Section 2: Suspension
One of the most underrated but best engineered aspects of the RX8 is the stock suspension system. There are two characteristics of the OEM suspension owners often see as negative when they are simply part of the design. First, owners tend to feel the overall ride height of the RX8 is too high and there is too much roll in the suspension handling. There are other changes that can be made to improve the RX8’s suspension but for a daily driven or street application the RX8 suspension is very capable. The RX8 is capable of much more than a typical driver can push out of the vehicle.
However, if you are interested in upgrading your suspension there are a few basic rules that BHR encourages you to follow when making your decisions.
Ride Height: Lower is NOT always better
If you have ever been to a car show you’ve no doubt seen the “slammed” prize winners using expensive suspension systems to get a low ride. This lowered look tends to be visually appealing as it gives the car more body and a sleek style. However, these vehicles are not meant for the track or any serious performance driving and their upgrades should not be mistaken for performance modifications.
Simply put, the lower your vehicle gets to the ground does not always translate into better handling. Lowering a vehicle is done to lower its center of gravity. The purpose of wanting a lower center of gravity is to limit weight transfer. Weight transfer is one problem that aftermarket suspensions attempt to solve. By keeping the weight distributed as evenly across the vehicle as possible you maximize grip. Large amount of weight shifts can cause a loss of traction during high speed maneuvers.
The other downside of excessive lowering is limiting your suspension travel. This is the most overlooked flaw in a suspension setup. Suspension travel is the amount of length the strut has to move when it compresses. While valve design and spring rate effect suspension travel, if your strut only has a small amount of movement then you risk bottoming out your suspension. When that happens it can induce massive over steer and cause you to lose control.
The second problem with excessive lowering is a disruption of the RX8's suspension geometry.
Choosing the right ride height is a process which requires you to evaluate what you want your suspension to do for you and how aggressive you plan on driving the car. Also, if your vehicle is daily driven you will need enough height to navigate speed bumps, pot holes, and other road hazards. Being too low to the ground can cause excessive body damage if you encounter them.
Coil-over systems vs. Struts and Spring Combo
So you have decided to upgrade the stock suspension parts for something a little bit more performance capable. Sadly, not all suspension parts are made alike so it’s important to understand what is out there and how it will affect your vehicle.
It should be pointed out that the RX8's suspension system is technically a "coil-over" design from the factory. The term "coil-over" is used in this context to represent a suspension system that can adjust height, dampening and spring pre-load. A Strut and Sping combination is a system which does not allow for spring pre-load adjustment or height adjustment and typically only allows for dampening adjustment.
The RX8 suspension, while being made up of other various parts, has two main upgradable items. First is the spring which is what actually supports the weight of the vehicle. The second is the strut which absorbs the energy the spring produces. Both have their roles and finding the right combination is important.
First let’s look at the strut packages. There are various types of strut manufacturers from Tokiko, Koni, and many others. Many of these struts will provide dampening adjustability. Dampening is a valve which can provide resistance to the fluid in the strut allowing you to adjust the bound and rebound. Simply put, you can adjust how quickly the strut operates which can soften or stiffen your suspension. It’s important to pick your strut based on your vehicle needs. It would be best to find a strut package that has remote adjusters for the rear struts as this will save you hours of time taking your rear suspension apart to make adjustments.
The second part to the suspension upgrade is the spring. While overall spring rate is important, making sure to get a quality spring with the right ride height is the end goal. Lowering springs are made by dozens of suspension manufacturers. There are special types of springs known as “progressive” which you should be aware of. Progressive springs have two different spring rates based on how much the spring has been compressed. This can give you a nice soft ride but provide a stiff rate when cornering. It’s important to take caution after first installing these springs as the rate increase can result in snap over steer if the driver is unprepared.
Non-progressive springs are not necessarily better than progressive. It all comes down to your needs as a driver. Strut and spring packages are suggested for any street or daily driven applications as well as light autocross or road course racing.
If you are interested in high adjustability and serious track time then a coil-over suspension system is going to be what you are looking for. Coil-over suspension systems should be addressed using the same information in the strut & spring section but there is some other items to consider.
Like struts and springs, no two coil-over suspension systems are alike. There exist various types of quality ratings, features and perks. The specific setup for you will be influenced by what levels of adjustability you are looking for and your overall budget. Making the best decision when it comes to your suspension system is important!
Coil-over features normally have various levels of adjustment that struts don’t give you. The most common is ride height adjustment. Depending on the quality of the coil-over there will be two main ways of adjusting the ride height. The first would be using the spring perch which is where the spring’s bottom coil rests on. By compressing the spring it forces the car’s height up or down. Changing the load (or preload) of the spring will affect your overall handling. It’s best to avoid these types of coil-over suspensions for ones which adjust ride height differently. Most standard coil-over suspension has a threaded piece which allows you to change the ride height of the vehicle without adjusting the spring perch and maintaining the same amount of suspension travel. This allows you to make adjustments to the height without affecting any other suspension adjustments.
The other more common adjustment device is dampening adjustment. This is also featured on many strut designs. It allows you to change the bound and rebound of the coil-over strut. Normally coil-over dampening adjustment is more precise but those precise settings will only benefit serious track cars looking to dial in a perfect suspension setup. Normally anything equal to or greater than 12 adjustments for dampening is enough.
While not listed as a feature, the advantage coil-over suspension gives a driver is the ability to corner balance your vehicle. Having equal weight distribution is one of the RX8’s greatest qualities but a coil-over setup will allow you to adjust for driver’s weight or any other factors which might cause a weight bias in the vehicle. Corner balancing isn’t something that a street driven or daily driven car will see benefits from and should be considered a track only benefit.
Sway Bars and endlinks:
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