The primary tasks of a vehicle's suspension have remained the same since the advent of the modern automobile. Suspensions help absorb irregularities in road surfaces, and at the same time help control chassis movement.
A suspension combines components that have different, yet interactive functions. The two most influential components are the vehicle's springs and shock absorbers:
The load bearing component of the suspension helps determine properties such as ride quality, load capacity and handling balance. In order to provide the best possible performance, the other suspension components have to be "matched" to the springs.
While often called "shock absorbers," they act as "motion dampers" that help control the suspension's movement by restricting the rate at which energy is stored in and returned by the vehicle's springs. Shock absorbers help influence ride quality, responsiveness and the vehicle's handling balance as it transitions from one action to another.
Most vehicle manufacturers design their vehicles with a suspension tuned to suit the needs of the average driver during average driving. However if you're not the average driver or ask your vehicle to deliver a higher level of performance, the original suspension may not be enough for you. If you desire to take your vehicle to a new level of control and handling, adding higher performance shock absorbers to your suspension may be just what you need.
In order to better understand the contribution that shock absorbers make towards ride comfort and handling, Tire Rack Team conducted a Real World Road Ride & Performance Track Test Drive comparing three Lexus IS300 sport sedans. All three cars were equipped with Eibach Pro-Kit Springs and Sumitomo HTR+ Ultra High Performance All Season tires in the 225/45ZR17 size mounted on 17" x 7" alloy wheels. The first IS300 retained Original Equipment Lexus shock absorbers, while the second was equipped with KONI Sport shock absorbers in their "softest" setting, and a third was equipped with KONI Sport shock absorbers in their "firmest" setting.
KONI suspension experts recognize that every vehicle has unique damping needs. The result is that KONI shock absorbers are not just average shock absorbers because they feature a number of standards that make them unique. They are adjustable, which means the driver can influence the behavior of the vehicle and compensate for wear. In addition, KONI shock absorbers are tailor-made for specific vehicles and their unique driving conditions. Overall, KONI products improve handling and comfort and carry a lifetime warranty. Read more about KONI.
Like KONI Shock absorbers, Eibach Pro-Kit Springs are designed specifically for each vehicle. Pro-Kit Springs are engineered to properly lower the vehicle and its center of gravity to help reduce the amount of vehicle movement during quick acceleration, cornering and braking maneuvers. Eibach Pro-Kit Springs typically use progressive rates to maximize improvements in handling while minimizing disturbances to the vehicle's ride quality. This allows Eibach to offer close-to-stock rates during normal driving for ride comfort, yet increase stiffness as the vehicle leans when it's pushed to the limit. Eibach Pro-Kit Spring Sets are engineered to remain securely in the vehicle's spring perches at all times to prevent them from shifting or rattling around (even when the vehicle is lifted off of the ground on a hoist) and maintain the vehicle's load capacity with little additional risk of "bottoming" the suspension.
The Sumitomo HTR+ Ultra High Performance All-Season Radial was developed to meet the year-round driving needs of sports car, sports coupe and sports sedan (such as our Lexus IS300) drivers by blending dry and wet road performance with light snow and slush traction. The Sumitomo HTR+ radial's all-season tread compound is molded into a pattern that features independent shoulder and intermediate tread blocks to enhance dry cornering and stability, while the tread's four wide circumferential and curvilinear grooves combine to enhance wet traction and reduce the risk of hydroplaning. Internally, every HTR+ radial's twin steel belts are reinforced by JointLess Band (JLB) technology which uses spirally wound nylon reinforcement to provide long term integrity under high speed conditions while it reduces weight and helps provide more uniform ride quality.
The Lexus IS300 sport sedan features a modern presentation of a classic driveline design combining four wheel independent suspension with rearwheel drive. The front suspension consists of double-wishbone control arms, coil springs, gas-pressurized shock absorbers and a stabilizer bar; while the rear suspension features double-wishbone (with L-shaped aluminum upper arms), coil springs, gas-pressurized shock absorbers and a stabilizer bar. The Original Equipment IS300 shock absorbers are gas-pressurized to minimize fade, but felt as though they were tuned by the Lexus engineers to emphasize ride comfort while maintaining good handling.
On the road, the stock IS300-equipped with the Lexus IS300 gas-pressurized shock absorbers was praised for its good ride comfort, but criticized for lacking some of the damping ability that would increase the responsiveness and sporty feel of the vehicle.
On the track, the IS300's Original Equipment gas-pressurized shock absorbers allowed it to run good lap times, but compared to the KONI Sports on the other two cars, the O.E. gas-pressurized shock absorbers allowed faster movement of the vehicle's body during transition associated with acceleration, braking and cornering. The O.E. shock equipped car's motions (squatting during acceleration, diving during braking and leaning in the corners) weren't controlled as quickly as with the KONI Sport shocks. This resulted in slightly less ultimate cornering power and slower vehicle response during transitions. The car with the Original Equipment Lexus gas-pressurized shock absorbers turned in the slowest lap times of the three combinations tested.
Vehicles equipped with higher performance wheels and tires benefit from the additional suspension performance. Performance tire and wheel packages usually generate more traction that provides quicker response and often results in faster body movement when the vehicle is driven hard. The KONI Sport low pressure gas, twin tube shock absorbers are designed for the Lexus IS300 with higher than stock damping rates to help control this faster body movement during transitions.
As KONI Sports leave the factory, they are set in their "softest" setting. This is the setting that the KONI engineers have decided is the best match to a vehicle's stock suspension. And while the KONI Sports could be tuned a little "firmer" to provide a little more damping force to control the Eibach Pro-Kit Springs, we left them in their full "soft" setting to experience both "ends" of the KONI Sport shock absorber's adjustment range.
Another thing we noticed is that the new KONI Sport shock absorbers appeared to "break-in" a little shortly after installation. Initially they had a "harsher" feeling that quickly mellowed out over the first few days of driving (before we began our test).
On the road, the "soft" KONI Sport shock absorber-equipped Lexus IS300 was praised for providing more responsive handling combined with a ride comfort that was considered to be just firmer than the stock suspension.
On the track, the KONI Sport shock absorbers allowed the IS300 to run lap times which were about 3/10 of a second faster than the IS300 with the Original Equipment shock absorbers. The KONI Sport-equipped Lexus' vehicles increased damping controlled the vehicle's motions (squatting during acceleration, diving during braking and leaning in the corners) more precisely and completely. This resulted in a little more cornering power and faster vehicle response during transitions. The car with the "soft" KONI Sport shock absorber turned in the middle lap times of the three combinations tested.
Our last test car was also equipped with KONI Sport low pressure gas, twin tube shock absorbers, but this time they were adjusted to their firmest setting. The KONI Sports for the IS300 are externally adjustable which allows them to be adjusted from full soft to full firm (or any point in between) in a matter of minutes by simply using a KONI supplied knob to turn the adjusting rods protruding from the top of each shock absorber. While all cars don't allow this easy an access to their shock absorbers, KONI Sport shock absorbers provide for external adjustment wherever possible.
KONI's primary reason for providing shock absorber adjustment is to compensate for the wear experienced during tens of thousands of miles of driving. The additional benefit is that a driver can tune the shocks to their ride and handling preference, tune the shocks to complement the stiffness of the vehicle's sport springs or match the vehicle's intended use (highway, autocross or track).
On the road, the "firm" KONI Sport shock-equipped Lexus IS300 was praised for its ability to quickly transmit the driver's inputs and provide more responsive handling, but criticized for its stiff and "jiggly" ride quality. Expansion joints, tar strips and potholes were all much more noticeable than with the KONI Sports in the "softest" setting or the O.E. shocks. Probably only the most zealous driving enthusiasts would want to run new KONI Sport shock absorbers on their firmest setting all of the time.
On the track, the "firm" KONI Sport shock absorber added more "sport" to the IS300 sport sedan's theme. Body roll was further slowed allowing even faster speeds through the slalom portion of our track, and driver input was more quickly rewarded with changes in the vehicle's direction during transitions. The "firm" KONI Sport shock absorber-equipped Lexus turned in the fastest laps of the day. It was an additional 4/10 of a second faster than the "soft" KONI Sport-equipped car and almost 7/10 of a second faster than the car with O.E. shock absorbers. This car was the easiest to drive at the limit and its tires showed the least wear at the end of the day.
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