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- May 5, 2021
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- www.coryinmotion.com
Cement
To Begin: This is a Tacoma3g exclusive! There is absolutely ZERO permission to reproduce, copy/paste, or use this info in any other location except on this forum without my express written consent. Everything you see here was written by myself and gathered from years of personal knuckle busting, racing, off roading, research, and education. PS: It's long as hell. Sorry?
Hey all, there seems to be a large misunderstanding on springs, preload, and how it all works. So, I wanted to put this info together in a simple thread. (A lot of this stems from FOX suspension conversations, but I digress)
You want to install a lift! But you have no idea what springs to get when your selected dealer asks you. Or, perhaps you're a skeptic of their recommendations. Whichever it is, here's some info that will help:
Spring Length and Spring Rate work together to determine your ride height.
Spring Rate is a measurement of how many pounds it takes to compress the spring 1 inch. For example, a 600lb spring takes 600lbs to compress 1 inch. This amount of weight needs to be added for every additional inch of compression. IE: 2 inches of compression would take 2x600lbs aka 1200lbs of weight.
Spring Height is the measurement of the length of the spring. Easy enough, right?
Whether you have a 13 inch or a 14 inch long 600lb spring, they will both compress the same amount under the same weight. 600 lbs = 1 inch, reducing your 13 inch spring to 12 inch and your 14 inch spring to 13 inch. Because they share the same spring rate, the ride remains exactly the same regardless of the springs height.
Spring Height will NOT change comfort/stiffness/road feel/response.
Spring Height WILL change your ride height, regardless of Spring Rate. For example, if you have a 13 inch 700lb spring and a 14 inch 600lb spring, the softer 14 inch spring will still result in a higher ride height than its 13 inch 700lb counterpart. In order to get a 13 inch and 14 inch spring to give the same amount of lift, the longer spring would have to have a significantly softer spring rate. So soft that your truck would probably roll over if you sneezed.
Think about it: The longer 14 inch spring would need 600lbs on it to compress down to the 13 inch uncompressed height of the 700lb spring. If you were to take another 600lb weight and place it on the 700lb 13 inch spring, that spring would STILL compress almost 1 inch as the Spring Rates are so close! This leaves nearly an entire inch of height difference between the two springs with the same weight applied. In order for the longer 14 inch spring to match the 13 inch springs compressed height, it would take nearly 1200lbs!
What does it mean? Spring Height is the biggest factor in your lift. Spring Rate determines ride quality vs weight handling and has only a small effect on lift unless you move in large variances, like 500lb vs 800lb springs.
BUT!
Lets talk about PRELOAD!
In my many years of road racing experience, Preload has been something widely misunderstood if not dismissed as meaningless and a "marketing gimmick." Mind you, there are some differences between tuning a track car vs an off-road truck. With either platform, the fact is that Preload is the most important piece of the puzzle.
But.. This is where it gets extremely confusing. Why?
Because a shock with adjustable spring perches (and thusly adjustable Spring Preload) can negate the advantages of a longer spring. *insert audible booing*
You see, a standard shock (such as OEM) with a fixed spring perch offers a static spring position that is non adjustable. With the shock uncompressed, the distance between the bottom spring perch and the upper spring perch (see: top hat) is a fixed height. As an example, say the measured height of an uncompressed standard shock is 13 inches perch-to-perch. This means that you can only fit a 13 inch spring between the perches unless you compress a taller spring to fit.
For this example, we are trying to squeeze in a 14 inch 600lb spring. When installed, our 14 inch spring will be compressed 1 inch to fit within the shock's 13 inches of space effectively reducing the springs overall height to 13 inches. Referring to our above talk about Spring Rates, we know that it takes 600lbs to compress this spring 1 inch. By stuffing this spring into the 13 inches of space available on our standard shock, we are effectively enacting 600lbs of force to reduce the springs height by 1 inch. This will be important later.
The means of compressing the spring with mechanical force to reduce its height without reducing shock travel is called Preload.
"Wait, you can preload a spring without adjustable shocks?!" - YES! In fact, many vehicles come from the factory with already set preload and non-adjustable shocks. Hence why your grand-pappy lost his eye fumbling around with the AutoZone spring compressor while trying to replace the shocks on his '94 Oldsmobile in the driveway. The means to doing so are different, though, as you have to physically change your springs.
Lets talk about what Preload DOES.
Preloading a spring isn't just so you can fit a taller spring in a smaller space. There are actually a few reasons and benefits.
On a basic level, Preload induces extra load on the shock to extend it fully and more quickly when the suspension comes unloaded. For example, hitting a large pothole in the street or coming down off the top of a whoop. Without preload, the only thing ensuring the shock extends is the weight of the drivetrain, wheel, and tire. With preload, not only do you get faster extension (for better reactivity to undulation) but you also get the benefit of more force being exerted on the tire, keeping it in contact with the surface below and providing grip until the vehicle weight settles again. The exact amount of force applied depends on the amount of set preload and the Spring Rate.
From a performance standpoint, Preload is obviously a necessary part of proper suspension tuning. But how does it relate to ride height?
When preloading a spring, like earlier fitting our 14 inch 600lb spring into a 13 inch shock, the amount preloaded is equal to a specific amount of weight being applied. In this case, we mechanically preloaded 1 inch of spring at 600lbs effective weight. The preloaded weight negates the equivalent amount being applied on top of the shock itself once installed. The shock will compress LESS thusly increasing ride height.
To put this into perspective, lets say your trucks corner weight (the weight measured at any single tire) is 1200lbs. The shock, spring and preload combination at this tire is what will determine your ride height. If we fit our standard 13 inch shock with a 13 inch 600lb spring, there is ZERO preload. At full shock extension (droop) the spring is simply captive and is having zero effect. On the ground, the 1200lb weight of the truck at that corner will compress our 600lb spring 2 inches. As we said earlier, every inch of compression requires another 600lbs added.
If we toss in our 14 inch 600lb spring to replace the 13 inch, we induce 1 inch or 600lbs of preload. This means that at full extension (droop) there is 600lbs of force applied to keeping the shock at full extension and keeping pressure on the tire even if no other weight is present on top of the shock. On the ground, our spring will only see 1 inch of compression since the first 600 lbs is offset with our preload. The result is a ride height increase of 1 inch, or a 1 inch lift.
*taps microphone* You all still ok out there?
Adjustable Shocks vs Spring Height and Preload
Ah yes, that top-dollar fully adjustable coil over setup is a super premium piece. Perfectly catered valving, full damping adjustment, and adjustable preload... All the more to confuse the sh*t out of you.
Damping adjustment is its own animal and has no place in this thread. You're here to learn about Springs, Preload, and Lift!
These shocks feature fully adjustable preload via externally threaded shock bodies with internally threaded spring perches. This is exceptionally good if you know what you are doing and can result in the exact ride height that you are looking for with minimal adjustments. Or, it can't. It can quickly leave you chasing your tail on a forum such as this one wondering why your expensive ass coilover system is only lifting your sick truck 1 inch above factory.
"What the hell, man?! They said 0-3 inch lift!"
The dirty truth is that you need to know how to set these things up. If you don't understand how preload works or how spring rates and heights work, you're gonna get nowhere. But, by this point you'll have some understanding of these concepts! At least, I hope so. This is a whole lotta' typin' for you not to be readin', son.
Reality is all the tools are here for you to set your ride height however you may please, all in one box. So long as you have the right spring selected for your trucks setup, you should be able to set your ride height by adjusting the spring preload to the point where the truck sits at your desired height. Simply screw the spring perch up or down to raise and lower the truck and you're good to go.
Problems will definitely arise if you don't have the right springs selected, however. If your springs are too soft, best case scenario is you won't get enough preload to achieve your desired lift. Worst case is you'll either bottom out your suspension on bumps (not good), or have so much preload you'll experience coil bind (doubly not good). Running out of preload adjustment can also happen if your springs are too short!
So what are the right steps? How do you get more lift?
Step 1: Longer Springs
Longer springs are many times the solution for the lack of lift you are seeing, or if your suspension is bottoming out. For these pre-built suspension systems, they come kitted with spring rates to match your specific vehicle that often times are perfectly capable of whatever you can throw at them, unless you're really over factory weight or need more lift. Adding a taller spring will allow you to add more preload before running out of threads, offering a higher ride height without sacrificing ride quality and handling. Stiffer is not always better.
If you recall earlier, I said that adjustable preload can negate the effect of a longer spring on ride height. *insert audible booing*
That's because two springs of different heights that hold the same spring rate will still compress the same amount under the same weight with the same amount of preload. The result is the same amount of lift.
The reason we have this issue is due to the adjustable spring collars. The same collars that offer adjustable preload also offer variable perch-to-perch heights. With a 13 inch spring, you can set your perch-to-perch height at 13 inches to perfectly fit the spring. You can swap that for a 14 inch spring and set your perch-to-perch height to 14 inches, too. If both of these springs have the same Spring Rate, they will offer the exact same ride heights and performance characteristics when set up like this.
If set up incorrectly, there is literally no difference.
The Fix? MORE PRELOAD.
The point of lengthening your springs, going from 13 inch to 14 inch, while keeping the same spring rate is to offer the same ride quality but a higher ride height. Longer springs allow a higher ride height because their increased length regains some preload adjustability on the shock. Effectively, you've moved your collar height 1 inch further away from its maximum adjustment, giving you an additional inch for preloading!
To put it simply: if your 13 inch spring with 2 inches of preload (theoretical maximum) is not giving you enough lift, upgrade to a 14 inch spring of the same Spring Rate. The additional inch of spring will allow an additional inch of preload reducing the risk of coil bind, avoiding pushing your preload past its limit. This gives a higher ride height without sacrifice to ride quality, comfort, and performance.
Step 2: Increase Spring Rate
This is step 2 only because Spring Rate has the least effect on ride height. The amount of difference you will get in a 600lb spring vs a 700lb spring are much more minimal than an increase in overall spring height. Not to mention, increasing the spring rate will sacrifice ride quality and give a rougher ride that's more likely to give you whiplash.
However! Spring Rate SHOULD be increased if you add on a ton of gear. The amount of weight you add to your vehicle is very important to factor into your build. A stock truck can get away with a 600lb spring, but something with a plate bumper and winch plus sliders, shields, etc is going to be a whole different animal.
So if you've got a beast of a Taco and you aren't getting the height you are looking for, consider increasing the spring rate AS WELL AS THE HEIGHT. Both of these items working together will help you get the results you are looking for.
As always, be weary. The softer your spring, the better your truck will ride and the better it will feel over obstacles on and off-road.
All of this information is provided to give a scope on how to set ride height PROPERLY. However, this doesn't mean you should lift the sh*t out of your truck. Pushing your truck too high can cause a ton of other parts to fail. Do research and be realistic with your ride height selection.
As a final note, I will leave you with this sweet bit of information I found regarding our trucks, straight from the Kings of Springs, Eibach. Big thanks to @joechef for this!
Hey all, there seems to be a large misunderstanding on springs, preload, and how it all works. So, I wanted to put this info together in a simple thread. (A lot of this stems from FOX suspension conversations, but I digress)
You want to install a lift! But you have no idea what springs to get when your selected dealer asks you. Or, perhaps you're a skeptic of their recommendations. Whichever it is, here's some info that will help:
Spring Length and Spring Rate work together to determine your ride height.
Spring Rate is a measurement of how many pounds it takes to compress the spring 1 inch. For example, a 600lb spring takes 600lbs to compress 1 inch. This amount of weight needs to be added for every additional inch of compression. IE: 2 inches of compression would take 2x600lbs aka 1200lbs of weight.
Spring Height is the measurement of the length of the spring. Easy enough, right?
Whether you have a 13 inch or a 14 inch long 600lb spring, they will both compress the same amount under the same weight. 600 lbs = 1 inch, reducing your 13 inch spring to 12 inch and your 14 inch spring to 13 inch. Because they share the same spring rate, the ride remains exactly the same regardless of the springs height.
Spring Height will NOT change comfort/stiffness/road feel/response.
Spring Height WILL change your ride height, regardless of Spring Rate. For example, if you have a 13 inch 700lb spring and a 14 inch 600lb spring, the softer 14 inch spring will still result in a higher ride height than its 13 inch 700lb counterpart. In order to get a 13 inch and 14 inch spring to give the same amount of lift, the longer spring would have to have a significantly softer spring rate. So soft that your truck would probably roll over if you sneezed.
Think about it: The longer 14 inch spring would need 600lbs on it to compress down to the 13 inch uncompressed height of the 700lb spring. If you were to take another 600lb weight and place it on the 700lb 13 inch spring, that spring would STILL compress almost 1 inch as the Spring Rates are so close! This leaves nearly an entire inch of height difference between the two springs with the same weight applied. In order for the longer 14 inch spring to match the 13 inch springs compressed height, it would take nearly 1200lbs!
What does it mean? Spring Height is the biggest factor in your lift. Spring Rate determines ride quality vs weight handling and has only a small effect on lift unless you move in large variances, like 500lb vs 800lb springs.
BUT!
Lets talk about PRELOAD!
In my many years of road racing experience, Preload has been something widely misunderstood if not dismissed as meaningless and a "marketing gimmick." Mind you, there are some differences between tuning a track car vs an off-road truck. With either platform, the fact is that Preload is the most important piece of the puzzle.
But.. This is where it gets extremely confusing. Why?
Because a shock with adjustable spring perches (and thusly adjustable Spring Preload) can negate the advantages of a longer spring. *insert audible booing*
You see, a standard shock (such as OEM) with a fixed spring perch offers a static spring position that is non adjustable. With the shock uncompressed, the distance between the bottom spring perch and the upper spring perch (see: top hat) is a fixed height. As an example, say the measured height of an uncompressed standard shock is 13 inches perch-to-perch. This means that you can only fit a 13 inch spring between the perches unless you compress a taller spring to fit.
For this example, we are trying to squeeze in a 14 inch 600lb spring. When installed, our 14 inch spring will be compressed 1 inch to fit within the shock's 13 inches of space effectively reducing the springs overall height to 13 inches. Referring to our above talk about Spring Rates, we know that it takes 600lbs to compress this spring 1 inch. By stuffing this spring into the 13 inches of space available on our standard shock, we are effectively enacting 600lbs of force to reduce the springs height by 1 inch. This will be important later.
The means of compressing the spring with mechanical force to reduce its height without reducing shock travel is called Preload.
"Wait, you can preload a spring without adjustable shocks?!" - YES! In fact, many vehicles come from the factory with already set preload and non-adjustable shocks. Hence why your grand-pappy lost his eye fumbling around with the AutoZone spring compressor while trying to replace the shocks on his '94 Oldsmobile in the driveway. The means to doing so are different, though, as you have to physically change your springs.
Lets talk about what Preload DOES.
Preloading a spring isn't just so you can fit a taller spring in a smaller space. There are actually a few reasons and benefits.
On a basic level, Preload induces extra load on the shock to extend it fully and more quickly when the suspension comes unloaded. For example, hitting a large pothole in the street or coming down off the top of a whoop. Without preload, the only thing ensuring the shock extends is the weight of the drivetrain, wheel, and tire. With preload, not only do you get faster extension (for better reactivity to undulation) but you also get the benefit of more force being exerted on the tire, keeping it in contact with the surface below and providing grip until the vehicle weight settles again. The exact amount of force applied depends on the amount of set preload and the Spring Rate.
From a performance standpoint, Preload is obviously a necessary part of proper suspension tuning. But how does it relate to ride height?
When preloading a spring, like earlier fitting our 14 inch 600lb spring into a 13 inch shock, the amount preloaded is equal to a specific amount of weight being applied. In this case, we mechanically preloaded 1 inch of spring at 600lbs effective weight. The preloaded weight negates the equivalent amount being applied on top of the shock itself once installed. The shock will compress LESS thusly increasing ride height.
To put this into perspective, lets say your trucks corner weight (the weight measured at any single tire) is 1200lbs. The shock, spring and preload combination at this tire is what will determine your ride height. If we fit our standard 13 inch shock with a 13 inch 600lb spring, there is ZERO preload. At full shock extension (droop) the spring is simply captive and is having zero effect. On the ground, the 1200lb weight of the truck at that corner will compress our 600lb spring 2 inches. As we said earlier, every inch of compression requires another 600lbs added.
If we toss in our 14 inch 600lb spring to replace the 13 inch, we induce 1 inch or 600lbs of preload. This means that at full extension (droop) there is 600lbs of force applied to keeping the shock at full extension and keeping pressure on the tire even if no other weight is present on top of the shock. On the ground, our spring will only see 1 inch of compression since the first 600 lbs is offset with our preload. The result is a ride height increase of 1 inch, or a 1 inch lift.
*taps microphone* You all still ok out there?
Adjustable Shocks vs Spring Height and Preload
Ah yes, that top-dollar fully adjustable coil over setup is a super premium piece. Perfectly catered valving, full damping adjustment, and adjustable preload... All the more to confuse the sh*t out of you.
Damping adjustment is its own animal and has no place in this thread. You're here to learn about Springs, Preload, and Lift!
These shocks feature fully adjustable preload via externally threaded shock bodies with internally threaded spring perches. This is exceptionally good if you know what you are doing and can result in the exact ride height that you are looking for with minimal adjustments. Or, it can't. It can quickly leave you chasing your tail on a forum such as this one wondering why your expensive ass coilover system is only lifting your sick truck 1 inch above factory.
"What the hell, man?! They said 0-3 inch lift!"
The dirty truth is that you need to know how to set these things up. If you don't understand how preload works or how spring rates and heights work, you're gonna get nowhere. But, by this point you'll have some understanding of these concepts! At least, I hope so. This is a whole lotta' typin' for you not to be readin', son.
Reality is all the tools are here for you to set your ride height however you may please, all in one box. So long as you have the right spring selected for your trucks setup, you should be able to set your ride height by adjusting the spring preload to the point where the truck sits at your desired height. Simply screw the spring perch up or down to raise and lower the truck and you're good to go.
Problems will definitely arise if you don't have the right springs selected, however. If your springs are too soft, best case scenario is you won't get enough preload to achieve your desired lift. Worst case is you'll either bottom out your suspension on bumps (not good), or have so much preload you'll experience coil bind (doubly not good). Running out of preload adjustment can also happen if your springs are too short!
So what are the right steps? How do you get more lift?
Step 1: Longer Springs
Longer springs are many times the solution for the lack of lift you are seeing, or if your suspension is bottoming out. For these pre-built suspension systems, they come kitted with spring rates to match your specific vehicle that often times are perfectly capable of whatever you can throw at them, unless you're really over factory weight or need more lift. Adding a taller spring will allow you to add more preload before running out of threads, offering a higher ride height without sacrificing ride quality and handling. Stiffer is not always better.
If you recall earlier, I said that adjustable preload can negate the effect of a longer spring on ride height. *insert audible booing*
That's because two springs of different heights that hold the same spring rate will still compress the same amount under the same weight with the same amount of preload. The result is the same amount of lift.
The reason we have this issue is due to the adjustable spring collars. The same collars that offer adjustable preload also offer variable perch-to-perch heights. With a 13 inch spring, you can set your perch-to-perch height at 13 inches to perfectly fit the spring. You can swap that for a 14 inch spring and set your perch-to-perch height to 14 inches, too. If both of these springs have the same Spring Rate, they will offer the exact same ride heights and performance characteristics when set up like this.
If set up incorrectly, there is literally no difference.
The Fix? MORE PRELOAD.
The point of lengthening your springs, going from 13 inch to 14 inch, while keeping the same spring rate is to offer the same ride quality but a higher ride height. Longer springs allow a higher ride height because their increased length regains some preload adjustability on the shock. Effectively, you've moved your collar height 1 inch further away from its maximum adjustment, giving you an additional inch for preloading!
To put it simply: if your 13 inch spring with 2 inches of preload (theoretical maximum) is not giving you enough lift, upgrade to a 14 inch spring of the same Spring Rate. The additional inch of spring will allow an additional inch of preload reducing the risk of coil bind, avoiding pushing your preload past its limit. This gives a higher ride height without sacrifice to ride quality, comfort, and performance.
Step 2: Increase Spring Rate
This is step 2 only because Spring Rate has the least effect on ride height. The amount of difference you will get in a 600lb spring vs a 700lb spring are much more minimal than an increase in overall spring height. Not to mention, increasing the spring rate will sacrifice ride quality and give a rougher ride that's more likely to give you whiplash.
However! Spring Rate SHOULD be increased if you add on a ton of gear. The amount of weight you add to your vehicle is very important to factor into your build. A stock truck can get away with a 600lb spring, but something with a plate bumper and winch plus sliders, shields, etc is going to be a whole different animal.
So if you've got a beast of a Taco and you aren't getting the height you are looking for, consider increasing the spring rate AS WELL AS THE HEIGHT. Both of these items working together will help you get the results you are looking for.
As always, be weary. The softer your spring, the better your truck will ride and the better it will feel over obstacles on and off-road.
All of this information is provided to give a scope on how to set ride height PROPERLY. However, this doesn't mean you should lift the sh*t out of your truck. Pushing your truck too high can cause a ton of other parts to fail. Do research and be realistic with your ride height selection.
As a final note, I will leave you with this sweet bit of information I found regarding our trucks, straight from the Kings of Springs, Eibach. Big thanks to @joechef for this!
Last edited:
good stuff.
