Specialty Shocks
While nonadjustable stock replacement shocks do an adequate job of improving handling over worn-out original shocks, when it comes to high-performance applications, stock shocks are often found wanting. Starting with drag racing, this situation actually requires shocks for the front and rear that are often much softer than stock. For a typical street/strip car, you're looking for front shocks that allow easier front-end travel to establish a given rate of front-end rise to help weight transfer to the rear tires. Competition Engineering, Koni, QA1, and others offer adjustable low-pressure twin-tube shocks that can be fine-tuned to work with your particular requirements, which can actually change from track-to-track. This is why adjustability is so important.
Rear shocks are also important in this traction equation, and also offer a slightly longer extension to prevent bottoming out the shock when planting the tires, especially with suspensions with an excess of 100 percent antisquat when there is separation between the tire and the body at launch. The last thing you want is for the rear shock to bottom out, which will cause instantaneous tire spin. These shocks are usually single-adjustables, although you can invest in specialty coilovers that are double-adjustable.
Drag-racing shocks are also referred to in a slightly different way than most other shocks. Often you will read references to rear shocks that are 50/50 or front shocks that are 90/10. Basically, these are references to the amount of force applied by the shock to resist movement. In the case of a 50/50 shock, the resistance is the same in both compression and rebound, while a 90/10 shock has nine times the resistance to compression than it does to rebound. The 90/10 is almost exclusively a front shock designed to extend (rebound) very easily and offer significant resistance to compression. This allows the front end of the car to rise very quickly and easily and then maintain that front-end rise throughout the entire run.
Better handling on your favorite twisty primary highway calls for a whole different set of shock requirements. Generally, this can start with a shock absorber that is shorter in length because the vehicle has been lowered, but also because the amount of suspension travel is greatly reduced. These shocks are almost the opposite of the drag shocks, since rebound damping is greatly increased given the increased spring rates that road-race-style cars generally employ. This is another area where adjustable shocks are an excellent investment. The key is to first choose a front and rear spring rate that works, and then begin tuning the ultimate handling and the relationship of the front to the rear with the shocks.
Up to a certain point, a stiffer shock, especially in rebound, is advantageous. But there also comes a point where a stiff shock will not allow the suspension to react to ruts or tall bumps. This stiff rebound allows the tire to skip over the tops of a series of bumps such as a washboard asphalt exit ramp. When this happens, the tires physically lose contact with the road, which means you've just lost all traction. This is quickly followed by a possible spin. If you've ever driven a car with too-stiff shocks, you know this is an extremely disconcerting and evil situation. This is yet another reason why adjustable shocks are a good idea. Another situation that can affect this is when you change to significantly lighter-weight wheels and tires on an otherwise optimized shock package. Suddenly, the car is very skittish because of the reduced unsprung weight.
Conclusion
We've just touched on the high points of the complex, yet intriguing, world of shock absorbers. There are vast performance improvements to be gained with the right shocks for your application, and it's worth the effort to learn more about how shocks can make a big difference in the performance of your car. It's certainly better than four pogo sticks.