Suspension – The Hidden Key to Your Car’s Performance and Handling
It’s no surprise that good tires and rims are important components of a well-performing car, and they can really improve your ride’s looks, too. But you can’t get full value from an investment in high-performance tires and top-of-the-line custom rims without paying close attention to the less visible, key link in your car’s performance and handling: the suspension.
A car’s shock absorbers, struts, and other suspension components are all but invisible (unless your auto happens to be up on a lift). But even though out of sight, the suspension system has a critical influence on the most important factor in handling, which is friction between your tires and the road. To understand why the suspension is so important, let’s take a quick look at what it is and how it works.
Your car’s wheels are mounted solidly to the axles – the shafts on which they rotate. If the axles were mounted just as solidly to the rest of your car, you would experience a Princess-and-the-Pea type of ride every time you rolled down the road! The slightest bump would be transferred to the entire car and everything in it. This would not only be mighty uncomfortably, it would also eventually knock your car to pieces; the succession of thunderous impacts would strain every screw, bolt and other fastener to the breaking point.
To prevent this unfortunate fate, the suspension system intervenes between your axles and the rest of your car or truck. Accomplishing this involves a variety of moving parts which may include A-frames, trailing links, struts and sway bars, but the most basic components that affect the ride are springs and shock absorbers.
The exact design of springs depends on the age and size of the vehicle. They may be layered sets of flexible, flat steel bars known as “leaf springs,” (particularly common on the rear axles of older cars and trucks). Another common configuration is large coil springs – flexible steel bars formed in a circular coil that function much like any coil spring. They flex to a shorter or longer profile, depending on the weight and forces exerted on them (just as if you compressed one of those small coil springs from a ball-point pen between your fingers). The job of the springs is to support the weight of the vehicle, while also isolating the car and its occupants from the impact of bumps and potholes in the road surface.
Left to themselves, springs would, naturally, be springy. The effect when driving with springs alone would often be rhythmic up-and-down motions while driving on uneven roads; this mechanical-bull movement would be capable of damaging your car – and would, in any case, make for a very unpleasant driving experience!
Enter the shock absorber. Working in concert with the springs, the shocks dampen that potentially catastrophic repetitive motion. There are a number of different shock absorber designs, but all are generally intended to provide two ends joined by a sliding piston. The piston travels through a cylinder filled with oil. (Some shocks have sections filled with compressed gas as well).
As the piston connected to one end of the shock slides into the cylinder attached to the other end, the device can become shorter or longer. Moving the shock’s piston rapidly through the oil requires substantial force, and different shocks require differing levels of force to compress and extend them. This varying level of force (and some shocks have settings to change the energy required) is sometimes referred to as the “ride” that a shock provides. Replacement shocks, for example, could be selected for their “soft” or “firm” ride, depending on the vehicle they were chosen for, the type of driving for which they are intended, and other factors.
The maximum range of a shock absorber’s length change as it is compressed and extended is known as the shock’s “travel.” If you replace the shock absorbers on your vehicle, you may discuss “ride” and “travel” with your shop mechanic, because the travel should be matched to the vehicle’s suspension system, and the ride will likely be based on your car and the type of driving you do.
Now let’s take a look at why the suspension is so important. Most drivers associate a vehicle’s suspension system with a smooth and comfortable ride. Your suspension does make that possible, but it actually has a much more important function – keeping your car under control. Turning the steering wheel deflects the front tires to the right or left, and, if all is well, the car follows. Putting your right foot down calls forth power from the engine, which, through the drive train, accelerates the driving rims and increases your speed – if all is well.
But what if all is not well? If your car has worn shocks or struts, or loose, bent or worn suspension hardware, solid contact between your tires and the rest of the world is no longer a sure thing. The most important job of your suspension system is to absorb the bumps and jolts that attack your tires and rims as you drive over terrain variations. Absorbing that energy not only keeps the car from taking it out on you, but also lets most of the car shift up and down while the tires themselves are pressed firmly to the roadway as consistently as possible.
The finest high-performance tires wrapped around the most spectacular after market wheels do you little good unless, second by second, the tread on those tires is in firm contact with the road surface. Everything about your car’s performance, from nimble steering in high-speed cornering to rapid acceleration as you send your engine’s horsepower to the ground, depends completely on how well your tires hold the road. That is the most important job your suspension does.
Any doubt you might have about the importance of high-quality suspension has likely been quickly erased if you have ever driven a car with worn shock absorbers on a rough road. The ride itself might be uncomfortably bumpy, but the real significance of the poorly performing suspension becomes apparent when cornering on that uneven surface. It is very common, under such circumstances, to feel the back end of the car actually skipping sideways!
The worn suspension system is allowing the rims to fly along without staying firmly in contact with the road, and the car’s inertia, freed by this lack of friction and control, is pulling the vehicle to the outside of the curve. In severe cases, poor suspension can allow the car to spin out of control, or drift uncontrollably into the oncoming lane or a roadside ditch.
The suspension system is one of the most highly engineered and finely designed components of the highest-performing race cars. Shouldn’t it receive serious consideration for your vehicle as well? Your car’s performance, acceleration and handling can only be as good as your suspension, so make sure you get the most from your investment in high quality custom wheels and tires with equally fine shocks, struts and other components. In a very real sense, your life is riding on it.