A lot has changed in the way of setups for both dirt and asphalt racing over the past five to ten years. Dirt setups have become more like asphalt setups and asphalt setups have become, well, crazy. In today's racing world, we have available pre-built shocks with any number of combinations of disk design and valving and with some types of designs, the ability to adjust shock rates quickly at the racetrack.

So, it would seem that we have what we need to choose the exact rate of compression and rebound necessary for a particular set of conditions if we know a little about the affect of rates on the setup. This wide range of choices can either be an advantage, or the proverbial "enough rope to hang..." syndrome. The more we can learn, the better we can make decisions regarding shock selection.

More and more, racers are being educated in all aspects of chassis tuning and they want to know more about shock technology. Today's racer is much more willing to learn than at any time in the past. The more we know about each of these subjects, the less fear we have. It is what we don't know that we fear the most. Shocks scare a lot of racers. Hopefully we can ease your pain and make understanding how shocks affect the car a simple process.

The information we present here is intended to be a guide to help you understand the basic principles of shock technology and the art of track tuning with shocks. The exact rates for the shocks that you need for your car are dependant on how your car is constructed, set up, and driven, as well as factors such as load distribution and racetrack characteristics.

We would really like to give you the exact shock values that will make your car as fast as it can be, but that would be impossible due to the many variables. That is exactly why you must work with your particular car and try not to follow what others are doing. Each car is a little different than another and each driver has his/her own style of driving.

An important aspect of shock technology is that there is no computer program or chart that will tell you exactly which shock rates to run on your car. This is, and always has been, a trial and error process. Where we have tell-tale signs and computer software that point us in the right direction for the chassis setup, with shocks we don't. It is all driver feel and stopwatch feedback that tells us when we are making progress or going backwards.

Part one of this series dealt with the basic construction of the racing shock. We learned that the two strokes of the shock, rebound and compression, are looked at separately and perform functions related to different areas of track tuning. If we deal with rebound and compression separately, then we need to be able to tune each independently. There are also different designs of shock pistons including the Linear design and the Digressive design. Again, we are able to achieve varying results by utilizing all of the variables of shock design.

For most situations, we would use Split Valve shocks. Split valving means that we have different rates of resistance for rebound and compression because we need to tune each movement a little differently than the other. We can also rate the two movements differently for each corner of the car to further tune the setup.

If we want, we can buy (at a greater expense) shocks that have external adjustments for rebound or compression, or both (called double adjustable). That way, we can experiment with different shock rates without removing them from the car. Regardless of how we arrive at the different shock rates, we do need to know beforehand what we are looking for and how to get there.

Shock companies provide a system of numbers or letters to reference the rates of rebound and compression. Most of these companies try to provide a cross reference so their numbering system can be compared to the other systems used by competing shock brands. The ultimate match between shock brands is not exact because of differences in design of the valving and the fact that each company may rate its shocks at a different shaft speed.