There are a lot of ways you can improve the performance of your vehicle. While tuning for performance, many people think of upgrades to intake and exhaust, spark plugs and wires, turbo/supercharging and nitrous oxide injection, even internal engine modifications like camshaft upgrades, porting and polishing, forged components like pistons and rods. While these upgrades do improve engine performance, besides many of those upgrades being quite expensive, too much upgrading under the hood and not enough attention to other areas of tuning can actually lead to a poor handling, and in some cases, a dangerous vehicle.

In this article, I’m going to address another area of performance tuning: Suspension. Suspension is an often overlooked upgrade area. Upgrades to suspension can often net you great performance boosts while keeping the expense down.  When your car rolled off the assembly line, it was configured to provide a required level of safety, as much luxury as possible in most cases, and usually, for as inexpensively as the manufacturer could get by with. When modifying suspension, certain ideas must be met. An example being what is the purpose behind the change? Are you going to be road racing or 1/4 mile drag racing? The suspension setup for each of these purposes can be very different. Keep in mind that the purpose of suspension is to keep your tires in contact with the road as much as absolutely possible. The more contact your tires keep, the more traction you have and better safety and performance will result. The following is a good start to suspension modification possibilities, but please remember, it is not meant to be a complete guide to all the possibilities out there.

SPRINGS: Springs are what maintain the ride height of your vehicle and allow the wheels to move up and down without the body jolting up and down with them as would happen if the suspension were simply solid (like that of a suspensionless bicycle). Some springs are in the form of a large coil while others are long steel strips called leaves. Strut-style suspension incorporates a coil-over design, where the coil spring is actually placed directly over the strut. Shock type suspensions can be found with the shocks inside the coil, or outside in a different location, providing for a different leverage point. As mentioned earlier, when your vehicle was designed, the manufacturer designed it to function in most everyday driving applications as possible.  Potholes, rough roads, and the like all have to be handled while maintaining passenger comfort and smoothness. The idea is not to have the vehicle bottom out, high center, or become bouncy.  When we change spring configurations for road racing, it is usually for the purpose of reducing airflow under the vehicle by lowering the vehicle’s ride height, or increasing the stiffness of the spring to reduce give and drop over bumps. When you change the spring configurations for off-roading, it is usually to increase ground clearance, and to absorb more bounce and drop, to keep the wheels in contact with the ground.

SHOCKS/STRUTS: The purpose behind shocks and struts are to dampen the rebound of the springs. When you hit a bump or pothole in the road the spring will compress or expand accordingly. The shock or strut is designed to slow down the return of the spring to it’s “normal” state.  By slowing down the return rate, the vehicle is kept from bouncing, and the tire is better kept in contact with the road. Performance shocks and struts typically give stronger resistance to change. Performance shocks will give the driver more road feedback and will usually feel a little rougher in ride. Most shocks and struts should be replaced every 5 years or 50,000 miles.

ANTI-SWAY BARS: Anti-sway bars are designed to keep the vehicle level, or reduce what is called body roll. The anti-sway bar connects the left and right suspension together and reduces the amount one side can move without the other. When your vehicle corners, the weight shifts to the outside set of wheels, causing the suspension on that side to compress. Without anti-sway bars, the inside wheels will tend lift due to lack of weight over them in the corner. Anti-sway bars force the inside and outside suspension sets to work together, keeping the vehicles weight better centered, the body from rolling out, and thus, the tires in better contact with the road. Anti-sway bars will also affect over-steer and under-steer characteristics. Over-steering is where the vehicle steering and front wheel traction is better than rear wheel traction, so a hard corner will cause the rear wheels to slip, skidding sideways before steering is lost. Under-steering is the opposite, where front wheel traction and steering are lost in a corner before the rear wheels. The stiffer the anti-sway bar, the sooner that set of tires will lose traction, versus losing steering. Most vehicles are equipped with at least a front anti-sway bar. Upgrades to anti-sway bars can include adjustability, allowing for softer or harder stiffness, depending on the road conditions expected.

BUSHINGS: Bushings are the material between two pieces of metal in your suspension. They cushion these components and protect them from grinding on each other while allowing them to move as intended. Most stock bushings are made from rubber and provide this cushioning well under normal driving conditions. Under hard driving conditions however (like high speed cornering), rubber bushings have a tendency to distort significantly and allow the components to work outside of their intended specifications. In some cases, the rubber bushings may tear or deform and not return to their proper shape, or even completely fail. An aftermarket upgrade to these rubber bushings are a polyurethane replacement type.  Polyurethane bushings are much harder, more resistant to distortion, and less likely to fail due to hard driving. And unlike rubber, they are less prone to aging and weathering.

STRUT TOWER BAR/BRACE: Up to this point, I’ve talked about upgrading existing components. The strut tower bar or brace (STB) is different in a couple of respects. First, most vehicles do not incorporate an STB stock. Secondly, you will only find a STB on a vehicle configure with struts, not shocks. When you open the hood of your vehicle, the strut tower is usually about center of the inside fender wheel, as the strut is typically located center (front-to back) of the wheel. This tower section has a hole in the center where the strut rod protrudes through. These tower areas support the entire weight of the vehicle for that corner. Under normal driving conditions, these towers provide ample support and rigidity. However, under harsh driving (cornering), these towers, and the overall unibody, may flex. More flex can be noted on some vehicles than others. This flexing, causes the suspension geometry to change and with that change, causes adverse steering characteristics. An STB is designed to tie the two strut towers together, keeping the towers from flexing during cornering, and much like an anti-sway bar, keeps the suspension better aligned.

The suspension is often an overlooked performance enhancement area. While engine modifications can provide substantial horse power gains, getting that power to the ground is the job of your suspension. What good will it do you to put out several thousand dollars to spice up your engine if you can’t make use of it? And the best part, most of the suspension enhancements in this article typically run a few hundred dollars or less each in materials, many can be done my you if you are mechanically inclined, and can improve track times without any engine modifications at all.

Filed under: Cars & Motorcycles

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