Step #3: Rear Shock Adjustment: When it comes to the back shock absorber, the idea is to shock the tire as hard as possible (track conditions permitting). Keep in mind that it's the shock that actually controls how much force or "hit" your applying to the slick. If the shock is too loose on the extension (rebound), then you might get way too much rear body separation. If the shock is too tight, then the car will flatten the tire excessively or simply cause the car to spin. Generally speaking, start soft on the rear and keep tightening up the valving until the car slows down.

Moving Up The Sophistication Ladder...

As the prices for shocks increase, so does the adjustment range. For example, AFCO shocks are available as single adjustable and double adjustable assemblies. A single adjustable shock allows adjustment of the rebound while the shock assembly is still mounted in the car.

This is the adjustment knob found on the Hal Corp Stocker Star. Once installed, the knob is accessible through the side of the spring.

A double adjustable shock allows adjustment of the compression valving and rebound valving. In an AFCO double adjustable, the compression is adjusted by adjusting the knob from 1 (softest) to 8 (stiffest). Due to the precision of the adjuster, only a 1/2 number change is necessary to make a noticeable change. The rebound adjuster is extremely sensitive to change. 1/4 turn will make a significant change in tuning the chassis. In the AFCO shock, there are 12 settings to choose from.

Internally, AFCO incorporates what they call "Velocity Sensitive Valving". According to AFCO, this valving package is extremely sensitive to the speed at which the shock piston is moving: "At the starting line, because of the intersection point, engine torque, gearing, tires, center of gravity relative to ground, the shocks will see the highest shaft or piston speeds. To control the suspension, the shock needs to be stiffer at the launch than down track. The AFCO Eliminator shocks with their new valving actually react more stiffly when needed at the launch yet stay softer for riding the track's irregularities down track. Also, this new valving system is extremely sensitive to chassis tuner input: Small changes in the valving will make a noticeable change in the performance of the chassis."

Typically, the Hal Corp Stocker Stars have an adjustment range of 12 clicks. The actual range works like this: six clicks clockwise equals 50/50 valving (approximately). The full stop counterclockwise (front shock baseline) has valving that's similar to a 90/10. Once you pass six clicks clockwise, the adjuster works primarily on extension (rebound). When the shock is past this point, the valving is quite stiff, and probably won't be needed on a drag car.