Suspension modifications car

The long, bumpy ride of our suspension series is drawing to a close.

In this, our final installment, we'll discuss some ways you can improve your car's handling ability through suspension modification. Then we'll close by taking a look back at where we've been, review some basic suspension principles, and set you free to go cruising down the road.

By now you should have a working understanding of automotive suspension systems. Clearly, engineers have a myriad of choices to make when designing a car's suspension. Just as clearly, those choices affect the quality and character of the car's ride. But there's one last area we haven't discussed: aftermarket modification.

First, a proviso. The average driver who commutes back and forth to the office every day may need to do nothing more than replace existing components to improve performance.

Think about it: two hundred-plus round trips to the office every year, multiplied by, say, five or ten years of commuting - things begin to wear and tear. Swapping out the existing components for OEM replacements can have a hugely positive effect on the car's handling ability. Shocks, springs, bushings - all these wear with time. If you're an average motorist with an average car who drives an average commute every day, consider replacing the worn components and going no further. This will save you time and money, and enhance your driving experience.

There are, however, those drivers who want or need better performance. Consider a soccer mom who pulls a trailer on the weekends. Or that young buck with an Acura who likes to challenge his buddies through the canyons.

What can you do to improve your car's suspension? What alterations can you make in your car's springs and shocks that will enhance its handling capabilities?

Another proviso: proceed with caution. As our Managing Editor likes to say, "It's much easier to screw up your suspension than make it better." Remember, well-trained engineers sometimes spend years tuning a car's suspension, balancing spring rate against shock stiffness. You can mess it up with one quick mod.

That being said, there are things you can do to improve your car's handling. Those same engineers often make design decisions based largely on cost. If your focus is less on the bottom line and more on the right-front strut that keeps bottoming out every time you hit a hard left turn, you can definitely make changes that will improve your ride.

Automotive engineers design passenger vehicles to appeal to a wide spectrum of drivers and perform competently under a variety of conditions. The suspension systems in the Honda Accord, Ford Taurus and Toyota Camry, for instance - like the other components in those cars - are intentionally designed to be as inoffensive as possible. They aim for the middle ground.

The manufacturers of these cars want to attract as many buyers as they can, to vie for the sales crown of "most popular passenger vehicle." Not best, mind you, just most popular. And, like that cheerleader back in high school whom everyone voted Most Popular until they really got to know her, at which point they couldn't stand her (she now lives in a one-room apartment with her three bratty children, one from each failed marriage), familiarity can sometimes breed contempt.

Taurus, Accord and Camry are designed to work moderately well across a broad range of performance parameters, something which may or may not match your individual requirements. This sort of democratic design-by-committee works well for the masses, but not for drivers with specific needs.

(Please don't write us defending Camry, Taurus and Accord. We like these cars - a lot, actually. We just use them to illustrate the performance tradeoffs auto manufacturers make when designing a bestseller.)

The point being, you may have specific needs. You may want to fly where others plod. A finely tuned suspension system can help you get there.

Let's a take a look at each component in the system and what you can do to improve its performance.

Springs

You may recall that in Part One we discussed spring rate. This is the amount of "give" or "stiffness" a spring has, measured in pounds per inch. As already mentioned, design engineers work across a broad spectrum of performance conditions. They paint on a large canvas.

But let's say someone is going to be pulling a fifth-wheel trailer. They have a Ford F250 pickup that "dips" too much in the back when the fifth-wheel is in its cradle. This may indicate the need for a stiffer suspension system.

Usually a buyer will know ahead of time about their towing needs and order the vehicle from the factory with a trailer-towing package. But let's assume this consumer came to the camping lifestyle late in life and now wants to retrofit their F250 for the task. What should he or she do?

First, beef up the rear springs. Replace the existing leaf springs with a set that offers a higher spring rate. This will create more resistance or "lift" on the back end, working against the weight of the fifth-wheel trailer. The new springs, because of their increased strength, will level off the vehicle and cause it to stand more upright on the road. In other words, the weight of the vehicle and the trailer will be more evenly distributed across all four wheels, making the truck handle and steer better (remember, as the tail end sinks the front will tend to rise, causing reduced steering control).

A word of caution here: UNLESS YOU HAVE THE NECESSARY TOOLS, DO NOT ATTEMPT TO CHANGE SPRINGS ON YOUR OWN.

Replacing springs requires a tool called a spring compressor. If you don't have one, don't do this procedure. Leave the job to the professionals. Springs - particularly coil springs - operate under thousands of pounds of pressure and tension. People have been seriously injured, even killed, trying to replace their own springs.

While you're talking to your mechanic, have him advise you on which springs to install. You don't necessarily want the stiffest springs available. If towing the fifth-wheel is a small part of what you'll be using the vehicle for - and for most people it is - then consider a medium-rate spring, something stiffer than the current springs on the vehicle, but not overly stiff. Avoid going too far the other way. Otherwise, you'll end up with a vehicle that rides like a brick sh__ - well, you know what we mean.

Some well-known aftermarket spring manufacturers include Eibach, Belltech, H&R, InTrax, Speedtech and Tokico.

Shocks

Let's go back to that Ford F250. Our camping aficionado has replaced the rear leaf springs with a stiffer set, and they work fine, but the truck dives excessively and recovers slowly when going over potholes or through dips. Our camper needs stiffer shocks.

Unlike springs, shock absorbers present a myriad of choices to the consumer. As you saw in Part Two of this series, there are almost as many shocks as there are cars. But in the case of our Ford F250, we can narrow our choices.

First, our camper can consider replacing the existing shocks with OEM replacements. If they are more they five years old, they have almost certainly lost peak performance. Or he could install gas shocks, which will be stiffer still. However, in this instance, we would suggest a more aggressive approach.

Air shocks afford the opportunity to adjust the stiffness of the ride on an "as needed" basis. When the fifth-wheel is on, pump 'em up. When it's not, deflate 'em.