Street Performance & Racing Suspension Tech & Tips
The following information is a general discussion regarding shock and spring selection. It is intended to offer a technical base from which to design, redesign or trouble shoot suspension. These principles will offer insight for drag racing and street performance applications. Valving recommendations have to be very generalized and are only intended to provide an approximate baseline to start fine-tuning. Every car is different, no matter how much you think your car is like your buddy’s car. There will always be differences in geometry, weight, torque, horsepower and more. Selecting the best shock and spring combination is dependent on many variables. In some cases the recommendations made could be very close, but we are not striving for mediocrity...we want you to win!
How does your car ride?
The best place to start any fine-tuning process is literally by the seat of your pants. Drivers have to become aware of what the car is actually going through, be it on the track or the road. On the track, one has to know if it is hooking initially and then spins, or doesn’t hook at all initially and then hooks. For street performance, it is definitely by the seat of the pants. There is no reason a street car has to have a bad ride. If the car is uncomfortable, then something was missed or overlooked when it was set up originally. In both situations, you should begin by experimenting with different shock valvings and spring combinations until you find a set-up that works for the widest range of conditions. Once you have established a good overall baseline for the set-up, you can adjust for different conditions whether it is at the track or on the road.
What is the function of the shock and spring?
In order to make the correct adjustments you first need to consider what the function is of the shock and spring. The spring is there to insulate the chassis from forces applied through the wheel by irregularities in the track and road surface. A spring that is too stiff can allow the chassis to accept too much of the force. The chassis movements cause unwanted weight movement and geometry changes. In drag race applications, springs with too much rate typically cause the car to hit the tire and rebound off too quickly. Too much rate on street cars results in the ride quality and handling being less than desirable. Springs that are too soft allow the cars in both situations to become lazy, possibly allowing the cars’ suspension to bottom out, thereby causing a whole new set of problems, including safety. Both of the above examples are typically worst case scenarios. When the correct range of spring rate is established, the spring can then begin its job of controlling weight transfer. The spring determines how much weight is transferred to each wheel. When you have arrived at the proper baseline spring set-up, you should then try to fine-tune the hit on the tire or the ride quality with shocks and other adjustments.
Now let’s move on to the shocks’ role in chassis tuning. One of the functions of the shock is to control the kinetic energy stored in the spring as it compresses and rebounds. That is a very simple statement, but it is an important function of the shock. The other, and most important shock function in a racecar, is controlling when weight is transferred. The different valve settings offered in QA1 shocks allow you to get the seat of the pants feel you desire. In drag racing, you can tailor the weight transfer in the front end and the hit of the rear tire depending on specific track conditions. In street use, the shock will allow the fine-tuning of the ride quality by setting the valving to what is needed to control the spring selected for your application. This style of valving offered by QA1 for street use is specific by type of vehicle. Each will be designed to offer superior control of the suspension.
Always check the clearance on all suspension arms, shocks and springs through the entire range of travel. This includes shock mounting locations and configurations. The extra clearance through the entire range of travel could mean the difference in being competitive or not, and whether or not the car handles and rides correctly. Never use the shock as a limiter.
The shock bearings should operate smoothly. Check them for wear and fit. QA1 PTFE lined bearings will offer smooth but firm operation. If metal-to-metal bearings are used, apply penetrating oil and then work in by hand for regular maintenance. Wipe the excess oil from the bearing when finished so that it does not collect dirt.
Check the entire suspension without springs and shocks for binding. If the suspension binds in the normal operating range, fix or replace the problem area. Binding and then freeing up in the typical suspension travel range will, in effect, be adding spring rate at times and not adding it at others, thereby making the chassis inconsistent. We hope that this information will get you on your way to quicker sets and/or a better ride from the start.