Guest Author - William Charles Vetter

Besides your car’s tires and seat it is the suspension system that keeps your butt from contacting solid surfaces. If you have ever ridden a skateboard or been on roller skates then you are painfully aware that with a solid system of mounting wheels to your car you would feel each and every ripple and pebble on the road, never mind potholes and uneven pavement blocks. Given the many developments of recent car design, it is beyond the scope of this article to go into suspension design and various systems. I would like to provide a simplified and brief general description of suspension systems with some tips on maintenance and keeping it performing like new. This information will be especially relevant to anyone who is trying to get a few more years out of a family car.

Believe it or not your comfort is not the major mission of your suspension, it’s a nice side benefit but without well designed and adjusted suspension your tires would have difficulty maintaining consistent contact with the road, seriously hampering your ability to maintain control in varying conditions. Your car has a dynamic suspension system that moves as it hits dips, bumps and forces such as cornering, braking and acceleration. Your suspension resists, slows, controls and to a certain extent counters all of these forces with a variety of mechanical interfaces. A Basic suspension system consists of a spring to hold up the weight of the car, pivoting arms that allow up and down movement from bumps and dips and oil filled shock absorbers to damp or slow the up and also the down movement of your wheels so that your car doesn’t bounce up and down after hitting a bump like a 4 ton basket ball.

The suspension system under your car is designed to keep your tires at an optimum angle to the roads surface to maximize traction, steering control, braking and acceleration as your car goes up and down with the road. In order to work at its best your suspension needs to be properly adjusted having this adjustment checked or readjusted is known as a wheel alignment. This system has a serious of rubber or urethane bushings at several component interfaces. If you occasionally hit curbs or large potholes your suspension will eventually exceed or fall out of proper alignment. Heat, cold and age will eventually harden and destroy the bushings. The four basic alignment adjustments are toe in/out, caster, camber and ride height. Toe in/out is the direction that your tires point in, caster is the steering axis line, camber is the lean angle of your tires with respect to the road surface and ride height is just that the height of your car’s chassis from the road.

Suspension problems: If your car drives like a boat in the waves or continues going up and down several times every time you hit a bump or a dip making you feel sea sick, then you are in need of new shock absorbers. Many cars have complex shock absorber mounts and this replacement may require special tools especially in the case of McPherson struts. If your car wanders around and takes an inordinate amount of concentration or steering wheel movement to keep it going straight then you may have worn bushings and/or your tires may have too little toe in. Your tires are normally set to point in just a little bit, sort of like walking “pigeon toed” which causes your car to be more stable going in a straight line, your car should go relatively straight on a flat road if you take your hands off of the steering wheel. If you have too much toe in, the outside edges of tread of your front tires will wear prematurely, toed out and the insides of your tires will wear. If your steering wheel is not level or it’s turned in one direction while your car goes straight, one tire is toed in too much or too little or it’s a tire inflation issue, check the air pressure first. Squeaking or creaking through dips is usually a sign of worn suspension bushings or joint lubrication. Other serious issues mimicking the above include worn ball joints, a broken shock shaft or kingpins on some older vehicles.

For safety’s sake always have your wheels aligned when you replace your tires or after a hard hit to a curb, rock or large pothole.