Suspension is an often overlooked part of tuning cars. Often times, people think buying a baller set of coilovers and every bolt-in bar known to man means you're good. But this is far from the truth. In actuality choosing the right suspension setup is much like choosing the right shoes. You wouldn't rock a pair of Air Max to play basketball, just as you wouldn't wear Jordans to play baseball. You could, but it wouldn't let you play at your highest potential.
So what are we talking about anyway? Most people commonly refer to shocks and springs as suspension. More properly, suspension is the term given to the system of springs, shocks and linkages that connects a vehicle to its wheels. OE manufacturers take a whole host of factors into account when they start designing suspension packages for factory vehicles: ride quality, cost and performance to name a few. Since they don't intend stock cars to operate over harsh conditions, ride quality and cost is king in engineering.
How does it all work? Well most modern tuning cars use what is called independent suspension. In the most simplistic terms, your tire/wheel is attached to an upright, which connects through an array of arms to the chassis itself. As the upright moves up and down on the road, based on the points they are attached at, the tire will change its angle characteristics. Engineers purposely design how these angles will change.
In terms of motor sports, the goal of suspension tuning is to get the tire to do what we want, whether that be gripping in a straight line, in a turn or giving us control in a drift. Using adjustments in caster, camber and toe we get the vehicle to react in a way that is controlled and predictable. We wanted to shed some light on different suspension parts and give some pointers on how choose what's right for you. The first place to start is to take a simplified look at the sum of parts that we are talking about.
Springs Probably the most elementary level of suspension tuning, springs are probably the first thing most enthusiasts swap out. The springs are the first thing to absorb impact from the road. Factory springs are usually set by the factory to absorb the bumps in the road yet have enough rate to hold up against the weight of the vehicle. The majority of modern tuning vehicles use a coil spring design, usually made of steel alloy wound in a shape of a helix. Springs are measured in inner diameter, length and spring rate.
Dampers If a car only had springs, it would bounce everywhere. Dampers (shocks or struts) smooth out the movement of the spring by absorbing some energy released. The simplest example would be if you dropped a spring from the air, it would bounce a couple times before it would come to a rest. With a damper/spring set up, at its optimum setting it would only bounce once and come to a rest. The damper absorbs some of the energy generated by the spring. Single-way adjustable dampers adjust the compression. Two-way adjustable dampers allow for a rebound adjustment as well as compression. Four-way dampers add two settings to those; high-speed setting for compression, low-speed setting for compression, high-speed setting for rebound and low-speed setting for rebound.
Coilovers A coilover is a pre-assembled set of matched spring and damper. The name refers to "coil springs over dampers." For our purposes, this generally is regarded as a set of spring and damper combination that has a threaded shock body for height adjustment. These can come is all sorts of applications from hardcore racing to a luxury spec ride. Ride adjustment comes from a combination of spring and damper, height can be adjusted via spring or damper length, preload can be adjusted via the spring perch, and compression/rebound characteristics through the damper itself.
Sway Bars Just as the name refers, each of the four corners in an independent suspension acts on its own. As you turn in, one corner will experience more load than the other resulting in body roll. A sway bar connects the two opposite sides (left and right) of the suspension and acts as a torsion spring. This limits the action one side sees in relation to the other. In the most simplistic terms, one side of your suspension goes up, the other side will pull in relation to it, keeping weight transfer in a controlled state and reducing body roll.
Arms And Rods As we mentioned before, the arms are what connect the upright (or knuckle) to the body. Each one of these arms has a function directly correlated to caster, camber or toe. Since the factory has to make these parts for mass production vehicles, the amount of adjustability and strength is pretty limited.
Over the past 10 years, options for these parts have made leaps and bounds. Circa 1999, if you were rolling on springs, Tokico blue shocks and a sway bar you were the man. Now there are all kinds of options to choose from. But understanding what to buy out of need is quite different than buying out of want. Take for example TEIN coilover shocks for CT9A Evolution. There are five different grades to choose from. What is the difference between these setups besides the price? The answer is that each is designed with a different purpose in mind.
So the first thing to really determine is what is going to be the main purpose of your build; whether that be spirited street driving, canyon/circuit attack, drifting, rally or drag racing. Since each one of these disciplines put a different type of strain on the vehicle dynamics, they require different settings and needs. Contrary to what you read on the message boards, no one setup is almighty. This is because how the alignment settings directly affects how the car will react.
The next step is to determine what tire you are going to run. But wait a minute, this story is about suspension. Since the tires are in direct contact with the ground, how they perform is directly related to how the suspension is setup. The control factor is the amount of grip your tires can optimally handle. This is why most manufacturers, like HKS, TEIN and Cusco, make varying grades of suspension. During development, they determine a general intended use for the suspension and tune in a range that is suitable according to a base tire. Most street level coilovers are optimally set for a high grip street tire, (ie Neova, R1-R, RS-3, etc...). Whereas competition level suspension parts are set aggressively for specialized tires such as circuit r-compounds or rally nobs. Overdoing your suspension will eat up your tires, and underdoing it will prevent you from taking the tires to its peak performance.
Street If you aren't really planning on hammering on your car and are more interested in a nice ride, then springs and a shock combo are your best friend. But don't go with just any set of springs off of eBay. Most manufacturers of lowering springs engineer them to give you the maximum of lowering without adversely affecting the ride and reliability of your shocks. For those seeking a little more adjustability, many manufacturers have started designing entry level coilovers intended for daily driving comfort, yet have limited adjustability. In conjunction, it's a good idea to invest in a camber adjuster to maximize tire wear.
Drift For drifting, not only should you scrutinize what tire you are running, you should also take into account how much power you are making. Since the purpose is to control a car once your tires have broken loose, the stiffness of you springs and shocks should work in relation to this. Basic rule of thumb is, no power, low grip tires, go with stiff suspension. Big power, high grip tires, work better, to a point, with a softer setup. Many companies now make suspension geared specifically towards drifting. This means a suspension setup that allows for more understeer, as most drifters prefer. Whereas in road race, drivers prefer a neutral car or a car with a bit of oversteer. Keep in mind that when drifting you want the rear tires to break lose. Just as important will be how much you invest in adjustment arms. The lateral forces are so great going sideways, weak and worn out arms snap like twigs. Furthermore, there usually isn't adjustment for you to get enough steering angle, caster and camber. The further your skills progress, the further you'll need to invest in these arms.e.
Autocross/Road Race This is probably the type of driving that will benefit the most from suspension tuning. But with so many different approaches to how a car should handle and so many variables, it can get overwhelming. The level of investment comes down to how much flexibility in adjustment and at what level you demand out of your car. It is quite intimidating when you see teams with $5-10,000 coilovers. But if you are not planning on competing at an unlimited class level (ie. dedicated racecar), it might be a little excessive.
If you are just enjoying the track on the weekends, you can definitely get away with a set of quality coilovers, upgraded sway bars and adjustment arms. Since many times, tires are limited by class, you can get a general idea of how stiff to set your suspension. Again start with a quality tire based on your needs. As you learn to understand your car more and more and drive it at full potential, you can start to adjust from there. Chassis stiffening, spring rates, sway bars, can all be adjusted to get the car to react in a way that is best suited to your driving style and ability.
Suspension shouldn't be approached as a per part perspective but as how the parts work as a whole. Tires, how much power you are making, and how you want your car to react, will all play a role in deciding how much adjustability you will need and what parts to invest in. Being able to properly understand what your needs are can reduce the amount of money wasted and get your car handling properly as well.
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Product: HTS Adjustable Dampers
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Product: Type R Double Adjustable Coilovers
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Product: Sustec Stabilizer Sway Bar
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Product: C-Pillar Bars
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Product: Outer Tie Rod Ends
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Product: Adjustable Camber A-Arm
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