone determined the ZL1 spring rates yet to compare?

Not to my knowledge. If anyone wants me to get them tested for them, PM me and we can work something out. The test costs $43.xx and during race season may take a week or two.

I'd expect higher front rate for the ZL1 due to engine/supercharger/cooling weight.

[F1FTY]

Originally Posted by Ryephile

Absolutely fantastic! Bravo for putting forth the effort to get the stock springs actually tested!

Wow only 3" of spring linear travel. Yikes. That's probably OK for the rear given it's motion ratio, but man that's very limited stroke up front.

Thank you!

How did you determine the spring travel? What formula? Curious because I didn't know that could also be calculated from this!