Verifying Spring Rates
Thread Starter
TECH Junkie
iTrader: (32)
Joined: Sep 2005
Posts: 3,179
Likes: 2
From: Southside Chicago
Verifying Spring Rates Hey guys, I'll be switching my Strano's to stock springs soon and I've always wanted to know the actual spring rate of cut stock springs. Well I finally found a shop nearby that tests spring rates and we'll all finally know soon. I think the unofficial quote is roughly a 10% increase for every coil you remove. Let's see how true this holds up.
Stay tuned!
Stay tuned!
Staging Lane
Joined: Apr 2013
Posts: 65
Likes: 0
I'm interested.
My buddy just did 2 coils off the front of his z28. It was crazy low... Basically too low to drive. So I'd say between 1 and 1.5 coils ought to be safe. It'll be nice to know what the spring rate becomes.
My buddy just did 2 coils off the front of his z28. It was crazy low... Basically too low to drive. So I'd say between 1 and 1.5 coils ought to be safe. It'll be nice to know what the spring rate becomes.
The rate change is dependent on how much of the working spring you remove. If there are 10 working coils and you take 1 out, that's about a 10% bump. But 1 coil on a 12 coil spring is less than that. 
Also you need to test that very spring before you do anything to verify the actual rate, and you need to make sure you testing working rate on springs that are progressive.
Also you need to test that very spring before you do anything to verify the actual rate, and you need to make sure you testing working rate on springs that are progressive.
__________________
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion
Thread Starter
TECH Junkie
iTrader: (32)
Joined: Sep 2005
Posts: 3,179
Likes: 2
From: Southside Chicago
The rate change is dependent on how much of the working spring you remove. If there are 10 working coils and you take 1 out, that's about a 10% bump. But 1 coil on a 12 coil spring is less than that.
Also you need to test that very spring before you do anything to verify the actual rate, and you need to make sure you testing working rate on springs that are progressive.
Also you need to test that very spring before you do anything to verify the actual rate, and you need to make sure you testing working rate on springs that are progressive.
Anyway, with cut rear springs, my ride jumped back up roughly .75". Dammit! (Before with Strano's+Isolator: 27.25"; After with cut springs and HH mod: 28") I was hoping to test these springs tomorrow but it looks like I'm going to have to take 'em out, cut some more and test fit them first.
How much more should I cut off? A quarter of a coil, half?
Last edited by 02TransAm/Batmobile; Jul 12, 2013 at 01:13 AM.
TECH Senior Member
Joined: Jan 2004
Posts: 5,798
Likes: 16
From: St.Charles MO
I'll be installing stock springs so its baseline numbers are what, 292/114? Is that the actual rate you are talking about? GM rears are linear fronts and progressive rears right?
Anyway, with cut rear springs, my ride jumped back up roughly .75". Dammit! (Before with Strano's+Isolator: 27.25"; After with cut springs and HH mod: 28") I was hoping to test these springs tomorrow but it looks like I'm going to have to take 'em out, cut some more and test fit them first.
How much more should I cut off? A quarter of a coil, half?
Anyway, with cut rear springs, my ride jumped back up roughly .75". Dammit! (Before with Strano's+Isolator: 27.25"; After with cut springs and HH mod: 28") I was hoping to test these springs tomorrow but it looks like I'm going to have to take 'em out, cut some more and test fit them first.
How much more should I cut off? A quarter of a coil, half?
I think what Sam is saying is make sure to get a base line number before you cut because there are many variables at play here that could skew the numbers (much like getting a baseline dyno run).
What if you actually have LT1 springs? 1LE springs? What if the springs have just worn overtime and lost rate?
Get a base line to spring rate first, then cut, then get that spring rate to verify how much rate was actually gained.
Often, lowering springs are both shorter and higher rate.
So getting there by checkbook, or by cutting, what's the
diff?
Other than, you're figuring it out as you go, and could go
too far. And have only one degree of freedom. Where a
store-bought'n lowering spring, you can shop rate and
height independently.
But if you wanted 10% shorter and 10% stiffer, cutting
off 10% of the length would get you where you wanted
to go.
Problem being, most people don't really know what they
want.
So getting there by checkbook, or by cutting, what's the
diff?
Other than, you're figuring it out as you go, and could go
too far. And have only one degree of freedom. Where a
store-bought'n lowering spring, you can shop rate and
height independently.
But if you wanted 10% shorter and 10% stiffer, cutting
off 10% of the length would get you where you wanted
to go.
Problem being, most people don't really know what they
want.
Trending Topics
What I'm saying is that you guys often put the numbers in stone. Like 292/114, that's an approximate number. I worked on a car that had the same front springs stock as my '01, but the rears were different (1 less coil about the same wire size, which means stiffer, i.e. *NOT* the same rate as mine). Which were 114? Maybe neither.
So I'm saying you ought to rate yours first, so you aren't assuming something from the result that isn't true.
As for the idea of getting where you want to be by checkbook or by cutting. Not so simple. A 10% increase in rate doesn't exactly cover a 10% drop in ride height. Suspensions are not linear in their actions. Generally the lower you go the more rate you need or you will end up with the bumpstops doing more of the work than the springs. Frankly there is no science to figuring that out, which makes randomly cutting stuff a bug time guess. I played with a LOT of spring rates and ride height until I settled on what worked best for me, and that's how I made my springs come to be.
So I'm saying you ought to rate yours first, so you aren't assuming something from the result that isn't true.
As for the idea of getting where you want to be by checkbook or by cutting. Not so simple. A 10% increase in rate doesn't exactly cover a 10% drop in ride height. Suspensions are not linear in their actions. Generally the lower you go the more rate you need or you will end up with the bumpstops doing more of the work than the springs. Frankly there is no science to figuring that out, which makes randomly cutting stuff a bug time guess. I played with a LOT of spring rates and ride height until I settled on what worked best for me, and that's how I made my springs come to be.
__________________
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
TECH Junkie
iTrader: (32)
Joined: Sep 2005
Posts: 3,179
Likes: 2
From: Southside Chicago
What I'm saying is that you guys often put the numbers in stone. Like 292/114, that's an approximate number. I worked on a car that had the same front springs stock as my '01, but the rears were different (1 less coil about the same wire size, which means stiffer, i.e. *NOT* the same rate as mine). Which were 114? Maybe neither.
So I'm saying you ought to rate yours first, so you aren't assuming something from the result that isn't true.
As for the idea of getting where you want to be by checkbook or by cutting. Not so simple. A 10% increase in rate doesn't exactly cover a 10% drop in ride height. Suspensions are not linear in their actions. Generally the lower you go the more rate you need or you will end up with the bumpstops doing more of the work than the springs. Frankly there is no science to figuring that out, which makes randomly cutting stuff a bug time guess. I played with a LOT of spring rates and ride height until I settled on what worked best for me, and that's how I made my springs come to be.
So I'm saying you ought to rate yours first, so you aren't assuming something from the result that isn't true.
As for the idea of getting where you want to be by checkbook or by cutting. Not so simple. A 10% increase in rate doesn't exactly cover a 10% drop in ride height. Suspensions are not linear in their actions. Generally the lower you go the more rate you need or you will end up with the bumpstops doing more of the work than the springs. Frankly there is no science to figuring that out, which makes randomly cutting stuff a bug time guess. I played with a LOT of spring rates and ride height until I settled on what worked best for me, and that's how I made my springs come to be.
I got ya... but remember this is the internet, and people tend to take what they read as gospel. Please bear that in mind, and it's for that reason it's pretty important to do a before/after test of the same springs otherwise it's not worth wasting your money because you'll get an erroneous result not knowing the baseline.
If it helps LT1 fronts were rated around 310 in front. A human can't feel anything less than about a 10% change, not really which is also something to consider.
If it helps LT1 fronts were rated around 310 in front. A human can't feel anything less than about a 10% change, not really which is also something to consider.
__________________
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion
www.stranoparts.com --814-849-3450
Results matter. Talk is cheap. We are miles beyond the success anyone else has had with the 4th gens, and C5, C6, C7 Corvettes,
10 SCCA Solo National Championships, 2008 Driver of they Year, 2012 Driver of Eminence
13 SCCA Pro Solo Nationals Championships
2023 UMI King of the Mountain Champion