Who Needs Good Shocks?
"Good shocks are probably the second most significant handling change you can make to a stock car," says autocross and road racing national champion Jeff Altenburg, "tires with an alignment being the most significant.
"The only car I competed in without [upgraded] shocks was my 1989 Formula 350 Firebird," he continues. "I ran one event in it at Jacksonville on an undulating lot, and it was floating like crazy. I had a set of hydraulic Konis for the next event which was the Sebring Pro Solo 1991, and the difference was night and day. I won the event and the Challenge."
While some limited-production performance cars like the Miata Sport and Camaro 1LE come from the factory with high-quality shocks, most cars are sold with only commercial-grade pieces.
"The average enthusiast needs a good set of shocks because he is an enthusiast," explains Advance Design's Jay Morris. "A difference in handling and performance will neither be discovered or cared about by a non-enthusiast, so why spend the money? This is the attitude (and usually correctly so) of the car manufacturers, so the average stock or replacement shock is engineered to be adequate, safe and inexpensive as priorities over performance.
"This begs the question of why can't a performance shock also be cheap? It is not so obvious. The primary reason is that a performance shock is both stiffer and simultaneously accurately stiffer. With the increased stiffness comes a requirement for less internal leakage, or bypass. For the non-enthusiast, internal leakage is softer and preferred.
"In an inexpensive shock, the advantageous internal leakage inherent in using cheaper parts (o-rings instead of actual piston wipers, for instance) is utilized as part of the softer damping characteristics desired in the non-enthusiast shock. This puts the base cost below any performance shock, because of the lower quality of parts reducing the need for accurate tolerances. An economist could probably work out an inverse exponential function to describe this, but let's just say that it costs a lot less."
Shocktek's Michael G. O'Callaghan further explains the problems encountered by most street cars: "Typically, when the shocks are at the end of their life cycle, the rod seal will fail (hopefully slowly) and the shock absorber fluid will leak out. The damping characteristics of these aged shocks are not good: the overall damping forces are much lower, the damping curves have changed and there may be air in the shock which may act like a spring. Bottom line: wheel hop, uncontrolled porpoising, excessive body roll. Very dangerous in a collision avoidance maneuver.
"A lot of the readers of Grassroots Motorsports might be changing the mission of a car, such as modifying the car to be more competitive in a weekend autocross, or installing stiffer springs, sways and shocks to make the car corner better on the street," he continues. "In this case, the idea of a 'good' shock is that it is very important to match the components carefully when modifying the suspension of a car.
"Not only does the shock have to control wheel motion and body sway," he further explains, "but it has an important influence in controlling the dive and squat of the car during braking and acceleration. And, of course, making sure that the shocks remain functional is an important preventative maintenance function that car owners should perform on a regular basis."
Enthusiasts who lower their cars-whether for looks or performance-also need to consider upgraded shocks. In most cases, the stock shocks will not properly operate when teamed with short, stiffer springs. "OEM equipment is not meant to be operated below stock height," explains Truechoice's Greg Calhoun. "Another thing to keep in mind is that when you lower a vehicle, travel is taken away from the unit. If there is not enough travel, the unit has the chance of bottoming out."
Those enthusiasts involved in competition also need to think about their vehicle's equipment and the effect those parts have on their lap times. "A vehicle's performance is directly related to the performance capabilities of its equipment," explains Jim Arentz, design engineer for Penske Racing Shocks. "When put to extreme conditions of a racing environment, typically the stock equipment does not provide the optimum handling package. Most road cars are equipped to handle everyday driving over a variety of road conditions.
"Racers need dampers that will outperform the stock parts in extreme driving conditions where comfort and ride aren't always a priority. The handling becomes paramount as the control of subtle variations in chassis platform movement and bump recovery can amount to a large gain in lap speed."
Charles Cadieux of Dynamic Suspensions further explains. "A properly-sprung and damped vehicle has a better chance of maximizing the tire contact patch, therefore better grip, better turn in, braking, acceleration, etc."
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Are My Shocks Shot?
So, how do you know when it's time for new shocks? Even if your car came with better-than-average shocks, they may be at the end of their lifespan.
"Generally when your shocks are shot, you will feel a lack of control or crispness in the suspension," says JRZ's Lex Carson. "The car may begin to bounce or float when you go over bumps or uneven pavement changes."
"First, the car will feel different on the track or on the road," continues Michael O'Callahan. "It might be different steering characteristics, different behavior over bumps or any other anomaly. Next, visually check the shocks for leaks. And finally, if you're still stumped, you can always have the shocks dynoed."
Note than sometimes you may have a spring problem and not a shock problem. "Spring problems tend to be persistent and consistent, shock problems tend to usually occur only in transitions," explains Jay Morris. "Theoretically, if you have a problem in the middle of a corner (shocks in low-influence mode) it will be springs. Virtually any other time can be shocks or springs."
Sometimes you'll need to take the shocks off the car and inspect them to determine if you have a problem. "A shock problem is easily detected usually by hand-compressing a damper off the car and comparing to another damper that seems to be working correctly," explains Penske's Jim Arentz. "The feel of the damper as it's compressed, the speed at which the shaft returns to an extended position, and the feel of the adjusters are easy hints at problem areas. For the best proof, a shock dynamometer usually can determine the source of a problem instantaneously, whether caused by system contamination, damaged parts, or an incorrectly-built damper."
Note than an on-track (or off-track) incident can also cause problems with your shocks. "If the car has been involved in an incident by hitting a wall, guardrail, or another car, then it is best to at least have the shocks looked at," explains Greg Calhoun of Truechoice. "Most times after a hit, the shock will need to be serviced depending on how heavy the hit was."
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