Double Adjustable Shocks


Shocks are just one of many suspension variables on a race car. Let's focus on the importance of the effects of shocks on the race cars performance.
A double adjustable shock allows compression (bump) and rebound (extension) to be adjusted separately. This shock is the top of the line and will allow the maximum performance to be squeezed from the given combination, provided the chassis tuner has properly adjusted the shocks.
The chassis tuner will need to have a shock that has a broad range of adjustments.I.E. a shock that will make a noticeable change in suspension characteristics when the shocks are adjusted. The double adjustable KONI shocks offer the benefit of seperate extention and compression control. As you sweep from left to right on the top shock adjustment you stiffen the way the shock pulls apart (extention). the bottom screw or knob controls the compression of the shock. Turning it clockwise is on full hard, counter clockwise is full soft.
Virtually every car will separate at the launch. The rear suspension system forces the chassis upward while pushing the axle housing down. This is typically the first movement for most drag cars. For this reason, the extension, or rebound control, of the shock is extremely critical.
The key elements to tuning the chassis are how quickly and with how much force the axle housing separates and drives the tires into the starting line. Starting lines that are bald, slick, or extremely hot will usually lack good traction. Therefore, a shock that has had the extension (rebound) softened will create more traction (greater separation).
As the tire wraps up, the axle is driven down, and the chassis pitch rotates, the sidewall of the tire is compressed. At some point, the torque from the engine will decrease or the chassis will reach maximum pitch rotation. When this occurs, the tires will start to return to their original form, perfectly round. This action can cause wheel hop or can "unhook" the tire.
Here is where the compression setting becomes critical. The compression valving can now be set stiffer to hold the tire down on the track.
This method of shock tuning is used by many of the most successful drag racers in the sport today.
An example of when a double adjustable shock can be used to enhance performance is when the starting line is less than ideal. The chassis tuner can soften up the rebound setting to apply the tires faster and with more force. The chassis tuner may also want to stiffen the compression (bump) setting to hold the tires on the track, thereby eliminating wheel slippage and also possible tire shake or wheel hop.
A general rule of thumb. Loose extension (rebound) and stiffer compression (bump) on a marginal to bad track.