I often get ask how coilovers springs differ from lowering springs and how mono-tube dampers differ from twin-tube damper, so I decided to write this article to provide the enthusiast community with some general information on suspensions.
Many owners install Coilovers suspension looking to enhance their vehicles looks and performance.
While there are many different parts that make up a suspension system, the heart of the suspension is the springs and the dampers.
So what exactly does a spring or a damper do?
Well, at the most basic level springs control the amount the suspension moves up and down.
The dampers control the speed at which the suspension moves.
In driving terms, the springs control the amount of body roll, squat and dive the vehicle has.
The dampers control the speed of those movements.
The combination of spring rate and damping force are what determines the performance and ride quality of the suspension.
Type of springs
There are two basic types of springs, linear and progressive.
A linear rate spring is one that has a fixed spring rate, this means the amount of weight, needed to compress the spring does not change with the load.
A progressive spring is one in which the spring rate changes depending on the amount of load placed on the spring, therefore the actual spring rate is not a fixed number.
Characteristics of Linear Springs
Linear rate springs have a fix springs rate throughout its rate of compression, therefore the first inch of compression will require the same weight as the second inch of compression.
Most coilovers suspension offers a straight internal diameter (ID) linear rate springs, this makes changing springs rate much easier and most springs manufacturers offer springs in a wide selection of springs rate, ID, and free length.
The main advantage of linear springs is the consistency in the way that the weight transfer from one side of the car to the other side, it should be very smooth and consistent, this makes the cars dynamics much easier to predict as the driver can anticipate weight transfer and body roll more accurately.
When exiting a corner, a linear spring will settle the cars body in a smooth manner because both sides of the car are compressing and rebounding at the same rate (1 mm of compression to 1 mm of rebound).
This is a great advantage and allows for more confident use of weight transfer because the driver will not experience unpredictable weight shifts.
Characteristics of Progressive Springs
Progressive springs rate changes depending on the loads placed on the springs, therefore the first inch of compression will require a different amount of weight to the second inch of compression.
Most aftermarket lowering springs are progressive springs.
The main reason, is that the springs must be soft enough initially for the car to reduce its ride height, but hard enough at the compressed state to prevent the standard damper from bottoming out.
When exiting a corner, a progressive spring will send the compressed force from outside of the car to the inside.
Since the spring rate is not constant from side to side, the spring on the inside of the car will compress from the force absorbed, it will then send the compressed force back to the outside.
This happens back and forth as the car slowly settles down. This excessive body roll requires more attention to control effectively.
In winding road driving, progressive springs make steering more complex and demanding compared to linear springs.
Type of Dampers
There are two basic types of dampers used in the auto industry, Mono-Tube and Twin-Tube dampers.
Mono-tube dampers use a single outer tube.
A floating piston separates the oil and nitrogen gas inside the damper unit.
Twin tube damper use an inner and outer tube which separate the oil and gas inside the damper.
The smaller inner tube houses the piston valve & shaft assembly, base valve and oil.
The outer tube contains both nitrogen gas and the damper oil.
Characteristics of Mono-tube Dampers
The main advantages of mono-tube dampers are that mono-tube pistons are much larger than those of twin-tube dampers.
The larger mono-tube piston create more flow through the valves than the smaller twin-tube piston as it can displace more oil through the valve; this makes the mono-tube damper more sensitive to small suspension movement.
The deflected-disc valve system found in mono-tube system is more precise and consistent than the system of check valve, springs, and orifices commonly used in twin-tube dampers.
Mono tube dampers use much higher gas pressure also run much cooler than a twin-tube damper.
These means mono-tube dampers are able to provide consistent damping performance under the harshest condition (such as track use).
The main disadvantage of a mono-tube damper over a twin tube damper is the cost.
Precision, consistency, and performance advantage mean parts used in mono-tube dampers have to be produce with higher accuracy than twin-tube dampers.
A much more expensive, seamless-type tube are needed for the mono-tube damper casing, and precision seal are needed to contain the high internal pressure of a mono-tube damper.
The performance advantages of the mono-tube dampers make them the choice for serious suspension tuners looking for the best possible dampers.
Most high end suspensions from renowned suspension tuner employ mono-tube dampers, as with high performance vehicle application such as Nissan GTR, Porsche Carrera, Mitsubishi EVO MR, Subaru WRX STi, etc.
Characteristics of Twin Tube Dampers
The main advantage of twin-tube dampers is lower manufacturing costs.
Twin-tube damper use much lower gas pressure than mono-tube dampers. This eliminates the need to have a highly polished piston chamber with a floating piston to separate the pressurized gas to the oil inside the damper.
Twin-tube damper are also more durable against external damage.
Since the internal of a twin-tube damper are located inside the inner tube, damage to the outer tube (such as dent) will not cause the damper to cease functioning.
The main disadvantage of a twin-tube damper over the mono-tube damper is the inferior performance.
By using smaller internal parts, twin-tube dampers provide less sensitive damping and produce higher temperature under hard use than a mono-tube damper.
While twin-tube dampers still offer great performance, their construction limits their performance when compared to that of mono-tube dampers.
Due to the lower cost and ease of manufacturing, twin-tube dampers are the most commonly used type of dampers by OEM (Original Equipment) manufacturer.
Most OEM replacement dampers and low-end aftermarket suspension products are twin-tube dampers.
With suspensions, there are alot of variance (such as some twin-tube dampers that use deflected-disc valve system) and it is impossible to cover everything.
I try to produce this article with an unbiased view, it is up to the reader to decide what product best suit their needs, budget, and requirement.
I hope this information is useful and should anyone have question, please feel free to contact me
Thank you for reading and I hope to be able to assist you in the near future.
Jerrick Lo
Director of MeisterR Ltd.
The goal of this article is to provide some general information to the enthusiast community.I often get ask how coilovers springs differ from lowering springs and how mono-tube dampers differ from twin-tube damper, so I decided to write this article to provide the enthusiast community with some general information on suspensions.Many owners install Coilovers suspension looking to enhance their vehicles looks and performance.While there are many different parts that make up a suspension system, the heart of the suspension is the springs and the dampers.Well, at the most basic level springs control the amount the suspension moves up and down.The dampers control the speed at which the suspension moves.In driving terms, the springs control the amount of body roll, squat and dive the vehicle has.The dampers control the speed of those movements.The combination of spring rate and damping force are what determines the performance and ride quality of the suspension.There are two basic types of springs, linear and progressive.A linear rate spring is one that has a fixed spring rate, this means the amount of weight, needed to compress the spring does not change with the load.A progressive spring is one in which the spring rate changes depending on the amount of load placed on the spring, therefore the actual spring rate is not a fixed number.Linear rate springs have a fix springs rate throughout its rate of compression, therefore the first inch of compression will require the same weight as the second inch of compression.Most coilovers suspension offers a straight internal diameter (ID) linear rate springs, this makes changing springs rate much easier and most springs manufacturers offer springs in a wide selection of springs rate, ID, and free length.The main advantage of linear springs is the consistency in the way that the weight transfer from one side of the car to the other side, it should be very smooth and consistent, this makes the cars dynamics much easier to predict as the driver can anticipate weight transfer and body roll more accurately.When exiting a corner, a linear spring will settle the cars body in a smooth manner because both sides of the car are compressing and rebounding at the same rate (1 mm of compression to 1 mm of rebound).This is a great advantage and allows for more confident use of weight transfer because the driver will not experience unpredictable weight shifts.Progressive springs rate changes depending on the loads placed on the springs, therefore the first inch of compression will require a different amount of weight to the second inch of compression.Most aftermarket lowering springs are progressive springs.The main reason, is that the springs must be soft enough initially for the car to reduce its ride height, but hard enough at the compressed state to prevent the standard damper from bottoming out.When exiting a corner, a progressive spring will send the compressed force from outside of the car to the inside.Since the spring rate is not constant from side to side, the spring on the inside of the car will compress from the force absorbed, it will then send the compressed force back to the outside.This happens back and forth as the car slowly settles down. This excessive body roll requires more attention to control effectively.In winding road driving, progressive springs make steering more complex and demanding compared to linear springs.There are two basic types of dampers used in the auto industry, Mono-Tube and Twin-Tube dampers.Mono-tube dampers use a single outer tube.A floating piston separates the oil and nitrogen gas inside the damper unit.Twin tube damper use an inner and outer tube which separate the oil and gas inside the damper.The smaller inner tube houses the piston valve & shaft assembly, base valve and oil.The outer tube contains both nitrogen gas and the damper oil.The main advantages of mono-tube dampers are that mono-tube pistons are much larger than those of twin-tube dampers.The larger mono-tube piston create more flow through the valves than the smaller twin-tube piston as it can displace more oil through the valve; this makes the mono-tube damper more sensitive to small suspension movement.The deflected-disc valve system found in mono-tube system is more precise and consistent than the system of check valve, springs, and orifices commonly used in twin-tube dampers.Mono tube dampers use much higher gas pressure also run much cooler than a twin-tube damper.These means mono-tube dampers are able to provide consistent damping performance under the harshest condition (such as track use).The main disadvantage of a mono-tube damper over a twin tube damper is the cost.Precision, consistency, and performance advantage mean parts used in mono-tube dampers have to be produce with higher accuracy than twin-tube dampers.A much more expensive, seamless-type tube are needed for the mono-tube damper casing, and precision seal are needed to contain the high internal pressure of a mono-tube damper.The performance advantages of the mono-tube dampers make them the choice for serious suspension tuners looking for the best possible dampers.Most high end suspensions from renowned suspension tuner employ mono-tube dampers, as with high performance vehicle application such as Nissan GTR, Porsche Carrera, Mitsubishi EVO MR, Subaru WRX STi, etc.The main advantage of twin-tube dampers is lower manufacturing costs.Twin-tube damper use much lower gas pressure than mono-tube dampers. This eliminates the need to have a highly polished piston chamber with a floating piston to separate the pressurized gas to the oil inside the damper.Twin-tube damper are also more durable against external damage.Since the internal of a twin-tube damper are located inside the inner tube, damage to the outer tube (such as dent) will not cause the damper to cease functioning.The main disadvantage of a twin-tube damper over the mono-tube damper is the inferior performance.By using smaller internal parts, twin-tube dampers provide less sensitive damping and produce higher temperature under hard use than a mono-tube damper.While twin-tube dampers still offer great performance, their construction limits their performance when compared to that of mono-tube dampers.Due to the lower cost and ease of manufacturing, twin-tube dampers are the most commonly used type of dampers by OEM (Original Equipment) manufacturer.Most OEM replacement dampers and low-end aftermarket suspension products are twin-tube dampers.With suspensions, there are alot of variance (such as some twin-tube dampers that use deflected-disc valve system) and it is impossible to cover everything.I try to produce this article with an unbiased view, it is up to the reader to decide what product best suit their needs, budget, and requirement.I hope this information is useful and should anyone have question, please feel free to contact me info@meisterr.com Thank you for reading and I hope to be able to assist you in the near future.Jerrick LoDirector of MeisterR Ltd.
For more information, please visit our website.
Which is better: Running shoes or hiking boots? We both know that’s a silly question that’s impossible to answer without knowing one vital piece of information: The use case.
Shock valving styles are the same way.
The best style of damping curve for you will depend on your driving style, racing surface, and more. There are things you should avoid when setting up your racing suspension for dirt and different challenges you’ll encounter when setting up for pavement. As a result of these diverse needs from different drivers and situations, shock valving styles have evolved a great deal over the years.
We will cover some of the more common examples and some of the more revolutionary models. We’ll also shed some light on where all these different shock builds have come from, where they are currently being used, and maybe how they might be able to help you master the process of suspension tuning.
Valve Stacks and Shock Absorbers: Parts and Interactions
Over decades of development and competition among shock manufacturers, damping curves have come a long way. Before we delve into the details of the different valving setups and their uses, let’s first talk about valve stacks and suspension tuning.
What components make up a proper stack? Generally speaking, your stack will consist of various shims in a multitude of diameters. The shims making up your stack will each carry out a different role in your stack’s construction. These shims include:
- Support shims
- Cover shims
- Bypass shims
- Bleed shims
- Preload shims
Your valve stack interacts with your shocks by controlling the pressure differentials created by the cycling of hydraulic fluid through your shock absorber. Shims on one stack will block oil flow through the piston, while the shims on the other stack allow oil to flow through. You can control the damping forces by increasing or decreasing the shims in each stack.
Related Read: How to Solve Handling Issues With A Shock Rebuild
Armed with this refresher course on valve stacks, let’s dive into your options for valving setups. Keep in mind that the setup that works like a dream on washboards won’t be the best fit for whoops. Your perfect damping curve will require you to make tradeoffs that ultimately result in the best performance for your vehicle, driving style, and events.
FREE DOWNLOAD - Damper Tuning Guide (Starter)
Ensuring a well-tuned damper setup can translate to significant performance gains on track. If you are unsure of where to begin the tuning process, this is a great starting point. Maximize the results of your shock adjustments with our free damper tuning guide download.
Linear Shock Valving
In the early days, most racing shocks had simple designs and damping curves. Linear damping curves were the norm at that time, but that doesn’t necessarily mean they’re entirely outdated.
Linear damping curves are designed like a spring curve: A linear rate controls the spring rate. The damping force increases at a constant rate as the velocity increases, giving us a linear damping curve.
Today’s popular use-cases for linear shock valving include streetcar applications, motorcycles, and even bicycles.
For other types of racing, you may still choose to use this damping style. A preference for linear shock valving depends on the driver’s feel, tire wear, race track surface, and the overall setup.
Progressive Shock Valving
At first glance, you might think a progressive-style damping curve looks most like a linear-style curve. However, delving into why this type of shock valve was developed, it’s easy to see that’s not the case.
As the name suggests, your setup starts out soft in a progressive setup and gets progressively stiffer as piston speed increases. This damping curve aims to have a higher rate of force gain in high-speed damping vs. low-speed damping. As a result, this damping curve is often associated with a smoother ride.
You can create this setup by modifying your shim stack or adding a bleed to the shock. This setup might be a good fit for you if you know you will encounter significant displacements or high velocities on your ride.
Some common applications for progressive shock valving are in off-road racing or riding environments. If you push on the rear of a dirt bike, you can feel it is very soft and moves freely, but when you hit a jump, the higher velocity is much stiffer damping.
Naturally, you would want a soft or compliant low-speed damping to allow the suspension to absorb bumps as easily as possible. Still, when you encounter larger bumps and displacements, you need to increase your damping, so your suspension doesn’t bottom out.
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Digressive Shock Valving
Digressive shock valving first gained popularity in the United States in the mid-90s, though in series like F1, it showed up a bit earlier on the timeline.
A digressive-style curve is exactly the opposite of a progressive setup. In this style, you start with a stiffer damping rate at a low speed that tapers off as the piston speed increases.
The draw of using this damping curve is that stiffer low-speed damping gives the driver a more stable feel, as low-speed damping is felt most strongly. When you’re using a linear curve, increasing the stiffness of low-speed damping creates even stiffer high-speed damping, which can cause trouble for large bumps or curbs.
This problem gave birth to the digressive-style curve, as it allows you to have a much stiffer rate of low-speed damping while avoiding that higher rate at high speeds. In other words, it allows you to enjoy the best of both worlds in this sense.
Some of the most common use-cases for digressive shock valving are in most forms of modern motorsports. Asphalt and dirt track racing for cars, motorcycles, and even bicycles have adopted digressive damping technology.
The digressive curve gave birth to other curve requests over the years.
The next two types of damping curves discussed in this post evolved directly from digressive shock valving.
Velocity Dependent Piston
The Velocity Dependent Piston, most often called the VDP, was developed based on the digressive piston’s design.
Driver feedback on the original digressive piston design reported challenges with unexpected bumps in the road—literally. Imagine this scenario: You’re entering a corner, your suspension is loaded… and you hit a bump in that corner. To a driver, this can be a feeling of loss of support, stability, or overall grip.
The request born from this scenario was a desire to tune high-speed damping completely separately from low-speed damping. In this setup, the two shim stacks work independently of one another.
- The main shim stack that seals on the digressive lip is responsible for the low-speed “knee” digressive portion of the curve.
- The inner shim stack is designed to allow increased oil flow at a higher velocity to interact to allow the user to tune the high-speed portion of the damping curve.
Regressive Shock Valving
Regressive shock valving is the latest development in shock valve technology. Essentially, a regressive-style curve is similar to the digressive style, simply taking the design to the next level.
The digressive damping curve came to be for two reasons:
- To increase low-speed damping to aid in support or platform
- To reduce high-speed force so as not to upset the chassis during large bumps
A regressive-style curve achieves this aim, becoming even softer at higher velocities than it is at low velocities. This type of control was long thought to be impossible—until the early 2000s.
In the 00s, an F1 customer determined that, though digressive-style curves were better than linear or progressive styles for curb strikes, a regressive-style curve would be even better. With this type of shock valving, a driver would be able to aggressively attack curbs and other large bumps without upsetting the chassis.
In the years since its development, racers have learned how to optimize the regressive damping style in the following ways:
- Approaching low-speed damping in increasingly aggressive ways, allowing the driver to get minimal
spring rates
, resulting in more mechanical grip.
- Approaching braking aggressively with rear rebound
low-speed compression
, resulting in stabler braking. (With other damping styles, this type of braking was impossible to achieve without damaging your tires or resulting in other handling issues.)
Digressive Shock Valving and More: How to Tune Any Shock Properly
Examining all the various setups for damping curves, you’ll see that there is truly no best-fit option for every scenario. All these shock valving styles have continued to develop and improve over the years, and each has its own use-cases, pros, and cons.
Regardless of your choice for your valving setup, you’ll need to keep your shocks tuned to maintain peak performance. Using a shock dyno is the only way to truly tune your shock to perfection. A shock dyno can also help you compare the different setup options, helping you make the right choice for your vehicle and race.
When you run each setup on a shock dyno, you’ll be able to see the exact numbers, helping you relate those changes to driver feel, tire wear, and other handling characteristics.
For support, guidance, and setup assistance with your shock valving, no matter your setup, explore Penske Racing Shocks S3 program today. With S3, you’ll have access to the right hardware for your application, a personalized shock setup, and the backend support you need.
If you are looking for more details, kindly visit Linear dampers.